Fixed race between creation of a child & cancellation of parent job
diff --git a/common/kotlinx-coroutines-core-common/src/JobSupport.kt b/common/kotlinx-coroutines-core-common/src/JobSupport.kt
index a8ae208..7c1ddf4 100644
--- a/common/kotlinx-coroutines-core-common/src/JobSupport.kt
+++ b/common/kotlinx-coroutines-core-common/src/JobSupport.kt
@@ -255,7 +255,7 @@
// fast-path method to finalize normally completed coroutines without children
private fun tryFinalizeSimpleState(state: Incomplete, update: Any?, mode: Int): Boolean {
- check(state !is Finishing) // only for non-finishing state
+ check(state is Empty || state is JobNode<*>) // only simple state without lists where children can concurrently add
check(update !is CompletedExceptionally) // only for normal completion
if (!_state.compareAndSet(state, update)) return false
completeStateFinalization(state, update, mode, false)
@@ -735,9 +735,9 @@
return COMPLETING_ALREADY_COMPLETING
// find first child
val child = firstChild(state)
- // FAST PATH -- no children to wait for && not finishing && not failing => can complete immediately
+ // FAST PATH -- no children to wait for && simple state (no list) && not failing => can complete immediately
// Failures always have to go through Finishing state to serialize exception handling
- if (child == null && state !is Finishing && proposedUpdate !is CompletedExceptionally) {
+ if (child == null && (state is Empty || state is JobNode<*>) && proposedUpdate !is CompletedExceptionally) {
if (!tryFinalizeSimpleState(state, proposedUpdate, mode)) return COMPLETING_RETRY
return COMPLETING_COMPLETED
}
diff --git a/core/kotlinx-coroutines-core/test/JobChildStressTest.kt b/core/kotlinx-coroutines-core/test/JobChildStressTest.kt
new file mode 100644
index 0000000..fca7ff6
--- /dev/null
+++ b/core/kotlinx-coroutines-core/test/JobChildStressTest.kt
@@ -0,0 +1,62 @@
+/*
+ * Copyright 2016-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
+ */
+
+package kotlinx.coroutines.experimental
+
+import org.junit.*
+import org.junit.Test
+import java.util.concurrent.*
+import kotlin.test.*
+
+class JobChildStressTest : TestBase() {
+ private val N_ITERATIONS = 10_000 * stressTestMultiplier
+ private val pool = newFixedThreadPoolContext(3, "JobChildStressTest")
+
+ @After
+ fun tearDown() {
+ pool.close()
+ }
+
+ /**
+ * Perform concurrent launch of a child job & cancellation of the explicit parent job
+ */
+ @Test
+ @Suppress("PLATFORM_CLASS_MAPPED_TO_KOTLIN")
+ fun testChild() = runTest {
+ val barrier = CyclicBarrier(3)
+ repeat(N_ITERATIONS) {
+ var wasLaunched = false
+ var unhandledException: Throwable? = null
+ val handler = CoroutineExceptionHandler { _, ex ->
+ unhandledException = ex
+ }
+ val scope = CoroutineScope(pool + handler)
+ val parent = CompletableDeferred<Unit>()
+ // concurrent child launcher
+ val launcher = scope.launch {
+ barrier.await()
+ // A: launch child for a parent job
+ launch(parent) {
+ wasLaunched = true
+ throw TestException()
+ }
+ }
+ // concurrent cancel
+ val canceller = scope.launch {
+ barrier.await()
+ // B: cancel parent job of a child
+ parent.cancel()
+ }
+ barrier.await()
+ joinAll(launcher, canceller, parent)
+ assertNull(unhandledException)
+ if (wasLaunched) {
+ val exception = parent.getCompletionExceptionOrNull()
+ assertTrue(exception is TestException, "exception=$exception")
+ }
+ }
+ }
+
+ private class TestException : Exception()
+}
\ No newline at end of file