Mutex not thread safe? PEP-3108.

[Roy Smith]

I'm perusing PEP-3108 and came upon this interesting statement (under the
"Hardly used" section):

mutex [...] Not thread-safe.

How can a mutex, whose sole reason for existence is to mediate thread
safety, not be thread safe?

 

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Roy> I'm perusing PEP-3108 and came upon this interesting statement
Roy> (under the "Hardly used" section):

Roy> mutex [...] Not thread-safe.

Roy> How can a mutex, whose sole reason for existence is to mediate thread
Roy> safety, not be thread safe?

Because it is a mutex in name only. Take a look at the code. There is
nothing in there which actually locks the internal data structure against
simultaneous manipulation (a collections.deque instance in this case) from
multiple threads.

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