Date: 12 Jul 2001 20:45:52 +0200 From: arno@heho.snv.jussieu.fr (Arno J. Klaassen) To: jasone@FreeBSD.ORG Cc: freebsd-stable@FreeBSD.ORG Subject: Changed behaviour of pthread_join (bug?) Message-ID: <wpbsmqq93z.fsf@heho.snv.jussieu.fr>
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Dear Sir,
since the recent (Jun 23 -- Jul 6) MFCs in lib/libc_r/uthread, our pthread programs
don't function any longer. The problem is that a joining a thread which
has been cancelled, either fails (with errno <3>) or hangs
in _thread_sys_poll :
gdb -core join_bug-bsd.core
GNU gdb 4.18
Core was generated by `join_bug-bsd'.
Program terminated with signal 3, Quit.
Reading symbols from /usr/lib/libc_r.so.4...done.
Reading symbols from /usr/libexec/ld-elf.so.1...done.
#0 0x280bb000 in _thread_sys_poll () from /usr/lib/libc_r.so.4
(gdb) where
#0 0x280bb000 in _thread_sys_poll () from /usr/lib/libc_r.so.4
#1 0x280ba365 in _thread_kern_sched_state_unlock () from /usr/lib/libc_r.so.4
#2 0x280b9c64 in _thread_kern_scheduler () from /usr/lib/libc_r.so.4
#3 0x0 in ?? ()
(gdb)
At the end of this mail you find a simple code fragment which produces
this behaviour. This code runs perfectly well under Solaris2.5 as well
as well as on a 4.3-STABLE #0: Sun Jun 10 00:24:49 MEST 2001 box.
Thanx in advance.
Arno J. Klaassen
--
SCITO S.A. INSERM U483
Le Grand Sablon University Pierre et Marie Curie
4, avenue de l'Obiou 9, quai Saint Bernard
38700 La Tronche 75 252 Paris Cedex 5
+33 - 1 - 44 27 33 87
arno@ccr.jussieu.fr
###################################################################
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <errno.h>
#include <pthread.h>
pthread_t control_thread;
pthread_t scheduler_thread;
#define NR_OF_ITERATIONS 500000
#define NR_OF_TESTMIPS_THREADS 10
static void *
testmips (void *data)
{
int i;
int a = 2;
int b = 3;
for (i = 1; i <= NR_OF_ITERATIONS; i++)
{
a += (b / a);
a -= (b / a);
}
return NULL;
}
static void *
scheduler (void * data)
{
int i = 0;
int ret = 0;
pthread_t testmips_thread;
for (i = 1; i <= NR_OF_TESTMIPS_THREADS; i++)
{
pthread_testcancel();
fprintf (stderr, "Starting new testmips_thread <%d>.\n", i);
pthread_create (&testmips_thread, 0, testmips, NULL);
ret = pthread_join (testmips_thread, NULL);
if (ret != 0)
fprintf(stderr, " FAILED to join testmips_thread.\n");
else
fprintf(stderr, " Successfully joined testmips_thread.\n");
}
fprintf (stderr, "Routine 'scheduler' finished.\n");
fprintf(stderr, "\nPRESS ENTER TO STOP.\n\n");
scheduler_thread = NULL;
return NULL;
}
static void *
control_routine (void * data)
{
int ret;
fprintf(stderr, "PRESS ENTER TO CANCEL THE TESTMIPS SCHEDULER.\n\n");
getchar();
if (scheduler_thread != NULL)
{
fprintf(stderr, "\n Canceling scheduler_thread.\n");
ret = pthread_cancel (scheduler_thread);
if (ret != 0)
{
fprintf(stderr, " FAILED to cancel scheduler_thread.\n");
fprintf(stderr, " Errno nr is <%d>.\n", errno);
}
fprintf(stderr, " Trying to join scheduler_thread.\n");
ret = pthread_join (scheduler_thread, NULL);
if (ret != 0)
{
fprintf(stderr, " FAILED to join scheduler_thread with errno <%d>.\n", errno);
}
else
fprintf(stderr, " Successfully joined scheduler_thread.\n");
}
fprintf (stderr, "Routine 'control_routine' finished.\n");
/* control_thread = NULL;*/
return NULL;
}
static void
do_the_job(void)
{
pthread_create (&scheduler_thread, 0, scheduler, NULL);
}
int
main (int argc, char *argv[])
{
int ret;
pthread_create (&control_thread, 0, control_routine, NULL);
do_the_job();
ret = pthread_join (control_thread, NULL);
if (ret != 0)
fprintf(stderr, " FAILED to join control_thread.\n");
return 0;
}
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