[GHC] #10081: SIGTERM ignored when process has been detached from terminal

11 Feb 2015

      #10081: SIGTERM ignored when process has been detached from terminal
-------------------------------------+-------------------------------------
              Reporter:  nakal       |             Owner:
                  Type:  bug         |            Status:  new
              Priority:  normal      |         Milestone:
             Component:              |           Version:  7.8.3
  libraries/unix                     |  Operating System:  FreeBSD
              Keywords:              |   Type of failure:  Incorrect result
          Architecture:  x86_64      |  at runtime
  (amd64)                            |        Blocked By:
             Test Case:              |   Related Tickets:
              Blocking:              |
Differential Revisions:              |
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 I've tried to write a simple Unix daemon that reacts to signals. Here is
 the reduced source code sample:

 {{{#!hs
 import Control.Concurrent
 import Control.Monad
 import System.Exit
 import System.IO
 import System.Posix.Signals

 loop = forever $ threadDelay 1000000

 main = do
         ppid <- myThreadId
         mapM (\sig -> installHandler sig (Catch $ trap ppid) Nothing)
                 [ lostConnection, keyboardSignal, softwareTermination,
 openEndedPipe ]
         loop

 trap tid = do
         hPutStrLn stderr "Signal received.\n"
         throwTo tid ExitSuccess
 }}}

 Such daemons usually run in background without a terminal attached. I
 verified that I can kill the process after being started on the terminal:

 {{{
...
./daemon
 Signal received.
 }}}
With:
 {{{
...
killall daemon
 }}}
in other terminal.

 Other test, when I run it in background:
 {{{
...
./daemon
 (press Ctrl+Z)
bg
killall daemon
 Signal received.
 }}}
This case is also ok. Now the third test which is also OK:

 {{{
...
./daemon > log 2>&1
 (press Ctrl+Z)
bg
exit
 }}}
In second terminal:
 {{{
...
cat log
killall daemon
cat log
 Signal received.
...
killall daemon
 No matching processes belonging to you were found
 }}}
Now the fourth test which is simply without a log file and this one fails:
 {{{
...
./daemon
 (press Ctrl+Z)
bg
exit
 }}}
On some other terminal try to kill the process:
 {{{
...
killall xxx
killall xxx
killall xxx
killall -9 xxx
killall xxx
 No matching processes belonging to you were found
 }}}
Signal 9 (SIGKILL) kills the process hard without the signal trap. That's
 why it works, of course, but SIGTERM is being ignored for some reason.
 Maybe I am forgetting something, but in my opinion this should end the
 process properly, too.

--
Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10081
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