Fix bug [57945b574a6df0332efc4ac96b066f7c347b28f7|57945b574a]: lock in forking process under heavy multithreading. Thanks to Joe Mistachkin for the implementation of the fix, and Gustaf Neumann for the original report and testing the fix.

1 files changed, 231 insertions, 0 deletions

diff --git a/unix/configure b/unix/configure
index 0b42510..31758c3 100755
--- a/unix/configure
+++ b/unix/configure
@@ -857,6 +857,8 @@ Optional Features:
   --enable-load           allow dynamic loading and "load" command (default:
                           on)
   --enable-symbols        build with debugging symbols (default: off)
+  --enable-usleep         use usleep if possible to sleep, otherwise use
+                          Tcl_Sleep (default: on)
   --enable-langinfo       use nl_langinfo if possible to determine encoding at
                           startup, otherwise use old heuristic (default: on)
   --enable-dll-unloading  enable the 'unload' command (default: on)
@@ -16728,6 +16730,235 @@ _ACEOF
 fi
 
 #--------------------------------------------------------------------
+# Check for support of usleep function
+#--------------------------------------------------------------------
+
+
+    # Check whether --enable-usleep or --disable-usleep was given.
+if test "${enable_usleep+set}" = set; then
+  enableval="$enable_usleep"
+  usleep_ok=$enableval
+else
+  usleep_ok=yes
+fi;
+
+    HAVE_USLEEP=0
+    if test "$usleep_ok" = "yes"; then
+	if test "${ac_cv_header_unistd_h+set}" = set; then
+  echo "$as_me:$LINENO: checking for unistd.h" >&5
+echo $ECHO_N "checking for unistd.h... $ECHO_C" >&6
+if test "${ac_cv_header_unistd_h+set}" = set; then
+  echo $ECHO_N "(cached) $ECHO_C" >&6
+fi
+echo "$as_me:$LINENO: result: $ac_cv_header_unistd_h" >&5
+echo "${ECHO_T}$ac_cv_header_unistd_h" >&6
+else
+  # Is the header compilable?
+echo "$as_me:$LINENO: checking unistd.h usability" >&5
+echo $ECHO_N "checking unistd.h usability... $ECHO_C" >&6
+cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+$ac_includes_default
+#include <unistd.h>
+_ACEOF
+rm -f conftest.$ac_objext
+if { (eval echo "$as_me:$LINENO: \"$ac_compile\"") >&5
+  (eval $ac_compile) 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } &&
+	 { ac_try='test -z "$ac_c_werror_flag"
+			 || test ! -s conftest.err'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; } &&
+	 { ac_try='test -s conftest.$ac_objext'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; }; then
+  ac_header_compiler=yes
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+ac_header_compiler=no
+fi
+rm -f conftest.err conftest.$ac_objext conftest.$ac_ext
+echo "$as_me:$LINENO: result: $ac_header_compiler" >&5
+echo "${ECHO_T}$ac_header_compiler" >&6
+
+# Is the header present?
+echo "$as_me:$LINENO: checking unistd.h presence" >&5
+echo $ECHO_N "checking unistd.h presence... $ECHO_C" >&6
+cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+#include <unistd.h>
+_ACEOF
+if { (eval echo "$as_me:$LINENO: \"$ac_cpp conftest.$ac_ext\"") >&5
+  (eval $ac_cpp conftest.$ac_ext) 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } >/dev/null; then
+  if test -s conftest.err; then
+    ac_cpp_err=$ac_c_preproc_warn_flag
+    ac_cpp_err=$ac_cpp_err$ac_c_werror_flag
+  else
+    ac_cpp_err=
+  fi
+else
+  ac_cpp_err=yes
+fi
+if test -z "$ac_cpp_err"; then
+  ac_header_preproc=yes
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+  ac_header_preproc=no
+fi
+rm -f conftest.err conftest.$ac_ext
+echo "$as_me:$LINENO: result: $ac_header_preproc" >&5
+echo "${ECHO_T}$ac_header_preproc" >&6
+
+# So?  What about this header?
