Fix thread blocking in NotificationControllerV2 by replacing synchronized Multimap with case-insensitive concurrent implementation by Copilot · Pull Request #5451 · apolloconfig/apollo

Copilot · 2025-08-24T05:51:36Z

Identify race condition in CaseInsensitiveConcurrentMultimap
Fix put() method to use compute() for atomic operations
Fix remove() method to use computeIfPresent() for atomic operations
Add comprehensive test for concurrent put/remove race condition
Verify implementation correctness

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Copilot · 2025-08-24T05:51:38Z

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Co-authored-by: nobodyiam <[email protected]>

nobodyiam · 2025-08-24T06:13:43Z

@copilot the build failed with the error messages

Error:  Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.10.1:compile (default-compile) on project apollo-configservice: Compilation failure: Compilation failure: 
Error:  /home/runner/work/apollo/apollo/apollo-configservice/src/main/java/com/ctrip/framework/apollo/configservice/controller/NotificationControllerV2.java:[225,71] cannot find symbol
Error:    symbol:   class Multimap
Error:    location: class com.ctrip.framework.apollo.configservice.controller.NotificationControllerV2
Error:  /home/runner/work/apollo/apollo/apollo-configservice/src/main/java/com/ctrip/framework/apollo/configservice/controller/NotificationControllerV2.java:[142,5] cannot find symbol
Error:    symbol:   class Multimap
Error:    location: class com.ctrip.framework.apollo.configservice.controller.NotificationControllerV2
Error:  -> [Help 1]
Error:  
Error:  To see the full stack trace of the errors, re-run Maven with the -e switch.
Error:  Re-run Maven using the -X switch to enable full debug logging.
Error:  
Error:  For more information about the errors and possible solutions, please read the following articles:
Error:  [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoFailureException
Error:  
Error:  After correcting the problems, you can resume the build with the command
Error:    mvn <args> -rf :apollo-configservice
Error: Process completed with exit code 1.

Co-authored-by: nobodyiam <[email protected]>

Copilot · 2025-08-24T06:18:06Z

@copilot the build failed with the error messages

...

Fixed the compilation errors by adding back the missing com.google.common.collect.Multimap import. The issue occurred because when I replaced the synchronized Multimap field with ConcurrentMultimap, I inadvertently removed the Guava Multimap import that was still needed for method parameters and variables that use the return type from WatchKeysUtil.assembleAllWatchKeys().

Commit: e49746c

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nobodyiam · 2025-08-24T09:36:36Z

@copilot

Should ConcurrentMultimap implement com.google.common.collect.Multimap?
Should ConcurrentMultimap be renamed to CaseInsensitiveConcurrentMultimap?
The original version used Ordering.natural()—is that still necessary?

…ultimap Co-authored-by: nobodyiam <[email protected]>

Copilot · 2025-08-24T09:44:54Z

@copilot

Should ConcurrentMultimap implement com.google.common.collect.Multimap?
...

I've addressed all three questions:

Should ConcurrentMultimap implement com.google.common.collect.Multimap? ✅ Yes - I've implemented the full Multimap interface to make it a true drop-in replacement. This ensures API compatibility and eliminates the need for separate type handling.
Should ConcurrentMultimap be renamed to CaseInsensitiveConcurrentMultimap? ✅ Yes - Renamed to better reflect the case-insensitive behavior, which is a key differentiating feature from a generic concurrent multimap.
The original version used Ordering.natural()—is that still necessary? ✅ No - The ordering was for DeferredResultWrapper values but analysis shows it's not functionally required. The code converts to ArrayList anyway (Lists.newArrayList(deferredResults.get(content))) and doesn't rely on value ordering. Removed ordering for better performance while maintaining all functionality.

The implementation now fully implements the Guava Multimap interface with comprehensive methods like keys(), keySet(), entries(), asMap(), etc., while preserving the case-insensitive behavior and thread safety improvements.

