UNIX works with processes. Your login shell, application programs, the edit session you run, and even the ls program that lists your files are all processes under control of the operating system.
In UNIX you can perform operations on these processes. For example, you can look at all the programs you're running at any time, stop and restart programs as you choose, and investigate and debug errant processes.
An errant process is a process that is not doing the job you expect it to do. For example, a process might be consuming a large percentage of your available resources due to a bug, or it might be interfering with another process. Use Process Manager to detect errant processes when you experience the following:
Workstation performance or response seems to have slowed.
A program will not respond to user input.
A standard service such as printing, file transfer or remote login does not respond.
When displaying all processes, Process Manager typically displays thirty to fifty processes, so finding the errant processes can be daunting to the untrained eye. The following tips may help (otherwise contact your System Administrator):
Use Performance Meter (see Chapter 18, Using Performance Meter) to see if performance parameters such as CPU usage or disk usage are exceptionally high. If so, you can use Process Manager to identify the errant process.
Use Process Manager to identify:
Processes using a large percentage of the available CPU or RAM when they shouldn't
Orphaned processes whose parent process has reverted to 1, that is init (but not processes such as sched, dtlogin, or cron whose parent process ID should be 1)
Processes that were started a long time ago and weren't terminated when they should have been
Large processes owned by another user that are degrading performance