This is the mail archive of the
pthreads-win32@sources.redhat.com
mailing list for the pthreas-win32 project.
RE: Handle leak when using pthread mutex with win32 api threads
- From: "Bossom, John" <John dot Bossom at Cognos dot COM>
- To: "Dmitrii Sernii" <bogolt at gmail dot com>,<pthreads-win32 at sources dot redhat dot com>
- Date: Sun, 6 Mar 2005 07:51:01 -0500
- Subject: RE: Handle leak when using pthread mutex with win32 api threads
My hands have been out of the pthreads-win32 code base for some time
(1998!)
However, I do know that on UNIX you can and will leak resources if
you do not treat your main line like any other thread. In otherwords,
call pthread_exit() to end your mainline.
I believe this is documented in the book written by Bil Lewis.
Cheers,
John Bossom
-----Original Message-----
From: pthreads-win32-owner@sources.redhat.com
[mailto:pthreads-win32-owner@sources.redhat.com] On Behalf Of Dmitrii
Sernii
Sent: Saturday, March 05, 2005 8:31 AM
To: pthreads-win32@sources.redhat.com
Subject: Re: Handle leak when using pthread mutex with win32 api threads
> > > static pthread_mutex_t
> > > mutex(PTHREAD_RECURSIVE_MUTEX_INITIALIZER);
> >
> > that line above is not thread safe. you might initialize the same
> > mutex multiple times. Not good.
> >
>
> The handle leak comes about because, in pthreads-win32,
> pthread_mutex_t is only a pointer, and the actual mutex struct is
> malloced by the library, in this case, the first time you call
pthread_mutex_lock().
> That is, the library just calls pthread_mutex_init() for you. Also,
> you must always call pthread_mutex_destroy() to clean up, just the
> same as if you had called pthread_mutex_init() yourself.
I've made small corrections in test sample, so now mutex initialised
only once, and i've added pthread_mutex_destroy() function call. But the
problem still remains.
Here is two test applications - one of them uses API threads, and the
other pthreads. Program with pthreads don't have any leaks, while
program with API threads produces lots of them.
//program with handle leaks
#include <pthread.h>
#include <windows.h>
#include <conio.h>
pthread_mutex_t mutex(PTHREAD_RECURSIVE_MUTEX_INITIALIZER);
DWORD WINAPI threadProc(void *param)
{
pthread_mutex_lock(&mutex);
pthread_mutex_unlock(&mutex);
return 0;
}
void main()
{
const int max_threads = 500;
DWORD id;
HANDLE th[max_threads];
int i;
for (i=0;i<max_threads;i++)
th[i]=CreateThread(0,0,threadProc,0,0,&id);
for (i=0;i<max_threads;i++)
{
WaitForSingleObject(th[i],INFINITE);
CloseHandle(th[i]);
}
pthread_mutex_destroy(&mutex);
getch();
}
==========================
//program without handle leaks
#include <pthread.h>
#include <windows.h>
#include <conio.h>
pthread_mutex_t mutex(PTHREAD_RECURSIVE_MUTEX_INITIALIZER);
void* threadProc(void *param)
{
pthread_mutex_lock(&mutex);
pthread_mutex_unlock(&mutex);
return 0;
}
void main()
{
const int max_threads = 500;
DWORD id;
pthread_t th[max_threads];
int i;
for (i=0;i<max_threads;i++)
pthread_create(&(th[i]),0,threadProc,(void*)i);
for (i=0;i<max_threads;i++)
pthread_join(th[i],(void**)&id);
pthread_mutex_destroy(&mutex);
getch();
}
Best regards,
Dmitrii Sernii
This message may contain privileged and/or confidential information. If you have received this e-mail in error or are not the intended recipient, you may not use, copy, disseminate or distribute it; do not open any attachments, delete it immediately from your system and notify the sender promptly by e-mail that you have done so. Thank you.