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Reduce socket read chunk size for queries over TCP/IP - #189
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WyriHaximus
approved these changes
Dec 6, 2021
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This changeset reduces the socket read chunk size for queries over TCP/IP to a reasonable value of 64 KiB. PHP's
fread()uses an underlyingread()call with the given chunk size (defaults to 8 KiB) instead of the size limit given to thefread()call. In an attempt to address a race condition on Mac, I've accidentally raised this default chunk size to 2 GiB via #172/#177. This means that any socket read would temporarily consume 2 GiB of memory, even if we only read a few bytes of data. Ouch.With these changes applied, the test suite now reports a memory usage of ~84 MB instead of 8 GB(!). I've only stumbled upon this recently while addressing PHP 8.1 compatibility (#188) and trying to execute this with PHP's default
memory_limitof just 128 MiB. The good news is this didn't usually happen during normal operation, as the TCP/IP transport will only be used as a fallback if the UDP query returns a truncated message.