kde-malloc pthread and system() hang

[Sancho Dauskardt]

Hi,

  calling system() from a thread using the kde-code malloc occasionally hangs.
KDE_MALLOC=0 seems to solve the problem (but breaks other thing).

Adding the code below to any simple KDE3 app (KDevelop kde-sdi skeleton) 
reproducibly causes this problem.

Running normally, is will start a master thread (to sepperate it from the 
GUI) which in turn starts 8 threads, each constantly doing system("echo im 
running..."). The master displays the success/failure counters of its slaves.
With KDE_MALLOC=0 all slave will be more-or-less equally outputing that 
they are running.
With KDE_MALLOC=1 the slaves start to hang. Connecting gdb to such a thread 
reveals that it's stuck in kde-cores malloc() of free().

Environment: out-of-the-box SuSE 8.0 & 8.1 (KDE 3.0.1 & 3.0.3).

Following code by it self (linked to kdecore, but no KApplication running) 
will NOT produce the hang. The App also needs to do some memory allocation 
(ie. opening / closing popup menus, etc.).

I managed to reproduce this running valgrind (takes ages), but didn't get 
any complaints.

Is KDE_MALLOC=0 still 'supported' and supposed to work ??

- sda


----- snip ----
#include <stdlib.h>
#include <stdio.h>
#include <pthread.h>
#include <unistd.h>

//
const int THREAD_CNT    = 8;

pthread_t       Threads[THREAD_CNT];
int             ThreadOks[THREAD_CNT];
int             ThreadFails[THREAD_CNT];

void *ThreadProc(void *arg)
{
         int     num = (int)arg;
         for(;;){
                 char    Str[256];

                 sprintf(Str,"echo \"%d(%d) live.\"\n",num,getpid());

                 if( 0 == system(Str) )
                         ThreadOks[num]++;
                 else
                         ThreadFails[num]++;
         }
         return (void *)0;
}

void *ThreadMain(void *arg)
{
         int     i;

         for(i=0;i<THREAD_CNT;i++){

                 if( 0 != pthread_create(&Threads[i],0,ThreadProc,(void*)i) ){
                         printf("Thread %d create failed.\n",i);
                         return (void *)1;
                 }

         }

         fprintf(stderr,"Created %d threads.\n",i);

         for(;;){
                 sleep(1);

                 for(i=0;i<THREAD_CNT;i++)
                         fprintf(stderr,"%d/%d 
",ThreadOks[i],ThreadFails[i]);

                 fprintf(stderr,"\n");
         }

         return (void *)EXIT_SUCCESS;
}

int main(int argc, char *argv[])
{
	...
         pthread_t       MainThreadID;
         pthread_create(&MainThreadID,0,ThreadMain,(void*)0);
	..
         app.exec();
}