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Posted to commits@pulsar.apache.org by "ChimdumebiNebolisa (via GitHub)" <gi...@apache.org> on 2026/02/04 11:23:06 UTC
[PR] Fix 25204 consumer epoch [pulsar]
ChimdumebiNebolisa opened a new pull request, #25210:
URL: https://github.com/apache/pulsar/pull/25210
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Re: [PR] [fix][client] Prevent epoch race in MultiTopicsConsumer batch receive [pulsar]
Posted by "ChimdumebiNebolisa (via GitHub)" <gi...@apache.org>.
ChimdumebiNebolisa commented on PR #25210:
URL: https://github.com/apache/pulsar/pull/25210#issuecomment-3865181468
Thank you for the review. To my knowledge, `receiveMessageFromConsumer` is `private` in `MultiTopicsConsumerImpl`, which makes it difficult to drive the batch receive path deterministically without either reflection or a small visibility adjustment.
Will it be ok to change `receiveMessageFromConsumer` from `private` to `protected` solely so a test subclass can invoke the existing logic (no new methods, no `@VisibleForTesting`)? If not, I will rework the regression to drive the path via the public subscribe flow.
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Re: [PR] [fix][client] Prevent epoch race in MultiTopicsConsumer batch receive [pulsar]
Posted by "BewareMyPower (via GitHub)" <gi...@apache.org>.
BewareMyPower commented on code in PR #25210:
URL: https://github.com/apache/pulsar/pull/25210#discussion_r2772131903
##########
docs/investigations/25204-consumer-epoch.md:
##########
@@ -0,0 +1,185 @@
+# Investigation: GitHub issue #25204 – MultiTopicsConsumer receives message with older ConsumerEpoch after redeliverUnacknowledgedMessages()
Review Comment:
You should not commit the investigation document to the code base. You can post it to Gist and share the link in the PR description
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Re: [PR] Fix 25204 consumer epoch [pulsar]
Posted by "github-actions[bot] (via GitHub)" <gi...@apache.org>.
github-actions[bot] commented on PR #25210:
URL: https://github.com/apache/pulsar/pull/25210#issuecomment-3846870999
@ChimdumebiNebolisa Please add the following content to your PR description and select a checkbox:
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Re: [PR] [fix][client] Prevent epoch race in MultiTopicsConsumer batch receive [pulsar]
Posted by "BewareMyPower (via GitHub)" <gi...@apache.org>.
BewareMyPower commented on code in PR #25210:
URL: https://github.com/apache/pulsar/pull/25210#discussion_r2772146142
##########
pulsar-client/src/test/java/org/apache/pulsar/client/impl/MultiTopicsConsumerEpochRaceTest.java:
##########
@@ -0,0 +1,289 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.pulsar.client.impl;
+
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.doNothing;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+import static org.testng.Assert.assertFalse;
+import static org.testng.Assert.assertTrue;
+import io.netty.util.concurrent.DefaultThreadFactory;
+import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.nio.ByteBuffer;
+import java.util.Collections;
+import java.util.List;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicInteger;
+import org.apache.pulsar.client.api.Consumer;
+import org.apache.pulsar.client.api.Messages;
+import org.apache.pulsar.client.api.Schema;
+import org.apache.pulsar.client.api.SubscriptionType;
+import org.apache.pulsar.client.impl.conf.ConsumerConfigurationData;
+import org.apache.pulsar.client.util.ExecutorProvider;
+import org.apache.pulsar.common.api.proto.MessageMetadata;
+import org.testng.annotations.AfterMethod;
+import org.testng.annotations.BeforeMethod;
+import org.testng.annotations.Test;
+
+/**
+ * Deterministic regression test for GitHub issue #25204: MultiTopicsConsumer can deliver one message
+ * with old consumerEpoch while other messages in the same batch are filtered, due to a race when
+ * redeliverUnacknowledgedMessages() runs between batch message iterations.
+ *
+ * <p>Uses a test-only subclass of MultiTopicsConsumerImpl that overrides isValidConsumerEpoch to
+ * block after the first validation (latch1/latch2). With a 2-thread internal executor, the test
+ * triggers redeliverUnacknowledgedMessages() while the receive thread is blocked between the two
+ * validations, so the epoch changes mid-batch. Without the fix, exactly one message is delivered
+ * (bug). The test asserts totalDelivered != 1.
