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detach-c.yaml

--- !ruby/object:RI::MethodDescription 
aliases: []

block_params: 
comment: 
- !ruby/struct:SM::Flow::P 
 body: Some operating systems retain the status of terminated child processes until the parent collects that status (normally using some variant of <tt>wait()</tt>. If the parent never collects this status, the child stays around as a zombie process. <tt>Process::detach</tt> prevents this by setting up a separate Ruby thread whose sole job is to reap the status of the process pid when it terminates. Use <tt>detach</tt> only when you do not intent to explicitly wait for the child to terminate. <tt>detach</tt> only checks the status periodically (currently once each second).
- !ruby/struct:SM::Flow::P 
 body: The waiting thread returns the exit status of the detached process when it terminates, so you can use <tt>Thread#join</tt> to know the result. If specified pid is not a valid child process ID, the thread returns <tt>nil</tt> immediately.
- !ruby/struct:SM::Flow::P 
 body: In this first example, we don't reap the first child process, so it appears as a zombie in the process status display.
- !ruby/struct:SM::Flow::VERB 
 body: " p1 = fork { sleep 0.1 }\n p2 = fork { sleep 0.2 }\n Process.waitpid(p2)\n sleep 2\n system(&quot;ps -ho pid,state -p #{p1}&quot;)\n"
- !ruby/struct:SM::Flow::P 
 body: produces:
- !ruby/struct:SM::Flow::VERB 
 body: " 27389 Z\n"
- !ruby/struct:SM::Flow::P 
 body: In the next example, <tt>Process::detach</tt> is used to reap the child automatically.
- !ruby/struct:SM::Flow::VERB 
 body: " p1 = fork { sleep 0.1 }\n p2 = fork { sleep 0.2 }\n Process.detach(p1)\n Process.waitpid(p2)\n sleep 2\n system(&quot;ps -ho pid,state -p #{p1}&quot;)\n"
- !ruby/struct:SM::Flow::P 
 body: (produces no output)
full_name: Process::detach
is_singleton: true
name: detach
params: |
 Process.detach(pid) => thread

visibility: public

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