I am posting this question again as it was sent before the long weekend
and didn't see any responses so far. Can anyone please explain the
discrepancy I am observing with the scenario explained in the post
below?
Thanks
Ananda
Sent: Tuesday, November 23, 2010 2:24 PM
To: de...@open-mpi.org
Subject: Warning on fork() disappears if I use MPI threads!!
Hi
I am running into a very wierd problem.
If I initialize MPI normally ie; with MPI_Init(), and make one of the
MPI process to do "popen()" call, I get the following warning/error
message:
== Message start ===
An MPI process has executed an operation involving a call to the
"fork()" system call to create a child process. Open MPI is currently
operating in a condition that could result in memory corruption or
other system errors; your MPI job may hang, crash, or produce silent
data corruption. The use of fork() (or system() or other calls that
create child processes) is strongly discouraged.
== Message end ====
However this error message goes away, if I initialize MPI with threads
ie; MPI_Init_thread(). Can anyone explain this discrepancy?
I am giving a snippet of the program that causes this problem:
== Code snippet start ======
if ( rank == 0) {
output = popen("ls -l", "r");
while((c=getc(output))!=EOF)
printf("%c",c);
pclose(output);
}
== Code snippet end ======
If this is a design constraint, how can I overcome this problem.
Thanks
Ananda
Ananda B Mudar, PMP
Senior Technical Architect
Wipro Technologies
Ph: 972 765 8093
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