[infinispan-issues] [JBoss JIRA] (ISPN-8889) Data race in NonTxInvocationContext

Data race in NonTxInvocationContext ----------------------------------- Key: ISPN-8889 URL: https://issues.jboss.org/browse/ISPN-8889 Project: Infinispan Issue Type: Bug Components: Core Affects Versions: 9.1.6.Final, 9.2.0.CR2 Environment: Java 8 (Oracle JDK 8), Solaris SPARC Reporter: Peter Levart Assignee: Dan Berindei Priority: Major Labels: data-race Fix For: 10.0.0.Beta1, 9.4.6.Final Attachments: DataRacer.java, DataRacer.java Got the following exceptions starting up an Infinispan node while joining the cluster: {noformat} 17:10:59.012 [remote-thread--p2-t8] ERROR org.infinispan.interceptors.impl.InvocationContextInterceptor - ISPN000136: Error executing command PutMapCommand, writing keys [11906696627, 11906696626, 11906696625, 11906696624, 11906696631, 11906696630, 11906696629, 11906696628...<9992 other elements>] java.lang.ClassCastException: java.util.HashMap$Node cannot be cast to java.util.HashMap$TreeNode at java.util.HashMap$TreeNode.moveRootToFront(HashMap.java:1832) ~[?:1.8.0_162] at java.util.HashMap$TreeNode.treeify(HashMap.java:1949) ~[?:1.8.0_162] at java.util.HashMap$TreeNode.split(HashMap.java:2175) ~[?:1.8.0_162] at java.util.HashMap.resize(HashMap.java:714) ~[?:1.8.0_162] at java.util.HashMap.putVal(HashMap.java:663) ~[?:1.8.0_162] at java.util.HashMap.put(HashMap.java:612) ~[?:1.8.0_162] at org.infinispan.context.impl.NonTxInvocationContext.putLookedUpEntry(NonTxInvocationContext.java:48) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.container.EntryFactoryImpl.wrapExternalEntry(EntryFactoryImpl.java:143) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.interceptors.distribution.BaseDistributionInterceptor.wrapRemoteEntry(BaseDistributionInterceptor.java:222) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.interceptors.distribution.BaseDistributionInterceptor.lambda$remoteGet$1(BaseDistributionInterceptor.java:192) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at java.util.concurrent.CompletableFuture.uniAccept(CompletableFuture.java:656) ~[?:1.8.0_162] at java.util.concurrent.CompletableFuture$UniAccept.tryFire(CompletableFuture.java:632) ~[?:1.8.0_162] at java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:474) ~[?:1.8.0_162] at java.util.concurrent.CompletableFuture.complete(CompletableFuture.java:1962) ~[?:1.8.0_162] at org.infinispan.remoting.transport.AbstractRequest.complete(AbstractRequest.java:66) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.remoting.transport.impl.MultiTargetRequest.onResponse(MultiTargetRequest.java:102) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.remoting.transport.jgroups.StaggeredRequest.onResponse(StaggeredRequest.java:50) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.remoting.transport.impl.RequestRepository.addResponse(RequestRepository.java:53) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.remoting.transport.jgroups.JGroupsTransport.processResponse(JGroupsTransport.java:1302) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.remoting.transport.jgroups.JGroupsTransport.processMessage(JGroupsTransport.java:1205) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.remoting.transport.jgroups.JGroupsTransport.access$200(JGroupsTransport.java:123) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.remoting.transport.jgroups.JGroupsTransport$ChannelCallbacks.receive(JGroupsTransport.java:1340) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.jgroups.JChannel.up(JChannel.java:819) ~[jgroups-4.0.10.Final.jar:4.0.10.Final] at org.jgroups.stack.ProtocolStack.up(ProtocolStack.java:893) ~[jgroups-4.0.10.Final.jar:4.0.10.Final] at org.jgroups.protocols.FRAG3.up(FRAG3.java:171) ~[jgroups-4.0.10.Final.jar:4.0.10.Final] at org.jgroups.protocols.FlowControl.up(FlowControl.java:343) ~[jgroups-4.0.10.Final.jar:4.0.10.Final] at org.jgroups.protocols.FlowControl.up(FlowControl.java:343) ~[jgroups-4.0.10.Final.jar:4.0.10.Final] at org.jgroups.protocols.pbcast.GMS.up(GMS.java:864) ~[jgroups-4.0.10.Final.jar:4.0.10.Final] at org.jgroups.protocols.pbcast.STABLE.up(STABLE.java:240) ~[jgroups-4.0.10.Final.jar:4.0.10.Final] at org.jgroups.protocols.UNICAST3.deliverMessage(UNICAST3.java:1002) ~[jgroups-4.0.10.Final.jar:4.0.10.Final] at org.jgroups.protocols.UNICAST3.handleDataReceived(UNICAST3.java:728) ~[jgroups-4.0.10.Final.jar:4.0.10.Final] at org.jgroups.protocols.UNICAST3.up(UNICAST3.java:383) ~[jgroups-4.0.10.Final.jar:4.0.10.Final] at