18 lines
720 B
ReStructuredText
18 lines
720 B
ReStructuredText
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Threading model
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===============
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All OpenStack services use *green thread* model of threading, implemented
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through using the Python `eventlet <http://eventlet.net/>`_ and
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`greenlet <http://packages.python.org/greenlet/>`_ libraries.
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Green threads use a cooperative model of threading: thread context
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switches can only occur when specific eventlet or greenlet library calls are
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made (e.g., sleep, certain I/O calls). From the operating system's point of
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view, each OpenStack service runs in a single thread.
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The use of green threads reduces the likelihood of race conditions, but does
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not completely eliminate them. In some cases, you may need to use the
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``@utils.synchronized(...)`` decorator to avoid races.
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