Process

Process::SubProcess - Perl Module for Multiprocessing

Running Sub Processes in an easy way while reading STDOUT, STDERR, Exit Code and possible System Errors.
It also implements running multiple Sub Processes simultaneously while keeping all Report and Error Messages and Exit Codes seperate.

Features

Some important Features are:

• Asynchronous Launch
• Reads Big Outputs
• Execution Timeout
• Configurable Read Interval
• Captures possible System Errors at Launch Time like "file not found" Errors

Motivation

This Module was conceived out of the need to launch multiple Tasks simultaneously while still keeping each Log and Error Messages and Exit Codes separately.
As I developed it as Prototype at:
Multi Process Manager
The Object Oriented Design permits the implementation of the Command Pattern / Manager-Worker Pattern with the Process::SubProcess::Group and Process::SubProcess::Pool Packages.
Having a similar implementation as the Capture::Tiny Package it eventually evolved as a Procedural Replacement for the Capture::Tiny::capture() Function which is demonstrated under Usage > runSubProcess() Function.
This capability also enabled its usage as Command Line Helper Tool with the run_subprocess.pl script as seen under Usage > Runner Script.

Example Use Case

The Usefulness of this Library is best shown by an Example Use Case as seen in the Process::SubProcess::Group::Run Test Sequence:
Having 3 Jobs at hand of 2 seconds, 3 seconds and 1 second running them sequencially would take aproximately 6 seconds.
But using the Process::SubProcess::Group it takes effectively only 3 seconds to complete.
And still each Job can be evaluated separately by their own Results keeping Log Message separate from Error Messages and viewing them in their context.

# Subtest: Process::SubProcess::Group::Run
    ok 1 - scripts (count: '3'): added correctly
Process Group Execution Start - Time Now: '1688542787.31262' s
    ok 2 - Process Group Execution: Execution correct
Process Group Execution End - Time Now: '1688542790.33528' s
Process Group Execution finished in '3022.66407012939' ms
    ok 3 - Process No. '0': Listed correctly
Process (8608) 'test-script:2s':
ERROR CODE: '0'
EXIT CODE: '0'
STDOUT: 'Start - Time Now: '1688542787.33535' s
script 'test_script.pl' START 0
script 'test_script.pl' PAUSE '2' ...
script 'test_script.pl' END 1
End - Time Now: '1688542789.33552' s
script 'test_script.pl' done in '2000.16403198242' ms
script 'test_script.pl' EXIT '0'
'
STDERR: 'script 'test_script.pl' START 0 ERROR
script 'test_script.pl' END 1 ERROR
'
    ok 4 - Process No. '1': Listed correctly
Process (8609) 'test-script:3s':
ERROR CODE: '0'
EXIT CODE: '0'
STDOUT: 'Start - Time Now: '1688542787.3336' s
script 'test_script.pl' START 0
script 'test_script.pl' PAUSE '3' ...
script 'test_script.pl' END 1
End - Time Now: '1688542790.3338' s
script 'test_script.pl' done in '3000.19979476929' ms
script 'test_script.pl' EXIT '0'
'
STDERR: 'script 'test_script.pl' START 0 ERROR
script 'test_script.pl' END 1 ERROR
'
    ok 5 - Process No. '2': Listed correctly
Process (8610) 'test-script:1s':
ERROR CODE: '0'
EXIT CODE: '0'
STDOUT: 'Start - Time Now: '1688542787.34636' s
script 'test_script.pl' START 0
script 'test_script.pl' PAUSE '1' ...
script 'test_script.pl' END 1
End - Time Now: '1688542788.34656' s
script 'test_script.pl' done in '1000.20098686218' ms
script 'test_script.pl' EXIT '0'
'
STDERR: 'script 'test_script.pl' START 0 ERROR
script 'test_script.pl' END 1 ERROR
'
    1..5
ok 3 - Process::SubProcess::Group::Run

Usage

Runner Script

The new Runner Script run_subprocess.pl lets process the output of different commandline tools in a organised manner and parse it correctly into JSON, YAML or Plain Text formats:

$ bin/run_subprocess.pl -n "test-script fails" -c "t/test_script.pl 2 6" -f json | jq '.'
{
  "stdout": "Start - Time Now: '1688630328.73393' s\nscript 'test_script.pl' START 0\nscript 'test_script.pl' PAUSE '2' ...\nscript 'test_script.pl' END 1\nEnd - Time Now: '1688630330.73409' s\nscript 'test_script.pl' done in '2000.15306472778' ms\nscript 'test_script.pl' EXIT '6'\n",
  "name": "test-script fails",
  "error_code": 1,
  "stderr": "script 'test_script.pl' START 0 ERROR\nscript 'test_script.pl' END 1 ERROR\n",
  "exit_code": 6,
  "command": "t/test_script.pl 2 6",
  "pid": "7273"
}

$ bin/run_subprocess.pl -n "test-script fails" -c "t/test_script.pl 2 6" -f json | jq '.error_code,.exit_code'
1
6

$ bin/run_subprocess.pl -n "test-script fails" -c "t/test_script.pl 2 6" -f json | jq '.stderr,.exit_code,.error_code'
"script 'test_script.pl' START 0 ERROR\nscript 'test_script.pl' END 1 ERROR\n"
6
1

runSubProcess() Function

Demonstrating the runSubProcess() Function Use Case:

use Process::SubProcess qw(runSubProcess);

use Test::More;


my $spath = '/path/to/test/script/';
my $stestscript = 'test_script.pl';
my $itestpause = 3;
my $iteststatus = 4;

my $rscriptlog = undef;
my $rscripterror = undef;
my $iscriptstatus = -1;
my $irunok = -1;


subtest 'runSubProcess() Function' => sub {

  #Execute the Command
  ($rscriptlog, $rscripterror, $iscriptstatus)
    = runSubProcess("${spath}${stestscript} $itestpause $iteststatus");

  #Evaluate the Results

  isnt($rscriptlog, undef, "STDOUT Ref is returned");
  isnt($rscripterror, undef, "STDERR Ref is returned");
  isnt($iscriptstatus, undef, "EXIT CODE is returned");
  ok($iscriptstatus =~ qr/^-?\d$/, "EXIT CODE is numeric");
  is($iscriptstatus, $iteststatus, 'EXIT CODE is correct');

  print("EXIT CODE: '$iscriptstatus'\n");

  if(defined $rscriptlog)
  {
    isnt($$rscriptlog, '', "STDOUT was captured");

    print("STDOUT: '$$rscriptlog'\n");
  } #if(defined $rscriptlog)

  if(defined $rscripterror)
  {
    isnt($$rscripterror, '', "STDERR was captured");

    print("STDERR: '$$rscripterror'\n");
  } #if(defined $rscripterror)
};

done_testing();

Documentation

The Class Diagramm kann be found at:
Class Diagram for the Package 'Process'