bpo-31370: Remove support for threads-less builds (#3385)

* Remove Setup.config
* Always define WITH_THREAD for compatibility.

27 files changed, 38 insertions, 455 deletions

diff --git a/Modules/Setup.config.in b/Modules/Setup.config.in
deleted file mode 100644
index 6450528..0000000
--- a/Modules/Setup.config.in
+++ /dev/null
@@ -1,10 +0,0 @@
-# This file is transmogrified into Setup.config by config.status.
-
-# The purpose of this file is to conditionally enable certain modules
-# based on configure-time options.
-
-# Threading
-@USE_THREAD_MODULE@_thread _threadmodule.c
-
-# The rest of the modules previously listed in this file are built
-# by the setup.py script in Python 2.1 and later.
diff --git a/Modules/Setup.dist b/Modules/Setup.dist
index dd533ef..9c3e1be 100644
--- a/Modules/Setup.dist
+++ b/Modules/Setup.dist
@@ -123,6 +123,7 @@ atexit atexitmodule.c      # Register functions to be run at interpreter-shutdow
 _signal signalmodule.c
 _stat _stat.c			# stat.h interface
 time timemodule.c	# -lm # time operations and variables
+_thread _threadmodule.c         # low-level threading interface
 
 # access to ISO C locale support
 _locale _localemodule.c  # -lintl
@@ -216,8 +217,6 @@ _symtable symtablemodule.c
 
 # The crypt module is now disabled by default because it breaks builds
 # on many systems (where -lcrypt is needed), e.g. Linux (I believe).
-#
-# First, look at Setup.config; configure may have set this for you.
 
 #_crypt _cryptmodule.c # -lcrypt	# crypt(3); needs -lcrypt on some systems
 
@@ -308,8 +307,6 @@ _symtable symtablemodule.c
 # Curses support, requiring the System V version of curses, often
 # provided by the ncurses library.  e.g. on Linux, link with -lncurses
 # instead of -lcurses).
-#
-# First, look at Setup.config; configure may have set this for you.
 
 #_curses _cursesmodule.c -lcurses -ltermcap
 # Wrapper for the panel library that's part of ncurses and SYSV curses.
@@ -323,18 +320,9 @@ _symtable symtablemodule.c
 # implementation independent wrapper for these; dbm/dumb.py provides
 # similar functionality (but slower of course) implemented in Python.
 
-# The standard Unix dbm module has been moved to Setup.config so that
-# it will be compiled as a shared library by default.  Compiling it as
-# a built-in module causes conflicts with the pybsddb3 module since it
-# creates a static dependency on an out-of-date version of db.so.
-#
-# First, look at Setup.config; configure may have set this for you.
-
 #_dbm _dbmmodule.c 	# dbm(3) may require -lndbm or similar
 
 # Anthony Baxter's gdbm module.  GNU dbm(3) will require -lgdbm:
-#
-# First, look at Setup.config; configure may have set this for you.
 
 #_gdbm _gdbmmodule.c -I/usr/local/include -L/usr/local/lib -lgdbm
 
diff --git a/Modules/_blake2/blake2b_impl.c b/Modules/_blake2/blake2b_impl.c
index ec9e3c1..b1ae3e9 100644
--- a/Modules/_blake2/blake2b_impl.c
+++ b/Modules/_blake2/blake2b_impl.c
@@ -15,9 +15,7 @@
 
 #include "Python.h"
 #include "pystrhex.h"
-#ifdef WITH_THREAD
 #include "pythread.h"
-#endif
 
 #include "../hashlib.h"
 #include "blake2ns.h"
@@ -41,9 +39,7 @@ typedef struct {
     PyObject_HEAD
     blake2b_param    param;
     blake2b_state    state;
-#ifdef WITH_THREAD
     PyThread_type_lock lock;
-#endif
 } BLAKE2bObject;
 
 #include "clinic/blake2b_impl.c.h"
@@ -60,11 +56,9 @@ new_BLAKE2bObject(PyTypeObject *type)
 {
     BLAKE2bObject *self;
     self = (BLAKE2bObject *)type->tp_alloc(type, 0);
-#ifdef WITH_THREAD
     if (self != NULL) {
         self->lock = NULL;
     }
-#endif
     return self;
 }
 
@@ -292,7 +286,6 @@ _blake2b_blake2b_update(BLAKE2bObject *self, PyObject *obj)
 
     GET_BUFFER_VIEW_OR_ERROUT(obj, &buf);
 
-#ifdef WITH_THREAD
     if (self->lock == NULL && buf.len >= HASHLIB_GIL_MINSIZE)
         self->lock = PyThread_allocate_lock();
 
@@ -305,9 +298,6 @@ _blake2b_blake2b_update(BLAKE2bObject *self, PyObject *obj)
     } else {
         blake2b_update(&self->state, buf.buf, buf.len);
     }
-#else
-    blake2b_update(&self->state, buf.buf, buf.len);
-#endif /* !WITH_THREAD */
     PyBuffer_Release(&buf);
 
     Py_RETURN_NONE;
@@ -407,12 +397,10 @@ py_blake2b_dealloc(PyObject *self)
     /* Try not to leave state in memory. */
     secure_zero_memory(&obj->param, sizeof(obj->param));
     secure_zero_memory(&obj->state, sizeof(obj->state));
-#ifdef WITH_THREAD
     if (obj->lock) {
         PyThread_free_lock(obj->lock);
         obj->lock = NULL;
     }
-#endif
     PyObject_Del(self);
 }
 
diff --git a/Modules/_blake2/blake2s_impl.c b/Modules/_blake2/blake2s_impl.c
index 42257a2..3615a38 100644
--- a/Modules/_blake2/blake2s_impl.c
+++ b/Modules/_blake2/blake2s_impl.c
@@ -15,9 +15,7 @@
 
 #include "Python.h"
 #include "pystrhex.h"
-#ifdef WITH_THREAD
 #include "pythread.h"
-#endif
 
 #include "../hashlib.h"
 #include "blake2ns.h"
@@ -41,9 +39,7 @@ typedef struct {
     PyObject_HEAD
     blake2s_param    param;
     blake2s_state    state;
-#ifdef WITH_THREAD
     PyThread_type_lock lock;
-#endif
 } BLAKE2sObject;
 
 #include "clinic/blake2s_impl.c.h"
@@ -60,11 +56,9 @@ new_BLAKE2sObject(PyTypeObject *type)
 {
     BLAKE2sObject *self;
     self = (BLAKE2sObject *)type->tp_alloc(type, 0);
-#ifdef WITH_THREAD
     if (self != NULL) {
         self->lock = NULL;
     }
-#endif
     return self;
 }
 
@@ -292,7 +286,6 @@ _blake2s_blake2s_update(BLAKE2sObject *self, PyObject *obj)
 
     GET_BUFFER_VIEW_OR_ERROUT(obj, &buf);
 
-#ifdef WITH_THREAD
     if (self->lock == NULL && buf.len >= HASHLIB_GIL_MINSIZE)
         self->lock = PyThread_allocate_lock();
 
@@ -305,9 +298,6 @@ _blake2s_blake2s_update(BLAKE2sObject *self, PyObject *obj)
     } else {
         blake2s_update(&self->state, buf.buf, buf.len);
     }
-#else
-    blake2s_update(&self->state, buf.buf, buf.len);
-#endif /* !WITH_THREAD */
     PyBuffer_Release(&buf);
 
     Py_RETURN_NONE;
@@ -407,12 +397,10 @@ py_blake2s_dealloc(PyObject *self)
     /* Try not to leave state in memory. */
     secure_zero_memory(&obj->param, sizeof(obj->param));
     secure_zero_memory(&obj->state, sizeof(obj->state));
-#ifdef WITH_THREAD
     if (obj->lock) {
         PyThread_free_lock(obj->lock);
         obj->lock = NULL;
     }
-#endif
     PyObject_Del(self);
 }
 
diff --git a/Modules/_bz2module.c b/Modules/_bz2module.c
index 409522f..dba0e19 100644
--- a/Modules/_bz2module.c
+++ b/Modules/_bz2module.c
@@ -5,9 +5,7 @@
 #include "Python.h"
 #include "structmember.h"
 
-#ifdef WITH_THREAD
 #include "pythread.h"
-#endif
 
 #include <bzlib.h>
 #include <stdio.h>
@@ -23,7 +21,6 @@
 #endif  /* ! BZ_CONFIG_ERROR */
 
 
-#ifdef WITH_THREAD
 #define ACQUIRE_LOCK(obj) do { \
     if (!PyThread_acquire_lock((obj)->lock, 0)) { \
         Py_BEGIN_ALLOW_THREADS \
@@ -31,19 +28,13 @@
         Py_END_ALLOW_THREADS \
     } } while (0)
 #define RELEASE_LOCK(obj) PyThread_release_lock((obj)->lock)
-#else
-#define ACQUIRE_LOCK(obj)
-#define RELEASE_LOCK(obj)
-#endif
 
 
 typedef struct {
     PyObject_HEAD
     bz_stream bzs;
     int flushed;
-#ifdef WITH_THREAD
     PyThread_type_lock lock;
-#endif
 } BZ2Compressor;
 
 typedef struct {
@@ -59,9 +50,7 @@ typedef struct {
        separately. Conversion and looping is encapsulated in
        decompress_buf() */
     size_t bzs_avail_in_real;
-#ifdef WITH_THREAD
     PyThread_type_lock lock;
-#endif
 } BZ2Decompressor;
 
 static PyTypeObject BZ2Compressor_Type;
@@ -325,13 +314,11 @@ _bz2_BZ2Compressor___init___impl(BZ2Compressor *self, int compresslevel)
         return -1;
     }
 
-#ifdef WITH_THREAD
     self->lock = PyThread_allocate_lock();
     if (self->lock == NULL) {
         PyErr_SetString(PyExc_MemoryError, "Unable to allocate lock");
         return -1;
     }
-#endif
 
     self->bzs.opaque = NULL;
     self->bzs.bzalloc = BZ2_Malloc;
@@ -343,10 +330,8 @@ _bz2_BZ2Compressor___init___impl(BZ2Compressor *self, int compresslevel)
     return 0;
 
 error:
-#ifdef WITH_THREAD
     PyThread_free_lock(self->lock);
     self->lock = NULL;
-#endif
     return -1;
 }
 
