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Full Discussion: Help! Zombies
Top Forums UNIX for Dummies Questions & Answers Help! Zombies Post 302859989 by jim mcnamara on Friday 4th of October 2013 11:12:58 AM
Old 10-04-2013
That is not "the" zombie. Note the pid change.

Why?

zombies arise from really poor programming practices - failing to call wait() on children. kill DOES NOT KILL A ZOMBIE!! Stop trying.
Are we clear on this point?

What you are seeing is:

Code:
1 Process 2564 is the parent.
2 It calls fork()
3 Process xxxx9 is created.
4 It runs.
5 It exits.
6 The OS twiddles its thumbs
7 The OS decides to make a zombies out of xxxx9
8 Meanwhile 2564 is asleep at the switch.
9 Later on, 2564 comes out of a coma calls wait(), when it wants to fork a new child
   xxxx10
10 goto #4 above, continue forever until process 2564 code is fixed.

This is a programming problem. NOT system management. Fix the code behind it.
If your management wants you to get rid of it, get a copy of Stevens & Rago, 'Advanced Programming in the UNIX Environment', look up zombie, show it to the manager. If he can read it, you are good. He will get that it is a programming problem.
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preap(1)                                                           User Commands                                                          preap(1)

NAME
preap - force a defunct process to be reaped by its parent SYNOPSIS
preap [-F] pid... DESCRIPTION
A defunct (or zombie) process is one whose exit status has yet to be reaped by its parent. The exit status is reaped via the wait(3C), waitid(2), or waitpid(3C) system call. In the normal course of system operation, zombies may occur, but are typically short-lived. This may happen if a parent exits without having reaped the exit status of some or all of its children. In that case, those children are reparented to PID 1. See init(1M), which periodically reaps such processes. An irresponsible parent process may not exit for a very long time and thus leave zombies on the system. Since the operating system destroys nearly all components of a process before it becomes defunct, such defunct processes do not normally impact system operation. However, they do consume a small amount of system memory. preap forces the parent of the process specified by pid to waitid(3C) for pid, if pid represents a defunct process. preap will attempt to prevent the administrator from unwisely reaping a child process which might soon be reaped by the parent, if: o The process is a child of init(1M). o The parent process is stopped and might wait on the child when it is again allowed to run. o The process has been defunct for less than one minute. OPTIONS
The following option is supported: -F Forces the parent to reap the child, overriding safety checks. OPERANDS
The following operand is supported: pid Process ID list. EXIT STATUS
The following exit values are returned by preap, which prints the exit status of each target process reaped: 0 Successfully operation. non-zero Failure, such as no such process, permission denied, or invalid option. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Availability |SUNWesu (32-bit) | +-----------------------------+-----------------------------+ | |SUNWesxu (64-bit) | +-----------------------------+-----------------------------+ SEE ALSO
proc(1), init(1M), waitid(2), wait(3C), waitpid(3C), proc(4), attributes(5) WARNINGS
preap should be applied sparingly and only in situations in which the administrator or developer has confirmed that defunct processes will not be reaped by the parent process. Otherwise, applying preap may damage the parent process in unpredictable ways. SunOS 5.10 26 Mar 2001 preap(1)
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