Ignore SIGCHLD to avoid zombies.

bin/pt-kill

@@ -3622,6 +3622,14 @@ sub main {
          . " at " . ($o->get('interval') || 0) . " second intervals");
    }
 
+   # We don't care about the executed command, and we don't want
+   # to wait for it, so we ignore dead children so we don't have
+   # to reap them and they won't become zombies.
+   # https://bugs.launchpad.net/percona-toolkit/+bug/919819
+   if ( $o->get('execute-command') ) {
+      $SIG{CHLD} = 'IGNORE';
+   }
+
    while ( (!$run_time || $now < $end) && !-f $sentinel ) {
       msg('Checking processlist');
       my $proclist;

t/pt-kill/execute_command.t

@@ -9,7 +9,7 @@ BEGIN {
 use strict;
 use warnings FATAL => 'all';
 use English qw(-no_match_vars);
-use Test::More tests => 4;
+use Test::More tests => 8;
 
 use PerconaTest;
 use Sandbox;
@@ -19,59 +19,103 @@ my $dp = new DSNParser(opts=>$dsn_opts);
 my $sb = new Sandbox(basedir => '/tmp', DSNParser => $dp);
 my $master_dbh = $sb->get_dbh_for('master');
 
-
 my $output;
-my $cnf='/tmp/12345/my.sandbox.cnf';
+my $cnf ='/tmp/12345/my.sandbox.cnf';
 my $cmd = "$trunk/bin/pt-kill -F $cnf -h 127.1";
+my $out = "/tmp/mk-kill-test.txt";
 
 # #############################################################################
 # Test --execute-command action.
 # #############################################################################
-diag(`rm -rf /tmp/mk-kill-test.txt`);
+diag(`rm $out 2>/dev/null`);
 
-$output = `$cmd $trunk/t/lib/samples/pl/recset001.txt --match-command Query --execute-command 'echo hello > /tmp/mk-kill-test.txt'`;
+$output = `$cmd $trunk/t/lib/samples/pl/recset001.txt --match-command Query --execute-command 'echo hello > $out'`;
 is(
    $output, 
    '',
    'No output without --print'
 );
 
-chomp($output = `cat /tmp/mk-kill-test.txt`),
+chomp($output = `cat $out`),
 is(
    $output,
    'hello',
    '--execute-command'
 );
 
-diag(`rm -rf /tmp/mk-kill-test.txt`);
+diag(`rm $out`);
 
 SKIP: {
    skip 'Cannot connect to sandbox master', 2 unless $master_dbh;
 
-   system("/tmp/12345/use -e 'select sleep(2)' >/dev/null 2>&1 &");
+   system "/tmp/12345/use -e 'select sleep(2)' >/dev/null 2>&1 &";
+
+   $output = `$cmd --match-info 'select sleep' --run-time 2 --interval 1 --print --execute-command 'echo batty > $out'`;
 
-   $output = `$cmd --match-info 'select sleep' --run-time 2 --interval 1 --print --execute-command 'echo batty > /tmp/mk-kill-test.txt'`;
    like(
       $output,
       qr/KILL .+ select sleep\(2\)/,
       '--print with --execute-command'
    );
 
-   chomp($output = `cat /tmp/mk-kill-test.txt`),
+   chomp($output = `cat $out`);
    is(
       $output,
       'batty',
       '--execute-command (online)'
    );
-   
+
    # Let our select sleep(2) go away before other tests are ran.
    sleep 1;
-}
+   diag(`rm $out`);
 
-diag(`rm -rf /tmp/mk-kill-test.txt`);
+   # Don't make zombies (https://bugs.launchpad.net/percona-toolkit/+bug/919819)
+   system "/tmp/12345/use -e 'select sleep(2)' >/dev/null 2>&1 &";
+
+   my $sentinel = "/tmp/pt-kill-test.$PID.stop";
+   my $pid_file = "/tmp/pt-kill-test.$PID.pid";
+   my $log_file = "/tmp/pt-kill-test.$PID.log";
+   diag(`rm $sentinel 2>/dev/null`);
+   diag(`rm $pid_file 2>/dev/null`);
+   diag(`rm $log_file 2>/dev/null`);
+
+   `$cmd --daemonize --match-info 'select sleep' --interval 1 --print --execute-command 'echo zombie > $out' --verbose --pid $pid_file --log $log_file --sentinel $sentinel`;
+   sleep 1;
+   $output = `grep Executed $log_file`;
+   like(
+      $output,
+      qr/Executed echo zombie/,
+      "Executed zombie command"
+   );
+
+   $output = `ps x | grep Z | grep -v grep`;
+   is(
+      $output,
+      "",
+      "No zombies"
+   );
+
+   diag(`touch $sentinel`);
+   sleep 1;
+   ok(
+      !-f $pid_file,
+      "pt-kill stopped"
+   );
+   $output = `ps x | grep Z | grep -v grep`;
+   is(
+      $output,
+      "",
+      "No zombies"
+   );
+
+   diag(`rm $sentinel 2>/dev/null`);
+   diag(`rm $pid_file 2>/dev/null`);
+   diag(`rm $log_file 2>/dev/null`);
+}
 
 # #############################################################################
 # Done.
 # #############################################################################
+diag(`rm $out 2>/dev/null`);
 $sb->wipe_clean($master_dbh) if $master_dbh;
 exit;