Re: [gentoo-user] HOWTO: Freezing/unfreezing (groups of) processes

[Ramon Fischer]

Awesome stuff!

It might be unrelated, but I would like to mention a script[1] here, 
which I have written in Bash to analyse process signals. It is called 
"psig", which mimics some of the behaviour of Solaris' "psig" binary:

    $ psig 23024

    PID: 23024
    Name: chrome
    Queued: 0/63858
    Signals caught:
    ---------------
    Signal 17: SIGCHLD
    Signal 15: SIGTERM
    Signal 2: SIGINT
    Signal 1: SIGHUP
    Hexadecimal:  0     0     0     0     0     0 0     1     8    
    0     0     1     4     0     0     3
    Binary:       0000  0000  0000  0000  0000  0000 0000  0001  1000 
    0000  0000  0001  0100  0000  0000  0011

    Signals pending (process):
    --------------------------
    No signals found.

    Signals pending (thread):
    -------------------------
    No signals found.

    Signals blocked:
    ----------------
    No signals found.

    Signals ignored:
    ----------------
    Signal 13: SIGPIPE
    Hexadecimal:  0     0     0     0     0     0 0     0     0    
    0     0     0     1     0     0     0
    Binary:       0000  0000  0000  0000  0000  0000 0000  0000  0000 
    0000  0000  0000  0001  0000  0000  0000

-Ramon

[1] https://github.com/keks24/psig


On 05/02/2021 08:45, Walter Dnes wrote:
>    Thanks for all the help over the years fellow Gentoo'ers.  Maybe I can
> return the favour.  So you've got a bunch of programs like Gnumeric or
> QEMU or Pale Moon ( or Firefox or Chrome or Opera ) sessions open, that
> are chewing up cpu and ram.  You need those resouces for another
> program, but you don't want to shut those programs down and lose your
> place.  If the programs could be frozen, cpu usage would go away, and
> memory could be swapped out.  Here's a real-life example subset of a
> "ps -ef" output on my system.  Replace "palemoon" with "firefox" or
> "chrome" or whatever browser you're using.
>
> waltdnes  4025  3173  0 Jan20 ?        01:54:21 /home/waltdnes/pm/palemoon/palemoon -new-instance -p palemoon
> waltdnes  7580  3173  4 Jan21 ?        17:45:11 /home/waltdnes/pm/palemoon/palemoon -new-instance -p dslr
> waltdnes  9813  3173  4 Jan21 ?        16:24:23 /home/waltdnes/pm/palemoon/palemoon -new-instance -p wxforum
> waltdnes 22455  3173 58 01:31 ?        00:08:29 /home/waltdnes/pm/palemoon/palemoon -new-instance -p slashdot
> waltdnes 22523  3173  0 01:31 ?        00:00:05 /home/waltdnes/pm/palemoon/palemoon -new-instance -p youtube
> waltdnes 22660  3173 12 01:45 ?        00:00:04 /usr/bin/gnumeric /home/waltdnes/worldtemps/temperatures/temperatures.gnumeric
> waltdnes 20346 20345  4 Jan28 ?        08:10:50 /usr/bin/qemu-system-x86_64 -enable-kvm -runas waltdnes -cpu host -monitor vc -display gtk -drive file=arcac.img,format=raw -netdev user,id=mynetwork -device e1000,netdev=mynetwork -rtc base=localtime,clock=host -m 1024 -name ArcaOS VM -vga std -parallel none
>
>    You might want to RTFM on the "kill" command if you're skeptical.  It
> does a lot more than kill programs.  "kill -L" will give you a nicely
> formatted list of available signals.  For this discussion we're
> interested in just "SIGCONT" and "SIGSTOP" ( *NOT* "SIGSTP" ).  If I
> want to freeze the Slashdot session, I can run "kill -SIGSTOP 22455". To
> unfreeze it, I can run "kill -SIGCONT 22455".  You can "SIGSTOP" on a
> pid multiple times consecutively without problems; ditto for "SIGCONT".
>
>    So far, so good, but running "ps -ef | grep whatever" and then
> typing the kill -SIGSTOP/SIGCONT command on the correct pid is grunt
> work, subject to typos. I've set up a couple of scripts in ~/bin to
> stop/continue processes, or groups thereof.  The following scripts do a
> "dumb grep" of "ps -ef" output, redirecting to /dev/shm/temp.txt.  That
> file is then read, and the second element of each line is the pid, which
> is fed to the "kill" command.  I store the scripts as ~/bin/pstop and
> ~/bin/pcont.
>
> ================== pstop (process stop) script ==================
> #!/bin/bash
> ps -ef | grep ${1} | grep -v "grep ${1}" | grep -v pstop > /dev/shm/temp.txt
> while read
> do
>     inputarray=(${REPLY})
>     kill -SIGSTOP ${inputarray[1]}
> done < /dev/shm/temp.txt
>
> ================ pcont (process continue) script ================
> #!/bin/bash
> ps -ef | grep ${1} | grep -v "grep ${1}" | grep -v pcont > /dev/shm/temp.txt
> while read
> do
>     inputarray=(${REPLY})
>     kill -SIGCONT ${inputarray[1]}
> done < /dev/shm/temp.txt
>
> =================================================================
>
>    To stop all Pale Moon instances, execute "pstop palemoon".  To stop
> only the Slashdot session, run "pstop slashdot".  Ditto for the pcont
> command.  I hope people find this useful.
>

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