From 04c819d87351b4b881032565d5e670f5a4e297f2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Felix=20Geisend=C3=B6rfer?=
 <felix.geisendoerfer@datadoghq.com>
Date: Wed, 27 Sep 2023 13:37:56 +0200
Subject: [PATCH] profiler: enable execution traces by default for go1.21+
 (#2226)

---
 profiler/go_lt_1_21.go    | 12 ++++++++++++
 profiler/options.go       |  8 +++++++-
 profiler/profiler_test.go |  7 +++++++
 3 files changed, 26 insertions(+), 1 deletion(-)
 create mode 100644 profiler/go_lt_1_21.go

diff --git a/profiler/go_lt_1_21.go b/profiler/go_lt_1_21.go
new file mode 100644
index 0000000000..bbb9a3fc03
--- /dev/null
+++ b/profiler/go_lt_1_21.go
@@ -0,0 +1,12 @@
+// Unless explicitly stated otherwise all files in this repository are licensed
+// under the Apache License Version 2.0.
+// This product includes software developed at Datadog (https://www.datadoghq.com/).
+// Copyright 2023 Datadog, Inc.
+
+//go:build !go1.21
+
+package profiler
+
+func init() {
+	executionTraceEnabledDefault = false
+}
diff --git a/profiler/options.go b/profiler/options.go
index e40593a5f1..8ee05316dd 100644
--- a/profiler/options.go
+++ b/profiler/options.go
@@ -552,11 +552,17 @@ type executionTraceConfig struct {
 	warned bool
 }
 
+// executionTraceEnabledDefault depends on the Go version and CPU architecture,
+// see go_lt_1_21.go and this [article][] for more details.
+//
+// [article]: https://blog.felixge.de/waiting-for-go1-21-execution-tracing-with-less-than-one-percent-overhead/
+var executionTraceEnabledDefault = runtime.GOARCH == "arm64" || runtime.GOARCH == "amd64"
+
 // Refresh updates the execution trace configuration to reflect any run-time
 // changes to the configuration environment variables, applying defaults as
 // needed.
 func (e *executionTraceConfig) Refresh() {
-	e.Enabled = internal.BoolEnv("DD_PROFILING_EXECUTION_TRACE_ENABLED", false)
+	e.Enabled = internal.BoolEnv("DD_PROFILING_EXECUTION_TRACE_ENABLED", executionTraceEnabledDefault)
 	e.Period = internal.DurationEnv("DD_PROFILING_EXECUTION_TRACE_PERIOD", 15*time.Minute)
 	e.Limit = internal.IntEnv("DD_PROFILING_EXECUTION_TRACE_LIMIT_BYTES", defaultExecutionTraceSizeLimit)
 
diff --git a/profiler/profiler_test.go b/profiler/profiler_test.go
index 592dc7a5b1..0721ca3a16 100644
--- a/profiler/profiler_test.go
+++ b/profiler/profiler_test.go
@@ -236,6 +236,10 @@ func TestProfilerPassthrough(t *testing.T) {
 	if testing.Short() {
 		return
 	}
+	beforeExecutionTraceEnabledDefault := executionTraceEnabledDefault
+	executionTraceEnabledDefault = false
+	defer func() { executionTraceEnabledDefault = beforeExecutionTraceEnabledDefault }()
+
 	out := make(chan batch)
 	p, err := newProfiler()
 	require.NoError(t, err)
@@ -378,6 +382,9 @@ func TestAllUploaded(t *testing.T) {
 			"goroutines.pprof",
 			"goroutineswait.pprof",
 		}
+		if executionTraceEnabledDefault && seq == 0 {
+			expected = append(expected, "go.trace")
+		}
 		assert.ElementsMatch(t, expected, profile.event.Attachments)
 
 		assert.Contains(t, profile.tags, fmt.Sprintf("profile_seq:%d", seq))