Question

我使代码与OpenJDk8兼容，并注意到有时以下代码片段会引发ConcurrentModificationException。

代码在一个线程中执行。

list = new ArrayList<>();

list.addAll(newElements);
list.stream().parallel().forEach(o -> {});

当流线程自己分割列表时，ForkJoin会引发异常。过了一会儿，我认为默认情况下这是合理的行为（未同步，简单集合），流线程不是新的，它们是从池中使用的（它们可能会看到列表处于不一致状态），但是在迭代之前复制集合看起来并不好。 / p>

我还没有发现有关此问题的错误，所以我问一个问题，Java内存模型对这种情况有何看法？

BTW要提交OJDK错误，您必须是一名开发人员。


java.util.ConcurrentModificationException: java.util.ConcurrentModificationException
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
    at java.util.concurrent.ForkJoinTask.getThrowableException(ForkJoinTask.java:593)
    at java.util.concurrent.ForkJoinTask.reportException(ForkJoinTask.java:677)
    at java.util.concurrent.ForkJoinTask.invoke(ForkJoinTask.java:735)
    at java.util.stream.ForEachOps$ForEachOp.evaluateParallel(ForEachOps.java:160)
    at java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateParallel(ForEachOps.java:174)
    at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:233)
    at java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:418)
    at java.util.stream.ReferencePipeline$Head.forEach(ReferencePipeline.java:583)
    at scheduler.JobScheduleUpdater.fetchJobSchedules(JobScheduleUpdater.java:118)
    at scheduler.JobScheduleUpdater.processOneUpdate(JobScheduleUpdater.java:102)
    at 
scheduler.JobScheduleUpdater.execute(JobScheduleUpdater.java:81)
    at scheduler.JobScheduleUpdater$$EnhancerByMockitoWithCGLIB$$ccd35a20.CGLIB$execute$11(<generated>)
    at scheduler.JobScheduleUpdater$$EnhancerByMockitoWithCGLIB$$ccd35a20$$FastClassByMockitoWithCGLIB$$bf9de679.invoke(<generated>)
    at org.mockito.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:216)
    at org.powermock.api.mockito.repackaged.DelegatingMockitoMethodProxy.invokeSuper(DelegatingMockitoMethodProxy.java:20)
    at org.mockito.internal.invocation.realmethod.DefaultRealMethod.invoke(DefaultRealMethod.java:21)
    at org.mockito.internal.invocation.realmethod.CleanTraceRealMethod.invoke(CleanTraceRealMethod.java:30)
    at org.mockito.internal.invocation.InvocationImpl.callRealMethod(InvocationImpl.java:112)
    at org.mockito.internal.stubbing.answers.CallsRealMethods.answer(CallsRealMethods.java:41)
    at org.mockito.internal.handler.MockHandlerImpl.handle(MockHandlerImpl.java:93)
    at org.mockito.internal.handler.NullResultGuardian.handle(NullResultGuardian.java:29)
    at org.mockito.internal.handler.InvocationNotifierHandler.handle(InvocationNotifierHandler.java:38)
    at org.powermock.api.mockito.repackaged.MethodInterceptorFilter.intercept(MethodInterceptorFilter.java:60)
    at scheduler.JobScheduleUpdater$$EnhancerByMockitoWithCGLIB$$ccd35a20.execute(<generated>)
    at commons.util.service.ShutdownCapableThread.run(ShutdownCapableThread.java:74)
    at scheduler.JobScheduleUpdater$$EnhancerByMockitoWithCGLIB$$ccd35a20.CGLIB$run$15(<generated>)
    at scheduler.JobScheduleUpdater$$EnhancerByMockitoWithCGLIB$$ccd35a20$$FastClassByMockitoWithCGLIB$$bf9de679.invoke(<generated>)
    at org.mockito.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:216)
    at org.powermock.api.mockito.repackaged.DelegatingMockitoMethodProxy.invokeSuper(DelegatingMockitoMethodProxy.java:20)
    at org.mockito.internal.invocation.realmethod.DefaultRealMethod.invoke(DefaultRealMethod.java:21)
    at org.mockito.internal.invocation.realmethod.CleanTraceRealMethod.invoke(CleanTraceRealMethod.java:30)
    at org.mockito.internal.invocation.InvocationImpl.callRealMethod(InvocationImpl.java:112)
    at org.mockito.internal.stubbing.answers.CallsRealMethods.answer(CallsRealMethods.java:41)
    at org.mockito.internal.handler.MockHandlerImpl.handle(MockHandlerImpl.java:93)
    at org.mockito.internal.handler.NullResultGuardian.handle(NullResultGuardian.java:29)
    at org.mockito.internal.handler.InvocationNotifierHandler.handle(InvocationNotifierHandler.java:38)
    at org.powermock.api.mockito.repackaged.MethodInterceptorFilter.intercept(MethodInterceptorFilter.java:60)
    at scheduler.JobScheduleUpdater$$EnhancerByMockitoWithCGLIB$$ccd35a20.run(<generated>)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
    at java.lang.Thread.run(Thread.java:748)
Caused by: java.util.ConcurrentModificationException
    at java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1388)
    at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:481)
    at java.util.stream.ForEachOps$ForEachTask.compute(ForEachOps.java:291)
    at java.util.concurrent.CountedCompleter.exec(CountedCompleter.java:731)
    at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:289)
    at java.util.concurrent.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1056)
    at java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1692)
    at java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:157)

Answer 1

代码在我的编辑器中运行良好。 ConcurrentModificationException在您修改要迭代的内容时触发。没有看到您所有的代码，我认为我无法解决这个问题。

ConcurrentModificationException的示例是：

List<Integer> integers = new ArrayList<>();

integers.add(12);
integers.add(11);
integers.add(1);



for (Integer integer : integers) {
   integers.remove(1);
}

有关如何解决问题的资源，请参见here。

集合更新后的并行流

1 个答案: