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intermittent failures on Darwin using java.lang.Process.waitFor()
- From: Geoffrey Keating <geoffk at apple dot com>
- To: gcc at gcc dot gnu dot org, java-patches at gcc dot gnu dot org
- Date: Fri, 29 Sep 2006 12:54:06 -0700
- Subject: intermittent failures on Darwin using java.lang.Process.waitFor()
The intermittent failures on Darwin are due to a kernel bug tripped by
java.lang.Process.waitFor().
The bug appears to be that if:
- the program is multithreaded
- it is blocking SIGCHLD
- it receives a SIGCHLD due to a process terminating
- later it calls sigsuspend (but not sigwait)
then the SIGCHLD may never be delivered, and so the process will wait
for one forever.
It's intermittent because it works fine if the sigsuspend starts
before the SIGCHLD is sent. This also explains why it happens more
often with gij.
I've filed this as <rdar://problem/4736203>. We could work around it
by using a timeout of some kind; for example, creating a new thread
which sends a SIGCHLD manually after some period of time. (Obviously,
only on Darwin, and maybe only on versions with the bug.) Do we think
this is a good idea?
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