| commit | c3b4c27fd31b51226274a0c038e9c10a65f11657 | [log] [tgz] |
|---|---|---|
| author | Joe Tsai <joetsai@digital-static.net> | Wed Feb 01 13:23:02 2023 -0800 |
| committer | Joseph Tsai <joetsai@digital-static.net> | Fri Feb 03 22:22:20 2023 +0000 |
| tree | 08389eb643928a9092308c100dcb5e933bf85f5a | |
| parent | cd1fc871568e9947e84377f82c8d7a4882a07067 [diff] |
log: reduce lock contention Logger.Log methods are called in a highly concurrent manner in many servers. Acquiring a lock in each method call results in high lock contention, especially since each lock covers a non-trivial amount of work (e.g., formatting the header and outputting to the writer). Changes made: * Modify the Logger to use atomics so that the header formatting can be moved out of the critical lock section. Acquiring the flags does not occur in the same critical section as outputting to the underlying writer, so this introduces a very slight consistency instability where concurrently calling multiple Logger.Output along with Logger.SetFlags may cause the older flags to be used by some ongoing Logger.Output calls even after Logger.SetFlags has returned. * Use a sync.Pool to buffer the intermediate buffer. This approach is identical to how fmt does it, with the same max cap mitigation for #23199. * Only protect outputting to the underlying writer with a lock to ensure serialized ordering of output. Performance: name old time/op new time/op delta Concurrent-24 19.9µs ± 2% 8.3µs ± 1% -58.37% (p=0.000 n=10+10) Updates #19438 Change-Id: I091beb7431d8661976a6c01cdb0d145e37fe3d22 Reviewed-on: https://go-review.googlesource.com/c/go/+/464344 TryBot-Result: Gopher Robot <gobot@golang.org> Run-TryBot: Joseph Tsai <joetsai@digital-static.net> Reviewed-by: Ian Lance Taylor <iant@google.com> Reviewed-by: Bryan Mills <bcmills@google.com>
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