BUG: Remove data race in mtrand: two threads could mutate the state. #7305
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E.g.: np.random.random_sample() uses the GIL for synchronization np.random.random_sample(1) releases the GIL and uses a separate lock. This means that both can run simultaneously, causing a data race when mutating the random number generator's state, which could lead to buffer overflow (from incrementing state->pos). The fix here is to always use the separate lock, so that exactly one thread at a time is mutating the random number generator's state.
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Hmm, tests aren't getting scheduled... |
| @@ -158,7 +158,9 @@ cdef object cont0_array(rk_state *state, rk_cont0 func, object size, | |||
| cdef npy_intp i | |||
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| if size is None: | |||
| return func(state) | |||
| with lock, nogil: | |||
| rv = func(state) | |||
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Any reason not to just do
with lock, nogil:
return func(state)
? Ditto for the other nine or so cases?
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That's what I wrote at first, but Cython forbids returning a PyObject without the GIL, apparently. (Seems like a bug in Cython, but whatever).
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I think that's a deliberate choice, not a bug. Either way, it's certainly a good reason to write the code the way you did. LGTM
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nice catch, thank you |
juliantaylor
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Feb 22, 2016
BUG: Remove data race in mtrand: two threads could mutate the state.
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E.g.:
This means that both can run simultaneously, causing a data race when mutating the random number generator's state, which could lead to buffer overflow (from incrementing state->pos).
The fix here is to always use the separate lock, so that exactly one thread at a time is mutating the random number generator's state.