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• Overview of Process-Monitor

Process-Monitor simplies managing and monitoring processes on Linux systems. It can be very helpful while creating self-healing services .

It can be useful when you want to get the process ids of those processes whose types or names are known.

• Show me some examples:

If you want to find out the process ids of all processes of type “ruby”

require 'process_monitor'
ruby_processes = ProcessMonitor.get_pid("ruby")

If you further want to prune your results you could do so by passing a string which is a part of the process name. So if you have a ruby script and you have set the name to “test_ruby_script” by setting the $0 variable in your script you could easily get the process id by:

test_ruby_script_process_information = ProcessMonitor.get_pid("ruby","test_ruby_script")

The get_pid method returns an array of hashes as follows:

[{:process => {:pid => pid, :command => command_to_launch_process, :status => status_of_process}}, ...]

In order to get individual process details you need to do the following:

test_ruby_script_pid = test_ruby_script_process_information[:process][:pid]

and similarly for command and status of process.

Once you have the pid of a process you can retrieve various details about the process as follows:

# If you want to check if the process exists simply do
is_running = ProcessMonitor.process_is_up?(pid)
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# Process is running/sleeping/stopped
process_status = ProcessMonitor.get_status(pid)
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# IO information of the process
io_details  = ProcessMonitor.get_io_details(pid)
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# Stack trace of the process
stack_trace = ProcessMonitor.get_stack_details(pid)
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# System call made by the process
process_syscall = ProcessMonitor.get_syscall_details(pid)
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# Resource limitations of the process.
process_limits = ProcessMonitor.get_limits_details(pid)

• Extras

If you want to fetch the first process that matches your criteria do

@first_process = ProcessMonitor.get_first_pid(“ruby”)

This will simply return a hash of the form :
{:process => {:pid => pid, :command => command_to_launch_process, :status => status_of_process}}