+ */
+@Test(groups = "flaky")
Review Comment:
Why is it flaky? If the bug is fixed, this test should not be flaky
##########
pulsar-client/src/test/java/org/apache/pulsar/client/impl/MultiTopicsConsumerEpochRaceTest.java:
##########
@@ -0,0 +1,289 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.pulsar.client.impl;
+
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.doNothing;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+import static org.testng.Assert.assertFalse;
+import static org.testng.Assert.assertTrue;
+import io.netty.util.concurrent.DefaultThreadFactory;
+import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.nio.ByteBuffer;
+import java.util.Collections;
+import java.util.List;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicInteger;
+import org.apache.pulsar.client.api.Consumer;
+import org.apache.pulsar.client.api.Messages;
+import org.apache.pulsar.client.api.Schema;
+import org.apache.pulsar.client.api.SubscriptionType;
+import org.apache.pulsar.client.impl.conf.ConsumerConfigurationData;
+import org.apache.pulsar.client.util.ExecutorProvider;
+import org.apache.pulsar.common.api.proto.MessageMetadata;
+import org.testng.annotations.AfterMethod;
+import org.testng.annotations.BeforeMethod;
+import org.testng.annotations.Test;
+
+/**
+ * Deterministic regression test for GitHub issue #25204: MultiTopicsConsumer can deliver one message
+ * with old consumerEpoch while other messages in the same batch are filtered, due to a race when
+ * redeliverUnacknowledgedMessages() runs between batch message iterations.
+ *
+ * <p>Uses a test-only subclass of MultiTopicsConsumerImpl that overrides isValidConsumerEpoch to
+ * block after the first validation (latch1/latch2). With a 2-thread internal executor, the test
+ * triggers redeliverUnacknowledgedMessages() while the receive thread is blocked between the two
+ * validations, so the epoch changes mid-batch. Without the fix, exactly one message is delivered
+ * (bug). The test asserts totalDelivered != 1.
+ */
+@Test(groups = "flaky")
+public class MultiTopicsConsumerEpochRaceTest {
+
+ private static final String TOPIC_NAME = "topic-25204";
+ private static final int AWAIT_SECONDS = 15;
+
+ private ExecutorProvider executorProvider;
+ private ExecutorService internalExecutor;
+ private PulsarClientImpl clientMock;
+
+ @BeforeMethod(alwaysRun = true)
+ public void setUp() {
+ executorProvider = new ExecutorProvider(2, "MultiTopicsConsumerEpochRaceTest");
+ internalExecutor = Executors.newFixedThreadPool(2,
+ new DefaultThreadFactory("internal-executor", true));
+ clientMock = ClientTestFixtures.createPulsarClientMockWithMockedClientCnx(
+ executorProvider, internalExecutor);
+ }
+
+ @AfterMethod(alwaysRun = true)
+ public void cleanUp() {
+ if (executorProvider != null) {
+ executorProvider.shutdownNow();
+ }
+ if (internalExecutor != null) {
+ internalExecutor.shutdownNow();
+ }
+ }
+
+ /**
+ * Deterministic reproduction: test subclass blocks inside isValidConsumerEpoch on the first
+ * call; test thread triggers redeliver (epoch increments on another executor thread), then
+ * unblocks. Second message is validated with new epoch and filtered. Outcome: exactly one
+ * message delivered. Assertion: totalDelivered must not be 1.
