From 57c7902c60b4b1d665b40ab5e19a869716acac1f Mon Sep 17 00:00:00 2001
From: Dmitry Khalanskiy <Dmitry.Khalanskiy@jetbrains.com>
Date: Tue, 17 Feb 2026 14:29:28 +0100
Subject: [PATCH 1/2] Optimize attaching the debug probes

I see a notable speed improvement even without any benchmarks,
simply by running `DebugProbes.withDebugProbes { }` in a loop.
---
 kotlinx-coroutines-debug/src/Attach.kt | 37 +++++++++++++++-----------
 1 file changed, 22 insertions(+), 15 deletions(-)

diff --git a/kotlinx-coroutines-debug/src/Attach.kt b/kotlinx-coroutines-debug/src/Attach.kt
index 291d913f3e..8d79daba10 100644
--- a/kotlinx-coroutines-debug/src/Attach.kt
+++ b/kotlinx-coroutines-debug/src/Attach.kt
@@ -16,23 +16,30 @@ internal class ByteBuddyDynamicAttach : Function1<Boolean, Unit> {
 
     private fun attach() {
         ByteBuddyAgent.install(ByteBuddyAgent.AttachmentProvider.ForEmulatedAttachment.INSTANCE)
-        val cl = Class.forName("kotlin.coroutines.jvm.internal.DebugProbesKt")
-        val cl2 = Class.forName("kotlinx.coroutines.debug.internal.DebugProbesKt")
-
-        ByteBuddy()
-            .redefine(cl2)
-            .name(cl.name)
-            .make()
-            .load(cl.classLoader, ClassReloadingStrategy.fromInstalledAgent())
+        dynamicTypeWithProbes.load(targetClassLoader, ClassReloadingStrategy.fromInstalledAgent())
     }
 
     private fun detach() {
-        val cl = Class.forName("kotlin.coroutines.jvm.internal.DebugProbesKt")
-        val cl2 = Class.forName("kotlinx.coroutines.debug.NoOpProbesKt")
-        ByteBuddy()
-            .redefine(cl2)
-            .name(cl.name)
-            .make()
-            .load(cl.classLoader, ClassReloadingStrategy.fromInstalledAgent())
+        dynamicTypeWithoutProbes.load(targetClassLoader, ClassReloadingStrategy.fromInstalledAgent())
     }
 }
+
+private val targetClassLoader = Class.forName(classNameToOverride).classLoader
+
+private const val classNameToOverride = "kotlin.coroutines.jvm.internal.DebugProbesKt"
+
+private val dynamicTypeWithProbes by lazy {
+    val classWithProbes = Class.forName("kotlinx.coroutines.debug.internal.DebugProbesKt")
+    ByteBuddy()
+        .redefine(classWithProbes)
+        .name(classNameToOverride)
+        .make()
+}
+
+private val dynamicTypeWithoutProbes by lazy {
+    val classWithoutProbes = Class.forName("kotlinx.coroutines.debug.NoOpProbesKt")
+    ByteBuddy()
+        .redefine(classWithoutProbes)
+        .name(classNameToOverride)
+        .make()
+}

From fb0981099976c5285cbdc27eaa3f232f4f5189a7 Mon Sep 17 00:00:00 2001
From: Dmitry Khalanskiy <dmitry.khalanskiy@jetbrains.com>
Date: Fri, 10 Jul 2026 14:40:57 +0200
Subject: [PATCH 2/2] Move the top-level cache variables into the companion
 object

---
 kotlinx-coroutines-debug/src/Attach.kt | 42 ++++++++++++++------------
 1 file changed, 23 insertions(+), 19 deletions(-)

diff --git a/kotlinx-coroutines-debug/src/Attach.kt b/kotlinx-coroutines-debug/src/Attach.kt
index 8d79daba10..102f8cf372 100644
--- a/kotlinx-coroutines-debug/src/Attach.kt
+++ b/kotlinx-coroutines-debug/src/Attach.kt
@@ -22,24 +22,28 @@ internal class ByteBuddyDynamicAttach : Function1<Boolean, Unit> {
     private fun detach() {
         dynamicTypeWithoutProbes.load(targetClassLoader, ClassReloadingStrategy.fromInstalledAgent())
     }
-}
-
-private val targetClassLoader = Class.forName(classNameToOverride).classLoader
-
-private const val classNameToOverride = "kotlin.coroutines.jvm.internal.DebugProbesKt"
 
-private val dynamicTypeWithProbes by lazy {
-    val classWithProbes = Class.forName("kotlinx.coroutines.debug.internal.DebugProbesKt")
-    ByteBuddy()
-        .redefine(classWithProbes)
-        .name(classNameToOverride)
-        .make()
-}
-
-private val dynamicTypeWithoutProbes by lazy {
-    val classWithoutProbes = Class.forName("kotlinx.coroutines.debug.NoOpProbesKt")
-    ByteBuddy()
-        .redefine(classWithoutProbes)
-        .name(classNameToOverride)
-        .make()
+    private companion object {
+        private const val classNameToOverride = "kotlin.coroutines.jvm.internal.DebugProbesKt"
+
+        private val targetClassLoader by lazy {
+            Class.forName(classNameToOverride).classLoader
+        }
+
+        private val dynamicTypeWithProbes by lazy {
+            val classWithProbes = Class.forName("kotlinx.coroutines.debug.internal.DebugProbesKt")
+            ByteBuddy()
+                .redefine(classWithProbes)
+                .name(classNameToOverride)
+                .make()
+        }
+
+        private val dynamicTypeWithoutProbes by lazy {
+            val classWithoutProbes = Class.forName("kotlinx.coroutines.debug.NoOpProbesKt")
+            ByteBuddy()
+                .redefine(classWithoutProbes)
+                .name(classNameToOverride)
+                .make()
+        }
+    }
 }