in reply to threads - cond_timedwait question

This worked for me:
#!/usr/bin/perl -

use strict;
use warnings;
use threads;
use threads::shared;

my $locked :shared;
lock($locked);
print "locked(main)\n ";

my $thr = async( sub { test() } );
print "starting\n";

my $wait = time() + 15;
until ( my $ok = lock($locked) ) {
    last if !cond_timedwait( $locked, $wait );
}
print "result: timeout\n" if defined $wait;
print "done\n";
exit;

sub test {
    print "started. \n";
    lock($locked);
    print "lock(test)\n ";
    sleep 10;
    print "exiting\n";
  { no warnings 'threads'; cond_signal($locked); }
}

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Re^2: threads - cond_timedwait question
by ethrbunny (Monk) on Dec 31, 2009 at 22:00 UTC
    Now suppose that 'test' was a wedged thread.
    1. Change the 'sleep 10' in 'test' to 'sleep 30'.
    2. Change the 'time() + 15' to 'time() + 5'.
    3. Add a 'print "waiting\n"' before the 'last' statement.


    I would expect the 'cond_timedwait' statement to return after 5 seconds and loop over the 'print ..' statement 5-6 times before the 'test' thread returned. Instead I see the 'test' thread start and block the loop until 'test' finishes.

    Am I completely misunderstanding how this process works?
[reply]
      FWIW: this appears to work at detecting a 'stopped' job. 
      #!/usr/bin/perl -w
use threads;
use Thread::Semaphore;

$mtx = new Thread::Semaphore(2);

$thr0 = async{ test() };
$thr1 = async{ timer( ) };
print "starting\n";
sleep(1);
$v = $mtx->down();

print "test finished 1st\n" if ( $v == 2 );
print "timer finished 1st\n" if ( $v == 1 );

$thr0->detach();
$thr1->detach();

sub test
{
    print " start(test)\n";
    my $d = $mtx->down();

    sleep( 5 );
    
    $mtx->up( 3 );
    print " exit(test)\n";
}

sub timer
{
    print " start(timer)\n";
    my $d = $mtx->down();
    
    sleep( 10 );
    
    $mtx->up( 2 );
    print " exit(timer)\n";
}

 start(test)
starting
 start(timer)
 exit(test)
test finished 1st

      [download]
      Unfortunately this also gives me a 'A thread exited while 2 threads were running.' message at the end. I don't know how big of an issue this is.
[reply]
[d/l]

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