On Mon, Feb 27, 2012 at 01:38:52PM +0000, David Xu wrote: > Author: davidxu > Date: Mon Feb 27 13:38:52 2012 > New Revision: 232209 > URL: http://svn.freebsd.org/changeset/base/232209 > > Log: > Follow changes made in revision 232144, pass absolute timeout to kernel, > this eliminates a clock_gettime() syscall.
This or some other change has broken CLOCK_MONOTONIC usage with
condition variables.
You should be able to reproduce this by something like this:
pthread_cond_t cv;
pthread_condattr_t attr;
pthread_mutex_t lock;
struct timespec ts;
int error;
(void)pthread_mutex_init(&lock, NULL);
(void)pthread_condattr_init(&attr);
(void)pthread_condattr_setclock(&attr, CLOCK_MONOTONIC);
(void)pthread_cond_init(&cv, &attr);
(void)pthread_condattr_destroy(&attr);
(void)clock_gettime(CLOCK_MONOTONIC, &ts);
ts.tv_sec += 10;
(void)pthread_mutex_lock(&lock);
(void)pthread_cond_timedwait(&cv, &lock, &ts);
(void)pthread_mutex_unlock(&lock);
This should timeout after 10 seconds, but pthread_cond_timedwait(3)
returns immediately with ETIMEDOUT. CLOCK_REALTIME works properly.
Bascially pthread_condattr_setclock(&attr, CLOCK_MONOTONIC) is no-op.
If you change CLOCK_MONOTONIC to CLOCK_REALTIME in clock_gettime(2)
call, it will timeout after 10 seconds.
--
Pawel Jakub Dawidek http://www.wheelsystems.com
FreeBSD committer http://www.FreeBSD.org
Am I Evil? Yes, I Am! http://tupytaj.pl
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