@@ -354,10 +339,8 @@ static void
 BZ2Compressor_dealloc(BZ2Compressor *self)
 {
     BZ2_bzCompressEnd(&self->bzs);
-#ifdef WITH_THREAD
     if (self->lock != NULL)
         PyThread_free_lock(self->lock);
-#endif
     Py_TYPE(self)->tp_free((PyObject *)self);
 }
 
@@ -651,13 +634,11 @@ _bz2_BZ2Decompressor___init___impl(BZ2Decompressor *self)
 {
     int bzerror;
 
-#ifdef WITH_THREAD
     self->lock = PyThread_allocate_lock();
     if (self->lock == NULL) {
         PyErr_SetString(PyExc_MemoryError, "Unable to allocate lock");
         return -1;
     }
-#endif
 
     self->needs_input = 1;
     self->bzs_avail_in_real = 0;
@@ -675,10 +656,8 @@ _bz2_BZ2Decompressor___init___impl(BZ2Decompressor *self)
 
 error:
     Py_CLEAR(self->unused_data);
-#ifdef WITH_THREAD
     PyThread_free_lock(self->lock);
     self->lock = NULL;
-#endif
     return -1;
 }
 
@@ -689,10 +668,8 @@ BZ2Decompressor_dealloc(BZ2Decompressor *self)
         PyMem_Free(self->input_buffer);
     BZ2_bzDecompressEnd(&self->bzs);
     Py_CLEAR(self->unused_data);
-#ifdef WITH_THREAD
     if (self->lock != NULL)
         PyThread_free_lock(self->lock);
-#endif
     Py_TYPE(self)->tp_free((PyObject *)self);
 }
 
diff --git a/Modules/_ctypes/_ctypes.c b/Modules/_ctypes/_ctypes.c
index 0255f76..1942c63 100644
--- a/Modules/_ctypes/_ctypes.c
+++ b/Modules/_ctypes/_ctypes.c
@@ -5410,9 +5410,7 @@ PyInit__ctypes(void)
    ob_type is the metatype (the 'type'), defaults to PyType_Type,
    tp_base is the base type, defaults to 'object' aka PyBaseObject_Type.
 */
-#ifdef WITH_THREAD
     PyEval_InitThreads();
-#endif
     m = PyModule_Create(&_ctypesmodule);
     if (!m)
         return NULL;
diff --git a/Modules/_ctypes/callbacks.c b/Modules/_ctypes/callbacks.c
index a11ae04..d579291 100644
--- a/Modules/_ctypes/callbacks.c
+++ b/Modules/_ctypes/callbacks.c
@@ -137,9 +137,7 @@ static void _CallPythonObject(void *mem,
     Py_ssize_t nArgs;
     PyObject *error_object = NULL;
     int *space;
-#ifdef WITH_THREAD
     PyGILState_STATE state = PyGILState_Ensure();
-#endif
 
     nArgs = PySequence_Length(converters);
     /* Hm. What to return in case of error?
@@ -281,9 +279,7 @@ if (x == NULL) _PyTraceback_Add(what, "_ctypes/callbacks.c", __LINE__ - 1), PyEr
     Py_XDECREF(result);
   Done:
     Py_XDECREF(arglist);
-#ifdef WITH_THREAD
     PyGILState_Release(state);
-#endif
 }
 
 static void closure_fcn(ffi_cif *cif,
@@ -347,7 +343,7 @@ CThunkObject *_ctypes_alloc_callback(PyObject *callable,
     assert(CThunk_CheckExact((PyObject *)p));
 
     p->pcl_write = ffi_closure_alloc(sizeof(ffi_closure),
-									 &p->pcl_exec);
+                                                                         &p->pcl_exec);
     if (p->pcl_write == NULL) {
         PyErr_NoMemory();
         goto error;
@@ -397,8 +393,8 @@ CThunkObject *_ctypes_alloc_callback(PyObject *callable,
     result = ffi_prep_closure(p->pcl_write, &p->cif, closure_fcn, p);
 #else
     result = ffi_prep_closure_loc(p->pcl_write, &p->cif, closure_fcn,
-				  p,
-				  p->pcl_exec);
+                                  p,
+                                  p->pcl_exec);
 #endif
     if (result != FFI_OK) {
         PyErr_Format(PyExc_RuntimeError,
@@ -422,9 +418,7 @@ CThunkObject *_ctypes_alloc_callback(PyObject *callable,
 static void LoadPython(void)
 {
     if (!Py_IsInitialized()) {
-#ifdef WITH_THREAD
         PyEval_InitThreads();
-#endif
         Py_Initialize();
     }
 }
@@ -495,18 +489,12 @@ STDAPI DllGetClassObject(REFCLSID rclsid,
                          LPVOID *ppv)
 {
     long result;
-#ifdef WITH_THREAD
     PyGILState_STATE state;
-#endif
 
     LoadPython();
-#ifdef WITH_THREAD
     state = PyGILState_Ensure();
-#endif
     result = Call_GetClassObject(rclsid, riid, ppv);
-#ifdef WITH_THREAD
     PyGILState_Release(state);
-#endif
     return result;
 }
 
@@ -558,13 +546,9 @@ long Call_CanUnloadNow(void)
 STDAPI DllCanUnloadNow(void)
 {
     long result;
-#ifdef WITH_THREAD
     PyGILState_STATE state = PyGILState_Ensure();
-#endif
     result = Call_CanUnloadNow();
-#ifdef WITH_THREAD
     PyGILState_Release(state);
-#endif
     return result;
 }
 
diff --git a/Modules/_ctypes/callproc.c b/Modules/_ctypes/callproc.c
index be757ef..3a6ad86 100644
--- a/Modules/_ctypes/callproc.c
+++ b/Modules/_ctypes/callproc.c
@@ -745,9 +745,7 @@ static int _call_function_pointer(int flags,
                                   void *resmem,
                                   int argcount)
 {
-#ifdef WITH_THREAD
     PyThreadState *_save = NULL; /* For Py_BLOCK_THREADS and Py_UNBLOCK_THREADS */
-#endif
     PyObject *error_object = NULL;
     int *space;
     ffi_cif cif;
@@ -786,10 +784,8 @@ static int _call_function_pointer(int flags,
         if (error_object == NULL)
             return -1;
     }
-#ifdef WITH_THREAD
     if ((flags & FUNCFLAG_PYTHONAPI) == 0)
         Py_UNBLOCK_THREADS
-#endif
     if (flags & FUNCFLAG_USE_ERRNO) {
         int temp = space[0];
         space[0] = errno;
@@ -826,10 +822,8 @@ static int _call_function_pointer(int flags,
         space[0] = errno;
         errno = temp;
     }
-#ifdef WITH_THREAD
     if ((flags & FUNCFLAG_PYTHONAPI) == 0)
         Py_BLOCK_THREADS
-#endif
     Py_XDECREF(error_object);
 #ifdef MS_WIN32
 #ifndef DONT_USE_SEH
@@ -982,9 +976,7 @@ GetComError(HRESULT errcode, GUID *riid, IUnknown *pIunk)
     /* We absolutely have to release the GIL during COM method calls,
        otherwise we may get a deadlock!
     */
-#ifdef WITH_THREAD
     Py_BEGIN_ALLOW_THREADS
-#endif
 
     hr = pIunk->lpVtbl->QueryInterface(pIunk, &IID_ISupportErrorInfo, (void **)&psei);
     if (FAILED(hr))
@@ -1008,9 +1000,7 @@ GetComError(HRESULT errcode, GUID *riid, IUnknown *pIunk)
     pei->lpVtbl->Release(pei);
 
   failed:
-#ifdef WITH_THREAD
     Py_END_ALLOW_THREADS
-#endif
 
     progid = NULL;
     ProgIDFromCLSID(&guid, &progid);
diff --git a/Modules/_hashopenssl.c b/Modules/_hashopenssl.c
index 8ef8c54..01f1671 100644
--- a/Modules/_hashopenssl.c
+++ b/Modules/_hashopenssl.c
@@ -53,9 +53,7 @@ typedef struct {
     PyObject_HEAD
     PyObject            *name;  /* name of this hash algorithm */
     EVP_MD_CTX          *ctx;   /* OpenSSL message digest context */
-#ifdef WITH_THREAD
     PyThread_type_lock   lock;  /* OpenSSL context lock */
-#endif
 } EVPobject;
 
 
@@ -122,9 +120,7 @@ newEVPobject(PyObject *name)
     /* save the name for .name to return */
     Py_INCREF(name);
     retval->name = name;
-#ifdef WITH_THREAD
     retval->lock = NULL;
-#endif
 
     return retval;
 }
@@ -153,10 +149,8 @@ EVP_hash(EVPobject *self, const void *vp, Py_ssize_t len)
 static void
 EVP_dealloc(EVPobject *self)
 {
-#ifdef WITH_THREAD
     if (self->lock != NULL)
         PyThread_free_lock(self->lock);
-#endif
     EVP_MD_CTX_free(self->ctx);
     Py_XDECREF(self->name);
     PyObject_Del(self);
@@ -267,7 +261,6 @@ EVP_update(EVPobject *self, PyObject *args)
 
     GET_BUFFER_VIEW_OR_ERROUT(obj, &view);
 
-#ifdef WITH_THREAD
     if (self->lock == NULL && view.len >= HASHLIB_GIL_MINSIZE) {
         self->lock = PyThread_allocate_lock();
         /* fail? lock = NULL and we fail over to non-threaded code. */
@@ -282,9 +275,6 @@ EVP_update(EVPobject *self, PyObject *args)
     } else {
         EVP_hash(self, view.buf, view.len);
     }
-#else
-    EVP_hash(self, view.buf, view.len);
-#endif
 
     PyBuffer_Release(&view);
     Py_RETURN_NONE;
diff --git a/Modules/_io/bufferedio.c b/Modules/_io/bufferedio.c
index 189b1cd..ba0932c 100644
--- a/Modules/_io/bufferedio.c
+++ b/Modules/_io/bufferedio.c
@@ -230,10 +230,8 @@ typedef struct {
        isn't ready for writing. */
     Py_off_t write_end;
 
-#ifdef WITH_THREAD
     PyThread_type_lock lock;
     volatile unsigned long owner;
-#endif
 
     Py_ssize_t buffer_size;
     Py_ssize_t buffer_mask;
@@ -267,8 +265,6 @@ typedef struct {
 
