Re: VOTE: --timeout with suspendable children or killing children?

[Jay Hacker]

Would this work?

http://search.cpan.org/~sharyanto/Process-KillTree-0.02/lib/Process/KillTree.pm



On Fri, Dec 2, 2011 at 7:25 AM, Ole Tange <tange@binf.ku.dk> wrote:
> On Thu, Dec 1, 2011 at 9:25 PM, Jay Hacker <jayqhacker@gmail.com> wrote:
>> So currently parallel runs all jobs in the same process group, and
>> CTRL-Z suspends everything in the current terminal process group,
>> which is a nice feature.
>
> Yep.
>
>> If you wanted to kill all descendants of a job, you'd have to put them
>> in a separate process group, but this breaks CTRL-Z.  So currently
>> parallel only kills its immediate children.  The timeout command (I'm
>> guessing) puts things in a different process group (so it can kill its
>> children), which prevents CTRL-Z from working.
>
> Yep.
>
>> Do I have that right?
>
> Yep.
>
>> Two ideas I can see exploring:
>>
>> 1. Walk the process tree and kill all descendents of all jobs.  I
>> don't know if there is a portable way to do this (surely CPAN has
>> something? ;)
>>
>> 2. Have parallel kill its own process group, effectively committing
>> mass family suicide.  Hey, it's about to exit anyway.  :)
>
> No good. The timeout is per job, so there may be others jobs in the queue.
>
>> This may be
>> unpalatable because parallel needs to do some cleanup; perhaps
>> parallel could install a SIGTERM handler, do its cleanup in there
>> (which seems reasonable anyway), and then send the final SIGKILL to
>> the process group.
>
> Currently parallel sends a TERM, waits 200 ms, sends another TERM,
> waits another 200 ms, and finally sends a KILL. So if the child was a
> respectful child it would propagate these signals to its children. But
> alas, children are not well behaved these days.
>
>> If neither of those works, I'd prefer --timeout kills a jobs children;
>> usually when using CTRL-Z I just want to get back to my terminal, and
>> the first thing I type is 'bg' anyway, so suspending the children is
>> not that big a deal.  Also FWIW, RedHat 5 doesn't have a timeout
>> command that I can find.
>
> Good to know.
>
>
> /Ole