Hang in cr_restart

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From: Karthik Gopalakrishnan (gopalakk_at_cse.ohio-state.edu)
Date: Wed Jan 28 2009 - 18:35:42 PST

  • Next message: Paul H. Hargrove: "Re: Hang in cr_restart" 
    Hello.

I apologize for the long mail in advance. :-)

I have an application which roughly works as follows:

main()
{
    do_cr_initialization();
    do_real_work();
 }

do_real_work()
{
   register(SIGCHLD_Handler);
   fork();
    if (child) {
        do_stuff();
        exit(0);
    }
    while(1);
}

SIGCHLD_Handler()
{
    wait_for_child();
    exit(0);
}

CR_Callback()
{
    if (restarting)
        do_real_work()
}

do_stuff() is intelligent enough to continue from where it left off.
Now, under normal execution, after the do_stuff() completes & exit(0)
is called, SIGCHLD_Handler() is invoked which terminates the
application. However, when cr_restart is called after a checkpoint,
the application just "hangs" after do_stuff() completes the remaining
work & calls exit(0). SIGCHLD_Handler() is not invoked at restart at
all. The output of 'ps' shows the following:

UID        PID  PPID  C STIME TTY      CMD
gopalakk 11886 12020  0 20:30 pts/0    a.out
gopalakk 12020 10333  0 20:30 pts/0    cr_restart context.11886
gopalakk 12026 11886  0 20:30 pts/0    [a.out] <defunct>

Can someone explain what's going on here.

Thanks & Regards,
Karthik
  • Next message: Paul H. Hargrove: "Re: Hang in cr_restart"
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