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Notes |
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(0000779)
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wangp
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2014-09-02 16:24
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Or just condition variables, though presumably they perform worse so we would want to stick to semaphores on better platforms. |
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This would have shown up more obviously had the return value of sem_init been checked!
There are also a bunch of calls to various pthread_* functions in the runtime, for example pthread_mutex_init and pthread_attr_init, where the return values are not checked. |
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(0000921)
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pbone
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2016-09-29 14:04
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I remember some things about writing this code but not others.
In particular I remember choosing semaphores for a very good reason, but I don't remember what that reason was :-(
I'm not sure what should be used instead on OS X. Except that if we want to use GCD, then we should essentially write a different implementation for the N:M threading on OS X, as GCD will (and should) handle this for us. I suspect windows is a similar case as it supports fibers. However that's about all I know of either platform/API.
So I'd recommend trying to replace this with named semaphores, if those are supported/work, or maybe condition variables - again there's a good reason why I didn't use those but I don't know what it is. And in the longer term consider writing an alternative implementation of all this code (maybe keep the work stealing) for OS X. |
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Hi Paul,
Using GCD to do the N:M threading is a separate issue; the semaphore implementation in libdispatch is close enough to POSIX unnamed semaphores that it should be easy enough to use as a drop-in replacement. Using GCD in general on OS X is a much larger change. |
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(0000923)
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pbone
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2016-09-29 14:24
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Agreed, which is why I said that's a longer term change, and by implication not really part of this bug. However I wasn't aware of the primitives provided by libdispatch so I didn't know that's what you meant when you said GCD. It sounds reasonable to me. |
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