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Nullpointer in SimpleInMemoryRepository

See original GitHub issue

We’re using spring boot 1.3.2 with Angel.SR6 for spring cloud. The service is a reverse proxy with zuul and occasionally we get this exception in the log:

2016-05-26T13:33:09.221+0200;1.3;0.0.0;http-nio-10.5.31.21-8080-exec-74:140;-;-;WARN ;org.springframework.boot.actuate.autoconfigure.MetricsFilter;[Unable to submit counter metric 'status.500.userservice-rest.star-star']
    java.lang.NullPointerException: null
    at org.springframework.boot.actuate.metrics.util.SimpleInMemoryRepository.update(SimpleInMemoryRepository.java:44)
    at org.springframework.boot.actuate.metrics.repository.InMemoryMetricRepository.increment(InMemoryMetricRepository.java:51)
    at org.springframework.boot.actuate.metrics.writer.DefaultCounterService.increment(DefaultCounterService.java:44)
    at org.springframework.boot.actuate.autoconfigure.MetricsFilter.incrementCounter(MetricsFilter.java:205)
    at org.springframework.boot.actuate.autoconfigure.MetricsFilter.recordMetrics(MetricsFilter.java:138)
    at org.springframework.boot.actuate.autoconfigure.MetricsFilter.doFilterInternal(MetricsFilter.java:110)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:212)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616)
    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:521)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1096)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:674)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1500)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1456)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:745)

It usually occurs at night on a test system with not much traffic.

Issue Analytics

State:
Created 7 years ago
Comments:7 (7 by maintainers)

Top GitHub Comments

2reactions

dsyercommented, Jun 3, 2016

It’s a race condition in SimpleInMemoryRepository when the app is under GC pressure. It uses a reference map internally, and the javadocs for that say that under GC pressure values can be removed from the map at any time. We could turn the if() into a while(). At the point where the pressure is applied the metrics repository will basically be unreliable though, so it might be good to log something as well.

1reaction

wilkinsonacommented, Jun 17, 2016

I haven’t managed to convince myself that we can just accept a ConcurrentMap as a plugin. It might well be possible to implement TTL expiry without requiring additional locking, but until I can convince myself that’s the case I’d rather not give people the opportunity to shoot themselves in the foot.

In short, I’ve gone for the let’s just fix it option.