rec: Add a distribution-pipe-buffer-size setting #7571
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rgacogne
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Rebased to fix a conflict. |
rgacogne
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Rebased to fix a conflict. |
omoerbeek
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Apr 30, 2019
| #endif /* F_GETPIPE_SZ */ | ||
| } | ||
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| bool setPipeBufferSize(int fd, size_t size) |
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Why a size_t ?
argsvMap.asNum() returns an int, and the fcntl takes an int as well.
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I used a size_t because a negative value makes no sense here. asNum() and fcntl() are generic interfaces, but IMHO that does not mean we can't use a more correct type.
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I'm happy with the unsigned part of size_t, but negative numbers will be converted to very large values by the int to size_t conversion. We probably need an asSize() or similar that rejects negative values.
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That would be awesome, yes!
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Short description
Allows setting the size in bytes of the internal buffer of the pipe used by the distributor to pass incoming queries to a worker thread.
Requires support for
F_SETPIPE_SZwhich is present in Linux since 2.6.35. The actual size might be rounded up to a multiple of a page size. 0 means that the OS default size is used.A large buffer might allow the recursor to deal with very short-lived load spikes during which a worker thread gets overloaded, but it will be at the cost of an increased latency.
Checklist
I have: