pthread_create followed by pthread_detach still results in possibly lost error in Valgrind.
- by alesplin
I'm having a problem with Valgrind telling me I have some memory possible lost:
==23205== 544 bytes in 2 blocks are possibly lost in loss record 156 of 265
==23205== at 0x6022879: calloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==23205== by 0x540E209: allocate_dtv (in /lib/ld-2.12.1.so)
==23205== by 0x540E91D: _dl_allocate_tls (in /lib/ld-2.12.1.so)
==23205== by 0x623068D: pthread_create@@GLIBC_2.2.5 (in /lib/libpthread-2.12.1.so)
==23205== by 0x758D66: MTPCreateThreadPool (MTP.c:290)
==23205== by 0x405787: main (MServer.c:317)
The code that creates these threads (MTPCreateThreadPool) basically gets an index into a block of waiting pthread_t slots, and creates a thread with that. TI becomes a pointer to a struct that has a thread index and a pthread_t. (simplified/sanitized):
for (tindex = 0; tindex < NumThreads; tindex++)
{
int rc;
TI = &TP->ThreadInfo[tindex];
TI->ThreadID = tindex;
rc = pthread_create(&TI->ThreadHandle,NULL,MTPHandleRequestsLoop,TI);
/* check for non-success that I've omitted */
pthread_detach(&TI->ThreadHandle);
}
Then we have a function MTPDestroyThreadPool that loops through all the threads we created and cancels them (since the MTPHandleRequestsLoop doesn't exit).
for (tindex = 0; tindex < NumThreads; tindex++)
{
pthread_cancel(TP->ThreadInfo[tindex].ThreadHandle);
}
I've read elsewhere (including other questions here on SO) that detaching a thread explicitly would prevent this possibly lost error, but it clearly isn't. Any thoughts?
