cmd/trace: also show end stack traces

felixge · gopherbot · commit 6405e60ca6be · 2024-11-27T06:35:34.000Z
Fix a regression that appeared in 1.23 when it comes to the stack traces shown in the trace viewer. In 1.22 and earlier, the viewer was always showing end stack traces. In 1.23 and later the viewer started to exclusively show start stack traces. Showing only the start stack traces made it impossible to see the last stack trace produced by a goroutine. It also made it hard to understand why a goroutine went off-cpu, as one had to hunt down the next running slice of the same goroutine. Emit end stack traces in addition to start stack traces to fix the issue. Fixes #70570 Change-Id: Ib22ea61388c1d94cdbc99fae2d207c4dce011a59 Reviewed-on: https://go-review.googlesource.com/c/go/+/631895 LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Michael Pratt <mpratt@google.com> Auto-Submit: Felix Geisendörfer <felix.geisendoerfer@datadoghq.com> Reviewed-by: Nick Ripley <nick.ripley@datadoghq.com> Reviewed-by: Michael Knyszek <mknyszek@google.com>
diff --git a/src/cmd/trace/gstate.go b/src/cmd/trace/gstate.go
@@ -257,6 +257,10 @@ func (gs *gState[R]) stop(ts trace.Time, stack trace.Stack, ctx *traceContext) {
 	if gs.lastStopStack != trace.NoStack {
 		stk = ctx.Stack(viewerFrames(gs.lastStopStack))
 	}
+	var endStk int
+	if stack != trace.NoStack {
+		endStk = ctx.Stack(viewerFrames(stack))
+	}
 	// Check invariants.
 	if gs.startRunningTime == 0 {
 		panic("silently broken trace or generator invariant (startRunningTime != 0) not held")
@@ -270,6 +274,7 @@ func (gs *gState[R]) stop(ts trace.Time, stack trace.Stack, ctx *traceContext) {
 		Dur:      ts.Sub(gs.startRunningTime),
 		Resource: uint64(gs.executing),
 		Stack:    stk,
+		EndStack: endStk,
 	})
 
 	// Flush completed ranges.
