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Old 03-05-2010, 04:39 AM   #1
visionofarun
LQ Newbie
 
Registered: Mar 2010
Posts: 1

Rep: Reputation: 0
valgrind - pthread memory leaks on AIX

Hi all,

I have written a small code just to invoke main and return immediately. When built with libpthread on AIX box, valgrind throws lots of memory leak errors. But when built without libpthread, no issues at all.

Here is the sample run for your look. Any idea where I might be going wrong?

Code:
On IBM AIX UNIX 5.1
03:23:36 ~/Arun$ cat dummy.c
int main()
{
        return 0;
}
03:23:36 ~/Arun$ gcc -o dummy dummy.c -Wall
03:23:23 ~/Arun$ valgrind --leak-check=full --show-reachable=yes ./dummy
==473082== Memcheck, a memory error detector.
==473082== Copyright (C) 2002-2008, and GNU GPL'd, by Julian Seward et al.
==473082== Using LibVEX rev 1884, a library for dynamic binary translation.
==473082== Copyright (C) 2004-2008, and GNU GPL'd, by OpenWorks LLP.
==473082== Using valgrind-3.4.1, a dynamic binary instrumentation framework.
==473082== Copyright (C) 2000-2008, and GNU GPL'd, by Julian Seward et al.
==473082== For more details, rerun with: -v
==473082==
==473082==
==473082== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)
==473082== malloc/free: in use at exit: 0 bytes in 0 blocks.
==473082== malloc/free: 0 allocs, 0 frees, 0 bytes allocated.
==473082== For counts of detected errors, rerun with: -v
==473082== All heap blocks were freed -- no leaks are possible.

Absolutely no leaks in the above run. But when built with -lpthread, valgrind throws a big list of memory leak for the same dummy.c. See the following.

