Re: How to kill runsv, no matter what?

[Gerrit Pape <pape@smarden.org>]

On Thu, Feb 22, 2007 at 10:51:50PM -0500, Daniel Clark wrote:
> I made a simple test case that should make this bug (or my error in
> using the software) easy to reproduce. I'm attaching it since it is so
> tiny; it is also available from
> http://opensysadmin.com/bugs/runit/test1-service.tar.bz2
> 
> Below is a transcript of using it to demonstrate the problem:
> 
> root@cmlab:/tmp# tar xfj test1-service.tar.bz2
> root@cmlab:/tmp# cd test1-service/
> root@cmlab:/tmp/test1-service# ./runsvdir-here
> ^C
> root@cmlab:/tmp/test1-service# ps auxw | grep [s]v
> root     19882  0.0  0.0   2516   348 ?        Ss   22:28   0:00 runsv
> test1-service
> root     19883  0.0  0.0   2656   368 ?        S    22:28   0:00
> /usr/local/bin/svlogd -tt ./logs
> root     19884  0.0  0.0  10060  1408 ?        S    22:28   0:00
> /bin/sh ./test1-sv.sh
> root@cmlab:/tmp/test1-service# sv exit
> /tmp/test1-service/var-service/test1-service
> root@cmlab:/tmp/test1-service# sleep 7
> root@cmlab:/tmp/test1-service# ps auxw | grep [s]v
> root     19882  0.0  0.0   2516   348 ?        Ss   22:28   0:00 runsv
> test1-service
> root     19883  0.0  0.0   2656   368 ?        S    22:28   0:00
> /usr/local/bin/svlogd -tt ./logs
> root@cmlab:/tmp/test1-service# rm var-service/test1-service
> root@cmlab:/tmp/test1-service# sleep 7
> root@cmlab:/tmp/test1-service# ps auxw | grep [s]v
> root     19882  0.0  0.0   2516   348 ?        Ss   22:28   0:00 runsv
> test1-service
> root     19883  0.0  0.0   2656   368 ?        S    22:28   0:00
> /usr/local/bin/svlogd -tt ./logs
> 
> (I would think runsv and svlogd should not be showing up here, because
> runsvdir is no longer running, sv exit has been called, and the run
> director has been removed, with >5 second pauses between the removal
> and the ps)

When asked to exit, the runsv supervisor makes sure that all logs are
written to the log service before terminating; it first sends TERM to
the main service, then waits for it to terminate, and finally waits for
the log service to terminate, before runsv exits itself.

In the case of your example service, the main run script execs into a
shell script that starts a 'sleep' subprocess.  Now when runsv is told
to exit, it sends the service (the ./test1-sv.sh shell script) a TERM
signal, the shell script terminates (fine), but is leaving behind the
'sleep' subprocess.  The log service's run script execs into a svlogd
process, svlogd will terminate as soon as it sees end-of-file on the
pipe connected to its standard input.  Because there's still the 'sleep'
subprocess running with its output connected to the pipe, and so to
svlogd's standard input, svlogd will wait; it might well be that there's
still data available on the pipe to be written to the logs.  Once the
'sleep' subprocess exits, runsv should exit too.

HTH, Gerrit.