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03.Process_Management_Stack

README.md

Process Management Stack: Use Case

1- First Let's Figure out those foggy commands:

g++ main.cpp -g -o process
  • -g : adds debugging information to executable, aiding debugging process with tools like GDB
ulimit -c unlimited
  • ulimit -c unlimited sets core file size limit to unlimited, allowing creation of core dumps.
sudo sysctl -w kernel.core_pattern=./core.%e.%p.%t
  • sets core dump filename pattern to include process name, PID, and timestamp.

2- Lets Go with the first task to check the CPU load for the system, after running the process software

  • Actully We Could Use $ top

  • But I just Found $ htop with fancy GUI

2

  • I also found that $ ps got some nice argu
ps -C process -o %cpu
  • -C : allows you to use process name without knowing it's pid.
  • -o %cpu: Specifies the output format to display only the CPU

3

$ ps -eo pcpu,pid,user,args | sort -k 1 -r | head -3
  • You can also use the ps command to view the top 2 most CPU-intensive processes
$ top -b -n 2 -d 0.2 -p 6962 | tail -1 | awk '{print $9}'
> 100.0 # yup that's simple D:
  • b: Batch-mode non-interactive mode, suitable for scripts.
  • -n 2: Number-of-iterations, use 2 because: When you first run it, it has no previous sample to compare to, so these initial values are the percentages since boot.
  • d 0.2: Delay-time(in second, here is 200ms)
  • p 6962: Monitor-PIDs
  • tail -1: the last row
  • awk '{print $9}': the 9-th column(the cpu usage number)

3- the main task Actually is Second Task :extract core-dump (tracing file) for this process :

  • To get the core-dump file we should $ kill the process with signal SIGQUIT as it requests controlled termination with core dump, aiding debugging by capturing program state.
kill -QUIT <PID>
  • Now we got :
Hello from process
Hello from process
Hello from process
Hello from process
Quit (core dumped)

  • And finally, I got core-dump file core.process.10902.

  • Lets Open gdb and where the process terminated:

$ gdb ./process core.process.10902. 
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Reading symbols from ./process...
[New LWP 10902]
Core was generated by `./process'.
Program terminated with signal SIGQUIT, Quit.
#0  0x000055fdbe05b262 in loadCPU () at main.cpp:17

warning: Source file is more recent than executable.
17      void loadCPU() {
(gdb)
  • And yes we got Program terminated with signal SIGQUIT, Quit #0 0x000055fdbe05b262 in loadCPU () at main.cpp:17

Process Stack

Assign Priority:

  • to Assign Priority at runtime
$ renice
  • to Assign Priority before runtime
$ nice

Execute a program with a custom scheduling priority (niceness).Niceness values range from -20 (the highest priority) to 19 (the lowest).

 - Launch a program with altered priority:
   nice -n {{niceness_value}} {{command}}

Example

   nice -n -10 
   dd if=/dev/zero of=/dev/null