 /* These macros protect the buffered object against concurrent operations. */
 
-#ifdef WITH_THREAD
-
 static int
 _enter_buffered_busy(buffered *self)
 {
@@ -315,11 +311,6 @@ _enter_buffered_busy(buffered *self)
         PyThread_release_lock(self->lock); \
     } while(0);
 
-#else
-#define ENTER_BUFFERED(self) 1
-#define LEAVE_BUFFERED(self)
-#endif
-
 #define CHECK_INITIALIZED(self) \
     if (self->ok <= 0) { \
         if (self->detached) { \
@@ -401,12 +392,10 @@ buffered_dealloc(buffered *self)
         PyMem_Free(self->buffer);
         self->buffer = NULL;
     }
-#ifdef WITH_THREAD
     if (self->lock) {
         PyThread_free_lock(self->lock);
         self->lock = NULL;
     }
-#endif
     Py_CLEAR(self->dict);
     Py_TYPE(self)->tp_free((PyObject *)self);
 }
@@ -753,7 +742,6 @@ _buffered_init(buffered *self)
         PyErr_NoMemory();
         return -1;
     }
-#ifdef WITH_THREAD
     if (self->lock)
         PyThread_free_lock(self->lock);
     self->lock = PyThread_allocate_lock();
@@ -762,7 +750,6 @@ _buffered_init(buffered *self)
         return -1;
     }
     self->owner = 0;
-#endif
     /* Find out whether buffer_size is a power of 2 */
     /* XXX is this optimization useful? */
     for (n = self->buffer_size - 1; n & 1; n >>= 1)
diff --git a/Modules/_lzmamodule.c b/Modules/_lzmamodule.c
index 26bfa0b..fd3bbb8 100644
--- a/Modules/_lzmamodule.c
+++ b/Modules/_lzmamodule.c
@@ -9,16 +9,13 @@
 
 #include "Python.h"
 #include "structmember.h"
-#ifdef WITH_THREAD
 #include "pythread.h"
-#endif
 
 #include <stdarg.h>
 #include <string.h>
 
 #include <lzma.h>
 
-#ifdef WITH_THREAD
 #define ACQUIRE_LOCK(obj) do { \
     if (!PyThread_acquire_lock((obj)->lock, 0)) { \
         Py_BEGIN_ALLOW_THREADS \
@@ -26,10 +23,6 @@
         Py_END_ALLOW_THREADS \
     } } while (0)
 #define RELEASE_LOCK(obj) PyThread_release_lock((obj)->lock)
-#else
-#define ACQUIRE_LOCK(obj)
-#define RELEASE_LOCK(obj)
-#endif
 
 
 /* Container formats: */
@@ -48,9 +41,7 @@ typedef struct {
     lzma_allocator alloc;
     lzma_stream lzs;
     int flushed;
-#ifdef WITH_THREAD
     PyThread_type_lock lock;
-#endif
 } Compressor;
 
 typedef struct {
@@ -63,9 +54,7 @@ typedef struct {
     char needs_input;
     uint8_t *input_buffer;
     size_t input_buffer_size;
-#ifdef WITH_THREAD
     PyThread_type_lock lock;
-#endif
 } Decompressor;
 
 /* LZMAError class object. */
@@ -757,13 +746,11 @@ Compressor_init(Compressor *self, PyObject *args, PyObject *kwargs)
     self->alloc.free = PyLzma_Free;
     self->lzs.allocator = &self->alloc;
 
-#ifdef WITH_THREAD
     self->lock = PyThread_allocate_lock();
     if (self->lock == NULL) {
         PyErr_SetString(PyExc_MemoryError, "Unable to allocate lock");
         return -1;
     }
-#endif
 
     self->flushed = 0;
     switch (format) {
@@ -790,10 +777,8 @@ Compressor_init(Compressor *self, PyObject *args, PyObject *kwargs)
             break;
     }
 
-#ifdef WITH_THREAD
     PyThread_free_lock(self->lock);
     self->lock = NULL;
-#endif
     return -1;
 }
 
@@ -801,10 +786,8 @@ static void
 Compressor_dealloc(Compressor *self)
 {
     lzma_end(&self->lzs);
-#ifdef WITH_THREAD
     if (self->lock != NULL)
         PyThread_free_lock(self->lock);
-#endif
     Py_TYPE(self)->tp_free((PyObject *)self);
 }
 
@@ -1180,13 +1163,11 @@ _lzma_LZMADecompressor___init___impl(Decompressor *self, int format,
     self->lzs.allocator = &self->alloc;
     self->lzs.next_in = NULL;
 
-#ifdef WITH_THREAD
     self->lock = PyThread_allocate_lock();
     if (self->lock == NULL) {
         PyErr_SetString(PyExc_MemoryError, "Unable to allocate lock");
         return -1;
     }
-#endif
 
     self->check = LZMA_CHECK_UNKNOWN;
     self->needs_input = 1;
@@ -1230,10 +1211,8 @@ _lzma_LZMADecompressor___init___impl(Decompressor *self, int format,
 
 error:
     Py_CLEAR(self->unused_data);
-#ifdef WITH_THREAD
     PyThread_free_lock(self->lock);
     self->lock = NULL;
-#endif
     return -1;
 }
 
@@ -1245,10 +1224,8 @@ Decompressor_dealloc(Decompressor *self)
 
     lzma_end(&self->lzs);
     Py_CLEAR(self->unused_data);
-#ifdef WITH_THREAD
     if (self->lock != NULL)
         PyThread_free_lock(self->lock);
-#endif
     Py_TYPE(self)->tp_free((PyObject *)self);
 }
 
diff --git a/Modules/_sha3/sha3module.c b/Modules/_sha3/sha3module.c
index 33b77b1..970ce16 100644
--- a/Modules/_sha3/sha3module.c
+++ b/Modules/_sha3/sha3module.c
@@ -139,9 +139,7 @@ class _sha3.shake_256 "SHA3object *" "&SHAKE256type"
 typedef struct {
     PyObject_HEAD
     SHA3_state hash_state;
-#ifdef WITH_THREAD
     PyThread_type_lock lock;
-#endif
 } SHA3object;
 
 static PyTypeObject SHA3_224type;
@@ -167,9 +165,7 @@ newSHA3object(PyTypeObject *type)
     if (newobj == NULL) {
         return NULL;
     }
-#ifdef WITH_THREAD
     newobj->lock = NULL;
-#endif
     return newobj;
 }
 
@@ -224,7 +220,6 @@ py_sha3_new_impl(PyTypeObject *type, PyObject *data)
 
     if (data) {
         GET_BUFFER_VIEW_OR_ERROR(data, &buf, goto error);
-#ifdef WITH_THREAD
         if (buf.len >= HASHLIB_GIL_MINSIZE) {
             /* invariant: New objects can't be accessed by other code yet,
              * thus it's safe to release the GIL without locking the object.
@@ -236,9 +231,6 @@ py_sha3_new_impl(PyTypeObject *type, PyObject *data)
         else {
             res = SHA3_process(&self->hash_state, buf.buf, buf.len * 8);
         }
-#else
-        res = SHA3_process(&self->hash_state, buf.buf, buf.len * 8);
-#endif
         if (res != SUCCESS) {
             PyErr_SetString(PyExc_RuntimeError,
                             "internal error in SHA3 Update()");
@@ -265,11 +257,9 @@ py_sha3_new_impl(PyTypeObject *type, PyObject *data)
 static void
 SHA3_dealloc(SHA3object *self)
 {
-#ifdef WITH_THREAD
     if (self->lock) {
         PyThread_free_lock(self->lock);
     }
-#endif
     PyObject_Del(self);
 }
 
@@ -373,7 +363,6 @@ _sha3_sha3_224_update(SHA3object *self, PyObject *obj)
     GET_BUFFER_VIEW_OR_ERROUT(obj, &buf);
 
     /* add new data, the function takes the length in bits not bytes */
-#ifdef WITH_THREAD
     if (self->lock == NULL && buf.len >= HASHLIB_GIL_MINSIZE) {
         self->lock = PyThread_allocate_lock();
     }
@@ -391,9 +380,6 @@ _sha3_sha3_224_update(SHA3object *self, PyObject *obj)
     else {
         res = SHA3_process(&self->hash_state, buf.buf, buf.len * 8);
     }
-#else
-    res = SHA3_process(&self->hash_state, buf.buf, buf.len * 8);
-#endif
 
     if (res != SUCCESS) {
         PyBuffer_Release(&buf);
diff --git a/Modules/_sqlite/connection.c b/Modules/_sqlite/connection.c
index e2ba758..f596bcf 100644
--- a/Modules/_sqlite/connection.c
+++ b/Modules/_sqlite/connection.c
@@ -170,9 +170,7 @@ int pysqlite_connection_init(pysqlite_Connection* self, PyObject* args, PyObject
     self->detect_types = detect_types;
     self->timeout = timeout;
     (void)sqlite3_busy_timeout(self->db, (int)(timeout*1000));
-#ifdef WITH_THREAD
     self->thread_ident = PyThread_get_thread_ident();
-#endif
     if (!check_same_thread && sqlite3_libversion_number() < 3003001) {
         PyErr_SetString(pysqlite_NotSupportedError, "shared connections not available");
         return -1;
@@ -592,11 +590,9 @@ void _pysqlite_func_callback(sqlite3_context* context, int argc, sqlite3_value**
     PyObject* py_retval = NULL;
     int ok;
 
-#ifdef WITH_THREAD
     PyGILState_STATE threadstate;
 
     threadstate = PyGILState_Ensure();
-#endif
 
     py_func = (PyObject*)sqlite3_user_data(context);
 
@@ -620,9 +616,7 @@ void _pysqlite_func_callback(sqlite3_context* context, int argc, sqlite3_value**
         _sqlite3_result_error(context, "user-defined function raised exception", -1);
     }
 
-#ifdef WITH_THREAD
     PyGILState_Release(threadstate);
-#endif
 }
 
 static void _pysqlite_step_callback(sqlite3_context *context, int argc, sqlite3_value** params)
@@ -633,11 +627,9 @@ static void _pysqlite_step_callback(sqlite3_context *context, int argc, sqlite3_
     PyObject** aggregate_instance;
     PyObject* stepmethod = NULL;
 
