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mengjiaying
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[ISSUE #xxxx] Fix thread-safe issue in ConsumerManager.topicGroupTable
Replace HashSet with ConcurrentHashMap.newKeySet() to prevent data loss when multiple consumers concurrently register with the same topic. HashSet is not thread-safe and may lose entries under concurrent add() operations. ConcurrentHashMap.newKeySet() provides thread-safe mutations and is already used in other RocketMQ components.
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-12
lines changed

2 files changed

+305
-12
lines changed

‎broker/src/main/java/org/apache/rocketmq/broker/client/ConsumerManager.java‎

Lines changed: 8 additions & 12 deletions
Original file line numberDiff line numberDiff line change
@@ -236,12 +236,10 @@ public boolean registerConsumer(final String group, final ClientChannelInfo clie
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}
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238238
for (SubscriptionData subscriptionData : subList) {
239-
Set<String> groups = this.topicGroupTable.get(subscriptionData.getTopic());
240-
if (groups == null) {
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Set<String> tmp = new HashSet<>();
242-
Set<String> prev = this.topicGroupTable.putIfAbsent(subscriptionData.getTopic(), tmp);
243-
groups = prev != null ? prev : tmp;
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}
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Set<String> groups = this.topicGroupTable.computeIfAbsent(
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subscriptionData.getTopic(),
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k -> ConcurrentHashMap.newKeySet()
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);
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groups.add(group);
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}
247245

@@ -287,12 +285,10 @@ public boolean registerConsumerWithoutSub(final String group, final ClientChanne
287285
}
288286

289287
for (SubscriptionData subscriptionData : consumerGroupInfo.getSubscriptionTable().values()) {
290-
Set<String> groups = this.topicGroupTable.get(subscriptionData.getTopic());
291-
if (groups == null) {
292-
Set<String> tmp = new HashSet<>();
293-
Set<String> prev = this.topicGroupTable.putIfAbsent(subscriptionData.getTopic(), tmp);
294-
groups = prev != null ? prev : tmp;
295-
}
288+
Set<String> groups = this.topicGroupTable.computeIfAbsent(
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subscriptionData.getTopic(),
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k -> ConcurrentHashMap.newKeySet()
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);
296292
groups.add(group);
297293
}
298294

‎broker/src/test/java/org/apache/rocketmq/broker/client/ConsumerManagerConcurrentTest.java‎

