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Posted to commits@pekko.apache.org by he...@apache.org on 2026/06/18 22:20:33 UTC
(pekko) branch fix/cancel-receive-timeout-npe created (now c20332f172)
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He-Pin pushed a change to branch fix/cancel-receive-timeout-npe
in repository https://gitbox.apache.org/repos/asf/pekko.git
at c20332f172 fix(actor-typed): cancelReceiveTimeout 后丢弃 stale ReceiveTimeout 避免 NPE
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new c20332f172 fix(actor-typed): cancelReceiveTimeout 后丢弃 stale ReceiveTimeout 避免 NPE
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(pekko) 01/01: fix(actor-typed): cancelReceiveTimeout 后丢弃 stale ReceiveTimeout 避免 NPE
Posted by he...@apache.org.
This is an automated email from the ASF dual-hosted git repository.
He-Pin pushed a commit to branch fix/cancel-receive-timeout-npe
in repository https://gitbox.apache.org/repos/asf/pekko.git
commit c20332f172093ae9aa33c858b27661d3d8a057b2
Author: 虎鸣 <he...@alibaba-inc.com>
AuthorDate: Fri Jun 19 06:20:14 2026 +0800
fix(actor-typed): cancelReceiveTimeout 后丢弃 stale ReceiveTimeout 避免 NPE
Motivation:
cancelReceiveTimeout() 将 receiveTimeoutMsg 置 null,
但已通过 scheduleOnce 入队邮箱的 classic ReceiveTimeout 无法撤回;
stale 消息以 null 传入 typed 行为栈, 导致 InterceptorImpl.receive
中 msg.getClass 抛出 NullPointerException。
Modification:
ActorAdapter.aroundReceive 在转发 receiveTimeoutMsg 前做 null 检查,
stale timeout 直接丢弃; 新增 CancelReceiveTimeoutSpec 回归测试。
Result:
typed actor 在 cancelReceiveTimeout 与 stale ReceiveTimeout 竞态下
不再崩溃, 行为栈对调用方透明。
---
.../actor/typed/CancelReceiveTimeoutSpec.scala | 98 ++++++++++++++++++++++
.../typed/internal/adapter/ActorAdapter.scala | 6 +-
2 files changed, 103 insertions(+), 1 deletion(-)
diff --git a/actor-typed-tests/src/test/scala/org/apache/pekko/actor/typed/CancelReceiveTimeoutSpec.scala b/actor-typed-tests/src/test/scala/org/apache/pekko/actor/typed/CancelReceiveTimeoutSpec.scala
new file mode 100644
index 0000000000..a1547e1930
--- /dev/null
+++ b/actor-typed-tests/src/test/scala/org/apache/pekko/actor/typed/CancelReceiveTimeoutSpec.scala
@@ -0,0 +1,98 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * license agreements; and to You under the Apache License, version 2.0:
+ *
+ * https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * This file is part of the Apache Pekko project, which was derived from Akka.
+ */
+
+package org.apache.pekko.actor.typed
+
+import scala.concurrent.duration._
+import scala.reflect.ClassTag
+
+import org.apache.pekko
+import pekko.actor.testkit.typed.scaladsl.LogCapturing
+import pekko.actor.testkit.typed.scaladsl.ScalaTestWithActorTestKit
+import pekko.actor.testkit.typed.scaladsl.TestProbe
+import pekko.actor.typed.scaladsl.Behaviors
+import pekko.actor.typed.scaladsl.adapter._
+
+import org.scalatest.wordspec.AnyWordSpecLike
+
+class CancelReceiveTimeoutSpec extends ScalaTestWithActorTestKit with AnyWordSpecLike with LogCapturing {
+
+ sealed trait Command
+ case object SetAndCancelTimeout extends Command
+ case object Timeout extends Command
+ case object Ping extends Command
+ case object Pong extends Event
+
+ sealed trait Event
+ case object Done extends Event
+
+ // A no-op interceptor that deepens the behavior stack so the message
+ // passes through InterceptorImpl.receive — the exact code path where
+ // msg.getClass throws NPE on a null message.
