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mitigate child processes with 100% CPU and/or zombies #76

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42daff7
mitigate child processes with 100% CPU and/or zombies
mmitch Apr 30, 2014
7e976ff
rely on Irssi::pidwait_add() and don't reap anything manually
mmitch May 2, 2014
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38 changes: 27 additions & 11 deletions twirssi.pl
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Original file line number Diff line number Diff line change
Expand Up @@ -2515,9 +2515,6 @@ sub monitor_child {
}
&debug("checking child log at $filename [$file_progress v $prev_mtime] ($attempts_to_go)");

# reap any random leftover processes - work around a bug in irssi on gentoo
waitpid( -1, WNOHANG );

# first time we run we don't want to print out *everything*, so we just
# pretend

Expand All @@ -2537,9 +2534,11 @@ sub monitor_child {
Irssi::timeout_add_once( $wait_time, 'monitor_child',
[ $filename, $attempts_to_go - 1, $wait_time, $is_update, $filename_tmp, $this_mtime ] );
} else {

&notice([ 'error' ], "Giving up on polling=$filename child_pid=$child_pid parent_pid=$$");

&debug("Giving up on polling $filename");
Irssi::pidwait_remove($child_pid);
waitpid( -1, WNOHANG );
remove_child($child_pid);
unlink $filename unless &debug();

if (not $is_update) {
Expand Down Expand Up @@ -2714,12 +2713,7 @@ sub monitor_child {
# file was opened, so we tried to parse...
close $fh;

# make sure the pid is removed from the waitpid list
Irssi::pidwait_remove($child_pid);

# and that we don't leave any zombies behind, somehow
waitpid( -1, WNOHANG );

remove_child($child_pid);
&debug("new last_poll = $last_poll{__poll}",
"new last_poll_id = " . Dumper( $state{__last_id} )) if $is_update;
if ($is_update and $first_call and not $settings{force_first}) {
Expand Down Expand Up @@ -2771,6 +2765,28 @@ sub monitor_child {
}
}

sub remove_child {
my $child_pid = shift;

# Check if the child is still running. (Look for PID with ourself as parent PID)
# If it is: kill it.
# There is the probability of a race-condition, but how to do it right[tm]?

# BEWARE: UGLY DIRTY HACK, shell code, unix only -> translate this to Perl!
# perhaps use Process::Table?
my $ps_cmdline = "ps --format pid= --ppid $$";
my @child_pids = split /\s+/, `$ps_cmdline`;
# &notice([ 'error' ], "remove_child: child_pid=<${child_pid}> ps_cmdline=<${ps_cmdline}> ps_output=<".join(', ', @child_pids).">");
foreach my $pid (@child_pids) {
if ($pid == $child_pid) {
&notice([ 'error' ], "remove_child: child was still running, killing it now! child_pid=$child_pid parent_pid=$$");
kill 15, $child_pid;
last;
}
}

}

sub cmp_id {
my $id1 = shift;
my $id2 = shift;
Expand Down