>> As far as I understand, helgrind is not more than just Eraser :)
helgrind is more than just Eraser :)
On Dec 5, 2007 3:16 PM, Konstantin Serebryany <
[EMAIL PROTECTED]> wrote:
> As far as I understand, helgrind is not more than just Eraser :)
>
> For example, the following program does not report any race, while GLOB is
> *not* protected by any lock.
>
> % cat cv2.cc
> #define _MULTI_THREADED
> #include <pthread.h>
> #include <stdio.h>
> #include <stdlib.h>
> #include <unistd.h>
>
> static int COND = 0;
> static int GLOB = 0;
> static pthread_cond_t CV = PTHREAD_COND_INITIALIZER;
> static pthread_mutex_t MU = PTHREAD_MUTEX_INITIALIZER;
>
> void *run_pm(void*) {
> sleep(2); // we want waiter to get there first
> GLOB = 1;
> pthread_mutex_lock(&MU);
> COND++;
> fprintf(stderr, "Signal: COND: %d\n", COND);
> pthread_cond_signal(&CV);
> pthread_mutex_unlock(&MU);
> return NULL;
> }
>
> int main() {
> pthread_t threadid;
> GLOB = 2;
> pthread_create(&threadid, NULL, run_pm, NULL);
>
> pthread_mutex_lock(&MU);
> while (COND != 1) {
> pthread_cond_wait(&CV, &MU);
> }
> pthread_mutex_unlock(&MU);
>
> GLOB = 2;
> fprintf(stderr, "GLOB: %d\n", GLOB);
> pthread_join(threadid, NULL);
> return 0;
> }
> % g++ -g cv2.cc -lpthread ; ~/race/valgrind32orig/Inst/bin/valgrind -q
> --tool=helgrind ./a.out
> Signal: COND: 1
> GLOB: 2
> %
>
>
>
> On Dec 5, 2007 3:10 PM, Bart Van Assche <[EMAIL PROTECTED]> wrote:
>
> > On Dec 5, 2007 10:56 AM, Konstantin Serebryany <
> > [EMAIL PROTECTED]> wrote:
> >
> > > Hi Julian, all,
> > >
> > > I get a report about a race from helgrind, while everything looks well
> > > synchronized to me.
> > > Am I wrong?
> > >
> >
> > I can be wrong, but my understanding is that the Eraser algorithm
> > (helgrind) reports any conflicting accesses to shared variables that are not
> > protected by proper locking, so I expect helgrind to complain on the last
> > COND access. DRD on the other hand looks for possible causes of
> > nondeterminism. There are no such issues in the program cv.cc, hence DRD
> > does not complain on any of the COND accesses in cv.cc.
> >
> > Regards,
> >
> > Bart Van Assche.
>
>
>
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