Date: Mon, 15 Jan 2001 05:08:57 -0800 (PST) From: fishkin@port.ru To: freebsd-gnats-submit@FreeBSD.org Subject: misc/24345: pthread library libc_r causes memory leak at termination of joinable thread Message-ID: <200101151308.f0FD8v470958@freefall.freebsd.org>
next in thread | raw e-mail | index | archive | help
>Number: 24345
>Category: misc
>Synopsis: pthread library libc_r causes memory leak at termination of joinable thread
>Confidential: no
>Severity: non-critical
>Priority: medium
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Mon Jan 15 05:10:01 PST 2001
>Closed-Date:
>Last-Modified:
>Originator: Andy Fedotov
>Release: 3.5-STABLE, 4.1-STABLE
>Organization:
Port.RU, Inc.
>Environment:
FreeBSD xxxxxx.xxx.xxxx.xx 3.5-STABLE FreeBSD 3.5-STABLE #0: Tue Jan 9 13:49:27 MSK 2001 root@xxxxxx.xxx.xxxx.xx:/usr/src/sys/compile/HELL i386
FreeBSD xxx.xxxxx 4.1-STABLE FreeBSD 4.1-STABLE #3: Thu Nov 30 21:00:56 MSK 2000 root@xxx.xxxxx:/usr/src/sys/compile/MAC i386
>Description:
Garbage collector looks into list of dead threads and freeing
resources only for threads with PTHREAD_DETACHED flag.
Unfortunattely pthread_join() doesn't set PTHREAD_DETACHED flag
on thread after fetching it return value. So, garbage collector
leave this thread in dead list and won't free() any resources
associated with it. This causes memory leak.
>How-To-Repeat:
Simply start thread in joinable state, and then join on it.
------
#ifndef _THREAD_SAFE
#define _THREAD_SAFE
#endif
#ifndef _REENTRANT
#define _REENTRANT
#endif
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <pthread.h>
unsigned long brk_value = 0;
void *check_leak(void *arg)
{
unsigned long current_brk = (unsigned long) sbrk(0);
if (current_brk > brk_value)
if (brk_value != 0)
fprintf(stdout, "Data segment grows up by 0x%lX bytes\n", current_brk - brk_value);
brk_value = current_brk;
pthread_exit(NULL);
}
int main()
{
pthread_t tid;
pthread_attr_t attr;
pthread_attr_init(&attr);
pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);
for (;;) {
if (pthread_create(&tid, &attr, check_leak, NULL)) {
perror("pthread_create");
exit(0);
}
else
pthread_join(tid, NULL);
}
}
-----
>Fix:
Should we simply set PTHREAD_DETACHED flag after sucessfuly
joining on thread ? But this is not solution for pthread_cancel(),
that also put threads in dead list w/o PTHREAD_DETACHED flag set.
--- uthread_join.c.orig Mon Jan 15 15:11:30 2001
+++ uthread_join.c Mon Jan 15 15:12:34 2001
@@ -117,6 +117,8 @@
/* Return the thread's return value: */
*thread_return = pthread->ret;
+ pthread->attr.flags |= PTHREAD_DETACHED;
+
_thread_leave_cancellation_point();
/* Return the completion status: */
>Release-Note:
>Audit-Trail:
>Unformatted:
To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-bugs" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200101151308.f0FD8v470958>