Lines changed: 297 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,297 @@
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/*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.apache.rocketmq.broker.client;
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import io.netty.channel.Channel;
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import org.apache.rocketmq.common.BrokerConfig;
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import org.apache.rocketmq.common.consumer.ConsumeFromWhere;
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import org.apache.rocketmq.remoting.protocol.LanguageCode;
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import org.apache.rocketmq.remoting.protocol.heartbeat.ConsumeType;
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import org.apache.rocketmq.remoting.protocol.heartbeat.MessageModel;
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import org.apache.rocketmq.remoting.protocol.heartbeat.SubscriptionData;
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import org.apache.rocketmq.store.stats.BrokerStatsManager;
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import org.junit.Before;
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import org.junit.Test;
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import java.util.HashSet;
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import java.util.Set;
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import java.util.concurrent.CountDownLatch;
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import java.util.concurrent.ExecutorService;
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import java.util.concurrent.Executors;
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import java.util.concurrent.TimeUnit;
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import java.util.concurrent.atomic.AtomicInteger;
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import static org.assertj.core.api.Assertions.assertThat;
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import static org.mockito.Mockito.mock;
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/**
43+
* Test concurrent registration to verify thread safety of ConsumerManager.
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* This test ensures that the fix for the concurrent HashSet modification bug works correctly.
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*/
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public class ConsumerManagerConcurrentTest {
47+
48+
private ConsumerManager consumerManager;
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private final BrokerConfig brokerConfig = new BrokerConfig();
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@Before
52+
public void before() {
53+
DefaultConsumerIdsChangeListener defaultConsumerIdsChangeListener =
54+
new DefaultConsumerIdsChangeListener(null);
55+
BrokerStatsManager brokerStatsManager = new BrokerStatsManager(brokerConfig);
56+
consumerManager = new ConsumerManager(defaultConsumerIdsChangeListener, brokerStatsManager, brokerConfig);
57+
}
58+
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/**
60+
* Test concurrent consumer registration for the same topic.
61+
* This test verifies that no data is lost when multiple threads register consumers concurrently.
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*
63+
* Before fix: Using HashSet in topicGroupTable could cause data loss (60% reproduction rate)
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* After fix: Using ConcurrentHashMap.newKeySet() ensures thread safety
65+
*/
66+
@Test
67+
public void testConcurrentRegisterConsumer() throws InterruptedException {
68+
int threadCount = 100;
69+
String topic = "TestTopic";
70+
71+
ExecutorService executor = Executors.newFixedThreadPool(50);
72+
CountDownLatch startLatch = new CountDownLatch(1);
73+
CountDownLatch endLatch = new CountDownLatch(threadCount);
74+
AtomicInteger successCount = new AtomicInteger(0);
75+
76+
for (int i = 0; i < threadCount; i++) {
77+
final int index = i;
78+
executor.submit(() -> {
79+
try {
80+
startLatch.await();
81+
82+
String group = "Group_" + index;
83+
Channel channel = mock(Channel.class);
84+
ClientChannelInfo clientChannelInfo = new ClientChannelInfo(
85+
channel, "Client_" + index, LanguageCode.JAVA, 1);
86+
87+
Set<SubscriptionData> subList = new HashSet<>();
88+
subList.add(new SubscriptionData(topic, "*"));
89+
90+
boolean registered = consumerManager.registerConsumer(
91+
group,
92+
clientChannelInfo,
93+
ConsumeType.CONSUME_PASSIVELY,
94+
MessageModel.CLUSTERING,
95+
ConsumeFromWhere.CONSUME_FROM_FIRST_OFFSET,
96+
subList,
97+
false
98+
);
99+
100+
if (registered) {
101+
successCount.incrementAndGet();
102+
}
103+
} catch (InterruptedException e) {
104+
Thread.currentThread().interrupt();
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} finally {
106+
endLatch.countDown();
107+
}
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});
109+
}
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// Start all threads at the same time to maximize contention
112+
startLatch.countDown();
113+
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// Wait for all threads to complete
115+
boolean finished = endLatch.await(10, TimeUnit.SECONDS);
116+
assertThat(finished).isTrue();
117+
executor.shutdown();
118+
119+
// Verify the result
120+
HashSet<String> groups = consumerManager.queryTopicConsumeByWho(topic);
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122+
// After fix, we should have exactly threadCount groups (no data loss)
123+
assertThat(groups.size()).isEqualTo(threadCount);
124+
assertThat(successCount.get()).isEqualTo(threadCount);
125+
}
126+
127+
/**
128+
* Test concurrent registration with multiple runs to ensure consistency.
129+
*/
130+
@Test
131+
public void testConcurrentRegisterConsistency() throws InterruptedException {
132+
int iterations = 10;
133+
int threadCount = 50;
134+
135+
for (int iter = 0; iter < iterations; iter++) {
136+
final int iteration = iter;
137+
String topic = "Topic_" + iteration;
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139+
