Dispatcher has no subscribers while trying to gracefully shutdown application - spring-integration

Question

I have the following requirement for my application:
I have an integration flow which takes files from a directory via
Files.inboundAdapter
and a polling configuration as follows:
#Bean public PollerSpec orderOutboundFlowTempFileInPoller() {
return Pollers
.fixedDelay(pollerDelay)
.maxMessagesPerPoll(100)
.transactional();
}
The files should be transferred to a remote host via RemoteFileTemplate. The application runs in a docker container which should be stoppable for maintainance or rollout purposes.
When the container is shutdown, the flow should finish writing the file to the remote host and should not accept new incoming files.
Therefore I have implemented a graceful shutdown as follows:
#Override public void onApplicationEvent(final ContextClosedEvent event) {
LOG.info("Trying to gracefully shutdown App");
//CHECKSTYLE:OFF
allFlowPollers.forEach(
p -> {
try {
p.destroy();
} catch (final Exception e) {
LOG.warn("Unable to destroy poller.");
}
}
);
//CHECKSTLYE:ON
FLOWS_TO_SHUTDOWN.forEach(GracefulShutdownAware::shutdown);
}
I assumed when I destroy the pollers, no further file would be read from source. The RemoteFileTemplate does send the current file correctly, there is no problem.
But the poller still seems to get new files and when the application is nearly shutdown, an exception appears as follows:
timestamp=15:55:56.599, thread=task-scheduler-2, severity=ERROR, class=o.s.i.h.LoggingHandler, message=org.springframework.messaging.MessageDeliveryException: Dispatcher has no subscribers for channel 'application.flowTempFileIn.channel#0'.; nested exception is org.springframework.integration.MessageDispatchingException: Dispatcher has no subscribers, failedMessage=GenericMessage [payload=/servicedata/tmp/1544088550162_57280.xml, headers={file_originalFile=/servicedata/tmp/1544088550162_57280.xml, id=d04473ff-d1bd-173e-d801-b7b9fd31596c, file_name=1544088550162_57280.xml, file_relativePath=1544088550162_57280.xml, timestamp=1544108156591}], failedMessage=GenericMessage [payload=/servicedata/tmp/1544088550162_57280.xml, headers={file_originalFile=/servicedata/tmp/1544088550162_57280.xml, id=d04473ff-d1bd-173e-d801-b7b9fd31596c, file_name=1544088550162_57280.xml, file_relativePath=1544088550162_57280.xml, timestamp=1544108156591}]
at org.springframework.integration.channel.AbstractSubscribableChannel.doSend(AbstractSubscribableChannel.java:77)
at org.springframework.integration.channel.AbstractMessageChannel.send(AbstractMessageChannel.java:445)
at org.springframework.integration.channel.AbstractMessageChannel.send(AbstractMessageChannel.java:394)
at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:181)
at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:160)
at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:47)
at org.springframework.messaging.core.AbstractMessageSendingTemplate.send(AbstractMessageSendingTemplate.java:108)
at org.springframework.integration.endpoint.SourcePollingChannelAdapter.handleMessage(SourcePollingChannelAdapter.java:227)
at org.springframework.integration.endpoint.AbstractPollingEndpoint.doPoll(AbstractPollingEndpoint.java:290)
at sun.reflect.GeneratedMethodAccessor292.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:343)
at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:197)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163)
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:294)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:98)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:185)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:212)
at com.sun.proxy.$Proxy138.call(Unknown Source)
at org.springframework.integration.endpoint.AbstractPollingEndpoint$Poller.lambda$run$0(AbstractPollingEndpoint.java:391)
at org.springframework.integration.util.ErrorHandlingTaskExecutor.lambda$execute$0(ErrorHandlingTaskExecutor.java:57)
at org.springframework.core.task.SyncTaskExecutor.execute(SyncTaskExecutor.java:50)
at org.springframework.integration.util.ErrorHandlingTaskExecutor.execute(ErrorHandlingTaskExecutor.java:55)
at org.springframework.integration.endpoint.AbstractPollingEndpoint$Poller.run(AbstractPollingEndpoint.java:385)
at org.springframework.scheduling.support.DelegatingErrorHandlingRunnable.run(DelegatingErrorHandlingRunnable.java:54)
at org.springframework.scheduling.concurrent.ReschedulingRunnable.run(ReschedulingRunnable.java:93)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:748)
Caused by: org.springframework.integration.MessageDispatchingException: Dispatcher has no subscribers, failedMessage=GenericMessage [payload=/servicedata/tmp/1544088550162_57280.xml, headers={file_originalFile=/servicedata/tmp/1544088550162_57280.xml, id=d04473ff-d1bd-173e-d801-b7b9fd31596c, file_name=1544088550162_57280.xml, file_relativePath=1544088550162_57280.xml, timestamp=1544108156591}]
at org.springframework.integration.dispatcher.UnicastingDispatcher.doDispatch(UnicastingDispatcher.java:138)
at org.springframework.integration.dispatcher.UnicastingDispatcher.dispatch(UnicastingDispatcher.java:105)
at org.springframework.integration.channel.AbstractSubscribableChannel.doSend(AbstractSubscribableChannel.java:73)
... 33 more
Is there any other way, I can achieve this requirement? Which is: stopping the application should let the current file finish, not accept further files to be read and still closing without any weird exceptions?
What I assume it's some kind of timing issue since the integration flow and the reaction to the ContextClosedEvent are running on different Threads. The poller isn't destroyed completely but the transform-subscriber of the outbound channel is already destroyed.
I also tried to stop the poller via control bus, but the outcome was the same.
Thanks in advance :)

Answer 1

The problem is not about poller, but InboundChannelAdapter. Would be great to see your IntegrationFlow definition. Actually it must stop during application context shutdown. And you don't need to do anything else from your side.
The point is that all active Spring Integration components implement SmartLifecycle and they are stop()'ed gracefully during appropriate application context close phase.