Bug 72881

i am using kernel 2.4.9-31. i have tried different variations of trying to get this to work. all of these variants work on solaris, but none work on linux. this process is a 
server that accepts connections from clients and attempts to fork a process to handle the client's requests. i have a version that actually just uses threads to handle 
the client requests. the problem is that some vendor software that we use is not the most stable and occasionallly cores, thus bringing down the entire process and 
all connected clients. i am attempting to try this approach so that each client is independent of the other.

Hi 
I am encountering the same problem and I am adding a source program that 
simulates the problem and the sample output.

Please compile this sample program and you will notice the problem...
If you comment out the lines that create the pthread the execvp will work
successfully

***********Program Start**********************************************
#include <iostream.h>
#include <stdlib.h>
#include <unistd.h>
#include <pthread.h>

void* monitorProcess(void *objProcessMgr)
{
   int icount;
   for (int icount=0;icount<20;icount++)
     {
       cout << "Printing in another thread in 4 secs \n" << endl;
       sleep(4);
     }
   return 0;
}


//
// Main
//

int main(void)
{
         pid_t pid;
	pthread_t m_MonitorThreadId;
	pthread_create(&m_MonitorThreadId,NULL,monitorProcess,NULL);
	void * retval;

         if ((pid = fork()) < 0)
         {
                 cerr << "Error creating fork" << endl;
         }
         else if (pid == 0)
         {
                 // This is the child process
	  char* argv[3] ={"Hello","World",NULL} ;
	  cout << "The PID of the child process is " << getpid() << endl;
	  execvp ("/home/krush/code/test/Printargs",argv);
	  cout << "Unknown command" << endl;
	  exit(0);
         }
         else
         {
                 // This is the parent process
                 cout << "The PID of the parent process is " << getpid() << 
endl;
         }
	// Line 2
	pthread_join(m_MonitorThreadId,&retval);

         return(0);
}
****************Program Ends********************************************
Program Output
root> ./forkThread
The PID of the child process is 12238
The PID of the parent process is 12238


Ps Output


000 S root     12235  1322  0  69   0    -  3061 rt_sig 22:37 pts/1
00:00:00 ./forkThread
044 Z root     12236 12235  0  69   0    -     0 do_exi 22:37 pts/1    
00:00:00
[forkThread <defunct>]
040 S root     12238 12235  0  69   0    -  3061 rt_sig 22:37 pts/1
00:00:00 ./forkThread
000 S root     12555 12132  0  72   0    -   433 pipe_w 23:04 pts/2    
00:00:00
grep fork

The behaviour of fork() with POSIX threads is undefined.  Do not depend on this
behaviour in your programs.

Actually, glibc's info pages document the behaviour of only copying the thread
that is currently executing.  info libc and look for Threads and Fork.

Ben

Thanks for the info, but if you notice that in the sample program that I have 
attached I am creating the fork in the main thread and not in the other thread.

Is this a problem in this version of the kernel or is it present in all 
versions. Is there an alternative approach that can solve this problem....

Krush

Try using RHL9 with NPTL (the default thread library).

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