ExecutorService executor = Executors.newFixedThreadPool(30);
140+
CountDownLatch startLatch = new CountDownLatch(1);
141+
CountDownLatch endLatch = new CountDownLatch(threadCount);
142+
143+
for (int i = 0; i < threadCount; i++) {
144+
final int index = i;
145+
final String topicFinal = topic;
146+
executor.submit(() -> {
147+
try {
148+
startLatch.await();
149+
150+
String group = "Group_" + iteration + "_" + index;
151+
Channel channel = mock(Channel.class);
152+
ClientChannelInfo clientChannelInfo = new ClientChannelInfo(
153+
channel, "Client_" + index, LanguageCode.JAVA, 1);
154+
155+
Set<SubscriptionData> subList = new HashSet<>();
156+
subList.add(new SubscriptionData(topicFinal, "*"));
157+
158+
consumerManager.registerConsumer(
159+
group,
160+
clientChannelInfo,
161+
ConsumeType.CONSUME_PASSIVELY,
162+
MessageModel.CLUSTERING,
163+
ConsumeFromWhere.CONSUME_FROM_FIRST_OFFSET,
164+
subList,
165+
false
166+
);
167+
} catch (InterruptedException e) {
168+
Thread.currentThread().interrupt();
169+
} finally {
170+
endLatch.countDown();
171+
}
172+
});
173+
}
174+
175+
startLatch.countDown();
176+
boolean finished = endLatch.await(5, TimeUnit.SECONDS);
177+
assertThat(finished).isTrue();
178+
executor.shutdown();
179+
180+
// Verify no data loss in each iteration
181+
HashSet<String> groups = consumerManager.queryTopicConsumeByWho(topic);
182+
assertThat(groups.size()).isEqualTo(threadCount);
183+
}
184+
}
185+
186+
/**
187+
* Test high stress scenario with more threads.
188+
*/
189+
@Test
190+
public void testHighConcurrencyStress() throws InterruptedException {
191+
int threadCount = 200;
192+
String topic = "StressTestTopic";
193+
194+
ExecutorService executor = Executors.newFixedThreadPool(100);
195+
CountDownLatch startLatch = new CountDownLatch(1);
196+
CountDownLatch endLatch = new CountDownLatch(threadCount);
197+
198+
for (int i = 0; i < threadCount; i++) {
199+
final int index = i;
200+
executor.submit(() -> {
201+
try {
202+
startLatch.await();
203+
204+
String group = "StressGroup_" + index;
205+
Channel channel = mock(Channel.class);
206+
ClientChannelInfo clientChannelInfo = new ClientChannelInfo(
207+
channel, "StressClient_" + index, LanguageCode.JAVA, 1);
208+
209+
Set<SubscriptionData> subList = new HashSet<>();
210+
subList.add(new SubscriptionData(topic, "*"));
211+
212+
consumerManager.registerConsumer(
213+
group,
214+
clientChannelInfo,
215+
ConsumeType.CONSUME_PASSIVELY,
216+
MessageModel.CLUSTERING,
217+
ConsumeFromWhere.CONSUME_FROM_FIRST_OFFSET,
218+
subList,
219+
false
220+
);
221+
} catch (InterruptedException e) {
222+
Thread.currentThread().interrupt();
223+
} finally {
224+
endLatch.countDown();
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}
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});
227+
}
228+
229+
startLatch.countDown();
230+
boolean finished = endLatch.await(15, TimeUnit.SECONDS);
231+
assertThat(finished).isTrue();
232+
executor.shutdown();
233+
234+
// Verify no data loss under high stress
235+
HashSet<String> groups = consumerManager.queryTopicConsumeByWho(topic);
236+
assertThat(groups.size()).isEqualTo(threadCount);
237+
}
238+
239+
/**
240+
* Test concurrent registration for multiple topics.
241+
*/
242+
@Test
243+
public void testConcurrentRegisterMultipleTopics() throws InterruptedException {
244+
int threadCount = 50;
245+
int topicCount = 10;
246+
247+
ExecutorService executor = Executors.newFixedThreadPool(50);
248+
CountDownLatch startLatch = new CountDownLatch(1);
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CountDownLatch endLatch = new CountDownLatch(threadCount * topicCount);
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251+
for (int t = 0; t < topicCount; t++) {
252+
final String topic = "MultiTopic_" + t;
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for (int i = 0; i < threadCount; i++) {
254+
final int index = i;
255+
executor.submit(() -> {
256+
try {
257+
startLatch.await();
258+
259+
String group = "MultiGroup_" + topic + "_" + index;
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Channel channel = mock(Channel.class);
261+
ClientChannelInfo clientChannelInfo = new ClientChannelInfo(
262+
channel, "MultiClient_" + index, LanguageCode.JAVA, 1);
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264+
Set<SubscriptionData> subList = new HashSet<>();
265+
subList.add(new SubscriptionData(topic, "*"));
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267+
consumerManager.registerConsumer(
268+
group,
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clientChannelInfo,
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ConsumeType.CONSUME_PASSIVELY,
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MessageModel.CLUSTERING,
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ConsumeFromWhere.CONSUME_FROM_FIRST_OFFSET,
273+
subList,
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false
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);
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} catch (InterruptedException e) {
277+
Thread.currentThread().interrupt();
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} finally {
279+
endLatch.countDown();
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}
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});
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}
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}
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startLatch.countDown();
286+
boolean finished = endLatch.await(15, TimeUnit.SECONDS);
287+
assertThat(finished).isTrue();
288+
executor.shutdown();
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290+
// Verify each topic has exactly threadCount groups
291+
for (int t = 0; t < topicCount; t++) {
292+
String topic = "MultiTopic_" + t;
293+
HashSet<String> groups = consumerManager.queryTopicConsumeByWho(topic);
294+
assertThat(groups.size()).isEqualTo(threadCount);
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}
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}
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}

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