Child process limits cumulative or instantaneous?
Child process limits cumulative or instantaneous?
- Subject: Child process limits cumulative or instantaneous?
- From: Ralph Castain <email@hidden>
- Date: Fri, 27 Feb 2009 09:13:00 -0700
Hello folks
I'm the run-time developer for Open MPI and am encountering a resource
starvation problem that I don't understand. What we have is a test
program that spawns a child process, exchanges a single message with
it, and then the child terminates. We then spawn another child process
and go through the same procedure.
This paradigm is typical of some of our users who want to build client-
server applications using MPI. In these cases, they want the job to
run essentially continuously, but have a rate limiter in their
application so only one client is alive at any time.
We have verified that the child processes are properly terminating. We
have monitored and observed that all file descriptors/pipes are being
fully recovered after each cycle.
However, after 263 cycles, the fork command returns an error
indicating that we have exceeded the number of allowed child processes
for a given process. This is fully repeatable, yet the number of child
processes in existence at any time is 1, as verified by ps.
Do you have any suggestions as to what could be causing this problem?
Is the limit on child processes a cumulative one, or instantaneous?
Appreciate any help you can give
Ralph
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