Java parallelStream运行任务总是等待很长时间，为什么？

问题描述

我使用parallelStream在Spring @Async批注中执行backgroud任务。但是任务总是被阻止然后停止。核心代码是：

    @Async
    public void task() {
        List<ConfigSymbol> symbols = SymbolUtils.getSaasOpenSymbol();
        symbols .parallelStream().forEach(symbol->{
            //execute task. 1 minute per loop
         }   
    }  

我捕获了线程堆栈以诊断问题。但找不到原因。

为什么ForkJoinTask状态正在等待。

 "SimpleAsyncTaskExecutor-1609" #1777 prio=5 os_prio=0 tid=0x00007fb968006800 nid=0x6f5 in Object.wait() [0x00007fba2d119000]
   java.lang.Thread.State: WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        at java.util.concurrent.ForkJoinTask.externalAwaitDone(ForkJoinTask.java:334)
        - locked <0x00000006428a0a38> (a java.util.stream.ForEachOps$ForEachTask)
        at java.util.concurrent.ForkJoinTask.doInvoke(ForkJoinTask.java:405)
        at java.util.concurrent.ForkJoinTask.invoke(ForkJoinTask.java:734)
        at java.util.stream.ForEachOps$ForEachOp.evaluateParallel(ForEachOps.java:159)
        at java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateParallel(ForEachOps.java:173)
        at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:233)
        at java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:485)
        at java.util.stream.ReferencePipeline$Head.forEach(ReferencePipeline.java:650)
        at com.chainup.stats.service.impl.StatsSymbolRateServiceImpl.getCalculationBTCExchangeRate(StatsSymbolRateServiceImpl.java:141)
        at com.chainup.stats.service.impl.StatsSymbolRateServiceImpl.runThreadExchangeRate(StatsSymbolRateServiceImpl.java:67)
        at com.chainup.stats.action.StatAct.insertStatsSymbolRate(StatAct.java:442)
        at com.chainup.stats.action.StatAct$$FastClassBySpringcglib$$74ae31d4.invoke(<generated>)
        at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:218)
        at org.springframework.aop.framework.cglibAopProxy$cglibMethodInvocation.invokeJoinpoint(cglibAopProxy.java:769)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163)
        at org.springframework.aop.framework.cglibAopProxy$cglibMethodInvocation.proceed(cglibAopProxy.java:747)
        at org.springframework.aop.aspectj.MethodInvocationProceedingJoinPoint.proceed(MethodInvocationProceedingJoinPoint.java:88)
        at org.springframework.cloud.sleuth.instrument.async.TraceAsyncAspect.traceBackgroundThread(TraceAsyncAspect.java:66)
        at sun.reflect.GeneratedMethodAccessor277.invoke(UnkNown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)
        at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethodWithGivenArgs(AbstractAspectJAdvice.java:644)
        at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethod(AbstractAspectJAdvice.java:633)
        at org.springframework.aop.aspectj.AspectJAroundAdvice.invoke(AspectJAroundAdvice.java:70)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
        at org.springframework.aop.framework.cglibAopProxy$cglibMethodInvocation.proceed(cglibAopProxy.java:747)
        at org.springframework.aop.aspectj.MethodInvocationProceedingJoinPoint.proceed(MethodInvocationProceedingJoinPoint.java:88)
        at com.chainup.stats.interceptor.StatsJobInterceptor.around(StatsJobInterceptor.java:99)
        at sun.reflect.GeneratedMethodAccessor273.invoke(UnkNown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)
        at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethodWithGivenArgs(AbstractAspectJAdvice.java:644)
        at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethod(AbstractAspectJAdvice.java:633)
        at org.springframework.aop.aspectj.AspectJAroundAdvice.invoke(AspectJAroundAdvice.java:70)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:175)
        at org.springframework.aop.framework.cglibAopProxy$cglibMethodInvocation.proceed(cglibAopProxy.java:747)
        at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:95)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
        at org.springframework.aop.framework.cglibAopProxy$cglibMethodInvocation.proceed(cglibAopProxy.java:747)
        at org.springframework.aop.interceptor.AsyncExecutionInterceptor.lambda$invoke$0(AsyncExecutionInterceptor.java:115)
        at org.springframework.aop.interceptor.AsyncExecutionInterceptor$$Lambda$790/775437217.call(UnkNown Source)
        at java.util.concurrent.FutureTask.run(FutureTask.java:266)
        at org.springframework.cloud.sleuth.instrument.async.TraceRunnable.run(TraceRunnable.java:65)
        at java.lang.Thread.run(Thread.java:748)

解决方法

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