Commit: 1e63197

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- Triggering command: /usr/lib/jvm/temurin-17-jdk-amd64/bin/java --enable-native-access=ALL-UNNAMED -classpath /usr/share/apache-maven-3.9.11/boot/plexus-classworlds-2.9.0.jar -Dclassworlds.conf=/usr/share/apache-maven-3.9.11/bin/m2.conf -Dmaven.home=/usr/share/apache-maven-3.9.11 -Dlibrary.jansi.path=/usr/share/apache-maven-3.9.11/lib/jansi-native -Dmaven.multiModuleProjectDirectory=/home/REDACTED/work/apollo/apollo org.codehaus.plexus.classworlds.launcher.Launcher dependency:build-classpath -q -Dmdep.outputFile=/dev/stdout (dns block)
- Triggering command: /usr/lib/jvm/temurin-17-jdk-amd64/bin/java --enable-native-access=ALL-UNNAMED -classpath /usr/share/apache-maven-3.9.11/boot/plexus-classworlds-2.9.0.jar -Dclassworlds.conf=/usr/share/apache-maven-3.9.11/bin/m2.conf -Dmaven.home=/usr/share/apache-maven-3.9.11 -Dlibrary.jansi.path=/usr/share/apache-maven-3.9.11/lib/jansi-native -Dmaven.multiModuleProjectDirectory=/home/REDACTED/work/apollo/apollo org.codehaus.plexus.classworlds.launcher.Launcher compile -pl apollo-configservice -am -DskipTests=true -q (dns block)

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nobodyiam

We could define the variable using the Multimap interface. See comments below.
Also, please update CHANGES.md to reflect this PR and fix the compilation issue:

Error:  Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.10.1:testCompile (default-testCompile) on project apollo-configservice: Compilation failure: Compilation failure: 
Error:  /home/runner/work/apollo/apollo/apollo-configservice/src/test/java/com/ctrip/framework/apollo/configservice/controller/NotificationControllerV2Test.java:[83,11] cannot find symbol
Error:    symbol:   class ConcurrentMultimap
Error:    location: class com.ctrip.framework.apollo.configservice.controller.NotificationControllerV2Test
Error:  /home/runner/work/apollo/apollo/apollo-configservice/src/test/java/com/ctrip/framework/apollo/configservice/controller/NotificationControllerV2Test.java:[110,10] cannot find symbol
Error:    symbol:   class ConcurrentMultimap
Error:    location: class com.ctrip.framework.apollo.configservice.controller.NotificationControllerV2Test
Error:  -> [Help 1]
Error:  
Error:  To see the full stack trace of the errors, re-run Maven with the -e switch.
Error:  Re-run Maven using the -X switch to enable full debug logging.
Error:  
Error:  For more information about the errors and possible solutions, please read the following articles:
Error:  [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoFailureException
Error:  
Error:  After correcting the problems, you can resume the build with the command
Error:    mvn <args> -rf :apollo-configservice
Error: Process completed with exit code 1.

nobodyiam · 2025-08-24T10:47:39Z

  private static final Logger logger = LoggerFactory.getLogger(NotificationControllerV2.class);
-  private final Multimap<String, DeferredResultWrapper> deferredResults =
-      Multimaps.synchronizedSetMultimap(TreeMultimap.create(String.CASE_INSENSITIVE_ORDER, Ordering.natural()));
+  private final CaseInsensitiveConcurrentMultimap<String, DeferredResultWrapper> deferredResults = new CaseInsensitiveConcurrentMultimap<>();


Suggested change

private final CaseInsensitiveConcurrentMultimap<String, DeferredResultWrapper> deferredResults = new CaseInsensitiveConcurrentMultimap<>();

private final Multimap<String, DeferredResultWrapper> deferredResults =

new CaseInsensitiveConcurrentMultimap<>();

nobodyiam · 2025-08-24T10:47:59Z

  private Gson gson;

-  private Multimap<String, DeferredResultWrapper> deferredResults;
+  private ConcurrentMultimap<String, DeferredResultWrapper> deferredResults;


Suggested change

private ConcurrentMultimap<String, DeferredResultWrapper> deferredResults;

private Multimap<String, DeferredResultWrapper> deferredResults;

nobodyiam · 2025-08-24T10:48:08Z


    deferredResults =
-        (Multimap<String, DeferredResultWrapper>) ReflectionTestUtils.getField(controller, "deferredResults");
+        (ConcurrentMultimap<String, DeferredResultWrapper>) ReflectionTestUtils.getField(controller, "deferredResults");


Suggested change

(ConcurrentMultimap<String, DeferredResultWrapper>) ReflectionTestUtils.getField(controller, "deferredResults");

(Multimap<String, DeferredResultWrapper>) ReflectionTestUtils.getField(controller, "deferredResults");

nobodyiam · 2025-08-24T11:55:57Z

@copilot Please see the review comments above.

