packets: reset read deadline before conn check #964
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If a MySQL connection has been configured with a short `ReadTimeout`, each read from the TCP connection will be preceded by a `SetReadDeadline` call, which lingers until the next `SetReadDeadline`. This can be an issue if the connection becomes stale after staying too long in the connection pool, because when we attempt to perform a stale connection check, the Go runtime scheduler will return a timedout error from the scheduler itself, without letting us get to the kernel to perform the non-blocking read. To fix this, reset the read deadline before we perform the connection check.
methane
reviewed
May 7, 2019
packets.go
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| // reads, reset it to its default value before we attempt a non-blocking | ||
| // read, otherwise the scheduler will just time us out before we can read | ||
| if mc.cfg.ReadTimeout != 0 { | ||
| err = conn.SetReadDeadline(time.Now().Add(mc.cfg.ReadTimeout)) |
julienschmidt
approved these changes
May 7, 2019
tz70s
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to tz70s/mysql
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Sep 5, 2020
* packets: reset read deadline before conn check If a MySQL connection has been configured with a short `ReadTimeout`, each read from the TCP connection will be preceded by a `SetReadDeadline` call, which lingers until the next `SetReadDeadline`. This can be an issue if the connection becomes stale after staying too long in the connection pool, because when we attempt to perform a stale connection check, the Go runtime scheduler will return a timedout error from the scheduler itself, without letting us get to the kernel to perform the non-blocking read. To fix this, reset the read deadline before we perform the connection check. * packets: set a 0 deadline
tz70s
pushed a commit
to tz70s/mysql
that referenced
this pull request
Sep 5, 2020
* packets: reset read deadline before conn check If a MySQL connection has been configured with a short `ReadTimeout`, each read from the TCP connection will be preceded by a `SetReadDeadline` call, which lingers until the next `SetReadDeadline`. This can be an issue if the connection becomes stale after staying too long in the connection pool, because when we attempt to perform a stale connection check, the Go runtime scheduler will return a timedout error from the scheduler itself, without letting us get to the kernel to perform the non-blocking read. To fix this, reset the read deadline before we perform the connection check. * packets: set a 0 deadline
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Hiii mysqlinos! Here's a fix for an issue that @lrita reported. Fixes #963.
cc @methane @julienschmidt
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