I'm attempting to implement a spring integration flow that requires a multithreaded call if an input variable in true. If this variable is true then the flow with execute a multithreaded call and the main thread will continue it's flow.

Then at the end it will be required to wait for both flows to finish before returning a response.

I've been successful at implementing a multithreaded spring integration flow using a splitter, but the splitter results in all of the messages going to the same channel, this is different since the multithreaded call requires calling a different channel than the main thread of execution.

Is there a way to set up a splitter to send to different channels based on if the parameter is true or not? Or how would I set up an executor channel to spawn a new thread if that value is true while continuing the main flow at the same time.

As for waiting for both of the flows to finish execution would a spring integration barrier or an aggregator be a better approach for this use case?

CodePudding user response：

Consider to use a PublishSubscribeChannel with an Executor configuration to let the same message to be sent to different parallel flows. This way you really can continue your main flow with one subscriber and do something else with other subscribers. With an Executor all of them are going to be executed in parallel.

Docs: https://docs.spring.io/spring-integration/docs/current/reference/html/core.html#channel-implementations-publishsubscribechannel

If you still insist that main flow must be executed only on the same thread, then consider to use a RecipientListRouter, where one of the recipients could be an unconditional next direct channel in a main flow. The other recipient could be conditional on your boolean variable and it can be an ExecutorChannel to let its subscriber to be invoked in parallel.

Docs: https://docs.spring.io/spring-integration/docs/current/reference/html/message-routing.html#router-implementations-recipientlistrouter

For waiting for both flows it is up to you to decide - barrier, an aggregator or more sophisticated scatter-gather. All of them will work for your "wait-for-all" requirements. Or you may implement some custom solution based on a CountDownLatch in some header. So, every time your parallel flow is done, you count it down. And this way you even will be able to determine the number according your boolean value. So, if no parallel, then just 1 and only main flow is going to be executed and only this one is going to count down that latch you are waiting for on original request.