Pigeonhole External pipe script going zombie?

[Matt Simpson]

I’m running dovecot 2.2.27 and pigeonhole 0.4.16 on FreeBSD 11.

I’m using the pigeonhole/sieve external pipe plugin to run a Perl program to send a Pushover notification when certain messages are received.

The Perl script is executed, and the notification is sent.  But then the script task seems to go zombie until it is killed after a timeout.

In the user’s sieve log, I get a message like

error: msgid=<20170112191921.66140.qmail at v1.redhorse.me>: pipe action: failed to pipe message to program `sievepush.pl': refer to server log for more information. [2017-01-12 14:19:36].

(even though the message really was piped to the program successfully)

In the dovecot server log, I see

Jan 12 14:19:21 v1 dovecot: lda(matt): Debug: sieve: Executing script from `/usr/home/matt/maildoms/.dovecot.svbin'
Jan 12 14:19:21 v1 dovecot: lda(matt): Debug: sieve: action pipe: running program: sievepush.pl
Jan 12 14:19:21 v1 dovecot: lda(matt): Debug: Mailbox stdin: Opened mail UID=1 because: mail stream
Jan 12 14:19:21 v1 dovecot: lda(matt): Debug: waiting for program `/usr/local/lib/dovecot/sieve-pipe/sievepush.pl' to finish after 0 msecs
Jan 12 14:19:31 v1 dovecot: lda(matt): Debug: program `/usr/local/lib/dovecot/sieve-pipe/sievepush.pl'(66145) execution timed out after 10000 milliseconds: sending TERM signal
Jan 12 14:19:36 v1 dovecot: lda(matt): Debug: program `/usr/local/lib/dovecot/sieve-pipe/sievepush.pl' (66145) did not die after 5000 milliseconds: sending KILL signal

In the process list during that 10 second interval, I see

matt     66142 29972   801   801    0 S     -      0:00.00 bin/qmail-local -- matt /home/matt/maildoms jmn-matt - jmn-m
matt     66143 66142   801   801    0 S     -      0:00.00 /var/qmail/bin/preline -f /usr/local/libexec/dovecot/dovecot
matt     66144 66143   801   801    0 S     -      0:00.01 /usr/local/libexec/dovecot/dovecot-lda
matt     66145 66144   801   801    0 Z     -      0:00.65 <defunct>

I’m not a Unix programming ace, but from what I’ve been able to find out, this seems to mean that the lda process is forking another process to run the pipe script, and not getting the proper notification when it finishes (not issuing a wait?).   So after 10 seconds, it sends a TERM to the task which is no longer running, and when that doesn’t work, it sends a KILL.  Anybody know what’s happening here?

doveconf -n
# 2.2.27 (c0f36b0): /usr/local/etc/dovecot/dovecot.conf
# Pigeonhole version 0.4.16 (fed8554)
# OS: FreeBSD 11.0-RELEASE-p2 amd64
auth_verbose = yes
default_vsz_limit = 128 M
lock_method = flock
mail_debug = yes
mail_location = maildir:~/Maildir
mail_privileged_group = mail
managesieve_notify_capability = mailto
managesieve_sieve_capability = fileinto reject envelope encoded-character vacation subaddress comparator-i;ascii-numeric relational regex imap4flags copy include variables body enotify environment mailbox date index ihave duplicate mime foreverypart extracttext vnd.dovecot.pipe vnd.dovecot.execute
namespace inbox {
  inbox = yes
  location =
  prefix =
}
passdb {
  args = imap
  driver = pam
}
plugin {
  recipient_delimiter = -
  sieve = file:~/sieve;active=~/.dovecot.sieve
  sieve_execute_bin_dir = /usr/local/lib/dovecot/sieve-pipe
  sieve_extensions = +vnd.dovecot.pipe +vnd.dovecot.execute
  sieve_pipe_bin_dir = /usr/local/lib/dovecot/sieve-pipe
  sieve_pipe_exec_timeout = 10s
  sieve_plugins = sieve_extprograms
}
protocols = imap
service auth {
  unix_listener auth-master {
    group = qnofiles
    mode = 0660
    user = alias
  }
  user = root
}
service imap-login {
  process_min_avail = 3
  vsz_limit = 94 M
}
ssl_cert = </usr/local/etc/letsencrypt/live/dummy.redhorse.me/cert.pem
ssl_key =  # hidden, use -P to show it
syslog_facility = local0
userdb {
  driver = passwd
}
verbose_proctitle = yes
protocol lda {
  mail_plugins = " sieve"
}