03:24:50 ~/Arun$ gcc -o dummy dummy.c -Wall -lpthread
03:27:30 ~/Arun$ valgrind --leak-check=full --show-reachable=yes ./dummy
==172006== Memcheck, a memory error detector.
==172006== Copyright (C) 2002-2008, and GNU GPL'd, by Julian Seward et al.
==172006== Using LibVEX rev 1884, a library for dynamic binary translation.
==172006== Copyright (C) 2004-2008, and GNU GPL'd, by OpenWorks LLP.
==172006== Using valgrind-3.4.1, a dynamic binary instrumentation framework.
==172006== Copyright (C) 2000-2008, and GNU GPL'd, by Julian Seward et al.
==172006== For more details, rerun with: -v
==172006==
==172006==
==172006== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 272 from 4)
==172006== malloc/free: in use at exit: 32,260 bytes in 73 blocks.
==172006== malloc/free: 75 allocs, 2 frees, 37,292 bytes allocated.
==172006== For counts of detected errors, rerun with: -v
==172006== searching for pointers to 73 not-freed blocks.
==172006== checked 9,271,124 bytes.
==172006==
==172006== 12 bytes in 1 blocks are still reachable in loss record 1 of 9
==172006==    at 0xD0E2B5B0: malloc (vg_replace_malloc.c:207)
==172006==    by 0xD005276F: _cleanup_push_72_6 (in /usr/lib/libpthread.a(shr_xpg5.o))
==172006==    by 0xD0050E5B: pthread_once (in /usr/lib/libpthread.a(shr_xpg5.o))
==172006==    by 0xD02E7D67: __getpwent_tsd_callback (in /usr/lib/libc.a(shr.o))
==172006==    by 0xD02E7893: _libc_inline_callbacks (in /usr/lib/libc.a(shr.o))
==172006==    by 0xD02E7827: _libc_declare_data_functions (in /usr/lib/libc.a(shr.o))
==172006==    by 0xD006AA4F: _pth_init_libc (in /usr/lib/libpthread.a(shr_xpg5.o))
==172006==    by 0xD004A0FB: __pth_init (in /usr/lib/libpthread.a(shr_xpg5.o))
==172006==    by 0x10000353: call_pth_init (in /proc/172006/object/a.out)
==172006==    by 0x1000026B: __threads_init (in /proc/172006/object/a.out)
==172006==    by 0xD02E6EFF: __modinit (in /usr/lib/libc.a(shr.o))
==172006==    by 0x100001AB: (below main) (in /proc/172006/object/a.out)
==172006==
==172006==
==172006== 56 bytes in 2 blocks are still reachable in loss record 2 of 9
==172006==    at 0xD0E2B5B0: malloc (vg_replace_malloc.c:207)
==172006==    by 0xD0068E7B: pthread_atfork (in /usr/lib/libpthread.a(shr_xpg5.o))
==172006==    by 0xD004A0AB: __pth_init (in /usr/lib/libpthread.a(shr_xpg5.o))
==172006==    by 0x10000353: call_pth_init (in /proc/172006/object/a.out)
==172006==    by 0x1000026B: __threads_init (in /proc/172006/object/a.out)
==172006==    by 0xD02E6EFF: __modinit (in /usr/lib/libc.a(shr.o))
==172006==    by 0x100001AB: (below main) (in /proc/172006/object/a.out)
==172006==
==172006==
==172006== 208 bytes in 1 blocks are still reachable in loss record 3 of 9
==172006==    at 0xD0E2B5B0: malloc (vg_replace_malloc.c:207)
==172006==    by 0xD006C08B: _lib_rwlock_init (in /usr/lib/libpthread.a(shr_xpg5.o))
==172006==    by 0xD0297E5F: _rec_rwlock_init_21_7 (in /usr/lib/libc.a(shr.o))
==172006==    by 0xD029DDEB: _libc_locks_init (in /usr/lib/libc.a(shr.o))
==172006==    by 0xD02975A7: _libc_declare_lock_functions (in /usr/lib/libc.a(shr.o))
==172006==    by 0xD006AA43: _pth_init_libc (in /usr/lib/libpthread.a(shr_xpg5.o))
==172006==    by 0xD004A0FB: __pth_init (in /usr/lib/libpthread.a(shr_xpg5.o))
==172006==    by 0x10000353: call_pth_init (in /proc/172006/object/a.out)
==172006==    by 0x1000026B: __threads_init (in /proc/172006/object/a.out)
==172006==    by 0xD02E6EFF: __modinit (in /usr/lib/libc.a(shr.o))
==172006==    by 0x100001AB: (below main) (in /proc/172006/object/a.out)
==172006==
==172006==
==172006== 1,800 bytes in 1 blocks are still reachable in loss record 4 of 9
==172006==    at 0xD0E2B5B0: malloc (vg_replace_malloc.c:207)
==172006==    by 0xD006962F: _pth_init_key (in /usr/lib/libpthread.a(shr_xpg5.o))
==172006==    by 0xD004A07F: __pth_init (in /usr/lib/libpthread.a(shr_xpg5.o))
==172006==    by 0x10000353: call_pth_init (in /proc/172006/object/a.out)
==172006==    by 0x1000026B: __threads_init (in /proc/172006/object/a.out)
==172006==    by 0xD02E6EFF: __modinit (in /usr/lib/libc.a(shr.o))
==172006==    by 0x100001AB: (below main) (in /proc/172006/object/a.out)
==172006==
==172006==
==172006== 4,096 bytes in 1 blocks are still reachable in loss record 5 of 9
==172006==    at 0xD0E2B5B0: malloc (vg_replace_malloc.c:207)
==172006==    by 0xD00695EB: _pth_init_key (in /usr/lib/libpthread.a(shr_xpg5.o))
