Exercises, examples and other material relating to training module P223. This topic is presented on public course Perl Extra
Related technical and longer articlesControlling multiple asynchronous processes in Perl
|Articles and tips on this subject||updated|
|3940||Run other processes from within your Perl program|
There are several ways in Perl that you can run another process from within your Perl program:
1. You can use a system call, which runs the other process independently and returns to you when it has completed. You can check the completion status of the system call by examining $?. Before it runs, ...
|3412||Handling binary data in Perl is easy!|
Perl can handle binary data just as easily as ASCII text - but YOU - if you're the programmer - must understand the format of the data that you'll be working with. With binary data it's every bit as important to get the right bytes in the right places as it is to get the appropriate separators between ...
|3010||Children, zombies, and reaping processes|
What is "Reaping Processes"?
Most programs are single processes - you write a program that runs sequentially from start to finish, interrupted only by the controls of conditionals like if, loops like while and subroutines / functions / methods, and you can always look at a program and say "it's HERE ...
|3011||What are .pid files?|
wizard:run graham$ ls *.pid
When a process that needs to be contacted / alerted by other processes is started, it often records its process id (PID) into a ".pid file" ...
|2970||Perl - doing several things at the same time|
What if you want a Perl process to go off in two different directions at the same time - perhaps a server that's going to handle several connections at the same time, or an application that's going to be doing heavy processing, but at the same time has to respond to inputs from elsewhere, such as the ...
|2694||Multiple processes (forking) in Python|
What is forking
If you want a process to head off in two different directions, you can fork it. That results in identical copies of the process being created - the original (parent) and the copy (child), each with their own complete set of variables, and program counter, etc.
The clever thing is that ...
|1918||Perl Socket Programming Examples|
It's always a pleasure to run private courses - for when a questions that's a little bit away from the normal comes up, I can take time to provide a full answer and demonstration without fear of loosing delegates from other companies who have no interest. And so it was today - I have two examples, plus ...
|604||Perl - multiprocess applications|
There are times that you'll be writing an application that you want to go off and perform task "x" and AT THE SAME TIME have it perform task "y", co-ordinating task "y" with task "x". Threading (NOT the subject covered here) is one possible approach. And another possible approach is forking. How does ...
Examples from our training material
|breadknife|| Forking a process, then the two communicating|
|breeder|| Parent forking multiple independent children|
|butter|| Send a signal to a registered process|
|check|| Expect - choreographing multiple pings and analysing result|
|dodo|| running another process from Perl|
|f1.pl|| Forking a process|
|fdem|| Forking in Perl, then communicating between processes|
|h_report|| Two processing in parallel (via fork) communicating (via a pipe)|
|kidgoes|| Children signalling to parents as they complete|
|knife|| fork and two separate processes|
|nonfat|| A process that responds to signals|
|pinga2|| Parallel (forked) processes communicating via signals and files|
|pinga3|| Parallel (forked) processes communicating via signals and pipes|
|pingalong|| Parallel (forked) processes communicating via pipes|
|pingpong|| piping from another process|
|talker|| Simple talker written in Perl|
|two_roles|| Forking in Perl - two processes|
PicturesForking a Perl Process, and pipe
Some modules are available for download
as a sample of our material or under an Open Training Notes License
for free download from [here]
Topics covered in this module
Forking; parents and children.
Overview of signals.
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