[Bug 406397] Re: init: job stuck with expect fork/daemon when parent reaps child

[J G Miller]

This issue also seems to be the cause of difficulties with minidlna if
the -R flag is added to rescan the media files directory because
minidlnad creates an additional process to do the rescanning.  So if
expect daemon is used for the two process at startup, then the shutdown
runs into difficulties because there is only one process to be killed,
the rescan process having ended by itself.

So until a fix is found for upstart, users should be advised not to add
-R for rescan to the upstart configuration file, and that if they need
to do a rescan at startup, use the traditional sysV  rc init.d script
and not upstart to start and stop the daemon.

It would also be very useful if there was some initctl command to wipe that state of service jobs which are in a bad state eg
 minidlna stop/killed, process 5114  or minidlna start/killed, process 5114
since once the upstart job gets into this state, using start or stop results in upstart hanging on

connect(3, {sa_family=AF_FILE, path=@"/com/ubuntu/upstart"}, 22) = 0
fcntl64(3, F_GETFL)                     = 0x2 (flags O_RDWR)
fcntl64(3, F_SETFL, O_RDWR|O_NONBLOCK)  = 0
geteuid32()                             = 0
getsockname(3, {sa_family=AF_FILE, NULL}, [2]) = 0
poll([{fd=3, events=POLLOUT}], 1, 0)    = 1 ([{fd=3, revents=POLLOUT}])
send(3, "\0", 1, MSG_NOSIGNAL)          = 1
send(3, "AUTH EXTERNAL 30\r\n", 18, MSG_NOSIGNAL) = 18
poll([{fd=3, events=POLLIN}], 1, -1)    = 1 ([{fd=3, revents=POLLIN}])
read(3, "OK 37d274edad794a392790c969525d3"..., 2048) = 37
poll([{fd=3, events=POLLOUT}], 1, -1)   = 1 ([{fd=3, revents=POLLOUT}])
send(3, "NEGOTIATE_UNIX_FD\r\n", 19, MSG_NOSIGNAL) = 19
poll([{fd=3, events=POLLIN}], 1, -1)    = 1 ([{fd=3, revents=POLLIN}])
read(3, "AGREE_UNIX_FD\r\n", 2048)      = 15
poll([{fd=3, events=POLLOUT}], 1, -1)   = 1 ([{fd=3, revents=POLLOUT}])
send(3, "BEGIN\r\n", 7, MSG_NOSIGNAL)   = 7
poll([{fd=3, events=POLLIN|POLLOUT}], 1, -1) = 1 ([{fd=3, revents=POLLOUT}])
sendmsg(3, {msg_name(0)=NULL, msg_iov(2)=[{"l\1\2\1\r\0\0\0\1\0\0\0_\0\0\0\1\1o\0\23\0\0\0/com/ubu"..., 112}, {"\10\0\0\0minidlna\0", 13}], msg_controllen=0, msg_flags=0}, MSG_NOSIGNAL) = 125
clock_gettime(CLOCK_MONOTONIC, {13369, 479497006}) = 0
poll([{fd=3, events=POLLIN}], 1, 25000) = 1 ([{fd=3, revents=POLLIN}])
recvmsg(3, {msg_name(0)=NULL, msg_iov(1)=[{"l\2\1\1&\0\0\0\1\0\0\0\17\0\0\0\5\1u\0\1\0\0\0\10\1g\0\1o\0\0"..., 2048}], msg_controllen=0, msg_flags=MSG_CMSG_CLOEXEC}, MSG_CMSG_CLOEXEC) = 70
recvmsg(3, 0xbfd42610, MSG_CMSG_CLOEXEC) = -1 EAGAIN (Resource temporarily unavailable)
sendmsg(3, {msg_name(0)=NULL, msg_iov(2)=[{"l\1\2\1\4\0\0\0\2\0\0\0x\0\0\0\1\1o\0!\0\0\0/com/ubu"..., 136}, {"\0\0\0\0", 4}], msg_controllen=0, msg_flags=0}, MSG_NOSIGNAL) = 140
clock_gettime(CLOCK_MONOTONIC, {13369, 504154425}) = 0
poll([{fd=3, events=POLLIN}], 1, 25000) = 1 ([{fd=3, revents=POLLIN}])
recvmsg(3, {msg_name(0)=NULL, msg_iov(1)=[{"l\2\1\1(\0\0\0\2\0\0\0\17\0\0\0\5\1u\0\2\0\0\0\10\1g\0\1o\0\0"..., 2048}], msg_controllen=0, msg_flags=MSG_CMSG_CLOEXEC}, MSG_CMSG_CLOEXEC) = 72
recvmsg(3, 0xbfd425d0, MSG_CMSG_CLOEXEC) = -1 EAGAIN (Resource temporarily unavailable)
sendmsg(3, {msg_name(0)=NULL, msg_iov(2)=[{"l\1\2\1\10\0\0\0\3\0\0\0q\0\0\0\1\1o\0!\0\0\0/com/ubu"..., 136}, {"\0\0\0\0\1\0\0\0", 8}], msg_controllen=0, msg_flags=0}, MSG_NOSIGNAL) = 144
clock_gettime(CLOCK_MONOTONIC, {13369, 509531849}) = 0
poll([{fd=3, events=POLLIN}], 1, -1)    = 1 ([{fd=3, revents=POLLIN}])
recvmsg(3, {msg_name(0)=NULL, msg_iov(1)=[{"l\4\1\1\t\0\0\0\3\0\0\0w\0\0\0\1\1o\0#\0\0\0/com/ubu"..., 2048}], msg_controllen=0, msg_flags=MSG_CMSG_CLOEXEC}, MSG_CMSG_CLOEXEC) = 145
recvmsg(3, 0xbfd42700, MSG_CMSG_CLOEXEC) = -1 EAGAIN (Resource temporarily unavailable)
clock_gettime(CLOCK_MONOTONIC, {13369, 516260329}) = 0
poll([{fd=3, events=POLLIN}], 1, -7)    = ? ERESTART_RESTARTBLOCK (To be restarted)

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https://bugs.launchpad.net/bugs/406397

Title:
  init: job stuck with expect fork/daemon when parent reaps child

Status in Upstart:
  Triaged
Status in “upstart” package in Ubuntu:
  Invalid
Status in “upstart” package in Debian:
  Confirmed
Status in PLD Linux Distribution:
  New

Bug description:
  Hi

  Wrong use of the expect fork stanza can create job with status
    job stop/killled, process nnn
  without any process nnn running on the system.

  As an example the following avahi.conf should have used
  "expect daemon", but will instead create a stuck job.

  stop on stopping dbus-system
  respawn
  expect fork
  exec avahi-daemon -D

  /Emil Renner Berthing

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