==172006==    by 0xD004A07F: __pth_init (in /usr/lib/libpthread.a(shr_xpg5.o))
==172006==    by 0x10000353: call_pth_init (in /proc/172006/object/a.out)
==172006==    by 0x1000026B: __threads_init (in /proc/172006/object/a.out)
==172006==    by 0xD02E6EFF: __modinit (in /usr/lib/libc.a(shr.o))
==172006==    by 0x100001AB: (below main) (in /proc/172006/object/a.out)
==172006==
==172006==
==172006== 5,224 bytes in 1 blocks are still reachable in loss record 6 of 9
==172006==    at 0xD0E2B5B0: malloc (vg_replace_malloc.c:207)
==172006==    by 0xD004BFAF: _alloc_initial_pthread (in /usr/lib/libpthread.a(shr_xpg5.o))
==172006==    by 0xD004A067: __pth_init (in /usr/lib/libpthread.a(shr_xpg5.o))
==172006==    by 0x10000353: call_pth_init (in /proc/172006/object/a.out)
==172006==    by 0x1000026B: __threads_init (in /proc/172006/object/a.out)
==172006==    by 0xD02E6EFF: __modinit (in /usr/lib/libc.a(shr.o))
==172006==    by 0x100001AB: (below main) (in /proc/172006/object/a.out)
==172006==
==172006==
==172006== 5,376 bytes in 8 blocks are still reachable in loss record 7 of 9
==172006==    at 0xD0E2B5B0: malloc (vg_replace_malloc.c:207)
==172006==    by 0xD0049DDF: __pth_init (in /usr/lib/libpthread.a(shr_xpg5.o))
==172006==    by 0x10000353: call_pth_init (in /proc/172006/object/a.out)
==172006==    by 0x1000026B: __threads_init (in /proc/172006/object/a.out)
==172006==    by 0xD02E6EFF: __modinit (in /usr/lib/libc.a(shr.o))
==172006==    by 0x100001AB: (below main) (in /proc/172006/object/a.out)
==172006==
==172006==
==172006== 7,296 bytes in 57 blocks are still reachable in loss record 8 of 9
==172006==    at 0xD0E2B5B0: malloc (vg_replace_malloc.c:207)
==172006==    by 0xD0047F73: _lib_spinlock_create (in /usr/lib/libpthread.a(shr_xpg5.o))
==172006==    by 0xD029DE13: _libc_locks_init (in /usr/lib/libc.a(shr.o))
==172006==    by 0xD02975A7: _libc_declare_lock_functions (in /usr/lib/libc.a(shr.o))
==172006==    by 0xD006AA43: _pth_init_libc (in /usr/lib/libpthread.a(shr_xpg5.o))
==172006==    by 0xD004A0FB: __pth_init (in /usr/lib/libpthread.a(shr_xpg5.o))
==172006==    by 0x10000353: call_pth_init (in /proc/172006/object/a.out)
==172006==    by 0x1000026B: __threads_init (in /proc/172006/object/a.out)
==172006==    by 0xD02E6EFF: __modinit (in /usr/lib/libc.a(shr.o))
==172006==    by 0x100001AB: (below main) (in /proc/172006/object/a.out)
==172006==
==172006==
==172006== 8,192 bytes in 1 blocks are still reachable in loss record 9 of 9
==172006==    at 0xD0E2B5B0: malloc (vg_replace_malloc.c:207)
==172006==    by 0xD005B847: _vp_create_locked (in /usr/lib/libpthread.a(shr_xpg5.o))
==172006==    by 0xD005BAEF: _vp_create (in /usr/lib/libpthread.a(shr_xpg5.o))
==172006==    by 0xD004C1CF: _alloc_initial_pthread (in /usr/lib/libpthread.a(shr_xpg5.o))
==172006==    by 0xD004A067: __pth_init (in /usr/lib/libpthread.a(shr_xpg5.o))
==172006==    by 0x10000353: call_pth_init (in /proc/172006/object/a.out)
==172006==    by 0x1000026B: __threads_init (in /proc/172006/object/a.out)
==172006==    by 0xD02E6EFF: __modinit (in /usr/lib/libc.a(shr.o))
==172006==    by 0x100001AB: (below main) (in /proc/172006/object/a.out)
==172006==
==172006== LEAK SUMMARY:
==172006==    definitely lost: 0 bytes in 0 blocks.
==172006==      possibly lost: 0 bytes in 0 blocks.
==172006==    still reachable: 32,260 bytes in 73 blocks.
==172006==         suppressed: 0 bytes in 0 blocks.
03:27:38 ~/Arun$

What is going wrong?! Same is the case with any multithreaded application that I wrote on this AIX box!
Thanks
Arun
Last edited by visionofarun; 03-15-2010 at 06:11 AM.
 
Old 04-23-2010, 06:20 AM   #2
anubhuti_k
LQ Newbie
 
Registered: Oct 2004
Location: India
Distribution: Suse 9.1
Posts: 29

Rep: Reputation: 15
Hi Arun,

As far as I know, pthread library on AIX does some pre allocations for efficiency purposes.
They preallocate the resources, and keep a pool of them. They use objects from that pool as and when needed and then return that back to the pool. This strategy is efficient in scenarios where resources are frequently allocated and freed, because they dont go thru the hazzles of malloc and free every time.

Thats why u r seeing leaks, but as such they are not leaks just pooled resources being reported
 
  


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