How to increase number of threads per process?
 

When I run the following code on linux it creates only 306 threads and exits.What should I do to increase threads per process?


* compile with: gcc -lpthread -o thread-limit thread-limit.c */
/* originally from:*/

#include <stdio.h>
#include <unistd.h>
#include <pthread.h>

#define MAX_THREADS 10000
int i;

void run(void) {
char c;
if (i < 10)
printf("Address of c = %u KB\n", (unsigned int) &c / 1024);
sleep(60 * 60);
}

int main(int argc, char *argv[]) {
int rc = 0;
pthread_t thread[MAX_THREADS];
printf("Creating threads ...\n");
for (i = 0; i < MAX_THREADS && rc == 0; i++) {
rc = pthread_create(&(thread[i]), NULL, (void *) &run, NULL);
if (rc == 0) {
pthread_detach(thread[i]);
if ((i + 1) % 100 == 0)
printf("%i threads so far ...\n", i + 1);
}
else
printf("Failed with return code %i creating thread %i.\n",
rc, i + 1);
}
exit(0);
}

When i run this program i get the o/p as :

[root@ENTERPRIZE ashish]# ./thread-limit
Creating threads ...
Address of c = 3002970 KB
Address of c = 2992726 KB
Address of c = 2982482 KB
Address of c = 2972238 KB
Address of c = 2961994 KB
Address of c = 2951750 KB
Address of c = 2941506 KB
Address of c = 2931262 KB
Address of c = 2921018 KB
Address of c = 2910774 KB
100 threads so far ...
200 threads so far ...
300 threads so far ...
Failed with return code 12 creating thread 306.
[root@ENTERPRIZE ashish]#

What should I do to increase this?

Thanks & Regards
Ashish Borkar

There is a thread on this somewhere that said RH inherently didn't allow many threads. I think its in the programming forum.

I run Slack 9.1 and get 1533

That would be the reason *if* you run RH.

Found it: http://www.linuxquestions.org/questi...aximum+threads

Address of c = 1130590 KB
100 threads so far ...
200 threads so far ...
Failed with return code 12 creating thread 256.

Hey, at least you got a few more threads. I have a 2.6.5 kernel I compiled, however, my gcc/glib is from Fedora FC2/rpm'd in. I've tried playing with some of the things I found on the net, such as /etc/security/limits.conf and ulimit -u, but none of those work. I ran in to a problem once where I ran out of processes for something, so this has been one of those things that I've always had on the back burner to figure out.

I get 1533 as well on Slack 9.1

--Shade

the way to change the pthread limit is to change the
ulimit stack_size

my ulimit -s was 10240 and I got something like 306 threads.
I changed ulimit -s to 1024 now I can create 3066 threads. Nice.

I just add ulimit -s 1024 to the .bash_profile.

same problem with num of working threads
 

Hi

Im trying to run 600 threads, but only 381 threads are creating. I did ulimit -s 1024.. but still Im getting same problem.

pls suggest any other way to increase number of threads.

How to increase number of Threads?
 

Hello,

I am also stuck at number '381'...

But I am exiting every newly created thread soon after creation.
According to me, there should not be 381 threads running at the same time as all are exited very soon.

My Code:
--------

void *receive(void *dummy)
{
pthread_t thread_idd;

while(1)
{
...
//Create a new thread to echo the data to the same host
err = pthread_create( &thread_idd, NULL, transmit, rx );
perror("Threadcreate ");
}

}

void *transmit(packet *tx)
{
void *dummy;

// Transmit the received datagram to the same host
txcount = sendto( sd, (*tx).data, (*tx).count, 0, &((*tx).host),(*tx).len );
...

pthread_exit(dummy);
}
}

Solution...
 

Hello All,

Even though we exit the thread, the threadi id is not released. Hence, if you are not waiting for the thread, use pthread_detach(tid) just after creating the thread. This will let you have as many threads as you want...

Code:
err = pthread_create( &thread_idd, NULL, transmit, rx );
perror("Threadcreate ");
err = pthread_detach(thread_idd);
perror("Threaddetach ");


Cheers!

Hi..

The problem is not actually with number of threads.. It is with the stack size.
so reduce ur stacksize per thread using

but be careful ur stack is not using more than 1024 bytes.
Have a good day..