org.jgroups.protocols.pbcast.NAKACK2.up(NAKACK2.java:600) ~[jgroups-4.0.10.Final.jar:4.0.10.Final] at org.jgroups.protocols.VERIFY_SUSPECT.up(VERIFY_SUSPECT.java:119) ~[jgroups-4.0.10.Final.jar:4.0.10.Final] at org.jgroups.protocols.FD_ALL.up(FD_ALL.java:199) ~[jgroups-4.0.10.Final.jar:4.0.10.Final] at org.jgroups.protocols.FD_SOCK.up(FD_SOCK.java:252) ~[jgroups-4.0.10.Final.jar:4.0.10.Final] at org.jgroups.protocols.MERGE3.up(MERGE3.java:276) ~[jgroups-4.0.10.Final.jar:4.0.10.Final] at org.jgroups.protocols.Discovery.up(Discovery.java:267) ~[jgroups-4.0.10.Final.jar:4.0.10.Final] at org.jgroups.protocols.TP.passMessageUp(TP.java:1248) ~[jgroups-4.0.10.Final.jar:4.0.10.Final] at org.jgroups.util.SubmitToThreadPool$SingleMessageHandler.run(SubmitToThreadPool.java:87) ~[jgroups-4.0.10.Final.jar:4.0.10.Final] at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [?:1.8.0_162] at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [?:1.8.0_162] at java.lang.Thread.run(Thread.java:748) [?:1.8.0_162] {noformat} Immediately suspected that plain HashMap is being modified from multiple threads without proper synchronization. But since I'm new to Infinispan, I can't know whether the usage of plain HashMap in NonTxInvocationContext is intentional and Infinispan code is relying on some external synchronization to be performed by other parts of system that calls NonTxInvocationContext.[lookupEntry|removeLookedUpEntry|putLookedUpEntry|getLookedUpEntries]. In any way, if this external synchronization is taking place, it has a bug and allows calling these methods concurrently without proper synchronization. I did some experiments to prove that and also to obtain stack traces of at least two of involved threads, but trivial things that I tried instrumenting those methods all involved some kind of synchronization and the symptom disappeared. I had to be extra smart to obtain the stack traces of two threads without inter-thread synchronization so that I could detect the data race. Here's how I instrumented NonTxInvocationContext code: {noformat} Index: core/src/main/java/org/infinispan/context/impl/NonTxInvocationContext.java IDEA additional info: Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP <+>UTF-8 =================================================================== --- core/src/main/java/org/infinispan/context/impl/NonTxInvocationContext.java (revision 6014e751c20daba1f00e23168281e02afb209905) +++ core/src/main/java/org/infinispan/context/impl/NonTxInvocationContext.java (date 1519744397000) @@ -22,6 +22,7 @@ private Set<Object> lockedKeys; private Object lockOwner; + private final DataRacer dataRacer = new DataRacer(); public NonTxInvocationContext(int numEntries, Address origin) { super(origin); @@ -35,22 +36,26 @@ @Override public CacheEntry lookupEntry(Object k) { + dataRacer.detect(); return lookedUpEntries.get(k); } @Override public void removeLookedUpEntry(Object key) { + dataRacer.detectAndWrite(); lookedUpEntries.remove(key); } @Override public void putLookedUpEntry(Object key, CacheEntry e) { + dataRacer.detectAndWrite(); lookedUpEntries.put(key, e); } @Override @SuppressWarnings("unchecked") public Map<Object, CacheEntry> getLookedUpEntries() { + dataRacer.detect(); return (Map<Object, CacheEntry>) (lookedUpEntries == null ? Collections.emptyMap() : lookedUpEntries); {noformat} Attached, you will find the DataRacer source. While running with such patched Infinispan, I got some of the following: {noformat} java.lang.IllegalThreadStateException: Thread[remote-thread--p2-t4,5,main]: data race detected with writer of state: 271f7814a414 - see suppressed for writer thread stack trace at org.infinispan.context.impl.DataRacer.detect(DataRacer.java:37) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.context.impl.NonTxInvocationContext.lookupEntry(NonTxInvocationContext.java:39) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.interceptors.distribution.NonTxDistributionInterceptor.addRemoteGet(NonTxDistributionInterceptor.java:405) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.interceptors.distribution.NonTxDistributionInterceptor.handleRemoteReadWriteManyCommand(NonTxDistributionInterceptor.java:385) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.interceptors.distribution.NonTxDistributionInterceptor.handleReadWriteManyCommand(NonTxDistributionInterceptor.java:303) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.interceptors.distribution.NonTxDistributionInterceptor.visitPutMapCommand(NonTxDistributionInterceptor.java:143) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.commands.write.PutMapCommand.acceptVisitor(PutMapCommand.java:80) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.interceptors.BaseAsyncInterceptor.invokeNextThenAccept(BaseAsyncInterceptor.java:98) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.interceptors.impl.EntryWrappingInterceptor.setSkipRemoteGetsAndInvokeNextForManyEntriesCommand(EntryWrappingInterceptor.java:614) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.interceptors.impl.EntryWrappingInterceptor.visitPutMapCommand(EntryWrappingInterceptor.java:385) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.commands.write.PutMapCommand.acceptVisitor(PutMapCommand.java:80) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.interceptors.BaseAsyncInterceptor.invokeNext(BaseAsyncInterceptor.java:54) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.interceptors.locking.NonTransactionalLockingInterceptor.handleWriteManyCommand(NonTransactionalLockingInterceptor.java:53) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.interceptors.locking.AbstractLockingInterceptor.visitPutMapCommand(AbstractLockingInterceptor.java:179) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.commands.write.PutMapCommand.acceptVisitor(PutMapCommand.java:80) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.interceptors.BaseAsyncInterceptor.invokeNext(BaseAsyncInterceptor.java:54) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.statetransfer.StateTransferInterceptor.handleNonTxWriteCommand(StateTransferInterceptor.java:306) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.statetransfer.StateTransferInterceptor.handleWriteCommand(StateTransferInterceptor.java:252) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.statetransfer.StateTransferInterceptor.visitPutMapCommand(StateTransferInterceptor.java:102) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.commands.write.PutMapCommand.acceptVisitor(PutMapCommand.java:80) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.interceptors.BaseAsyncInterceptor.invokeNext(BaseAsyncInterceptor.java:54) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.interceptors.impl.CacheMgmtInterceptor.visitPutMapCommand(CacheMgmtInterceptor.java:154) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.commands.write.PutMapCommand.acceptVisitor(PutMapCommand.java:80) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.interceptors.BaseAsyncInterceptor.invokeNextAndExceptionally(BaseAsyncInterceptor.java:123) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.interceptors.impl.InvocationContextInterceptor.visitCommand(InvocationContextInterceptor.java:90) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.interceptors.BaseAsyncInterceptor.invokeNext(BaseAsyncInterceptor.java:56) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.interceptors.DDAsyncInterceptor.handleDefault(DDAsyncInterceptor.java:54) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.interceptors.DDAsyncInterceptor.visitPutMapCommand(DDAsyncInterceptor.java:90) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.commands.write.PutMapCommand.acceptVisitor(PutMapCommand.java:80) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.interceptors.DDAsyncInterceptor.visitCommand(DDAsyncInterceptor.java:50) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.interceptors.impl.AsyncInterceptorChainImpl.invokeAsync(AsyncInterceptorChainImpl.java:234) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.commands.remote.BaseRpcInvokingCommand.processVisitableCommandAsync(BaseRpcInvokingCommand.java:63) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.commands.remote.SingleRpcCommand.invokeAsync(SingleRpcCommand.java:57) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.remoting.inboundhandler.BasePerCacheInboundInvocationHandler.invokeCommand(BasePerCacheInboundInvocationHandler.java:94) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.remoting.inboundhandler.BaseBlockingRunnable.invoke(BaseBlockingRunnable.java:99) [infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.remoting.inboundhandler.BaseBlockingRunnable.runAsync(BaseBlockingRunnable.java:71) [infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.remoting.inboundhandler.BaseBlockingRunnable.run(BaseBlockingRunnable.java:40) [infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [?:1.8.0_162] at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [?:1.8.0_162] at java.lang.Thread.run(Thread.java:748) [?:1.8.0_162] Suppressed: org.infinispan.context.impl.DataRacer$StackTrace: Thread[jgroups-13,tbd2-40757,5,main], state: 271f7814a414 at