-#ifdef WITH_THREAD
     PyGILState_STATE threadstate;
 
     threadstate = PyGILState_Ensure();
-#endif
 
     aggregate_class = (PyObject*)sqlite3_user_data(context);
 
@@ -684,9 +676,7 @@ error:
     Py_XDECREF(stepmethod);
     Py_XDECREF(function_result);
 
-#ifdef WITH_THREAD
     PyGILState_Release(threadstate);
-#endif
 }
 
 void _pysqlite_final_callback(sqlite3_context* context)
@@ -698,11 +688,9 @@ void _pysqlite_final_callback(sqlite3_context* context)
     PyObject *exception, *value, *tb;
     int restore;
 
-#ifdef WITH_THREAD
     PyGILState_STATE threadstate;
 
     threadstate = PyGILState_Ensure();
-#endif
 
     aggregate_instance = (PyObject**)sqlite3_aggregate_context(context, sizeof(PyObject*));
     if (!*aggregate_instance) {
@@ -746,12 +734,7 @@ void _pysqlite_final_callback(sqlite3_context* context)
     }
 
 error:
-#ifdef WITH_THREAD
     PyGILState_Release(threadstate);
-#endif
-    /* explicit return to avoid a compilation error if WITH_THREAD
-       is not defined */
-    return;
 }
 
 static void _pysqlite_drop_unused_statement_references(pysqlite_Connection* self)
@@ -884,11 +867,9 @@ static int _authorizer_callback(void* user_arg, int action, const char* arg1, co
 {
     PyObject *ret;
     int rc;
-#ifdef WITH_THREAD
     PyGILState_STATE gilstate;
 
     gilstate = PyGILState_Ensure();
-#endif
 
     ret = PyObject_CallFunction((PyObject*)user_arg, "issss", action, arg1, arg2, dbname, access_attempt_source);
 
@@ -917,9 +898,7 @@ static int _authorizer_callback(void* user_arg, int action, const char* arg1, co
         Py_DECREF(ret);
     }
 
-#ifdef WITH_THREAD
     PyGILState_Release(gilstate);
-#endif
     return rc;
 }
 
@@ -927,11 +906,9 @@ static int _progress_handler(void* user_arg)
 {
     int rc;
     PyObject *ret;
-#ifdef WITH_THREAD
     PyGILState_STATE gilstate;
 
     gilstate = PyGILState_Ensure();
-#endif
     ret = _PyObject_CallNoArg((PyObject*)user_arg);
 
     if (!ret) {
@@ -948,9 +925,7 @@ static int _progress_handler(void* user_arg)
         Py_DECREF(ret);
     }
 
-#ifdef WITH_THREAD
     PyGILState_Release(gilstate);
-#endif
     return rc;
 }
 
@@ -959,11 +934,9 @@ static void _trace_callback(void* user_arg, const char* statement_string)
     PyObject *py_statement = NULL;
     PyObject *ret = NULL;
 
-#ifdef WITH_THREAD
     PyGILState_STATE gilstate;
 
     gilstate = PyGILState_Ensure();
-#endif
     py_statement = PyUnicode_DecodeUTF8(statement_string,
             strlen(statement_string), "replace");
     if (py_statement) {
@@ -981,9 +954,7 @@ static void _trace_callback(void* user_arg, const char* statement_string)
         }
     }
 
-#ifdef WITH_THREAD
     PyGILState_Release(gilstate);
-#endif
 }
 
 static PyObject* pysqlite_connection_set_authorizer(pysqlite_Connection* self, PyObject* args, PyObject* kwargs)
@@ -1120,7 +1091,6 @@ static PyObject* pysqlite_load_extension(pysqlite_Connection* self, PyObject* ar
 
 int pysqlite_check_thread(pysqlite_Connection* self)
 {
-#ifdef WITH_THREAD
     if (self->check_same_thread) {
         if (PyThread_get_thread_ident() != self->thread_ident) {
             PyErr_Format(pysqlite_ProgrammingError,
@@ -1131,7 +1101,6 @@ int pysqlite_check_thread(pysqlite_Connection* self)
         }
 
     }
-#endif
     return 1;
 }
 
@@ -1365,15 +1334,11 @@ pysqlite_collation_callback(
     PyObject* callback = (PyObject*)context;
     PyObject* string1 = 0;
     PyObject* string2 = 0;
-#ifdef WITH_THREAD
     PyGILState_STATE gilstate;
-#endif
     PyObject* retval = NULL;
     long longval;
     int result = 0;
-#ifdef WITH_THREAD
     gilstate = PyGILState_Ensure();
-#endif
 
     if (PyErr_Occurred()) {
         goto finally;
@@ -1409,9 +1374,7 @@ finally:
     Py_XDECREF(string1);
     Py_XDECREF(string2);
     Py_XDECREF(retval);
-#ifdef WITH_THREAD
     PyGILState_Release(gilstate);
-#endif
     return result;
 }
 
diff --git a/Modules/_sqlite/module.c b/Modules/_sqlite/module.c
index 59406e1..5f8aaf9 100644
--- a/Modules/_sqlite/module.c
+++ b/Modules/_sqlite/module.c
@@ -478,9 +478,7 @@ PyMODINIT_FUNC PyInit__sqlite3(void)
      * threads have already been initialized.
      *  (see pybsddb-users mailing list post on 2002-08-07)
      */
-#ifdef WITH_THREAD
     PyEval_InitThreads();
-#endif
 
 error:
     if (PyErr_Occurred())
diff --git a/Modules/_ssl.c b/Modules/_ssl.c
index 2fa6bd2..b8509ac 100644
--- a/Modules/_ssl.c
+++ b/Modules/_ssl.c
@@ -18,7 +18,6 @@
 
 #include "Python.h"
 
-#ifdef WITH_THREAD
 #include "pythread.h"
 
 /* Redefined below for Windows debug builds after important #includes */
@@ -35,17 +34,6 @@
 #define PySSL_UNBLOCK_THREADS   PySSL_BEGIN_ALLOW_THREADS_S(_save);
 #define PySSL_END_ALLOW_THREADS PySSL_END_ALLOW_THREADS_S(_save); }
 
-#else   /* no WITH_THREAD */
-
-#define PySSL_BEGIN_ALLOW_THREADS_S(save)
-#define PySSL_END_ALLOW_THREADS_S(save)
-#define PySSL_BEGIN_ALLOW_THREADS
-#define PySSL_BLOCK_THREADS
-#define PySSL_UNBLOCK_THREADS
-#define PySSL_END_ALLOW_THREADS
-
-#endif
-
 /* Include symbols from _socket module */
 #include "socketmodule.h"
 
@@ -171,9 +159,7 @@ static void _PySSLFixErrno(void) {
 #define OPENSSL_NO_SSL2
 #endif
 #else /* OpenSSL < 1.1.0 */
-#if defined(WITH_THREAD)
 #define HAVE_OPENSSL_CRYPTO_LOCK
-#endif
 
 #define TLS_method SSLv23_method
 #define TLS_client_method SSLv23_client_method
@@ -285,15 +271,11 @@ enum py_ssl_version {
     PY_SSL_VERSION_TLS_SERVER,
 };
 
-#ifdef WITH_THREAD
-
 /* serves as a flag to see whether we've initialized the SSL thread support. */
 /* 0 means no, greater than 0 means yes */
 
 static unsigned int _ssl_locks_count = 0;
 
-#endif /* def WITH_THREAD */
-
 /* SSL socket object */
 
 #define X509_NAME_MAXLEN 256
@@ -3768,16 +3750,12 @@ _servername_callback(SSL *s, int *al, void *args)
     /* The high-level ssl.SSLSocket object */
     PyObject *ssl_socket;
     const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name);
-#ifdef WITH_THREAD
     PyGILState_STATE gstate = PyGILState_Ensure();
-#endif
 
     if (ssl_ctx->set_hostname == NULL) {
         /* remove race condition in this the call back while if removing the
          * callback is in progress */
-#ifdef WITH_THREAD
         PyGILState_Release(gstate);
-#endif
         return SSL_TLSEXT_ERR_OK;
     }
 
@@ -3846,18 +3824,14 @@ _servername_callback(SSL *s, int *al, void *args)
         Py_DECREF(result);
     }
 
-#ifdef WITH_THREAD
     PyGILState_Release(gstate);
-#endif
     return ret;
 
 error:
     Py_DECREF(ssl_socket);
     *al = SSL_AD_INTERNAL_ERROR;
     ret = SSL_TLSEXT_ERR_ALERT_FATAL;
-#ifdef WITH_THREAD
     PyGILState_Release(gstate);
-#endif
     return ret;
 }
 #endif
@@ -5117,7 +5091,7 @@ static int _setup_ssl_threads(void) {
     return 1;
 }
 
-#endif  /* HAVE_OPENSSL_CRYPTO_LOCK for WITH_THREAD && OpenSSL < 1.1.0 */
+#endif  /* HAVE_OPENSSL_CRYPTO_LOCK for OpenSSL < 1.1.0 */
 
 PyDoc_STRVAR(module_doc,
 "Implementation module for SSL socket operations.  See the socket module\n\
@@ -5193,7 +5167,6 @@ PyInit__ssl(void)
     SSL_library_init();
 #endif
 
-#ifdef WITH_THREAD
 #ifdef HAVE_OPENSSL_CRYPTO_LOCK
     /* note that this will start threading if not already started */
     if (!_setup_ssl_threads()) {
@@ -5203,7 +5176,6 @@ PyInit__ssl(void)
     /* OpenSSL 1.1.0 builtin thread support is enabled */
     _ssl_locks_count++;
 #endif
-#endif  /* WITH_THREAD */
 
     /* Add symbols to module dict */
     sslerror_type_slots[0].pfunc = PyExc_OSError;
diff --git a/Modules/_testcapimodule.c b/Modules/_testcapimodule.c
index 2952317..1a29621 100644
--- a/Modules/_testcapimodule.c
+++ b/Modules/_testcapimodule.c
@@ -22,9 +22,7 @@
 #include <sys/wait.h>           /* For W_STOPCODE */
 #endif
 
-#ifdef WITH_THREAD
 #include "pythread.h"
-#endif /* WITH_THREAD */
 static PyObject *TestError;     /* set to exception object in init */
 
 /* Raise TestError with test_name + ": " + msg, and return NULL. */
@@ -2229,8 +2227,6 @@ test_datetime_capi(PyObject *self, PyObject *args) {
 }
 
