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Fix crash when libomp loaded/unloaded multiple times 

The problem scenario is the following:
A dynamic library, libfoo.so, depends on libomp.so (it creates parallel region
and calls some omp functions).  An application has a loop where it dynamically
loads libfoo.so, calls the function from it, unloads libfoo.so.  After several
loop iterations application crashes with the message about lack of resources
OMP: Error #34: System unable to allocate necessary resources for OMP thread:

The problem is that pthread_kill() was not followed by pthread_join() in case
of terminated thread. This patch fixes this problem for both worker and monitor
threads.

Differential Revision: http://reviews.llvm.org/D21200

llvm-svn: 272567
This commit is contained in:
Jonathan Peyton 2016-06-13 17:36:40 +00:00
parent 248190ba69
commit 93495de265
1 changed files with 23 additions and 38 deletions
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61
openmp/runtime/src/z_Linux_util.c
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@ -1268,27 +1268,23 @@ __kmp_reap_monitor( kmp_info_t *th )
KMP_MB(); /* Flush all pending memory write invalidates. */ KMP_MB(); /* Flush all pending memory write invalidates. */
/* First, check to see whether the monitor thread exists. This could prevent a hang, /* First, check to see whether the monitor thread exists to wake it up. This is
but if the monitor dies after the pthread_kill call and before the pthread_join to avoid performance problem when the monitor sleeps during blocktime-size
call, it will still hang. */ interval */
status = pthread_kill( th->th.th_info.ds.ds_thread, 0 ); status = pthread_kill( th->th.th_info.ds.ds_thread, 0 );
if (status == ESRCH) { if (status != ESRCH) {
KA_TRACE( 10, ("__kmp_reap_monitor: monitor does not exist, returning\n") );
} else
{
__kmp_resume_monitor(); // Wake up the monitor thread __kmp_resume_monitor(); // Wake up the monitor thread
status = pthread_join( th->th.th_info.ds.ds_thread, & exit_val); }
if (exit_val != th) { KA_TRACE( 10, ("__kmp_reap_monitor: try to join with monitor\n") );
__kmp_msg( status = pthread_join( th->th.th_info.ds.ds_thread, & exit_val);
kmp_ms_fatal, if (exit_val != th) {
KMP_MSG( ReapMonitorError ), __kmp_msg(
KMP_ERR( status ), kmp_ms_fatal,
__kmp_msg_null KMP_MSG( ReapMonitorError ),
); KMP_ERR( status ),
} __kmp_msg_null
);
} }
th->th.th_info.ds.ds_tid = KMP_GTID_DNE; th->th.th_info.ds.ds_tid = KMP_GTID_DNE;
@ -1311,28 +1307,17 @@ __kmp_reap_worker( kmp_info_t *th )
KA_TRACE( 10, ("__kmp_reap_worker: try to reap T#%d\n", th->th.th_info.ds.ds_gtid ) ); KA_TRACE( 10, ("__kmp_reap_worker: try to reap T#%d\n", th->th.th_info.ds.ds_gtid ) );
/* First, check to see whether the worker thread exists. This could prevent a hang, status = pthread_join( th->th.th_info.ds.ds_thread, & exit_val);
but if the worker dies after the pthread_kill call and before the pthread_join
call, it will still hang. */
status = pthread_kill( th->th.th_info.ds.ds_thread, 0 );
if (status == ESRCH) {
KA_TRACE( 10, ("__kmp_reap_worker: worker T#%d does not exist, returning\n", th->th.th_info.ds.ds_gtid ) );
}
else {
KA_TRACE( 10, ("__kmp_reap_worker: try to join with worker T#%d\n", th->th.th_info.ds.ds_gtid ) );
status = pthread_join( th->th.th_info.ds.ds_thread, & exit_val);
#ifdef KMP_DEBUG #ifdef KMP_DEBUG
/* Don't expose these to the user until we understand when they trigger */ /* Don't expose these to the user until we understand when they trigger */
if ( status != 0 ) { if ( status != 0 ) {
__kmp_msg(kmp_ms_fatal, KMP_MSG( ReapWorkerError ), KMP_ERR( status ), __kmp_msg_null); __kmp_msg(kmp_ms_fatal, KMP_MSG( ReapWorkerError ), KMP_ERR( status ), __kmp_msg_null);
}
if ( exit_val != th ) {
KA_TRACE( 10, ( "__kmp_reap_worker: worker T#%d did not reap properly, exit_val = %p\n",
th->th.th_info.ds.ds_gtid, exit_val ) );
}
#endif /* KMP_DEBUG */
} }
if ( exit_val != th ) {
KA_TRACE( 10, ( "__kmp_reap_worker: worker T#%d did not reap properly, exit_val = %p\n",
th->th.th_info.ds.ds_gtid, exit_val ) );
}
#endif /* KMP_DEBUG */
KA_TRACE( 10, ("__kmp_reap_worker: done reaping T#%d\n", th->th.th_info.ds.ds_gtid ) ); KA_TRACE( 10, ("__kmp_reap_worker: done reaping T#%d\n", th->th.th_info.ds.ds_gtid ) );