Valgrind – DRD – while Helgrind is the major tool for concurrency issue detection, some options of DRD are also helpful on debugging concurrency issue, especially –exclusive-threshold, used to report mutex locked for long, and –shared-threshold, used to report shared rwlock locked for long, by certain thread.
# DRD http://valgrind.org/docs/manual/drd-manual.html --tool=drd --read-var-info=yes --exclusive-threshold=<n> --shared-threshold=<n> [root@localhost tests]# cat hold_lock.c /** Hold several types of synchronization objects locked as long as specified. */ #define _GNU_SOURCE 1 #include <assert.h> #include <pthread.h> #include <stdio.h> #include <stdlib.h> #include <time.h> #include <unistd.h> static void delay_ms(const int ms) { struct timespec ts; assert(ms >= 0); ts.tv_sec = ms / 1000; ts.tv_nsec = (ms % 1000) * 1000 * 1000; nanosleep(&ts, 0); } int main(int argc, char** argv) { int interval = 0; int optchar; pthread_mutex_t mutex; pthread_mutexattr_t mutexattr; pthread_rwlock_t rwlock; while ((optchar = getopt(argc, argv, "i:")) != EOF) { switch (optchar) { case 'i': interval = atoi(optarg); break; default: fprintf(stderr, "Usage: %s [-i <interval time in ms>].n", argv[0]); break; } } fprintf(stderr, "Locking mutex ...n"); pthread_mutexattr_init(&mutexattr); pthread_mutexattr_settype(&mutexattr, PTHREAD_MUTEX_RECURSIVE); pthread_mutex_init(&mutex, &mutexattr); pthread_mutexattr_destroy(&mutexattr); pthread_mutex_lock(&mutex); delay_ms(interval); pthread_mutex_lock(&mutex); pthread_mutex_unlock(&mutex); pthread_mutex_unlock(&mutex); pthread_mutex_destroy(&mutex); fprintf(stderr, "Locking rwlock exclusively ...n"); pthread_rwlock_init(&rwlock, 0); pthread_rwlock_wrlock(&rwlock); delay_ms(interval); pthread_rwlock_unlock(&rwlock); pthread_rwlock_destroy(&rwlock); fprintf(stderr, "Locking rwlock shared ...n"); pthread_rwlock_init(&rwlock, 0); pthread_rwlock_rdlock(&rwlock); delay_ms(interval); pthread_rwlock_rdlock(&rwlock); pthread_rwlock_unlock(&rwlock); pthread_rwlock_unlock(&rwlock); pthread_rwlock_destroy(&rwlock); fprintf(stderr, "Done.n"); return 0; } [root@localhost valgrindTest]# gcc -Wall -g -lpthread -o hold_lock hold_lock.c [root@localhost valgrindTest]# valgrind --tool=drd --exclusive-threshold=50 --shared-threshold=100 ./hold_lock -i 150 ==32519== drd, a thread error detector ==32519== Copyright (C) 2006-2011, and GNU GPL'd, by Bart Van Assche. ==32519== Using Valgrind-3.7.0 and LibVEX; rerun with -h for copyright info ==32519== Command: ./hold_lock -i 150 ==32519== Locking mutex ... ==32519== Acquired at: ==32519== at 0x400D21B: pthread_mutex_lock (drd_pthread_intercepts.c:615) ==32519== by 0x80489F1: main (hold_lock.c:51) ==32519== Lock on mutex 0xbe9b79a4 was held during 158 ms (threshold: 50 ms). ==32519== at 0x400D7C4: pthread_mutex_unlock (drd_pthread_intercepts.c:665) ==32519== by 0x8048A1D: main (hold_lock.c:55) ==32519== mutex 0xbe9b79a4 was first observed at: ==32519== at 0x401133F: pthread_mutex_init (drd_pthread_intercepts.c:576) ==32519== by 0x80489DB: main (hold_lock.c:49) ==32519== Locking rwlock exclusively ... ==32519== Acquired at: ==32519== at 0x4010846: pthread_rwlock_wrlock (drd_pthread_intercepts.c:1134) ==32519== by 0x8048A6B: main (hold_lock.c:61) ==32519== Lock on rwlock 0xbe9b7980 was held during 153 ms (threshold: 50 ms). ==32519== at 0x401112F: pthread_rwlock_unlock (drd_pthread_intercepts.c:1221) ==32519== by 0x8048A81: main (hold_lock.c:63) ==32519== rwlock 0xbe9b7980 was first observed at: ==32519== at 0x401034C: pthread_rwlock_init (drd_pthread_intercepts.c:1080) ==32519== by 0x8048A60: main (hold_lock.c:60) ==32519== Locking rwlock shared ... ==32519== Acquired at: ==32519== at 0x4010666: pthread_rwlock_rdlock (drd_pthread_intercepts.c:1116) ==32519== by 0x8048ACF: main (hold_lock.c:69) ==32519== Lock on rwlock 0xbe9b7980 was held during 154 ms (threshold: 100 ms). ==32519== at 0x401112F: pthread_rwlock_unlock (drd_pthread_intercepts.c:1221) ==32519== by 0x8048AFB: main (hold_lock.c:73) ==32519== rwlock 0xbe9b7980 was first observed at: ==32519== at 0x401034C: pthread_rwlock_init (drd_pthread_intercepts.c:1080) ==32519== by 0x8048AC4: main (hold_lock.c:68) ==32519== Done. ==32519== ==32519== For counts of detected and suppressed errors, rerun with: -v ==32519== ERROR SUMMARY: 3 errors from 3 contexts (suppressed: 0 from 0) [root@localhost valgrindTest]#