org.infinispan.context.impl.DataRacer.write(DataRacer.java:59) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.context.impl.DataRacer.detectAndWrite(DataRacer.java:49) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.context.impl.NonTxInvocationContext.putLookedUpEntry(NonTxInvocationContext.java:51) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.container.EntryFactoryImpl.wrapExternalEntry(EntryFactoryImpl.java:143) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.interceptors.distribution.BaseDistributionInterceptor.wrapRemoteEntry(BaseDistributionInterceptor.java:222) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.interceptors.distribution.BaseDistributionInterceptor.lambda$remoteGet$1(BaseDistributionInterceptor.java:192) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at java.util.concurrent.CompletableFuture.uniAccept(CompletableFuture.java:656) ~[?:1.8.0_162] at java.util.concurrent.CompletableFuture$UniAccept.tryFire(CompletableFuture.java:632) ~[?:1.8.0_162] at java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:474) ~[?:1.8.0_162] at java.util.concurrent.CompletableFuture.complete(CompletableFuture.java:1962) ~[?:1.8.0_162] at org.infinispan.remoting.transport.AbstractRequest.complete(AbstractRequest.java:66) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.remoting.transport.impl.MultiTargetRequest.onResponse(MultiTargetRequest.java:102) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.remoting.transport.jgroups.StaggeredRequest.onResponse(StaggeredRequest.java:50) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.remoting.transport.impl.RequestRepository.addResponse(RequestRepository.java:53) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.remoting.transport.jgroups.JGroupsTransport.processResponse(JGroupsTransport.java:1302) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.remoting.transport.jgroups.JGroupsTransport.processMessage(JGroupsTransport.java:1205) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.remoting.transport.jgroups.JGroupsTransport.access$200(JGroupsTransport.java:123) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.infinispan.remoting.transport.jgroups.JGroupsTransport$ChannelCallbacks.receive(JGroupsTransport.java:1340) ~[infinispan-core-9.2.0-SNAPSHOT.jar:9.2.0-SNAPSHOT] at org.jgroups.JChannel.up(JChannel.java:819) ~[jgroups-4.0.10.Final.jar:4.0.10.Final] at org.jgroups.stack.ProtocolStack.up(ProtocolStack.java:893) ~[jgroups-4.0.10.Final.jar:4.0.10.Final] at org.jgroups.protocols.FRAG3.up(FRAG3.java:171) ~[jgroups-4.0.10.Final.jar:4.0.10.Final] at org.jgroups.protocols.FlowControl.up(FlowControl.java:343) ~[jgroups-4.0.10.Final.jar:4.0.10.Final] at org.jgroups.protocols.FlowControl.up(FlowControl.java:343) ~[jgroups-4.0.10.Final.jar:4.0.10.Final] at org.jgroups.protocols.pbcast.GMS.up(GMS.java:864) ~[jgroups-4.0.10.Final.jar:4.0.10.Final] at org.jgroups.protocols.pbcast.STABLE.up(STABLE.java:240) ~[jgroups-4.0.10.Final.jar:4.0.10.Final] at org.jgroups.protocols.UNICAST3.deliverMessage(UNICAST3.java:1002) ~[jgroups-4.0.10.Final.jar:4.0.10.Final] at org.jgroups.protocols.UNICAST3.handleDataReceived(UNICAST3.java:728) ~[jgroups-4.0.10.Final.jar:4.0.10.Final] at org.jgroups.protocols.UNICAST3.up(UNICAST3.java:383) ~[jgroups-4.0.10.Final.jar:4.0.10.Final] at org.jgroups.protocols.pbcast.NAKACK2.up(NAKACK2.java:600) ~[jgroups-4.0.10.Final.jar:4.0.10.Final] at org.jgroups.protocols.VERIFY_SUSPECT.up(VERIFY_SUSPECT.java:119) ~[jgroups-4.0.10.Final.jar:4.0.10.Final] at org.jgroups.protocols.FD_ALL.up(FD_ALL.java:199) ~[jgroups-4.0.10.Final.jar:4.0.10.Final] at org.jgroups.protocols.FD_SOCK.up(FD_SOCK.java:252) ~[jgroups-4.0.10.Final.jar:4.0.10.Final] at org.jgroups.protocols.MERGE3.up(MERGE3.java:276) ~[jgroups-4.0.10.Final.jar:4.0.10.Final] at org.jgroups.protocols.Discovery.up(Discovery.java:267) ~[jgroups-4.0.10.Final.jar:4.0.10.Final] at org.jgroups.protocols.TP.passMessageUp(TP.java:1248) ~[jgroups-4.0.10.Final.jar:4.0.10.Final] at org.jgroups.util.SubmitToThreadPool$SingleMessageHandler.run(SubmitToThreadPool.java:87) ~[jgroups-4.0.10.Final.jar:4.0.10.Final] at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [?:1.8.0_162] at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [?:1.8.0_162] at java.lang.Thread.run(Thread.java:748) [?:1.8.0_162] {noformat} So here you have it. Either using plain HashMap in NonTxInvocationContext is wrong and ConcurrentHashMap should be used instead or some external synchronization has a bug and is inadequate. I hope this helps to fix it.