Race condition in staggered gets -------------------------------- Key: ISPN-6925 URL: https://issues.jboss.org/browse/ISPN-6925 Project: Infinispan Issue Type: Bug Components: Core Affects Versions: 9.0.0.Alpha3, 8.2.3.Final Reporter: Radim Vansa Assignee: Dan Berindei There's a race condition in {{CommandAwareRpcDispatcher}}, as we do staggered gets. When the {{RspList}} is prepared, and then in {{processCallsStaggered$lambda}} the {{Rsp}} is filled in - both of them can set is as received but later see that the other response was not received yet, because there's no memory barrieri n between the {{setValue}}/{{setException}} and checking {{wasReceived}}. The race above happens when two responses come but none of them is accepted by the filter, but there's a second one in JGroupsTransport when the first response is accepted but then comes another one. In {{JGroupsTransport.invokeRemotelyAsync}} in the lambda handling {{rspListFuture.thenApply}} we may see another thread concurrently modifying the rsps; e.g. in {{checkRsp}} you find out that the concurrently written response was received and it's not an exception according to flags, but the value will be null, so you return null while you can have valid response in the other {{Rsp}}.