From efe80a14399fefd0ec15c9b8bf2510a3c144be89 Mon Sep 17 00:00:00 2001
From: Vsevolod Tolstopyatov <qwwdfsad@gmail.com>
Date: Mon, 19 Jun 2023 19:12:12 +0200
Subject: [PATCH] Properly re-adjust DebugSequenceOverheadBenchmark

---
 ...k.kt => DebugSequenceOverheadBenchmark.kt} | 85 ++++++++++++-------
 1 file changed, 52 insertions(+), 33 deletions(-)
 rename benchmarks/src/jmh/kotlin/benchmarks/debug/{DebugProbesConcurrentBenchmark.kt => DebugSequenceOverheadBenchmark.kt} (50%)

diff --git a/benchmarks/src/jmh/kotlin/benchmarks/debug/DebugProbesConcurrentBenchmark.kt b/benchmarks/src/jmh/kotlin/benchmarks/debug/DebugSequenceOverheadBenchmark.kt
similarity index 50%
rename from benchmarks/src/jmh/kotlin/benchmarks/debug/DebugProbesConcurrentBenchmark.kt
rename to benchmarks/src/jmh/kotlin/benchmarks/debug/DebugSequenceOverheadBenchmark.kt
index 4c1a67a4d0..16e93e1f1b 100644
--- a/benchmarks/src/jmh/kotlin/benchmarks/debug/DebugProbesConcurrentBenchmark.kt
+++ b/benchmarks/src/jmh/kotlin/benchmarks/debug/DebugSequenceOverheadBenchmark.kt
@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2022 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
+ * Copyright 2016-2023 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
  */
 
 package benchmarks.debug
@@ -9,46 +9,24 @@ import kotlinx.coroutines.debug.*
 import org.openjdk.jmh.annotations.*
 import org.openjdk.jmh.annotations.State
 import java.util.concurrent.*
+import java.util.concurrent.atomic.AtomicInteger
 
+/**
+ * The benchmark is supposed to show the DebugProbes overhead for a non-concurrent sequence builder.
+ * The code is actually part of the IDEA codebase, originally reported here: https://github.com/Kotlin/kotlinx.coroutines/issues/3527
+ */
 @Warmup(iterations = 5, time = 1)
 @Measurement(iterations = 5, time = 1)
 @Fork(value = 1)
 @BenchmarkMode(Mode.AverageTime)
 @OutputTimeUnit(TimeUnit.MICROSECONDS)
 @State(Scope.Benchmark)
-open class DebugProbesConcurrentBenchmark {
-
-    @Setup
-    fun setup() {
-        DebugProbes.sanitizeStackTraces = false
-        DebugProbes.enableCreationStackTraces = false
-        DebugProbes.install()
-    }
-
-    @TearDown
-    fun tearDown() {
-        DebugProbes.uninstall()
-    }
-
+open class DebugSequenceOverheadBenchmark {
 
-    @Benchmark
-    fun run() = runBlocking<Long> {
-        var sum = 0L
-        repeat(8) {
-            launch(Dispatchers.Default) {
-                val seq = stressSequenceBuilder((1..100).asSequence()) {
-                    (1..it).asSequence()
-                }
-
-                for (i in seq) {
-                    sum += i.toLong()
-                }
-            }
-        }
-        sum
-    }
-
-    private fun <Node> stressSequenceBuilder(initialSequence: Sequence<Node>, children: (Node) -> Sequence<Node>): Sequence<Node> {
+    private fun <Node> generateRecursiveSequence(
+        initialSequence: Sequence<Node>,
+        children: (Node) -> Sequence<Node>
+    ): Sequence<Node> {
         return sequence {
             val initialIterator = initialSequence.iterator()
             if (!initialIterator.hasNext()) {
@@ -68,4 +46,45 @@ open class DebugProbesConcurrentBenchmark {
             }
         }
     }
+
+    @Param("true", "false")
+    var withDebugger = false
+
+    @Setup
+    fun setup() {
+        DebugProbes.sanitizeStackTraces = false
+        DebugProbes.enableCreationStackTraces = false
+        if (withDebugger) {
+            DebugProbes.install()
+        }
+    }
+
+    @TearDown
+    fun tearDown() {
+        if (withDebugger) {
+            DebugProbes.uninstall()
+        }
+    }
+
+    // Shows the overhead of sequence builder with debugger enabled
+    @Benchmark
+    fun runSequenceSingleThread(): Int = runBlocking {
+        generateRecursiveSequence((1..100).asSequence()) {
+            (1..it).asSequence()
+        }.sum()
+    }
+
+    // Shows the overhead of sequence builder with debugger enabled and debugger is concurrently stressed out
+    @Benchmark
+    fun runSequenceMultipleThreads(): Int = runBlocking {
+        val result = AtomicInteger(0)
+        repeat(Runtime.getRuntime().availableProcessors()) {
+            launch(Dispatchers.Default) {
+                result.addAndGet(generateRecursiveSequence((1..100).asSequence()) {
+                    (1..it).asSequence()
+                }.sum())
+            }
+        }
+        result.get()
+    }
 }