Fix race condition in stopping FSEvent runner #40

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merged 1 commit into from Dec 28, 2012

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dbussink commented Dec 28, 2012

The race condition is the following. When a FSEvent#stop is called, it
kills the child process and closes the pipe. It can happen that the kill
signal is sent and then succesfully the pipe is closed, before the child
process dies and the pipe in the parent is closed.

This means that IO::select() can raise a Errno::EBADF if the file
descriptor is closed while waiting in select(). This additional rescue
makes sure we shutdown in this case just like any others. This is a much
more reliable solution than adding for example a sleep() between
Process.kill and @pipe.close in FSEvent#stop.

Found because of rubinius/rubinius#2102.

Handle potential race condition when stopping
The race conditionn is the following. When a FSEvent#stop is called, it
kills the child process and closes the pipe. It can happen that the kill
signal is sent and then succesfully the pipe is closed, before the child
process dies and the pipe in the parent is closed.

This means that IO::select() can raise a Errno::EBADF if the file
descriptor is closed while waiting in select(). This additional rescue
makes sure we shutdown in this case just like any others. This is a much
more reliable solution than adding for example a sleep() between
Process.kill and @pipe.close in FSEvent#stop.

Found because of rubinius/rubinius#2102.
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ttilley Dec 28, 2012

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Good catch. Thanks. :)

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ttilley commented Dec 28, 2012

Good catch. Thanks. :)

ttilley added a commit that referenced this pull request Dec 28, 2012

Merge pull request #40 from rubinius/master
Fix race condition in stopping FSEvent runner

@ttilley ttilley merged commit fa8ad08 into thibaudgg:master Dec 28, 2012

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