perf: skip the per-write debug log when debug is off (-7.5% on the tcp write path, -57% allocations) - #147
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gettyTCPConn.Send logs every write, and its `...any` arguments are boxed at the call site, so a Debugf that the configured level discards still cost one allocation (the []any backing array) on every single write. The same pattern sat on the udp send path, the udp receive path, and twice inside the udp package loop. util.IsDebugEnabled() now reports the level configured through SetLoggerLevel, and those six per-operation debug records are guarded by it. A level query was added as a package function rather than as a method on the Logger interface, because growing that interface would break every external implementation. Measured against upstream/master with the benchmarks from AlexStocks#143 (-benchtime=1s -count=5, Apple M1), on the 64-byte payload where the per-write cost dominates: sec/op B/op SessionWriteBytes/64 2.246us -> 2.078us -7.48% 112 -> 48 -57% SessionSend/64 2.236us -> 2.066us -7.60% 112 -> 48 -57% UDPSend/64 2.164us -> 2.105us -2.73% 148 -> 100 -32% Under an external load generator (100 connections, 6-byte messages, the standalone server from AlexStocks#143) leaving debug logging on costs about 4x on the echo path: 362k-451k msg/s at -log_level error against 77k-100k msg/s at -log_level debug, and 2.28 million log lines in 15 seconds. The regression test asserts the observable contract rather than an allocation count: with the level at warn, a recording logger installed through SetLogger must receive no debug records from Send at all. On master it reports "Send built 1 debug records with debug disabled".
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Included review availability: Your plan provides up to 4 included reviews per hour; 3 remain after this review. 📝 WalkthroughWalkthroughThe change synchronizes logger-level updates, guards TCP and UDP debug logging before message evaluation, and adds tests for disabled debug logging and concurrent logger-level access. ChangesDebug logging guards
Priority: ⬇️ Low Estimated code review effort: 2 (Simple) | ~10 minutes Change: Bug fix Suggested reviewers: Merge Risk: ⚪ Minimal · up to The logging optimization preserves configured logger-level behavior and includes race coverage for concurrent level access. The change is ready to merge. 🚥 Pre-merge checks | ✅ 5✅ Passed checks (5 passed)
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Inline comments:
In `@transport/connection_test.go`:
- Around line 1085-1093: Update the t.Cleanup logger restoration in the affected
test to capture the exact prior logger level rather than deriving it from
wasDebugEnabled, then restore that level first and call
gettylog.SetLogger(previousLogger) second so the original logger instance and
level are preserved.
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transport/connection.gotransport/connection_test.gotransport/session.goutil/logger.go
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Review feedback: the cleanup called SetLogger(previousLogger) and then SetLoggerLevel(...), but SetLoggerLevel rebuilds and installs the built-in sugared logger, so it replaced the logger that had just been restored. The level was also derived from an IsDebugEnabled() snapshot, which mapped every prior non-debug level onto Warn instead of the real one. util.GetLoggerLevel() (the counterpart of SetLoggerLevel, with the same caveat about loggers installed through SetLogger) lets the test capture both exactly, and the cleanup now restores the level first and the logger second.
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Inline comments:
In `@util/logger.go`:
- Around line 132-139: Update SetLoggerLevel to mutate the existing
zapLoggerConfig.Level via SetLevel instead of replacing it with a new
zap.AtomicLevel, so concurrent GetLoggerLevel reads do not race with level
updates.
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…Level SetLoggerLevel assigned a fresh zap.AtomicLevel to zapLoggerConfig.Level while IsDebugEnabled/GetLoggerLevel read that field from other goroutines, and IsDebugEnabled now sits on the per-connection paths (connection.go send/recv, session.go udp loop). It is reachable from any management thread and the race job was green only because nothing drove both directions at once. The level is mutated through AtomicLevel.SetLevel, which is what that type exists for; Build() stays, to rebuild the logger the new level applies to. util/logger_test.go drives both directions, so the race detector sees it, and `make test-race` now covers ./util in addition to ./transport - the race job was transport-only, which is why this was invisible. The SetLoggerLevel doc comment now states directly that it replaces a logger installed with SetLogger.
The previous run failed with no steps executed at all (Race) and at the SARIF upload step (Analyze). Test and Lint, all three Build jobs and the license check passed in those same runs, and the affected jobs never reached this change: make test-race now covers ./util and passes locally (transport 29.7s, util 1.3s).
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Found while building the benchmarks in #143 - the per-write debug record turned out to be the largest single cost in the write path.
The cost
gettyTCPConn.Sendlogs every write:The
...anyarguments are boxed at the call site, so a record the configured level discards still costs one allocation - the[]anybacking array - on every write. The same pattern sits on the udp send path, the udp receive path, and twice inside the udp package loop.The fix
util.IsDebugEnabled()reports the level configured throughSetLoggerLevel, and those six per-operation records are now guarded by it:IsDebugEnabledis a package function rather than a method on theLoggerinterface on purpose: adding a method to that interface would break every implementation outside the module. It reports the level of the built-in logger, so a logger installed throughSetLoggeris opaque to it - that caveat is in the doc comment.Measurements
Against
upstream/master, with the benchmarks from #143 (-benchtime=1s -count=5, Apple M1), on the 64-byte payload where the per-write cost dominates:(All three
p=0.008,n=5; the B/op difference is exactly the one boxed[]anyper call.)And under an external load generator - 100 connections of 6-byte messages against the standalone server from #143 - leaving debug logging on costs about 4x on the echo path:
Test
The regression test asserts the observable contract instead of an allocation count: with the level at
warn, a recording logger installed throughSetLoggermust receive no debug records fromSend. On master it fails withgo test ./transport -race,go test ./...,make check-fmtandmake lintare green.Summary by CodeRabbit
Performance
Reliability
Tests