From d17474d0f6f0d5128207bcde850c042c39624a2d Mon Sep 17 00:00:00 2001 From: Austin Clements Date: Wed, 20 Jul 2022 21:49:15 -0400 Subject: [PATCH] runtime: add missing trace lock edges We're missing lock edges to trace.lock that happen only rarely. Any trace event can potentially fill up a trace buffer and acquire trace.lock in order to flush the buffer, but this happens relatively rarely, so we simply haven't seen some of these lock edges that could happen. With this change, we promote "fin, notifyList < traceStackTab" to "fin, notifyList < trace" and now everything that emits trace events with a P enters the tracer lock ranks via "trace", rather than some things entering at "trace" and others at "traceStackTab". This was found by inspecting the rank graph for things that didn't make sense. Ideally we would add a mayAcquire annotation that any trace event can potentially acquire trace.lock, but there are actually cases that violate this ranking right now. This is #53979. The chance of a lock cycle is extremely low given the number of conditions that have to happen simultaneously. For #53789. Change-Id: Ic65947d27dee88d2daf639b21b2c9d37552f0ac0 Reviewed-on: https://go-review.googlesource.com/c/go/+/418716 Reviewed-by: Michael Pratt Run-TryBot: Austin Clements TryBot-Result: Gopher Robot --- src/runtime/lockrank.go | 2 +- src/runtime/mklockrank.go | 4 ++-- 2 files changed, 3 insertions(+), 3 deletions(-) diff --git a/src/runtime/lockrank.go b/src/runtime/lockrank.go index 1e83839120d180..c817de1aa46876 100644 --- a/src/runtime/lockrank.go +++ b/src/runtime/lockrank.go @@ -159,7 +159,7 @@ var lockPartialOrder [][]lockRank = [][]lockRank{ lockRankSpanSetSpine: {lockRankSysmon, lockRankSweepWaiters, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankPollDesc, lockRankItab, lockRankNotifyList, lockRankScavenge, lockRankForcegc, lockRankSched, lockRankAllg, lockRankAllp, lockRankTimers, lockRankReflectOffs, lockRankHchan, lockRankTraceBuf, lockRankTraceStrings}, lockRankMheapSpecial: {lockRankSysmon, lockRankSweepWaiters, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankPollDesc, lockRankItab, lockRankNotifyList, lockRankScavenge, lockRankForcegc, lockRankSched, lockRankAllg, lockRankAllp, lockRankTimers, lockRankReflectOffs, lockRankHchan, lockRankTraceBuf, lockRankTraceStrings}, lockRankProfMemFuture: {lockRankSysmon, lockRankSweepWaiters, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankPollDesc, lockRankItab, lockRankNotifyList, lockRankScavenge, lockRankForcegc, lockRankSched, lockRankAllg, lockRankAllp, lockRankTimers, lockRankReflectOffs, lockRankHchan, lockRankTraceBuf, lockRankTraceStrings, lockRankProfMemActive}, - lockRankTrace: {lockRankSysmon, lockRankSweepWaiters, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankPollDesc, lockRankRoot, lockRankScavenge, lockRankForcegc, lockRankSched, lockRankHchan, lockRankTraceBuf, lockRankTraceStrings}, + lockRankTrace: {lockRankSysmon, lockRankSweepWaiters, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankPollDesc, lockRankItab, lockRankNotifyList, lockRankRoot, lockRankScavenge, lockRankForcegc, lockRankSched, lockRankAllg, lockRankAllp, lockRankTimers, lockRankReflectOffs, lockRankHchan, lockRankTraceBuf, lockRankFin, lockRankTraceStrings}, lockRankTraceStackTab: {lockRankSysmon, lockRankSweepWaiters, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankPollDesc, lockRankItab, lockRankNotifyList, lockRankRoot, lockRankScavenge, lockRankForcegc, lockRankSched, lockRankAllg, lockRankAllp, lockRankTimers, lockRankReflectOffs, lockRankHchan, lockRankTraceBuf, lockRankFin, lockRankTraceStrings, lockRankTrace}, lockRankNetpollInit: {lockRankSysmon, lockRankSweepWaiters, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankPollDesc, lockRankScavenge, lockRankForcegc, lockRankSched, lockRankAllp, lockRankTimers}, lockRankRwmutexR: {lockRankSysmon, lockRankRwmutexW}, diff --git a/src/runtime/mklockrank.go b/src/runtime/mklockrank.go index 9cb51bedcaec06..110d57faf07c69 100644 --- a/src/runtime/mklockrank.go +++ b/src/runtime/mklockrank.go @@ -47,8 +47,8 @@ allg, hchan, reflectOffs, timers, traceBuf < fin; traceBuf < traceStrings; allg, hchan, notifyList, reflectOffs, timers, traceStrings < mspanSpecial, profInsert, profBlock, profMemActive, gcBitsArenas, spanSetSpine, mheapSpecial; profMemActive < profMemFuture; -hchan, root, sched, traceStrings < trace; -fin, notifyList, trace < traceStackTab; +hchan, root, sched, traceStrings, notifyList, fin < trace; +trace < traceStackTab; timers < netpollInit; rwmutexW, sysmon < rwmutexR; gcBitsArenas, netpollInit, profBlock, profInsert, profMemFuture, spanSetSpine, traceStackTab < gscan;