Bug 217236

Summary:	Mac OS X: pthread_cond_wait reports still reachable leaked memory
Product:	[Developer tools] valgrind	Reporter:	Evan Jones <evanj>
Component:	memcheck	Assignee:	Julian Seward <jseward>
Status:	RESOLVED FIXED
Severity:	normal	CC:	rhyskidd, tom
Priority:	NOR
Version:	3.6 SVN
Target Milestone:	---
Platform:	Unlisted Binaries
OS:	macOS
Latest Commit:		Version Fixed In:
Sentry Crash Report:
Attachments:	test program that causes the valgrind warning corrected test program that causes the warning add a suppression for new_sem_from_pool

Description Evan Jones 2009-12-03 18:10:22 UTC

Created attachment 38801 [details]
test program that causes the valgrind warning

On Mac OS X, pthread_cond_wait ends up calling new_sem_from_pool, which allocates a pool of semaphore objects that gets reused. This causes Valgrind to report a "still reachable" warning for this memory that is not leaked. Occasionally for more complex programs, this reports a full-blown "definitely lost" error. The attached program causes the SVN version of Valgrind to report this warning. The attached patch to the suppressions suppresses it.

The source of the new_sem_from_pool function can be found:

http://www.opensource.apple.com/source/Libc/Libc-583/pthreads/pthread.c

Comment 1 Evan Jones 2009-12-03 18:14:47 UTC

Created attachment 38802 [details]
corrected test program that causes the warning

Comment 2 Evan Jones 2009-12-03 18:16:36 UTC

Created attachment 38803 [details]
add a suppression for new_sem_from_pool

Comment 3 Evan Jones 2009-12-03 18:17:07 UTC

The original warning is:

=23593== 64 bytes in 1 blocks are still reachable in loss record 2 of 3
==23593==    at 0x15416: malloc (vg_replace_malloc.c:195)
==23593==    by 0x17225: realloc (vg_replace_malloc.c:476)
==23593==    by 0x229507: new_sem_from_pool (in /usr/lib/libSystem.B.dylib)
==23593==    by 0x2291A5: _pthread_cond_wait (in /usr/lib/libSystem.B.dylib)
==23593==    by 0x228DCC: pthread_cond_wait$UNIX2003 (in /usr/lib/libSystem.B.dylib)
==23593==    by 0x1E4A: main (in ./test)


The original suppression is:

{
   darwin-still-reachable-4
   Memcheck:Leak
   fun:malloc
   fun:realloc
   fun:new_sem_from_pool
   fun:_pthread_cond_wait
   fun:pthread_cond_wait$UNIX2003
   fun:main
}

Comment 4 Rhys Kidd 2015-05-07 13:21:21 UTC

Resolved in r15190 for OS X 10.8.