Handle unexpected exceptions in the dispatcher when throwing runnable…

… is passed as an argument
Kotlin · Sep 7, 2021 · 183fe19 · 183fe19
1 parent 778bfbc
commit 183fe19
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Showing 2 changed files with 29 additions and 4 deletions.
diff --git 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
@@ -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()
+    }
 }