java.util.ConcurrentModificationException when saving the session

[joshiste]

Describe the bug
java.util.ConcurrentModificationException is thrown while persisting the session

To Reproduce
I don't have that. But looking at the stack trace - I guess the Session is somehow modified while saving 🤷

Expected behavior
No exception

** Version **
Spring Session JDBC 3.0.0

Stack Trace

java.util.ConcurrentModificationException: null
    at java.util.HashMap$EntrySpliterator.forEachRemaining(HashMap.java:1855)
    at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:509)
    at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499)
    at java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:921)
    at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
    at java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:682)
    at org.springframework.session.jdbc.JdbcIndexedSessionRepository$JdbcSession.lambda$save$11(JdbcIndexedSessionRepository.java:910)
    at org.springframework.transaction.support.TransactionOperations.lambda$executeWithoutResult$0(TransactionOperations.java:68)
    at org.springframework.transaction.support.TransactionTemplate.execute(TransactionTemplate.java:140)
    at org.springframework.transaction.support.TransactionOperations.executeWithoutResult(TransactionOperations.java:67)
    at org.springframework.session.jdbc.JdbcIndexedSessionRepository$JdbcSession.save(JdbcIndexedSessionRepository.java:894)
    at org.springframework.session.jdbc.JdbcIndexedSessionRepository.save(JdbcIndexedSessionRepository.java:473)
    at org.springframework.session.jdbc.JdbcIndexedSessionRepository.save(JdbcIndexedSessionRepository.java:139)
    at org.springframework.session.web.http.SessionRepositoryFilter$SessionRepositoryRequestWrapper.commitSession(SessionRepositoryFilter.java:228)
    at org.springframework.session.web.http.SessionRepositoryFilter.doFilterInternal(SessionRepositoryFilter.java:146)
    at org.springframework.session.web.http.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:82)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:185)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:158)
    at org.springframework.web.filter.ServerHttpObservationFilter.doFilterInternal(ServerHttpObservationFilter.java:109)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:185)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:158)
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:185)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:158)
    at com.steadybit.platform.server.application.web.FilterChainExceptionHandler.doFilterInternal(FilterChainExceptionHandler.java:35)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:185)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:158)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:177)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:542)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:119)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78)
    at org.apache.catalina.valves.RemoteIpValve.invoke(RemoteIpValve.java:741)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:357)
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:400)
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:859)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1734)
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:52)
    at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1191)
    at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:833)

[marcusdacoregio]

Hi @joshiste, thanks for the report.

Since there is a lot that could be going on in your application, are you able to provide a minimal, reproducible sample so we can isolate the problem?

[joshiste]

Sorry, I don't have any reproducer for this. I guess some session data was added while saving....

[marcusdacoregio]

Have you tried an implementation of https://github.com/spring-projects/spring-session/blob/main/spring-session-core/src/main/java/org/springframework/session/config/SessionRepositoryCustomizer.java?

[joshiste]

No. How could that help?