On Mon, 22 Feb 2016 10:58:53 -0800 Rick Stevens <ricks(a)alldigital.com> wrote:
On 02/22/2016 10:50 AM, Ranjan Maitra wrote:
> On Mon, 22 Feb 2016 10:38:30 -0800 Rick Stevens <ricks(a)alldigital.com> wrote:
>
>> On 02/22/2016 10:19 AM, Ranjan Maitra wrote:
>>> Hi,
>>>
>>> I am running a fully updated F23 box but this question does not have much to
do with Fedora itself, hence the designator and the disclaimer.
>>>
>>> I am wanting to run a script which will look at all the jobs that are
running and renice all of them which have been on for more than five minutes. (Then I can
run the script as a cron job as root and be done with automating the process.)
>>>
>>> Are there any suggestions as to how to go about this task efficiently?
Actually, before I reinvent the wheel, are there any standard options that already exist
and which would be more suitable for me than just to do everything from scratch.
>>
>> Use the "-o pid,etimes=" options of ps to get the elapsed time of
>> tasks in seconds. To get a full list, for example, as root:
>>
>> ps ax -o pid,uid,etimes=
>> ...
>> 21412 0 833
>> 21499 0 631433
>> 21541 0 773
>> 21597 1000 769
>> 21604 1000 769
>> 21605 1000 769
>> 21608 1000 769
>> 21610 1000 769
>> 21613 1000 769
>> 21681 1000 769
>> 21686 1000 769
>> 21697 1000 769
>> 21751 1000 742
>> ...
>>
>> (run it as root so you can see ALL of the processes)
>>
>> As you can see, you get three columns: the first is the PID of the
>> task, the second is the EUID of the user running it, and the third is
>> the elapsed time.
>>
>> So, pull that data into a shell array, look for stuff that has the
>> second column equal to the user ID you're interested in and the third
>> column >= 300 seconds and renice the PID in the first column. Note that
>> I'd avoid renicing any tasks with UIDs < your lowest normal user ID
>> (typically 100) to keep from starving system tasks.
>>
>> Hope that helps!
>
> Yes, this absolutely helps, thanks!! But is there a 2-d array in bash (or do we do
array of arrays)? (I am presuming that I need to store this in a 2-d array and then look
at columns 2 and 3 and renice the PIDs in column 1.) Also, how does one assign the output
of the ps to a 2-d array?
Uhm, no. You can simulate them using associative arrays, but it gets
rather hairy. You may want to try something like awk or PHP or Perl to
do this more easily.
OK, thanks! I guess i will have to figure out one of awk, etc then. Separately, I have
realized that I should also output nice as part of the ps options because there is no
point in renicing jobs that are already niced.
Best wishes,
Ranjan
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