Memory leak with threads + guile 1.8.7 ?

Memory leak with threads + guile 1.8.7 ?

[Cedric Cellier]

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Hello dear hackers !

I'm using guile in an C program that spawn a lot of short lived
threads, each of which passing in guile mode (guile 1.8.7), and I'm
facing a memory leak even when the threads does nothing (ie. the
C function called by scm_with_guile consists only of a return NULL.
After some time, if I call a gc-stats I have many many segments of
21Mb allocated, although gc-live-object-stats reports that almost
nothing is alive (acording to expectations).

I am under the impression that some of these segments, created by a
now defunct thread, can not be reused by others.

So I made a small program that continuously creates thread and run
a NOP scm_with_guile in it, and then join it (so that thre thread local
storage itself is not leaked).

With the useless scm_with_guile call, this programm leaks memory
very quickly. Comment out the scm_with_guile call and there is no more
leak.

What do you think ?


[-- Attachment #2: Makefile --]
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CFLAGS += $(shell guile-config compile) -std=c99
CPPFLAGS += -D_GNU_SOURCE
LDLIBS += $(shell guile-config link) -lpthread

all: many_threads

clean:
	rm -f *.o many_threads

[-- Attachment #3: many_threads.c --]
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#include <unistd.h>
#include <pthread.h>
#include <time.h>
#include <libguile.h>

static void *thread_with_guile(void *null)
{
    return NULL;
}

static void *the_thread(void *args)
{
    (void)scm_with_guile(thread_with_guile, NULL);	// comment me to remove the memory leak
    return NULL;
}


int main(void)
{
	// We create many threads
	while (1) {
	    pthread_t ptid;
    	pthread_create(&ptid, NULL, the_thread, NULL);
		void *ret;
		pthread_join(ptid, &ret);
	}

	return 0;
}

Re: Memory leak with threads + guile 1.8.7 ?

[Andy Wingo]

Hi Cedric,

You posted a mail to the list some months ago:

On Wed 15 Sep 2010 15:47, Cedric Cellier <rixed@happyleptic.org> writes:

> I'm using guile in an C program that spawn a lot of short lived
> threads, each of which passing in guile mode (guile 1.8.7), and I'm
> facing a memory leak even when the threads does nothing (ie. the
> C function called by scm_with_guile consists only of a return NULL.
> After some time, if I call a gc-stats I have many many segments of
> 21Mb allocated, although gc-live-object-stats reports that almost
> nothing is alive (acording to expectations).
>
> I am under the impression that some of these segments, created by a
> now defunct thread, can not be reused by others.
>
> So I made a small program that continuously creates thread and run
> a NOP scm_with_guile in it, and then join it (so that thre thread local
> storage itself is not leaked).
>
> With the useless scm_with_guile call, this programm leaks memory
> very quickly. Comment out the scm_with_guile call and there is no more
> leak.
>
> What do you think ?

It's a bug, but with interesting implications in 1.9.  I have filed bug
#32436 about this.

Thanks for the test case,

Andy
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