<sigh>
Never mind, you can close this. I've managed to reproduce the leak without GM:
/*
* gcc -o gomparena gomparena.c -fopenmp
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <time.h>
#include <pthread.h>
static void* go_omp(void* arg) {
const int m = 1024;
double* a = alloca(m*sizeof(double));
#pragma omp parallel for
for( int n = 0; n < m; n ++ ) {
a[n] = n*n;
}
return NULL;
}
int main ( int argc, char **argv )
{
int cycles = 10;
while(cycles--) {
pid_t myp = getpid();
char s[1024];
#if 1
/* this code path has a thread arena leak */
pthread_t thread_id;
pthread_create(&thread_id, NULL, go_omp, NULL);
/* pthread_detach(thread_id); also shows the problem */
pthread_join(thread_id, NULL);
#else
/* this code path doesn't have a thread arena leak */
go_omp(NULL);
#endif
sleep(1);
fprintf(stderr,"%lld\n", (long long)time(0));
snprintf(s,sizeof(s),
"ps -o vsz -o rss -o user -o command -p %lld", (long
long)myp);
system(s);
snprintf(s,sizeof(s),
"pmap -x %lld | grep 65404 | wc -l", (long long)myp);
system(s);
}
return 0;
}
________________________________
From: Beauregard,Christophe (ECCC) <[email protected]>
Sent: Monday, June 5, 2023 08:58
To: László Böszörményi (GCS) <[email protected]>; Bob Friesenhahn
<[email protected]>; [email protected]
<[email protected]>
Subject: Re: Bug#1037042: graphicsmagick: GetImageDepth has a thread arena and
memory leak
>Do you think it might be a problem with another system component, a
GCC optimization or this is fixed meanwhile?
I'm not sure. It took me most of a week to even properly isolate the problem
and find a repeatable test case on that one machine, and even then I feel like
it's still a moving target.
I've done more poking and it's not 100% exclusive to GetImageDepth(). In fact,
I'm seeing the problem now if I comment out the call to GetImageDepth() (but in
my original application, ReadImage() without GetImageDepth() in another code
path isn't enough to trigger the bug).
My working theory is something about how GM uses the OpenMP/libgomp API is
tickling a bug in a code path that's only seen with certain CPU/memory configs.
The questions I can't answer are (a) is there possibly something
incomplete/incorrect in how GM uses OpenMP which could lead to this sort of
bug? and (b) just how deep does this rabbit hole go (glibc? kernel?)?
I'm starting to think that I might need to peel off a machine from the
development cluster and investigate whether I can reproduce the error in a
container, at which point I can play around with different configurations of
libraries, compilers, etc.
c.
________________________________
From: László Böszörményi (GCS) <[email protected]>
Sent: Sunday, June 4, 2023 06:25
To: Bob Friesenhahn <[email protected]>; [email protected]
<[email protected]>
Cc: Beauregard,Christophe (ECCC) <[email protected]>
Subject: Re: Bug#1037042: graphicsmagick: GetImageDepth has a thread arena and
memory leak
[You don't often get email from [email protected]. Learn why this is important at
https://aka.ms/LearnAboutSenderIdentification ]
Hi,
On Sat, Jun 3, 2023 at 8:30 PM Bob Friesenhahn
<[email protected]> wrote:
> I am definitely able to confirm that memory consumption builds due to
> invoking GetImageDepth() via a POSIX thread. The rate that it builds
> is image sensitive since some images cause GetImageDepth() to perform
> more OpenMP loops.
Unfortunately I can not reproduce. My processor is an Intel K variant
CPU, six cores and twelve threads, 64 Gb of RAM.
GM is 1.3.40 with two security fixes backported, compiled with GCC
v12.2.0. Tried with three PNG images, all memory consumption is static
from the beginning. Do I need some special case of PNG files to
experience this issue?
> My own testing is under Ubuntu 20.04 using GCC 10.
Do you think it might be a problem with another system component, a
GCC optimization or this is fixed meanwhile? At least I do wonder why
this issue is CPU / machine dependent.
Regards,
Laszlo/GCS