+case $ac_header_compiler:$ac_header_preproc:$ac_c_preproc_warn_flag in
+  yes:no: )
+    { echo "$as_me:$LINENO: WARNING: unistd.h: accepted by the compiler, rejected by the preprocessor!" >&5
+echo "$as_me: WARNING: unistd.h: accepted by the compiler, rejected by the preprocessor!" >&2;}
+    { echo "$as_me:$LINENO: WARNING: unistd.h: proceeding with the compiler's result" >&5
+echo "$as_me: WARNING: unistd.h: proceeding with the compiler's result" >&2;}
+    ac_header_preproc=yes
+    ;;
+  no:yes:* )
+    { echo "$as_me:$LINENO: WARNING: unistd.h: present but cannot be compiled" >&5
+echo "$as_me: WARNING: unistd.h: present but cannot be compiled" >&2;}
+    { echo "$as_me:$LINENO: WARNING: unistd.h:     check for missing prerequisite headers?" >&5
+echo "$as_me: WARNING: unistd.h:     check for missing prerequisite headers?" >&2;}
+    { echo "$as_me:$LINENO: WARNING: unistd.h: see the Autoconf documentation" >&5
+echo "$as_me: WARNING: unistd.h: see the Autoconf documentation" >&2;}
+    { echo "$as_me:$LINENO: WARNING: unistd.h:     section \"Present But Cannot Be Compiled\"" >&5
+echo "$as_me: WARNING: unistd.h:     section \"Present But Cannot Be Compiled\"" >&2;}
+    { echo "$as_me:$LINENO: WARNING: unistd.h: proceeding with the preprocessor's result" >&5
+echo "$as_me: WARNING: unistd.h: proceeding with the preprocessor's result" >&2;}
+    { echo "$as_me:$LINENO: WARNING: unistd.h: in the future, the compiler will take precedence" >&5
+echo "$as_me: WARNING: unistd.h: in the future, the compiler will take precedence" >&2;}
+    (
+      cat <<\_ASBOX
+## ------------------------------ ##
+## Report this to the tcl lists.  ##
+## ------------------------------ ##
+_ASBOX
+    ) |
+      sed "s/^/$as_me: WARNING:     /" >&2
+    ;;
+esac
+echo "$as_me:$LINENO: checking for unistd.h" >&5
+echo $ECHO_N "checking for unistd.h... $ECHO_C" >&6
+if test "${ac_cv_header_unistd_h+set}" = set; then
+  echo $ECHO_N "(cached) $ECHO_C" >&6
+else
+  ac_cv_header_unistd_h=$ac_header_preproc
+fi
+echo "$as_me:$LINENO: result: $ac_cv_header_unistd_h" >&5
+echo "${ECHO_T}$ac_cv_header_unistd_h" >&6
+
+fi
+if test $ac_cv_header_unistd_h = yes; then
+  usleep_ok=yes
+else
+  usleep_ok=no
+fi
+
+
+    fi
+    echo "$as_me:$LINENO: checking whether to use usleep" >&5
+echo $ECHO_N "checking whether to use usleep... $ECHO_C" >&6
+    if test "$usleep_ok" = "yes"; then
+	if test "${tcl_cv_usleep_h+set}" = set; then
+  echo $ECHO_N "(cached) $ECHO_C" >&6
+else
+
+	    cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+#include <unistd.h>
+int
+main ()
+{
+usleep(0);
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (eval echo "$as_me:$LINENO: \"$ac_compile\"") >&5
+  (eval $ac_compile) 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } &&
+	 { ac_try='test -z "$ac_c_werror_flag"
+			 || test ! -s conftest.err'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; } &&
+	 { ac_try='test -s conftest.$ac_objext'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; }; then
+  tcl_cv_usleep_h=yes
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+tcl_cv_usleep_h=no
+fi
+rm -f conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+
+	echo "$as_me:$LINENO: result: $tcl_cv_usleep_h" >&5
+echo "${ECHO_T}$tcl_cv_usleep_h" >&6
+	if test $tcl_cv_usleep_h = yes; then
+
+cat >>confdefs.h <<\_ACEOF
+#define HAVE_USLEEP 1
+_ACEOF
+
+	fi
+    else
+	echo "$as_me:$LINENO: result: $usleep_ok" >&5
+echo "${ECHO_T}$usleep_ok" >&6
+    fi
+
+
+#--------------------------------------------------------------------
 # Check for support of nl_langinfo function
 #--------------------------------------------------------------------