Spring Integration Reactor configuration - spring

Question

I'm running an application that process tasks using spring integration.
I'd like to make it process multiple tasks concurrently but any attempt failed so far.
My configuration is:
ReactorConfiguration.java
#Configuration
#EnableAutoConfiguration
public class ReactorConfiguration {
#Bean
Environment reactorEnv() {
return new Environment();
}
#Bean
Reactor createReactor(Environment env) {
return Reactors.reactor()
.env(env)
.dispatcher(Environment.THREAD_POOL)
.get();
}
}
TaskProcessor.java
#MessagingGateway(reactorEnvironment = "reactorEnv")
public interface TaskProcessor {
#Gateway(requestChannel = "routeTaskByType", replyChannel = "")
Promise<Result> processTask(Task task);
}
IntegrationConfiguration.java (simplified)
#Bean
public IntegrationFlow routeFlow() {
return IntegrationFlows.from(MessageChannels.executor("routeTaskByType", Executors.newFixedThreadPool(10)))
.handle(Task.class, (payload, headers) -> {
logger.info("Task submitted!" + payload);
payload.setRunning(true);
//Try-catch
Thread.sleep(999999);
return payload;
})
.route(/*...*/)
.get();
}
My testing code can be simplified like this:
Task task1 = new Task();
Task task2 = new Task();
Promise<Result> resultPromise1 = taskProcessor.processTask(task1).flush();
Promise<Result> resultPromise2 = taskProcessor.processTask(task2).flush();
while( !task1.isRunning() || !task2.isRunning() ){
logger.info("Task2: {}, Task2: {}", task1, task2);
Thread.sleep(1000);
}
logger.info("Yes! your tasks are running in parallel!");
But unfortunately, the last log line, will never get executed!
Any ideas?
Thanks a lot

Answer 1

Well, I've reproduced it just with simple Reactor test-case:
#Test
public void testParallelPromises() throws InterruptedException {
Environment environment = new Environment();
final AtomicBoolean first = new AtomicBoolean(true);
for (int i = 0; i < 10; i++) {
final Promise<String> promise = Promises.task(environment, () -> {
if (!first.getAndSet(false)) {
try {
Thread.sleep(1000);
}
catch (InterruptedException e) {
e.printStackTrace();
}
}
return "foo";
}
);
String result = promise.await(10, TimeUnit.SECONDS);
System.out.println(result);
assertNotNull(result);
}
}
(It is with Reactor-2.0.6).
The problem is because of:
public static <T> Promise<T> task(Environment env, Supplier<T> supplier) {
return task(env, env.getDefaultDispatcher(), supplier);
}
where DefaultDispatcher is RingBufferDispatcher extends SingleThreadDispatcher.
Since the #MessagingGateway is based on the request/reply scenario, we are waiting for reply within that RingBufferDispatcher's Thread. Since you don't return reply there (Thread.sleep(999999);), we aren't able to accept the next event within RingBuffer.
Your dispatcher(Environment.THREAD_POOL) doesn't help here because it doesn't affect the Environment. You should consider to use reactor.dispatchers.default = threadPoolExecutor property. Something like this file: https://github.com/reactor/reactor/blob/2.0.x/reactor-net/src/test/resources/META-INF/reactor/reactor-environment.properties#L46.
And yes: upgrade, please, to the latest Reactor.