Bug:ConcurrentModificationException at feign.SynchronousMethodHandler.targetRequest(SynchronousMethodHandler.java:162)

[dousw]

we use FeignClient request, when an exception occurs, we print the exception, but we do not know the cause, the version is io.github.openfeign:feign-core:9.7.0, so we need help.

com.netflix.hystrix.exception.HystrixRuntimeException: queryXXX failed and no fallback available.
at com.netflix.hystrix.AbstractCommand$22.call(AbstractCommand.java:819)
at com.netflix.hystrix.AbstractCommand$22.call(AbstractCommand.java:804)
at rx.internal.operators.OperatorOnErrorResumeNextViaFunction$4.onError(OperatorOnErrorResumeNextViaFunction.java:140)
at rx.internal.operators.OnSubscribeDoOnEach$DoOnEachSubscriber.onError(OnSubscribeDoOnEach.java:87)
at rx.internal.operators.OnSubscribeDoOnEach$DoOnEachSubscriber.onError(OnSubscribeDoOnEach.java:87)
at com.netflix.hystrix.AbstractCommand$DeprecatedOnFallbackHookApplication$1.onError(AbstractCommand.java:1472)
at com.netflix.hystrix.AbstractCommand$FallbackHookApplication$1.onError(AbstractCommand.java:1397)
at rx.internal.operators.OnSubscribeDoOnEach$DoOnEachSubscriber.onError(OnSubscribeDoOnEach.java:87)
at rx.observers.Subscribers$5.onError(Subscribers.java:230)
at rx.internal.operators.OnSubscribeThrow.call(OnSubscribeThrow.java:44)
at rx.internal.operators.OnSubscribeThrow.call(OnSubscribeThrow.java:28)
at rx.Observable.unsafeSubscribe(Observable.java:10327)
at rx.internal.operators.OnSubscribeDefer.call(OnSubscribeDefer.java:51)
at rx.internal.operators.OnSubscribeDefer.call(OnSubscribeDefer.java:35)
at rx.Observable.unsafeSubscribe(Observable.java:10327)
at rx.internal.operators.OnSubscribeDoOnEach.call(OnSubscribeDoOnEach.java:41)
at rx.internal.operators.OnSubscribeDoOnEach.call(OnSubscribeDoOnEach.java:30)
at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:48)
at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:30)
at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:48)
at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:30)
at rx.Observable.unsafeSubscribe(Observable.java:10327)
at rx.internal.operators.OnSubscribeDoOnEach.call(OnSubscribeDoOnEach.java:41)
at rx.internal.operators.OnSubscribeDoOnEach.call(OnSubscribeDoOnEach.java:30)
at rx.Observable.unsafeSubscribe(Observable.java:10327)
at rx.internal.operators.OnSubscribeDoOnEach.call(OnSubscribeDoOnEach.java:41)
at rx.internal.operators.OnSubscribeDoOnEach.call(OnSubscribeDoOnEach.java:30)
at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:48)
at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:30)
at rx.Observable.unsafeSubscribe(Observable.java:10327)
at rx.internal.operators.OnSubscribeDoOnEach.call(OnSubscribeDoOnEach.java:41)
at rx.internal.operators.OnSubscribeDoOnEach.call(OnSubscribeDoOnEach.java:30)
at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:48)
at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:30)
at rx.Observable.unsafeSubscribe(Observable.java:10327)
at rx.internal.operators.OperatorOnErrorResumeNextViaFunction$4.onError(OperatorOnErrorResumeNextViaFunction.java:142)
at rx.internal.operators.OnSubscribeDoOnEach$DoOnEachSubscriber.onError(OnSubscribeDoOnEach.java:87)
at rx.internal.operators.OnSubscribeDoOnEach$DoOnEachSubscriber.onError(OnSubscribeDoOnEach.java:87)
at com.netflix.hystrix.AbstractCommand$HystrixObservableTimeoutOperator$2.onError(AbstractCommand.java:1194)