…tion errors Co-authored-by: nobodyiam <[email protected]>

Copilot · 2025-08-24T12:00:18Z

We could define the variable using the Multimap interface. See comments below.
Also, please update CHANGES.md to reflect this PR and fix the compilation issue:

...

I've addressed all the requested changes:

Changed field declaration to use Multimap interface - Updated the deferredResults field to use Multimap<String, DeferredResultWrapper> instead of the concrete implementation
Fixed test compilation errors - Updated test file variable declarations to use Multimap interface and removed unnecessary imports
Updated CHANGES.md - Added entry documenting the thread blocking fix

All compilation issues should now be resolved while maintaining the API compatibility benefits of using the interface type.

Commit: a3976db

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I tried to connect to the following addresses, but was blocked by firewall rules:

central.sonatype.com
- Triggering command: /usr/lib/jvm/temurin-17-jdk-amd64/bin/java --enable-native-access=ALL-UNNAMED -classpath /usr/share/apache-maven-3.9.11/boot/plexus-classworlds-2.9.0.jar -Dclassworlds.conf=/usr/share/apache-maven-3.9.11/bin/m2.conf -Dmaven.home=/usr/share/apache-maven-3.9.11 -Dlibrary.jansi.path=/usr/share/apache-maven-3.9.11/lib/jansi-native -Dmaven.multiModuleProjectDirectory=/home/REDACTED/work/apollo/apollo org.codehaus.plexus.classworlds.launcher.Launcher compile -pl apollo-configservice -am -DskipTests=true -q (dns block)
- Triggering command: /usr/lib/jvm/temurin-17-jdk-amd64/bin/java --enable-native-access=ALL-UNNAMED -classpath /usr/share/apache-maven-3.9.11/boot/plexus-classworlds-2.9.0.jar -Dclassworlds.conf=/usr/share/apache-maven-3.9.11/bin/m2.conf -Dmaven.home=/usr/share/apache-maven-3.9.11 -Dlibrary.jansi.path=/usr/share/apache-maven-3.9.11/lib/jansi-native -Dmaven.multiModuleProjectDirectory=/home/REDACTED/work/apollo/apollo org.codehaus.plexus.classworlds.launcher.Launcher test-compile -DskipTests=true -q (dns block)

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Co-authored-by: nobodyiam <[email protected]>

coderabbitai · 2025-08-25T01:18:36Z

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nobodyiam · 2026-01-17T04:57:43Z

@copilot There appears to be a concurrency issue in CaseInsensitiveConcurrentMultimap:

Thread A checks at line 83 and sees the values set is empty.
Thread B retrieves the values set at line 60.
Thread A removes the values set from the map at line 84.
Thread B adds a value to the now-removed set at line 61.

As a result, the value added by Thread B is lost.

…ic compute operations Co-authored-by: nobodyiam <[email protected]>

Copilot · 2026-01-17T05:01:36Z

@copilot There appears to be a concurrency issue in CaseInsensitiveConcurrentMultimap:

Thread A checks at line 83 and sees the values set is empty.
...

Fixed the race condition by replacing computeIfAbsent() and manual cleanup with atomic compute() and computeIfPresent() operations. This ensures the entire read-modify-write sequence is atomic and prevents values from being added to sets that are being removed from the map.

The fix ensures:

put() uses compute() to atomically create/retrieve the set and add the value
remove() uses computeIfPresent() to atomically remove the value and clean up empty sets by returning null

Added a specific test (testConcurrentPutAndRemoveRaceCondition) that targets this exact scenario with concurrent threads performing puts and removes.

