[arch-projects] [initscripts] [PATCH 09/11] functions: Speed up reboot/shutdown by recognizing killall5 exit code 2

[Kurt J. Bosch]

Dave Reisner, 2011-07-02 21:05:
> On Sat, Jul 02, 2011 at 08:44:27PM +0200, Kurt J. Bosch wrote:
>> killall5 returns 2 if it didn't kill any processes. Using this avoids sleeping longer than needed. This saves another up to six seconds of reboot/shutdown/go-single time.
>> ---
>>   functions |   16 ++++++++++++----
>>   1 files changed, 12 insertions(+), 4 deletions(-)
>>
>> diff --git a/functions b/functions
>> index 69f06eb..401e323 100644
>> --- a/functions
>> +++ b/functions
>> @@ -293,13 +293,21 @@ kill_everything() {
>>
>>   	# Terminate all processes
>>   	stat_busy "Sending SIGTERM To Processes"
>> -		killall5 -15 ${omit_pids[@]/#/-o }&>/dev/null
>> -		sleep 5
>> +		local i
>> +		for (( i=0; i<500; i+=25 )); do
>> +			killall5 -15 ${omit_pids[@]/#/-o }&>/dev/null
>> +			(( $? == 2 ))&&  break
>> +			sleep .25
>> +		done
>
> In the context of killall5, 'killed' means a signal was sent. This will
> cause a zombie process to hang shutdown for 2 minutes.

Sorry, but i can't see how sending multiple SIGTERM to a zombie should 
cause any problem. Why 2 minutes? Could you please explain this a bit more?

>
>>   	stat_done
>>
>>   	stat_busy "Sending SIGKILL To Processes"
>> -		killall5 -9 ${omit_pids[@]/#/-o }&>/dev/null
>> -		sleep 1
>> +		local i
>> +		for (( i=0; i<100; i+=25 )); do
>> +			killall5 -9 ${omit_pids[@]/#/-o }&>/dev/null
>> +			(( $? == 2 ))&&  break
>> +			sleep .25
>> +		done
>
> Ideally, this never kills anything, because all our processes exited
> nicely in the loop above. However, if it does successfully send a signal
> to a process, then we just spent the past 125 seconds waiting on the
> above SIGTERM spam to time out. When it does time out, we're going to
> spend another 25 seconds here waiting for the same process to be spammed
> with SIGKILL.

We would spend up to 5 seconds for waiting above - not more as without 
the patch, but maybe less. Here we spend up to 1 second as before.
Note: Time is measured in centiseconds here.
>
>>   	stat_done
>>
>>   	run_hook "$1_postkillall"
>> --
>> 1.7.1
>>
>
> There's probably a handful of programs who don't appreciate receiving
> SIGTERM every 1/4 of a second.
>
> dave
>
Works good here. Would you recommend some longer interval?

-- 
Kurt