 
-#ifdef WITH_THREAD
-
 /* test_thread_state spawns a thread of its own, and that thread releases
  * `thread_done` when it's finished.  The driver code has to know when the
  * thread finishes, because the thread uses a PyObject (the callable) that
@@ -2348,7 +2344,6 @@ PyObject *pending_threadfunc(PyObject *self, PyObject *arg)
     }
     Py_RETURN_TRUE;
 }
-#endif
 
 /* Some tests of PyUnicode_FromFormat().  This needs more tests. */
 static PyObject *
@@ -3617,7 +3612,6 @@ PyDoc_STRVAR(docstring_with_signature_with_defaults,
 "and the parameters take defaults of varying types."
 );
 
-#ifdef WITH_THREAD
 typedef struct {
     PyThread_type_lock start_event;
     PyThread_type_lock exit_event;
@@ -3704,7 +3698,6 @@ exit:
         PyThread_free_lock(test_c_thread.exit_event);
     return res;
 }
-#endif   /* WITH_THREAD */
 
 static PyObject*
 test_raise_signal(PyObject* self, PyObject *args)
@@ -4420,10 +4413,8 @@ static PyMethodDef TestMethods[] = {
     {"unicode_encodedecimal",   unicode_encodedecimal,           METH_VARARGS},
     {"unicode_transformdecimaltoascii", unicode_transformdecimaltoascii, METH_VARARGS},
     {"unicode_legacy_string",   unicode_legacy_string,           METH_VARARGS},
-#ifdef WITH_THREAD
     {"_test_thread_state",      test_thread_state,               METH_VARARGS},
     {"_pending_threadfunc",     pending_threadfunc,              METH_VARARGS},
-#endif
 #ifdef HAVE_GETTIMEOFDAY
     {"profile_int",             profile_int,                     METH_NOARGS},
 #endif
@@ -4483,10 +4474,8 @@ static PyMethodDef TestMethods[] = {
         docstring_with_signature_with_defaults},
     {"raise_signal",
      (PyCFunction)test_raise_signal, METH_VARARGS},
-#ifdef WITH_THREAD
     {"call_in_temporary_c_thread", call_in_temporary_c_thread, METH_O,
      PyDoc_STR("set_error_class(error_class) -> None")},
-#endif
     {"pymarshal_write_long_to_file",
         pymarshal_write_long_to_file, METH_VARARGS},
     {"pymarshal_write_object_to_file",
diff --git a/Modules/_threadmodule.c b/Modules/_threadmodule.c
index da750c0..d58ebc3 100644
--- a/Modules/_threadmodule.c
+++ b/Modules/_threadmodule.c
@@ -4,13 +4,6 @@
 
 #include "Python.h"
 #include "structmember.h" /* offsetof */
-
-#ifndef WITH_THREAD
-#error "Error!  The rest of Python is not compiled with thread support."
-#error "Rerun configure, adding a --with-threads option."
-#error "Then run `make clean' followed by `make'."
-#endif
-
 #include "pythread.h"
 
 static PyObject *ThreadError;
diff --git a/Modules/_tkinter.c b/Modules/_tkinter.c
index 7ed2b02..91d3dd5 100644
--- a/Modules/_tkinter.c
+++ b/Modules/_tkinter.c
@@ -26,9 +26,7 @@ Copyright (C) 1994 Steen Lumholt.
 #include "Python.h"
 #include <ctype.h>
 
-#ifdef WITH_THREAD
 #include "pythread.h"
-#endif
 
 #ifdef MS_WINDOWS
 #include <windows.h>
@@ -161,8 +159,6 @@ _get_tcl_lib_path()
 }
 #endif /* MS_WINDOWS */
 
-#ifdef WITH_THREAD
-
 /* The threading situation is complicated.  Tcl is not thread-safe, except
    when configured with --enable-threads.
 
@@ -264,18 +260,6 @@ static PyThreadState *tcl_tstate = NULL;
         return 0; \
     }
 
-#else
-
-#define ENTER_TCL
-#define LEAVE_TCL
-#define ENTER_OVERLAP
-#define LEAVE_OVERLAP_TCL
-#define ENTER_PYTHON
-#define LEAVE_PYTHON
-#define CHECK_TCL_APPARTMENT
-
-#endif
-
 #ifndef FREECAST
 #define FREECAST (char *)
 #endif
@@ -340,7 +324,6 @@ Tkinter_Error(PyObject *v)
 
 static int Tkinter_busywaitinterval = 20;
 
-#ifdef WITH_THREAD
 #ifndef MS_WINDOWS
 
 /* Millisecond sleep() for Unix platforms. */
@@ -374,7 +357,6 @@ WaitForMainloop(TkappObject* self)
     PyErr_SetString(PyExc_RuntimeError, "main thread is not in main loop");
     return 0;
 }
-#endif /* WITH_THREAD */
 
 
 
@@ -652,13 +634,11 @@ Tkapp_New(const char *screenName, const char *className,
         return 0;
     }
 #endif
-#ifdef WITH_THREAD
     if (v->threaded && tcl_lock) {
         /* If Tcl is threaded, we don't need the lock. */
         PyThread_free_lock(tcl_lock);
         tcl_lock = NULL;
     }
-#endif
 
     v->OldBooleanType = Tcl_GetObjType("boolean");
     v->BooleanType = Tcl_GetObjType("booleanString");
@@ -790,7 +770,6 @@ Tkapp_New(const char *screenName, const char *className,
 }
 
 
-#ifdef WITH_THREAD
 static void
 Tkapp_ThreadSend(TkappObject *self, Tcl_Event *ev,
                  Tcl_Condition *cond, Tcl_Mutex *mutex)
@@ -803,7 +782,6 @@ Tkapp_ThreadSend(TkappObject *self, Tcl_Event *ev,
     Tcl_MutexUnlock(mutex);
     Py_END_ALLOW_THREADS
 }
-#endif
 
 
 /** Tcl Eval **/
@@ -1340,7 +1318,6 @@ FromObj(PyObject* tkapp, Tcl_Obj *value)
     return newPyTclObject(value);
 }
 
-#ifdef WITH_THREAD
 /* This mutex synchronizes inter-thread command calls. */
 TCL_DECLARE_MUTEX(call_mutex)
 
@@ -1353,7 +1330,6 @@ typedef struct Tkapp_CallEvent {
     PyObject **exc_type, **exc_value, **exc_tb;
     Tcl_Condition *done;
 } Tkapp_CallEvent;
-#endif
 
 void
 Tkapp_CallDeallocArgs(Tcl_Obj** objv, Tcl_Obj** objStore, int objc)
@@ -1444,7 +1420,6 @@ Tkapp_CallResult(TkappObject *self)
     return res;
 }
 
-#ifdef WITH_THREAD
 
 /* Tkapp_CallProc is the event procedure that is executed in the context of
    the Tcl interpreter thread. Initially, it holds the Tcl lock, and doesn't
@@ -1490,7 +1465,6 @@ done:
     return 1;
 }
 
-#endif
 
 /* This is the main entry point for calling a Tcl command.
    It supports three cases, with regard to threading:
@@ -1520,7 +1494,6 @@ Tkapp_Call(PyObject *selfptr, PyObject *args)
         if (PyTuple_Check(item))
             args = item;
     }
-#ifdef WITH_THREAD
     if (self->threaded && self->thread_id != Tcl_GetCurrentThread()) {
         /* We cannot call the command directly. Instead, we must
            marshal the parameters to the interpreter thread. */
@@ -1554,7 +1527,6 @@ Tkapp_Call(PyObject *selfptr, PyObject *args)
         Tcl_ConditionFinalize(&cond);
     }
     else
-#endif
     {
 
         objv = Tkapp_CallArgs(args, objStore, &objc);
@@ -1695,7 +1667,6 @@ _tkinter_tkapp_adderrinfo_impl(TkappObject *self, const char *msg)
 
 typedef PyObject* (*EventFunc)(PyObject*, PyObject *args, int flags);
 
-#ifdef WITH_THREAD
 TCL_DECLARE_MUTEX(var_mutex)
 
 typedef struct VarEvent {
@@ -1709,7 +1680,6 @@ typedef struct VarEvent {
     PyObject **exc_val;
     Tcl_Condition *cond;
 } VarEvent;
-#endif
 
 /*[python]
 
@@ -1765,7 +1735,6 @@ varname_converter(PyObject *in, void *_out)
     return 0;
 }
 
-#ifdef WITH_THREAD
 
 static void
 var_perform(VarEvent *ev)
@@ -1794,12 +1763,10 @@ var_proc(VarEvent* ev, int flags)
     return 1;
 }
 
-#endif
 
 static PyObject*
 var_invoke(EventFunc func, PyObject *selfptr, PyObject *args, int flags)
 {
-#ifdef WITH_THREAD
     TkappObject *self = (TkappObject*)selfptr;
     if (self->threaded && self->thread_id != Tcl_GetCurrentThread()) {
         VarEvent *ev;
@@ -1836,7 +1803,6 @@ var_invoke(EventFunc func, PyObject *selfptr, PyObject *args, int flags)
         }
         return res;
     }
-#endif
     /* Tcl is not threaded, or this is the interpreter thread. */
     return func(selfptr, args, flags);
 }
@@ -2455,7 +2421,6 @@ PythonCmdDelete(ClientData clientData)
 
 
 
-#ifdef WITH_THREAD
 TCL_DECLARE_MUTEX(command_mutex)
 
 typedef struct CommandEvent{
@@ -2482,7 +2447,6 @@ Tkapp_CommandProc(CommandEvent *ev, int flags)
     Tcl_MutexUnlock(&command_mutex);
     return 1;
 }
-#endif
 
 /*[clinic input]
 _tkinter.tkapp.createcommand
@@ -2507,11 +2471,9 @@ _tkinter_tkapp_createcommand_impl(TkappObject *self, const char *name,
         return NULL;
     }
 