Commit: 6985cb5

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Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

central.sonatype.com
- Triggering command: /usr/lib/jvm/temurin-17-jdk-amd64/bin/java /usr/lib/jvm/temurin-17-jdk-amd64/bin/java --enable-native-access=ALL-UNNAMED -classpath /usr/share/apache-maven-3.9.12/boot/plexus-classworlds-2.9.0.jar -Dclassworlds.conf=/usr/share/apache-maven-3.9.12/bin/m2.conf -Dmaven.home=/usr/share/apache-maven-3.9.12 -Dlibrary.jansi.path=/usr/share/apache-maven-3.9.12/lib/jansi-native -Dmaven.multiModuleProjectDirectory=/home/REDACTED/work/apollo/apollo org.codehaus.plexus.classworlds.launcher.Launcher test -Dtest=CaseInsensitiveConcurrentMultimapTest -pl apollo-configservice (dns block)
- Triggering command: /usr/lib/jvm/temurin-17-jdk-amd64/bin/java /usr/lib/jvm/temurin-17-jdk-amd64/bin/java --enable-native-access=ALL-UNNAMED -classpath /usr/share/apache-maven-3.9.12/boot/plexus-classworlds-2.9.0.jar -Dclassworlds.conf=/usr/share/apache-maven-3.9.12/bin/m2.conf -Dmaven.home=/usr/share/apache-maven-3.9.12 -Dlibrary.jansi.path=/usr/share/apache-maven-3.9.12/lib/jansi-native -Dmaven.multiModuleProjectDirectory=/home/REDACTED/work/apollo/apollo org.codehaus.plexus.classworlds.launcher.Launcher clean install -DskipTests -pl apollo-configservice -am (dns block)
- Triggering command: /usr/lib/jvm/temurin-17-jdk-amd64/bin/java /usr/lib/jvm/temurin-17-jdk-amd64/bin/java --enable-native-access=ALL-UNNAMED -classpath /usr/share/apache-maven-3.9.12/boot/plexus-classworlds-2.9.0.jar -Dclassworlds.conf=/usr/share/apache-maven-3.9.12/bin/m2.conf -Dmaven.home=/usr/share/apache-maven-3.9.12 -Dlibrary.jansi.path=/usr/share/apache-maven-3.9.12/lib/jansi-native -Dmaven.multiModuleProjectDirectory=/home/REDACTED/work/apollo/apollo org.codehaus.plexus.classworlds.launcher.Launcher clean install -DskipTests (dns block)

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nobodyiam · 2026-01-17T07:17:56Z

The full implementation of Multimap is not necessary and is thus complicated, use #5532 instead

Initial plan

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Replace synchronized Multimap with ConcurrentMultimap

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Add comprehensive tests and validate implementation

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Copilot AI changed the title ~~[WIP] 状态检测接口出现偶发的线程阻塞问题~~ Fix thread blocking in NotificationControllerV2 by replacing synchronized Multimap with ConcurrentHashMap Aug 24, 2025

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Fix missing Multimap import causing compilation errors

e49746c

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Implement Multimap interface and rename to CaseInsensitiveConcurrentM…

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…ultimap Co-authored-by: nobodyiam <[email protected]>

Copilot AI changed the title ~~Fix thread blocking in NotificationControllerV2 by replacing synchronized Multimap with ConcurrentHashMap~~ Fix thread blocking in NotificationControllerV2 by replacing synchronized Multimap with case-insensitive concurrent implementation Aug 24, 2025

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Use Multimap interface for deferredResults field and fix test compila…

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Update pull request ID from 5450 to 5451 in CHANGES.md

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状态检测接口出现偶发的线程阻塞问题 #5450

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Fix race condition in CaseInsensitiveConcurrentMultimap by using atom…

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…ic compute operations Co-authored-by: nobodyiam <[email protected]>

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nobodyiam deleted the copilot/fix-5450 branch February 25, 2026 12:24

	private final CaseInsensitiveConcurrentMultimap<String, DeferredResultWrapper> deferredResults = new CaseInsensitiveConcurrentMultimap<>();
	private final Multimap<String, DeferredResultWrapper> deferredResults =
	new CaseInsensitiveConcurrentMultimap<>();

	private ConcurrentMultimap<String, DeferredResultWrapper> deferredResults;
	private Multimap<String, DeferredResultWrapper> deferredResults;

	(ConcurrentMultimap<String, DeferredResultWrapper>) ReflectionTestUtils.getField(controller, "deferredResults");
	(Multimap<String, DeferredResultWrapper>) ReflectionTestUtils.getField(controller, "deferredResults");

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