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Avoid Division by Zero #11397
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Avoid Division by Zero #11397
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toddsundsted
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src/operator/random/sampler.h
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| */ | ||
| template<typename OP, typename xpu, typename GType, typename ...Args> | ||
| inline static void LaunchRNG(mshadow::Stream<xpu> *s, | ||
| common::random::RandGenerator<xpu, GType> *gen, | ||
| const int N, Args... args) { | ||
| // minimal check to avoid division by zero, below. | ||
| // if `N` is zero the map operation is a no-op in any case. | ||
| if (N == 0) { |
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to be a more stable check, use N <= 0
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@zhreshold fixed in 6075fc2. cleaned up commit history with rebase.
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* Return if iteration counter `N` is less than or equal to zero. * Fix spelling.
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Description
In Python, expressions like
nd.random_uniform(shape=[5, 5, 0])cause the runtime to crash. The underlying problem seems to be a division by zero inLaunchRNG(...)at line 50. The divisornthreadis zero becausenloopis zero whenNis zero due to C++ integer division rules (Nis zero because the size of theNDArrayabove is zero).See #11398 for the bug report.
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Essentials
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LaunchRNG(...)to ensureNis not zero. Small negative values forNwould also cause division by zero, but small negative numbers (induced by things likend.random_uniform(shape=[5, 5, -1])) cause allocation failures before this code is even reached, but I check that case to be safe.N <= 0should be sufficient because the map operation effectively does nothing in this case.