+ private def noopInterceptor[T: ClassTag] = new BehaviorInterceptor[T, T] {
+ override def aroundReceive(
+ ctx: TypedActorContext[T],
+ msg: T,
+ target: BehaviorInterceptor.ReceiveTarget[T]): Behavior[T] =
+ target(ctx, msg)
+ }
+
+ "A typed actor with receive timeout" must {
+
+ // Regression test for #3084: cancelReceiveTimeout() sets receiveTimeoutMsg to
+ // null, but a classic ReceiveTimeout already enqueued in the mailbox cannot be
+ // retracted. Before the fix the stale ReceiveTimeout was forwarded to the typed
+ // behavior stack as a null message, causing NPE in InterceptorImpl.receive.
+ "silently discard a stale ReceiveTimeout after cancelReceiveTimeout" in {
+ val probe = TestProbe[Event]()
+
+ def behavior: Behavior[Command] =
+ Behaviors.setup { context =>
+ // Wrap in an interceptor so the message traverses InterceptorImpl.receive,
+ // the exact location where msg.getClass throws NPE on a null message.
+ Behaviors.intercept[Command, Command](() => noopInterceptor[Command]) {
+ Behaviors.receiveMessage {
+ case SetAndCancelTimeout =>
+ // Set a very long timeout (won't actually fire), then immediately
+ // cancel it. This leaves receiveTimeoutMsg as null.
+ context.setReceiveTimeout(1.hour, Timeout)
+ context.cancelReceiveTimeout()
+ probe.ref ! Done
+ Behaviors.same
+
+ case Timeout =>
+ // Should never reach here: the timeout was cancelled and we send
+ // the classic ReceiveTimeout ourselves to simulate the stale case.
+ Behaviors.unhandled
+
+ case Ping =>
+ probe.ref ! Pong
+ Behaviors.same
+ }
+ }
+ }
+
+ val ref = spawn(behavior)
+
+ // Step 1: actor sets and cancels the receive timeout → receiveTimeoutMsg is now null
+ ref ! SetAndCancelTimeout
+ probe.expectMessage(Done)
+
+ // Step 2: simulate a stale classic ReceiveTimeout arriving in the mailbox.
+ // This is what happens when the scheduler fires ReceiveTimeout before
+ // cancelReceiveTimeout() is processed but the actor dequeues them in the
+ // opposite order.
+ ref.toClassic ! pekko.actor.ReceiveTimeout
+
+ // Step 3: verify the actor is still alive and responsive (no NPE crash).
+ ref ! Ping
+ probe.expectMessage(Pong)
+ }
+ }
+}
diff --git a/actor-typed/src/main/scala/org/apache/pekko/actor/typed/internal/adapter/ActorAdapter.scala b/actor-typed/src/main/scala/org/apache/pekko/actor/typed/internal/adapter/ActorAdapter.scala
index 5b7b131b6c..7bee9f44f1 100644
--- a/actor-typed/src/main/scala/org/apache/pekko/actor/typed/internal/adapter/ActorAdapter.scala
+++ b/actor-typed/src/main/scala/org/apache/pekko/actor/typed/internal/adapter/ActorAdapter.scala
@@ -100,7 +100,11 @@ import pekko.util.OptionVal
} else Terminated(ActorRefAdapter(ref))
handleSignal(msg)
case classic.ReceiveTimeout =>
- handleMessage(ctx.receiveTimeoutMsg)
+ // cancelReceiveTimeout() sets receiveTimeoutMsg to null, but a classic ReceiveTimeout
+ // that was already enqueued in the mailbox before the cancel cannot be retracted.
+ // Discard the stale timeout to avoid passing null into the typed behavior stack (#3084).
+ val timeoutMsg = ctx.receiveTimeoutMsg
+ if (timeoutMsg != null) handleMessage(timeoutMsg)
case wrapped: AdaptMessage[Any, T] @unchecked =>
withSafelyAdapted(() => wrapped.adapt()) {
case AdaptWithRegisteredMessageAdapter(msg) =>
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