Infinite Loop in the Transaction Profiler

[mpass99]

Summary

The transaction profiler profiler.go loops infinite if the transaction duration exceeds the profilerRuntimeLimit, causing the application to terminate due to OOM.

Steps To Reproduce

func main() {
	err := sentry.Init(sentry.ClientOptions{EnableTracing: true, ProfilesSampleRate: 1})
	if err != nil {
		fmt.Printf("sentry.Init: %s", err.Error())
		return
	}

	span := sentry.StartSpan(context.Background(), "main", sentry.WithSpanSampled(sentry.SampledTrue))
	time.Sleep(35 * time.Second)
	span.Finish()
}

Expected Behavior

Either:

• The Sentry SDK is able to profile also transactions lasting longer than 30 seconds without crashing the application.
• The Sentry SDK discards the profiling of transactions exceeding the profilerRuntimeLimit.

Environment

SDK

• sentry-go version: v0.24.1
• Go version: 1.21.1
• Using Go Modules? yes

Sentry

• No Sentry Backend required to reproduce the behavior.

Additional context

The following loop runs infinite:

sentry-go/profiler.go

Lines 243 to 251 in 7e37ede

	for start.Value != nil {
	var bucket = start.Value.(*profileSamplesBucket)
	if bucket.relativeTimeNS < relativeStartNS {
	break
	}
	samplesCount += len(bucket.goIDs)
	buckets = append(buckets, bucket)
	start = start.Prev()
	}

The profilerRuntimeLimit defines a limit of 30 seconds. If the transaction lasts longer, the start-30-second-ring-structure is filled completely which causes both break conditions to not apply.

[cleptric]

@vaind Can you take a look, please?

[cjcormack]

#725 fixes this issue for me. Thank you for getting a PR with the fix out so quickly!

[cleptric]

The fix was released in 0.25.0. Thanks for confirming the fix @cjcormack 🙏

[mpass99]

I can confirm that release 0.25.0 resolves our issue. Thank you for your quick solution!