Issue #9260: A finer-grained import lock.

Most of the import sequence now uses per-module locks rather than the
global import lock, eliminating well-known issues with threads and imports.

3 files changed, 30 insertions, 3 deletions

diff --git a/Lib/test/lock_tests.py b/Lib/test/lock_tests.py
index d88f364..bfbf44e 100644
--- a/Lib/test/lock_tests.py
+++ b/Lib/test/lock_tests.py
@@ -247,7 +247,6 @@ class RLockTests(BaseLockTests):
         # Cannot release an unacquired lock
         lock = self.locktype()
         self.assertRaises(RuntimeError, lock.release)
-        self.assertRaises(RuntimeError, lock._release_save)
         lock.acquire()
         lock.acquire()
         lock.release()
@@ -255,6 +254,17 @@ class RLockTests(BaseLockTests):
         lock.release()
         lock.release()
         self.assertRaises(RuntimeError, lock.release)
+
+    def test_release_save_unacquired(self):
+        # Cannot _release_save an unacquired lock
+        lock = self.locktype()
+        self.assertRaises(RuntimeError, lock._release_save)
+        lock.acquire()
+        lock.acquire()
+        lock.release()
+        lock.acquire()
+        lock.release()
+        lock.release()
         self.assertRaises(RuntimeError, lock._release_save)
 
     def test_different_thread(self):
diff --git a/Lib/test/test_pkg.py b/Lib/test/test_pkg.py
index 4d0eee8..355efe7 100644
--- a/Lib/test/test_pkg.py
+++ b/Lib/test/test_pkg.py
@@ -23,6 +23,8 @@ def cleanout(root):
 def fixdir(lst):
     if "__builtins__" in lst:
         lst.remove("__builtins__")
+    if "__initializing__" in lst:
+        lst.remove("__initializing__")
     return lst
 
 
diff --git a/Lib/test/test_threaded_import.py b/Lib/test/test_threaded_import.py
index bb72ad4..d67c904 100644
--- a/Lib/test/test_threaded_import.py
+++ b/Lib/test/test_threaded_import.py
@@ -12,7 +12,7 @@ import time
 import shutil
 import unittest
 from test.support import (
-    verbose, import_module, run_unittest, TESTFN, reap_threads)
+    verbose, import_module, run_unittest, TESTFN, reap_threads, forget)
 threading = import_module('threading')
 
 def task(N, done, done_tasks, errors):
@@ -187,7 +187,7 @@ class ThreadedImportTests(unittest.TestCase):
             contents = contents % {'delay': delay}
             with open(os.path.join(TESTFN, name + ".py"), "wb") as f:
                 f.write(contents.encode('utf-8'))
-            self.addCleanup(sys.modules.pop, name, None)
+            self.addCleanup(forget, name)
 
         results = []
         def import_ab():
@@ -204,6 +204,21 @@ class ThreadedImportTests(unittest.TestCase):
         t2.join()
         self.assertEqual(set(results), {'a', 'b'})
 
+    def test_side_effect_import(self):
+        code = """if 1:
+            import threading
+            def target():
+                import random
+            t = threading.Thread(target=target)
+            t.start()
+            t.join()"""
+        sys.path.insert(0, os.curdir)
+        self.addCleanup(sys.path.remove, os.curdir)
+        with open(TESTFN + ".py", "wb") as f:
+            f.write(code.encode('utf-8'))
+        self.addCleanup(forget, TESTFN)
+        __import__(TESTFN)
+
 
 @reap_threads
 def test_main():