-#ifdef WITH_THREAD
     if (self->threaded && self->thread_id != Tcl_GetCurrentThread() &&
         !WaitForMainloop(self))
         return NULL;
-#endif
 
     data = PyMem_NEW(PythonCmd_ClientData, 1);
     if (!data)
@@ -2520,7 +2482,6 @@ _tkinter_tkapp_createcommand_impl(TkappObject *self, const char *name,
     Py_INCREF(func);
     data->self = (PyObject *) self;
     data->func = func;
-#ifdef WITH_THREAD
     if (self->threaded && self->thread_id != Tcl_GetCurrentThread()) {
         Tcl_Condition cond = NULL;
         CommandEvent *ev = (CommandEvent*)attemptckalloc(sizeof(CommandEvent));
@@ -2540,7 +2501,6 @@ _tkinter_tkapp_createcommand_impl(TkappObject *self, const char *name,
         Tcl_ConditionFinalize(&cond);
     }
     else
-#endif
     {
         ENTER_TCL
         err = Tcl_CreateCommand(
@@ -2575,7 +2535,6 @@ _tkinter_tkapp_deletecommand_impl(TkappObject *self, const char *name)
 
     CHECK_STRING_LENGTH(name);
 
-#ifdef WITH_THREAD
     if (self->threaded && self->thread_id != Tcl_GetCurrentThread()) {
         Tcl_Condition cond = NULL;
         CommandEvent *ev;
@@ -2595,7 +2554,6 @@ _tkinter_tkapp_deletecommand_impl(TkappObject *self, const char *name)
         Tcl_ConditionFinalize(&cond);
     }
     else
-#endif
     {
         ENTER_TCL
         err = Tcl_DeleteCommand(self->interp, name);
@@ -2898,9 +2856,7 @@ static PyObject *
 _tkinter_tkapp_mainloop_impl(TkappObject *self, int threshold)
 /*[clinic end generated code: output=0ba8eabbe57841b0 input=036bcdcf03d5eca0]*/
 {
-#ifdef WITH_THREAD
     PyThreadState *tstate = PyThreadState_Get();
-#endif
 
     CHECK_TCL_APPARTMENT;
     self->dispatching = 1;
@@ -2912,7 +2868,6 @@ _tkinter_tkapp_mainloop_impl(TkappObject *self, int threshold)
     {
         int result;
 
-#ifdef WITH_THREAD
         if (self->threaded) {
             /* Allow other Python threads to run. */
             ENTER_TCL
@@ -2930,9 +2885,6 @@ _tkinter_tkapp_mainloop_impl(TkappObject *self, int threshold)
                 Sleep(Tkinter_busywaitinterval);
             Py_END_ALLOW_THREADS
         }
-#else
-        result = Tcl_DoOneEvent(0);
-#endif
 
         if (PyErr_CheckSignals() != 0) {
             self->dispatching = 0;
@@ -3366,9 +3318,7 @@ MyFileProc(void *clientData, int mask)
 }
 #endif
 
-#ifdef WITH_THREAD
 static PyThreadState *event_tstate = NULL;
-#endif
 
 static int
 EventHook(void)
@@ -3376,9 +3326,7 @@ EventHook(void)
 #ifndef MS_WINDOWS
     int tfile;
 #endif
-#ifdef WITH_THREAD
     PyEval_RestoreThread(event_tstate);
-#endif
     stdin_ready = 0;
     errorInCmd = 0;
 #ifndef MS_WINDOWS
@@ -3393,7 +3341,6 @@ EventHook(void)
             break;
         }
 #endif
-#if defined(WITH_THREAD) || defined(MS_WINDOWS)
         Py_BEGIN_ALLOW_THREADS
         if(tcl_lock)PyThread_acquire_lock(tcl_lock, 1);
         tcl_tstate = event_tstate;
@@ -3405,9 +3352,6 @@ EventHook(void)
         if (result == 0)
             Sleep(Tkinter_busywaitinterval);
         Py_END_ALLOW_THREADS
-#else
-        result = Tcl_DoOneEvent(0);
-#endif
 
         if (result < 0)
             break;
@@ -3421,9 +3365,7 @@ EventHook(void)
         excInCmd = valInCmd = trbInCmd = NULL;
         PyErr_Print();
     }
-#ifdef WITH_THREAD
     PyEval_SaveThread();
-#endif
     return 0;
 }
 
@@ -3434,9 +3376,7 @@ EnableEventHook(void)
 {
 #ifdef WAIT_FOR_STDIN
     if (PyOS_InputHook == NULL) {
-#ifdef WITH_THREAD
         event_tstate = PyThreadState_Get();
-#endif
         PyOS_InputHook = EventHook;
     }
 #endif
@@ -3470,11 +3410,9 @@ PyInit__tkinter(void)
 {
   PyObject *m, *uexe, *cexe, *o;
 
-#ifdef WITH_THREAD
     tcl_lock = PyThread_allocate_lock();
     if (tcl_lock == NULL)
         return NULL;
-#endif
 
     m = PyModule_Create(&_tkintermodule);
     if (m == NULL)
diff --git a/Modules/_tracemalloc.c b/Modules/_tracemalloc.c
index 6966b86..feb32a0 100644
--- a/Modules/_tracemalloc.c
+++ b/Modules/_tracemalloc.c
@@ -51,7 +51,7 @@ static struct {
     int use_domain;
 } tracemalloc_config = {TRACEMALLOC_NOT_INITIALIZED, 0, 1, 0};
 
-#if defined(TRACE_RAW_MALLOC) && defined(WITH_THREAD)
+#if defined(TRACE_RAW_MALLOC)
 /* This lock is needed because tracemalloc_free() is called without
    the GIL held from PyMem_RawFree(). It cannot acquire the lock because it
    would introduce a deadlock in PyThreadState_DeleteCurrent(). */
@@ -164,7 +164,7 @@ tracemalloc_error(const char *format, ...)
 #endif
 
 
-#if defined(WITH_THREAD) && defined(TRACE_RAW_MALLOC)
+#if defined(TRACE_RAW_MALLOC)
 #define REENTRANT_THREADLOCAL
 
 /* If your OS does not provide native thread local storage, you can implement
@@ -212,8 +212,7 @@ set_reentrant(int reentrant)
 
 #else
 
-/* WITH_THREAD not defined: Python compiled without threads,
-   or TRACE_RAW_MALLOC not defined: variable protected by the GIL */
+/* TRACE_RAW_MALLOC not defined: variable protected by the GIL */
 static int tracemalloc_reentrant = 0;
 
 static int
@@ -455,11 +454,7 @@ traceback_get_frames(traceback_t *traceback)
     PyThreadState *tstate;
     PyFrameObject *pyframe;
 
-#ifdef WITH_THREAD
     tstate = PyGILState_GetThisThreadState();
-#else
-    tstate = PyThreadState_Get();
-#endif
     if (tstate == NULL) {
 #ifdef TRACE_DEBUG
         tracemalloc_error("failed to get the current thread state");
@@ -483,9 +478,7 @@ traceback_new(void)
     traceback_t *traceback;
     _Py_hashtable_entry_t *entry;
 
-#ifdef WITH_THREAD
     assert(PyGILState_Check());
-#endif
 
     /* get frames */
     traceback = tracemalloc_traceback;
@@ -848,9 +841,7 @@ tracemalloc_realloc_gil(void *ctx, void *ptr, size_t new_size)
 static void*
 tracemalloc_raw_alloc(int use_calloc, void *ctx, size_t nelem, size_t elsize)
 {
-#ifdef WITH_THREAD
     PyGILState_STATE gil_state;
-#endif
     void *ptr;
 
     if (get_reentrant()) {
@@ -866,13 +857,9 @@ tracemalloc_raw_alloc(int use_calloc, void *ctx, size_t nelem, size_t elsize)
        disabled. */
     set_reentrant(1);
 
-#ifdef WITH_THREAD
     gil_state = PyGILState_Ensure();
     ptr = tracemalloc_alloc(use_calloc, ctx, nelem, elsize);
     PyGILState_Release(gil_state);
-#else
-    ptr = tracemalloc_alloc(use_calloc, ctx, nelem, elsize);
-#endif
 
     set_reentrant(0);
     return ptr;
@@ -896,9 +883,7 @@ tracemalloc_raw_calloc(void *ctx, size_t nelem, size_t elsize)
 static void*
 tracemalloc_raw_realloc(void *ctx, void *ptr, size_t new_size)
 {
-#ifdef WITH_THREAD
     PyGILState_STATE gil_state;
-#endif
     void *ptr2;
 
     if (get_reentrant()) {
@@ -920,13 +905,9 @@ tracemalloc_raw_realloc(void *ctx, void *ptr, size_t new_size)
        not disabled. */
     set_reentrant(1);
 
-#ifdef WITH_THREAD
     gil_state = PyGILState_Ensure();
     ptr2 = tracemalloc_realloc(ctx, ptr, new_size);
     PyGILState_Release(gil_state);
-#else
-    ptr2 = tracemalloc_realloc(ctx, ptr, new_size);
-#endif
 
     set_reentrant(0);
     return ptr2;
@@ -962,10 +943,8 @@ traceback_free_traceback(_Py_hashtable_t *ht, _Py_hashtable_entry_t *entry,
 static void
 tracemalloc_clear_traces(void)
 {
-#ifdef WITH_THREAD
     /* The GIL protects variables againt concurrent access */
     assert(PyGILState_Check());
-#endif
 
     TABLES_LOCK();
     _Py_hashtable_clear(tracemalloc_traces);
@@ -1007,7 +986,7 @@ tracemalloc_init(void)
     }
 #endif
 
-#if defined(WITH_THREAD) && defined(TRACE_RAW_MALLOC)
+#if defined(TRACE_RAW_MALLOC)
     if (tables_lock == NULL) {
         tables_lock = PyThread_allocate_lock();
         if (tables_lock == NULL) {
@@ -1074,7 +1053,7 @@ tracemalloc_deinit(void)
     _Py_hashtable_destroy(tracemalloc_filenames);
     _Py_hashtable_destroy(tracemalloc_traces);
 
-#if defined(WITH_THREAD) && defined(TRACE_RAW_MALLOC)
+#if defined(TRACE_RAW_MALLOC)
     if (tables_lock != NULL) {
         PyThread_free_lock(tables_lock);
         tables_lock = NULL;
@@ -1723,9 +1702,7 @@ _PyTraceMalloc_Init(void)
     char *p;
     int nframe;
 
-#ifdef WITH_THREAD
     assert(PyGILState_Check());
-#endif
 
     if ((p = Py_GETENV("PYTHONTRACEMALLOC")) && *p != '\0') {
         char *endptr = p;
@@ -1778,9 +1755,7 @@ _PyTraceMalloc_Init(void)
 void
 _PyTraceMalloc_Fini(void)
 {
-#ifdef WITH_THREAD
     assert(PyGILState_Check());
-#endif
     tracemalloc_deinit();
 }
 
