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From "Joseph Wu" <jos...@mesosphere.io>
Subject Review Request 39949: Document and simplify libprocess initialization synchronization logic.
Date Wed, 04 Nov 2015 18:58:58 GMT

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This is an automatically generated e-mail. To reply, visit:
https://reviews.apache.org/r/39949/
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Review request for mesos, Benjamin Hindman and Joris Van Remoortere.


Repository: mesos


Description
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The initialization synchronization logic contains three conditions, which check:
1) Was `initialize` called and is it done?
2) Was `initialize` called and is it not done?
3) Are you the first to call `initialize`?

Condition (3) uses `compare_exchange_strong` between `initialized` and `false`.  This returns
`true` (and sets `initialized` to true) iff the caller is the first to reach that expression.

The second simultaneous caller of `initialize` will either satisify condition (2) or (3) and
then wait on `initializing`.  For the second caller, (2) and (3) are identical because `compare_exchange_strong`
between `true` and `false` will always return false, thereby putting the second caller into
the waiting loop.


Diffs
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  3rdparty/libprocess/src/process.cpp a94712b9ac3b60fb047b3a5a4d84a56fa4d02313 

Diff: https://reviews.apache.org/r/39949/diff/


Testing
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`make check`


Thanks,

Joseph Wu


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