From 00122c511ffe73306dc00c142df5d9180c5bcdd5 Mon Sep 17 00:00:00 2001
From: Vsevolod Tolstopyatov <qwwdfsad@gmail.com>
Date: Tue, 7 Sep 2021 15:54:40 +0300
Subject: [PATCH] Handle unexpected exceptions in the dispatcher when throwing
 runnable is passed as an argument

---
 .../common/src/internal/LimitedDispatcher.kt  |  9 ++++---
 .../jvm/test/LimitedParallelismTest.kt        | 24 ++++++++++++++++++-
 2 files changed, 29 insertions(+), 4 deletions(-)

diff --git a/kotlinx-coroutines-core/common/src/internal/LimitedDispatcher.kt b/kotlinx-coroutines-core/common/src/internal/LimitedDispatcher.kt
index 38298507eb..5cbd5b8eef 100644
--- a/kotlinx-coroutines-core/common/src/internal/LimitedDispatcher.kt
+++ b/kotlinx-coroutines-core/common/src/internal/LimitedDispatcher.kt
@@ -33,7 +33,11 @@ internal class LimitedDispatcher(
         while (true) {
             val task = queue.removeFirstOrNull()
             if (task != null) {
-                task.run()
+                try {
+                    task.run()
+                } catch (e: Throwable) {
+                    handleCoroutineException(EmptyCoroutineContext, e)
+                }
                 // 16 is our out-of-thin-air constant to emulate fairness. Used in JS dispatchers as well
                 if (++fairnessCounter >= 16 && dispatcher.isDispatchNeeded(EmptyCoroutineContext)) {
                     // Do "yield" to let other views to execute their runnable as well
@@ -62,8 +66,7 @@ internal class LimitedDispatcher(
         }
 
         /*
-         * Protect against race when the worker is finished
-         * right after our check
+         * Protect against race when the worker is finished right after our check.
          */
         @Suppress("CAST_NEVER_SUCCEEDS")
         synchronized(this as SynchronizedObject) {
diff --git a/kotlinx-coroutines-core/jvm/test/LimitedParallelismTest.kt b/kotlinx-coroutines-core/jvm/test/LimitedParallelismTest.kt
index c58fa6ba3b..30c54117a9 100644
--- a/kotlinx-coroutines-core/jvm/test/LimitedParallelismTest.kt
+++ b/kotlinx-coroutines-core/jvm/test/LimitedParallelismTest.kt
@@ -4,7 +4,10 @@
 
 package kotlinx.coroutines
 
-import org.junit.*
+import org.junit.Test
+import java.util.concurrent.*
+import kotlin.coroutines.*
+import kotlin.test.*
 
 class LimitedParallelismTest : TestBase() {
 
@@ -30,4 +33,23 @@ class LimitedParallelismTest : TestBase() {
         joinAll(j1, j2)
         executor.close()
     }
+
+    @Test
+    fun testUnhandledException() = runTest {
+        var caughtException: Throwable? = null
+        val executor = Executors.newFixedThreadPool(
+            1
+        ) {
+            Thread(it).also {
+                it.uncaughtExceptionHandler = Thread.UncaughtExceptionHandler { _, e -> caughtException = e }
+            }
+        }.asCoroutineDispatcher()
+        val view = executor.limitedParallelism(1)
+        view.dispatch(EmptyCoroutineContext, Runnable { throw TestException() })
+        withContext(view) {
+            // Verify it is in working state and establish happens-before
+        }
+        assertTrue { caughtException is TestException }
+        executor.close()
+    }
 }