at rx.internal.operators.OperatorSubscribeOn$SubscribeOnSubscriber.onError(OperatorSubscribeOn.java:80)
at rx.observers.Subscribers$5.onError(Subscribers.java:230)
at rx.internal.operators.OnSubscribeDoOnEach$DoOnEachSubscriber.onError(OnSubscribeDoOnEach.java:87)
at rx.observers.Subscribers$5.onError(Subscribers.java:230)
at com.netflix.hystrix.AbstractCommand$DeprecatedOnRunHookApplication$1.onError(AbstractCommand.java:1431)
at com.netflix.hystrix.AbstractCommand$ExecutionHookApplication$1.onError(AbstractCommand.java:1362)
at rx.observers.Subscribers$5.onError(Subscribers.java:230)
at rx.observers.Subscribers$5.onError(Subscribers.java:230)
at rx.internal.operators.OnSubscribeThrow.call(OnSubscribeThrow.java:44)
at rx.internal.operators.OnSubscribeThrow.call(OnSubscribeThrow.java:28)
at rx.Observable.unsafeSubscribe(Observable.java:10327)
at rx.internal.operators.OnSubscribeDefer.call(OnSubscribeDefer.java:51)
at rx.internal.operators.OnSubscribeDefer.call(OnSubscribeDefer.java:35)
at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:48)
at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:30)
at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:48)
at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:30)
at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:48)
at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:30)
at rx.Observable.unsafeSubscribe(Observable.java:10327)
at rx.internal.operators.OnSubscribeDefer.call(OnSubscribeDefer.java:51)
at rx.internal.operators.OnSubscribeDefer.call(OnSubscribeDefer.java:35)
at rx.Observable.unsafeSubscribe(Observable.java:10327)
at rx.internal.operators.OnSubscribeDoOnEach.call(OnSubscribeDoOnEach.java:41)
at rx.internal.operators.OnSubscribeDoOnEach.call(OnSubscribeDoOnEach.java:30)
at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:48)
at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:30)
at rx.Observable.unsafeSubscribe(Observable.java:10327)
at rx.internal.operators.OperatorSubscribeOn$SubscribeOnSubscriber.call(OperatorSubscribeOn.java:100)
at com.netflix.hystrix.strategy.concurrency.HystrixContexSchedulerAction$1.call(HystrixContexSchedulerAction.java:56)
at com.netflix.hystrix.strategy.concurrency.HystrixContexSchedulerAction$1.call(HystrixContexSchedulerAction.java:47)
at com.xxx.cloud.feign.hystrix.MdcHystrixConcurrencyStrategy$MdcAwareCallable.call(MdcHystrixConcurrencyStrategy.java:48)
at org.springframework.cloud.sleuth.instrument.async.TraceCallable.call(TraceCallable.java:63)
at com.netflix.hystrix.strategy.concurrency.HystrixContexSchedulerAction.call(HystrixContexSchedulerAction.java:69)
at rx.internal.schedulers.ScheduledAction.run(ScheduledAction.java:55)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
Caused by: java.util.ConcurrentModificationException: null
at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:909)
at java.util.ArrayList$Itr.next(ArrayList.java:859)
at feign.SynchronousMethodHandler.targetRequest(SynchronousMethodHandler.java:162)
at feign.SynchronousMethodHandler.executeAndDecode(SynchronousMethodHandler.java:89)
at feign.SynchronousMethodHandler.invoke(SynchronousMethodHandler.java:77)
at feign.hystrix.HystrixInvocationHandler$1.run(HystrixInvocationHandler.java:107)
at com.netflix.hystrix.HystrixCommand$2.call(HystrixCommand.java:302)
at com.netflix.hystrix.HystrixCommand$2.call(HystrixCommand.java:298)
at rx.internal.operators.OnSubscribeDefer.call(OnSubscribeDefer.java:46)
... 28 common frames omitted