+ */
+ @Test(timeOut = 15000, description = "Issue 25204: redeliver blocked by lock during batch; acceptedByEpochCount == 2")
+ @SuppressWarnings("unchecked")
+ public void testEpochConsistencyWhenRedeliverRunsMidBatch() throws Exception {
+ CountDownLatch afterFirstValidationLatch = new CountDownLatch(1);
+ CountDownLatch releaseValidationLatch = new CountDownLatch(1);
+ CountDownLatch redeliverDoneLatch = new CountDownLatch(1);
+ CountDownLatch forEachCompleteLatch = new CountDownLatch(1);
+ AtomicInteger validationCallCount = new AtomicInteger(0);
+ AtomicInteger acceptedByEpochCount = new AtomicInteger(0);
+
+ ConsumerConfigurationData<byte[]> conf = new ConsumerConfigurationData<>();
+ conf.setTopicNames(Collections.emptySet());
+ conf.setSubscriptionName("sub-25204");
+ conf.setSubscriptionType(SubscriptionType.Exclusive);
+ conf.setReceiverQueueSize(10);
+ conf.setMessageListener((consumer, msg) -> { });
+
+ CompletableFuture<Consumer<byte[]>> subscribeFuture = new CompletableFuture<>();
+ TestableMultiTopicsConsumerImpl multiConsumer = new TestableMultiTopicsConsumerImpl(
+ clientMock, conf, executorProvider, subscribeFuture, Schema.BYTES, null, true);
+ multiConsumer.setEpochRaceTestLatches(
+ afterFirstValidationLatch, releaseValidationLatch, redeliverDoneLatch,
+ forEachCompleteLatch, validationCallCount, acceptedByEpochCount);
+
+ subscribeFuture.get(AWAIT_SECONDS, TimeUnit.SECONDS);
+ assertTrue(multiConsumer.getConsumers().isEmpty(), "Empty topic set gives 0 consumers");
+
+ ConsumerImpl<byte[]> mockConsumer = mock(ConsumerImpl.class);
+ when(mockConsumer.getTopic()).thenReturn(TOPIC_NAME);
+ doNothing().when(mockConsumer).increaseAvailablePermits(any(ClientCnx.class));
+ ClientCnx cnxMock = mock(ClientCnx.class);
+ org.apache.pulsar.client.impl.ConnectionHandler connectionHandlerMock =
+ mock(org.apache.pulsar.client.impl.ConnectionHandler.class);
+ when(connectionHandlerMock.cnx()).thenReturn(cnxMock);
+ when(mockConsumer.getConnectionHandler()).thenReturn(connectionHandlerMock);
+ when(mockConsumer.getCurrentReceiverQueueSize()).thenReturn(10);
+
+ CompletableFuture<Messages<byte[]>> batchFuture = new CompletableFuture<>();
+ when(mockConsumer.batchReceiveAsync()).thenReturn(batchFuture);
+
+ Field consumersField = MultiTopicsConsumerImpl.class.getDeclaredField("consumers");
+ consumersField.setAccessible(true);
+ java.util.Map<String, ConsumerImpl<byte[]>> consumersMap =
+ (java.util.Map<String, ConsumerImpl<byte[]>>) consumersField.get(multiConsumer);
Review Comment:
Don't use reflection. `consumers` is a `protected` field, you can access `consumers` directly
In addition, AI tends to use full qualified type name (`java.util.Map`) rather than `Map` with `import java.util.Map`. You can customize the AGENTS.md or manually review the AI generated code.
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Re: [PR] [fix][client] Prevent epoch race in MultiTopicsConsumer batch receive [pulsar]
Posted by "merlimat (via GitHub)" <gi...@apache.org>.
merlimat commented on PR #25210:
URL: https://github.com/apache/pulsar/pull/25210#issuecomment-6229834018
Thanks @ChimdumebiNebolisa for digging into this. Looking at current master, the batch loop in `receiveMessageFromConsumer` and `redeliverUnacknowledgedMessages()` both run on the consumer's `internalPinnedExecutor`, which is single-threaded, so the epoch can't change mid-batch. The test only reproduces it by injecting a 2-thread pool as the pinned executor. I think #25204 is caused by something else: `redeliverUnacknowledgedMessages()` just enqueues the work and returns, so a following `receive()` can still return old-epoch messages already in `incomingMessages`. I'm going to close this one. If you'd like to pursue the real gap (e.g. having `internalReceive`/`batchReceive` filter by epoch, or making redeliver take effect before it returns), a new PR with a test against the real executor would be very welcome.
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Re: [PR] [fix][client] Prevent epoch race in MultiTopicsConsumer batch receive [pulsar]
Posted by "merlimat (via GitHub)" <gi...@apache.org>.
merlimat closed pull request #25210: [fix][client] Prevent epoch race in MultiTopicsConsumer batch receive
URL: https://github.com/apache/pulsar/pull/25210
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