@@ -1789,26 +1764,20 @@ PyTraceMalloc_Track(unsigned int domain, uintptr_t ptr,
                     size_t size)
 {
     int res;
-#ifdef WITH_THREAD
     PyGILState_STATE gil_state;
-#endif
 
     if (!tracemalloc_config.tracing) {
         /* tracemalloc is not tracing: do nothing */
         return -2;
     }
 
-#ifdef WITH_THREAD
     gil_state = PyGILState_Ensure();
-#endif
 
     TABLES_LOCK();
     res = tracemalloc_add_trace(domain, ptr, size);
     TABLES_UNLOCK();
 
-#ifdef WITH_THREAD
     PyGILState_Release(gil_state);
-#endif
     return res;
 }
 
diff --git a/Modules/clinic/signalmodule.c.h b/Modules/clinic/signalmodule.c.h
index 4405d60..a4542cc 100644
--- a/Modules/clinic/signalmodule.c.h
+++ b/Modules/clinic/signalmodule.c.h
@@ -363,7 +363,7 @@ exit:
 
 #endif /* defined(HAVE_SIGTIMEDWAIT) */
 
-#if (defined(HAVE_PTHREAD_KILL) && defined(WITH_THREAD))
+#if defined(HAVE_PTHREAD_KILL)
 
 PyDoc_STRVAR(signal_pthread_kill__doc__,
 "pthread_kill($module, thread_id, signalnum, /)\n"
@@ -395,7 +395,7 @@ exit:
     return return_value;
 }
 
-#endif /* (defined(HAVE_PTHREAD_KILL) && defined(WITH_THREAD)) */
+#endif /* defined(HAVE_PTHREAD_KILL) */
 
 #ifndef SIGNAL_ALARM_METHODDEF
     #define SIGNAL_ALARM_METHODDEF
@@ -440,4 +440,4 @@ exit:
 #ifndef SIGNAL_PTHREAD_KILL_METHODDEF
     #define SIGNAL_PTHREAD_KILL_METHODDEF
 #endif /* !defined(SIGNAL_PTHREAD_KILL_METHODDEF) */
-/*[clinic end generated code: output=9403ef0c5d0f7ee0 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=3f6e6298696f1b75 input=a9049054013a1b77]*/
diff --git a/Modules/faulthandler.c b/Modules/faulthandler.c
index 39b70bc..4f3d971 100644
--- a/Modules/faulthandler.c
+++ b/Modules/faulthandler.c
@@ -17,9 +17,7 @@
 /* Allocate at maximum 100 MB of the stack to raise the stack overflow */
 #define STACK_OVERFLOW_MAX_SIZE (100*1024*1024)
 
-#ifdef WITH_THREAD
-#  define FAULTHANDLER_LATER
-#endif
+#define FAULTHANDLER_LATER
 
 #ifndef MS_WINDOWS
    /* register() is useless on Windows, because only SIGSEGV, SIGABRT and
@@ -228,7 +226,6 @@ faulthandler_dump_traceback(int fd, int all_threads,
 
     reentrant = 1;
 
-#ifdef WITH_THREAD
     /* SIGSEGV, SIGFPE, SIGABRT, SIGBUS and SIGILL are synchronous signals and
        are thus delivered to the thread that caused the fault. Get the Python
        thread state of the current thread.
@@ -238,9 +235,6 @@ faulthandler_dump_traceback(int fd, int all_threads,
        used. Read the thread local storage (TLS) instead: call
        PyGILState_GetThisThreadState(). */
     tstate = PyGILState_GetThisThreadState();
-#else
-    tstate = _PyThreadState_UncheckedGet();
-#endif
 
     if (all_threads) {
         (void)_Py_DumpTracebackThreads(fd, NULL, tstate);
@@ -977,7 +971,6 @@ faulthandler_sigsegv(PyObject *self, PyObject *args)
     Py_RETURN_NONE;
 }
 
-#ifdef WITH_THREAD
 static void
 faulthandler_fatal_error_thread(void *plock)
 {
@@ -1027,7 +1020,6 @@ faulthandler_fatal_error_c_thread(PyObject *self, PyObject *args)
 
     Py_RETURN_NONE;
 }
-#endif
 
 static PyObject *
 faulthandler_sigfpe(PyObject *self, PyObject *args)
@@ -1198,11 +1190,9 @@ static PyMethodDef module_methods[] = {
                "a SIGSEGV or SIGBUS signal depending on the platform")},
     {"_sigsegv", faulthandler_sigsegv, METH_VARARGS,
      PyDoc_STR("_sigsegv(release_gil=False): raise a SIGSEGV signal")},
-#ifdef WITH_THREAD
     {"_fatal_error_c_thread", faulthandler_fatal_error_c_thread, METH_NOARGS,
      PyDoc_STR("fatal_error_c_thread(): "
                "call Py_FatalError() in a new C thread.")},
-#endif
     {"_sigabrt", faulthandler_sigabrt, METH_NOARGS,
      PyDoc_STR("_sigabrt(): raise a SIGABRT signal")},
     {"_sigfpe", (PyCFunction)faulthandler_sigfpe, METH_NOARGS,
diff --git a/Modules/hashlib.h b/Modules/hashlib.h
index 530b6b1..978593e 100644
--- a/Modules/hashlib.h
+++ b/Modules/hashlib.h
@@ -39,24 +39,19 @@
  * an operation.
  */
 
-#ifdef WITH_THREAD
 #include "pythread.h"
-    #define ENTER_HASHLIB(obj) \
-        if ((obj)->lock) { \
-            if (!PyThread_acquire_lock((obj)->lock, 0)) { \
-                Py_BEGIN_ALLOW_THREADS \
-                PyThread_acquire_lock((obj)->lock, 1); \
-                Py_END_ALLOW_THREADS \
-            } \
-        }
-    #define LEAVE_HASHLIB(obj) \
-        if ((obj)->lock) { \
-            PyThread_release_lock((obj)->lock); \
-        }
-#else
-    #define ENTER_HASHLIB(obj)
-    #define LEAVE_HASHLIB(obj)
-#endif
+#define ENTER_HASHLIB(obj) \
+    if ((obj)->lock) { \
+        if (!PyThread_acquire_lock((obj)->lock, 0)) { \
+            Py_BEGIN_ALLOW_THREADS \
+            PyThread_acquire_lock((obj)->lock, 1); \
+            Py_END_ALLOW_THREADS \
+        } \
+    }
+#define LEAVE_HASHLIB(obj) \
+    if ((obj)->lock) { \
+        PyThread_release_lock((obj)->lock); \
+    }
 
 /* TODO(gps): We should probably make this a module or EVPobject attribute
  * to allow the user to optimize based on the platform they're using. */
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
index 7b57d8b..83135e5 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -359,7 +359,7 @@ static int win32_can_symlink = 0;
 
 /* Don't use the "_r" form if we don't need it (also, won't have a
    prototype for it, at least on Solaris -- maybe others as well?). */
-#if defined(HAVE_CTERMID_R) && defined(WITH_THREAD)
+#if defined(HAVE_CTERMID_R)
 #define USE_CTERMID_R
 #endif
 
@@ -454,14 +454,12 @@ PyOS_AfterFork_Parent(void)
 void
 PyOS_AfterFork_Child(void)
 {
-#ifdef WITH_THREAD
     /* PyThread_ReInitTLS() must be called early, to make sure that the TLS API
      * can be called safely. */
     PyThread_ReInitTLS();
     _PyGILState_Reinit();
     PyEval_ReInitThreads();
     _PyImport_ReInitLock();
-#endif
     _PySignal_AfterFork();
 
     run_at_forkers(PyThreadState_Get()->interp->after_forkers_child, 0);
diff --git a/Modules/readline.c b/Modules/readline.c
index f4a5e5a..951bc82 100644
--- a/Modules/readline.c
+++ b/Modules/readline.c
@@ -896,13 +896,9 @@ on_startup_hook()
 #endif
 {
     int r;
-#ifdef WITH_THREAD
     PyGILState_STATE gilstate = PyGILState_Ensure();
-#endif
     r = on_hook(readlinestate_global->startup_hook);
-#ifdef WITH_THREAD
     PyGILState_Release(gilstate);
-#endif
     return r;
 }
 
@@ -915,13 +911,9 @@ on_pre_input_hook()
 #endif
 {
     int r;
-#ifdef WITH_THREAD
     PyGILState_STATE gilstate = PyGILState_Ensure();
-#endif
     r = on_hook(readlinestate_global->pre_input_hook);
-#ifdef WITH_THREAD
     PyGILState_Release(gilstate);
-#endif
     return r;
 }
 #endif
@@ -936,9 +928,7 @@ on_completion_display_matches_hook(char **matches,
 {
     int i;
     PyObject *sub, *m=NULL, *s=NULL, *r=NULL;
-#ifdef WITH_THREAD
     PyGILState_STATE gilstate = PyGILState_Ensure();
-#endif
     m = PyList_New(num_matches);
     if (m == NULL)
         goto error;
@@ -967,9 +957,7 @@ on_completion_display_matches_hook(char **matches,
         Py_XDECREF(m);
         Py_XDECREF(r);
     }
-#ifdef WITH_THREAD
     PyGILState_Release(gilstate);
-#endif
 }
 
 #endif
@@ -1002,9 +990,7 @@ on_completion(const char *text, int state)
     char *result = NULL;
     if (readlinestate_global->completer != NULL) {
         PyObject *r = NULL, *t;
-#ifdef WITH_THREAD
         PyGILState_STATE gilstate = PyGILState_Ensure();
-#endif
         rl_attempted_completion_over = 1;
         t = decode(text);
         r = PyObject_CallFunction(readlinestate_global->completer, "Ni", t, state);
@@ -1026,9 +1012,7 @@ on_completion(const char *text, int state)
         PyErr_Clear();
         Py_XDECREF(r);
       done:
-#ifdef WITH_THREAD
         PyGILState_Release(gilstate);
-#endif
         return result;
     }
     return result;
@@ -1045,9 +1029,7 @@ flex_complete(const char *text, int start, int end)
     char saved;
     size_t start_size, end_size;
     wchar_t *s;
-#ifdef WITH_THREAD
     PyGILState_STATE gilstate = PyGILState_Ensure();
-#endif
 #ifdef HAVE_RL_COMPLETION_APPEND_CHARACTER
     rl_completion_append_character ='\0';
 #endif
@@ -1080,9 +1062,7 @@ done:
     readlinestate_global->begidx = PyLong_FromLong((long) start);
     readlinestate_global->endidx = PyLong_FromLong((long) end);
     result = completion_matches((char *)text, *on_completion);
-#ifdef WITH_THREAD
     PyGILState_Release(gilstate);
-#endif
     return result;
 }
 
