RE: Multiple processes started when explicit start commands areused on dependant processes.

[P Holdaway]

Hi,

  Does this mean that you could indeed reproduce the problem with the
original run.sh script?

  The run.sh script is fairly typical of scripts found in /etc/init.d where
the script exits normally and does not exec.

  Making the change you suggested I now find that I get two processes on
startup.

  Note that I am *not* using "monit start all" to start all the processors
but I am issuing a "monit start" command for each process separately.

  The machine I am using for this testing is a SunBlade 150 with an
UltraSparc IIIi processor @ 650MHz. Perhaps the relative poor performance of
this machine makes the problem more reproducible?

  Conceptually, does the code make an effort to block other start/stop
process commands while the start/stop of a dependency tree is executing?

  Here is the log I see at startup...

[ Jan 30 10:59:24] 'a' start: /tmp/monit/run.sh
[ Jan 30 10:59:24] Monitoring enabled -- service a
[ Jan 30 10:59:24] 'b8' start: /tmp/monit/run.sh
[ Jan 30 10:59:24] Monitoring enabled -- service b8
[ Jan 30 10:59:24] 'b7' start: /tmp/monit/run.sh
[ Jan 30 10:59:24] Monitoring enabled -- service b7
[ Jan 30 10:59:24] 'b6' start: /tmp/monit/run.sh
[ Jan 30 10:59:24] Monitoring enabled -- service b6
[ Jan 30 10:59:24] 'b5' start: /tmp/monit/run.sh
[ Jan 30 10:59:24] Monitoring enabled -- service b5
[ Jan 30 10:59:24] 'b4' start: /tmp/monit/run.sh
[ Jan 30 10:59:24] Monitoring enabled -- service b4
[ Jan 30 10:59:24] 'b3' start: /tmp/monit/run.sh
[ Jan 30 10:59:24] Monitoring enabled -- service b3
[ Jan 30 10:59:24] 'b2' start: /tmp/monit/run.sh
[ Jan 30 10:59:24] Monitoring enabled -- service b2
[ Jan 30 10:59:24] 'b1' start: /tmp/monit/run.sh
[ Jan 30 10:59:24] Monitoring enabled -- service b1
[ Jan 30 10:59:24] 'b1' start: /tmp/monit/run.sh
[ Jan 30 10:59:24] monit: Process already running -- process b2
[ Jan 30 10:59:24] monit: Process already running -- process b3
[ Jan 30 10:59:24] monit: Process already running -- process b4
[ Jan 30 10:59:24] monit: Process already running -- process b5
[ Jan 30 10:59:24] monit: Process already running -- process b6
[ Jan 30 10:59:24] monit: Process already running -- process b7
[ Jan 30 10:59:24] monit: Process already running -- process b8


Regards,

  Peter
  

> -----Original Message-----
> From: address@hidden
> [mailto:address@hidden
> On Behalf Of Jan-Henrik Haukeland
> Sent: Saturday, 28 January 2006 4:48 PM
> To: This is the general mailing list for monit
> Subject: Re: Multiple processes started when explicit start commands
> areused on dependant processes.
> 
> 
> On 27. jan. 2006, at 20.36, P Holdaway wrote:
> 
> >   There appears to be a race condition when issuing monit start
> > commands on
> > processes that are dependant on each other.
> >
> >   To illustrate...
> >
> >   Given processes b1 to b8 are dependant on process a.
> >
> >   If I stop all processes and then issue a separate start command
> > for each
> > process, I see in monit.log that the process b1 is being started
> > twice. Once
> > as a result of the dependency on process a, and once because of an
> > explicit
> > start command.
> >
> >   I have attached some files to help reproduce this problem.
> 
> 
> You have a bug in your run.sh script I think. If I use this,
> 
> 'start')
>       echo "Starting $name"
>       echo $$ > "$this_dir/$name.pid"
>       exec sleep 123456
>       ;;
> 
> every process start and stop in order without any race condition...
> 
> --
> Jan-Henrik Haukeland
> Mobil +47 97141255
> 
> 
> 
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