@@ -1234,13 +1214,9 @@ readline_until_enter_or_signal(const char *prompt, int *signal)
         }
         else if (err == EINTR) {
             int s;
-#ifdef WITH_THREAD
             PyEval_RestoreThread(_PyOS_ReadlineTState);
-#endif
             s = PyErr_CheckSignals();
-#ifdef WITH_THREAD
             PyEval_SaveThread();
-#endif
             if (s < 0) {
                 rl_free_line_state();
 #if defined(RL_READLINE_VERSION) && RL_READLINE_VERSION >= 0x0700
diff --git a/Modules/signalmodule.c b/Modules/signalmodule.c
index 1c827ac..6633108 100644
--- a/Modules/signalmodule.c
+++ b/Modules/signalmodule.c
@@ -85,12 +85,10 @@ module signal
    thread.  XXX This is a hack.
 */
 
-#ifdef WITH_THREAD
 #include <sys/types.h> /* For pid_t */
 #include "pythread.h"
 static unsigned long main_thread;
 static pid_t main_pid;
-#endif
 
 static volatile struct {
     _Py_atomic_int tripped;
@@ -316,10 +314,8 @@ signal_handler(int sig_num)
 {
     int save_errno = errno;
 
-#ifdef WITH_THREAD
     /* See NOTES section above */
     if (getpid() == main_pid)
-#endif
     {
         trip_signal(sig_num);
     }
@@ -439,13 +435,11 @@ signal_signal_impl(PyObject *module, int signalnum, PyObject *handler)
             return NULL;
     }
 #endif
-#ifdef WITH_THREAD
     if (PyThread_get_thread_ident() != main_thread) {
         PyErr_SetString(PyExc_ValueError,
                         "signal only works in main thread");
         return NULL;
     }
-#endif
     if (signalnum < 1 || signalnum >= NSIG) {
         PyErr_SetString(PyExc_ValueError,
                         "signal number out of range");
@@ -571,13 +565,11 @@ signal_set_wakeup_fd(PyObject *self, PyObject *args)
         return NULL;
 #endif
 
-#ifdef WITH_THREAD
     if (PyThread_get_thread_ident() != main_thread) {
         PyErr_SetString(PyExc_ValueError,
                         "set_wakeup_fd only works in main thread");
         return NULL;
     }
-#endif
 
 #ifdef MS_WINDOWS
     is_socket = 0;
@@ -1104,7 +1096,7 @@ signal_sigtimedwait_impl(PyObject *module, PyObject *sigset,
 #endif   /* #ifdef HAVE_SIGTIMEDWAIT */
 
 
-#if defined(HAVE_PTHREAD_KILL) && defined(WITH_THREAD)
+#if defined(HAVE_PTHREAD_KILL)
 
 /*[clinic input]
 signal.pthread_kill
@@ -1137,7 +1129,7 @@ signal_pthread_kill_impl(PyObject *module, unsigned long thread_id,
     Py_RETURN_NONE;
 }
 
-#endif   /* #if defined(HAVE_PTHREAD_KILL) && defined(WITH_THREAD) */
+#endif   /* #if defined(HAVE_PTHREAD_KILL) */
 
 
 
@@ -1217,10 +1209,8 @@ PyInit__signal(void)
     PyObject *m, *d, *x;
     int i;
 
-#ifdef WITH_THREAD
     main_thread = PyThread_get_thread_ident();
     main_pid = getpid();
-#endif
 
     /* Create the module and add the functions */
     m = PyModule_Create(&signalmodule);
@@ -1523,10 +1513,8 @@ PyErr_CheckSignals(void)
     if (!_Py_atomic_load(&is_tripped))
         return 0;
 
-#ifdef WITH_THREAD
     if (PyThread_get_thread_ident() != main_thread)
         return 0;
-#endif
 
     /*
      * The is_tripped variable is meant to speed up the calls to
@@ -1599,10 +1587,8 @@ int
 PyOS_InterruptOccurred(void)
 {
     if (_Py_atomic_load_relaxed(&Handlers[SIGINT].tripped)) {
-#ifdef WITH_THREAD
         if (PyThread_get_thread_ident() != main_thread)
             return 0;
-#endif
         _Py_atomic_store_relaxed(&Handlers[SIGINT].tripped, 0);
         return 1;
     }
@@ -1628,20 +1614,14 @@ _PySignal_AfterFork(void)
      * in both processes if they came in just before the fork() but before
      * the interpreter had an opportunity to call the handlers.  issue9535. */
     _clear_pending_signals();
-#ifdef WITH_THREAD
     main_thread = PyThread_get_thread_ident();
     main_pid = getpid();
-#endif
 }
 
 int
 _PyOS_IsMainThread(void)
 {
-#ifdef WITH_THREAD
     return PyThread_get_thread_ident() == main_thread;
-#else
-    return 1;
-#endif
 }
 
 #ifdef MS_WINDOWS
diff --git a/Modules/socketmodule.c b/Modules/socketmodule.c
index a431e25..2c2f98d 100644
--- a/Modules/socketmodule.c
+++ b/Modules/socketmodule.c
@@ -163,10 +163,6 @@ if_indextoname(index) -- return the corresponding interface name\n\
 # include <sys/uio.h>
 #endif
 
-#if !defined(WITH_THREAD)
-# undef HAVE_GETHOSTBYNAME_R
-#endif
-
 #if defined(__ANDROID__) && __ANDROID_API__ < 23
 # undef HAVE_GETHOSTBYNAME_R
 #endif
@@ -185,8 +181,7 @@ if_indextoname(index) -- return the corresponding interface name\n\
 # endif
 #endif
 
-#if !defined(HAVE_GETHOSTBYNAME_R) && defined(WITH_THREAD) && \
-    !defined(MS_WINDOWS)
+#if !defined(HAVE_GETHOSTBYNAME_R) && !defined(MS_WINDOWS)
 # define USE_GETHOSTBYNAME_LOCK
 #endif
 
@@ -210,8 +205,7 @@ if_indextoname(index) -- return the corresponding interface name\n\
 
 http://cvsweb.netbsd.org/bsdweb.cgi/src/lib/libc/net/getaddrinfo.c.diff?r1=1.82&r2=1.83
  */
-#if defined(WITH_THREAD) && ( \
-    (defined(__APPLE__) && \
+#if ((defined(__APPLE__) && \
         MAC_OS_X_VERSION_MIN_REQUIRED < MAC_OS_X_VERSION_10_5) || \
     (defined(__FreeBSD__) && __FreeBSD_version+0 < 503000) || \
     (defined(__OpenBSD__) && OpenBSD+0 < 201311) || \
@@ -656,10 +650,8 @@ internal_select(PySocketSockObject *s, int writing, _PyTime_t interval,
     struct timeval tv, *tvp;
 #endif
 
-#ifdef WITH_THREAD
     /* must be called with the GIL held */
     assert(PyGILState_Check());
-#endif
 
     /* Error condition is for output only */
     assert(!(connect && !writing));
@@ -758,10 +750,8 @@ sock_call_ex(PySocketSockObject *s,
     int deadline_initialized = 0;
     int res;
 
-#ifdef WITH_THREAD
     /* sock_call() must be called with the GIL held. */
     assert(PyGILState_Check());
-#endif
 
     /* outer loop to retry select() when select() is interrupted by a signal
        or to retry select()+sock_func() on false positive (see above) */
diff --git a/Modules/zlibmodule.c b/Modules/zlibmodule.c
index 32dd817..cf086de 100644
--- a/Modules/zlibmodule.c
+++ b/Modules/zlibmodule.c
@@ -10,17 +10,12 @@
 #include "zlib.h"
 
 
-#ifdef WITH_THREAD
-    #include "pythread.h"
-    #define ENTER_ZLIB(obj) \
-        Py_BEGIN_ALLOW_THREADS; \
-        PyThread_acquire_lock((obj)->lock, 1); \
-        Py_END_ALLOW_THREADS;
-    #define LEAVE_ZLIB(obj) PyThread_release_lock((obj)->lock);
-#else
-    #define ENTER_ZLIB(obj)
-    #define LEAVE_ZLIB(obj)
-#endif
+#include "pythread.h"
+#define ENTER_ZLIB(obj) \
+    Py_BEGIN_ALLOW_THREADS; \
+    PyThread_acquire_lock((obj)->lock, 1); \
+    Py_END_ALLOW_THREADS;
+#define LEAVE_ZLIB(obj) PyThread_release_lock((obj)->lock);
 
 #if defined(ZLIB_VERNUM) && ZLIB_VERNUM >= 0x1221
 #  define AT_LEAST_ZLIB_1_2_2_1
@@ -51,9 +46,7 @@ typedef struct
     char eof;
     int is_initialised;
     PyObject *zdict;
-    #ifdef WITH_THREAD
-        PyThread_type_lock lock;
-    #endif
+    PyThread_type_lock lock;
 } compobject;
 
 static void
@@ -112,14 +105,12 @@ newcompobject(PyTypeObject *type)
         Py_DECREF(self);
         return NULL;
     }
-#ifdef WITH_THREAD
     self->lock = PyThread_allocate_lock();
     if (self->lock == NULL) {
         Py_DECREF(self);
         PyErr_SetString(PyExc_MemoryError, "Unable to allocate lock");
         return NULL;
     }
-#endif
     return self;
 }
 
@@ -615,9 +606,7 @@ zlib_decompressobj_impl(PyObject *module, int wbits, PyObject *zdict)
 static void
 Dealloc(compobject *self)
 {
-#ifdef WITH_THREAD
     PyThread_free_lock(self->lock);
-#endif
     Py_XDECREF(self->unused_data);
     Py_XDECREF(self->unconsumed_tail);
     Py_XDECREF(self->zdict);