I have a queue channel, and a service activator with a poller which reads from that queue. I'd like to have configuration to say "I want 50 threads to poll that queue, and each time you poll and get a message back, on this thread, invoke the service the service-activator points to."
The service has no #Async annotations, but is stateless and safe to run in a concurrent fashion.
Will the below do that? Are there other preferred ways of achieving this?
<int:channel id="titles">
<int:queue/>
</int:channel>
<int:service-activator output-channel="resolvedIds" ref="searchService" method="searchOnTitle" input-channel="titles">
<int:poller fixed-delay="100" time-unit="MILLISECONDS" task-executor="taskExecutor"></int:poller>
</int:service-activator>
<task:executor id="taskExecutor" pool-size="50" keep-alive="120" />
Yes I think it does what you want. Once you introduce a QueueChannel the interaction becomes async - you don't need #Async. If you don't explicitly set up a poller it will use the default poller.
What you have outlined is the best way to achieve it. You might also consider putting a limit on the queue size - so that in case there is a lag in keeping up with the producer it doesn't lead to out of memory issue. If a size is specified then the send calls on the channel will block - acting as a throttle.
The configuration you have will work as you expect. The only issue is that once you start creating executors and pollers for each end point it becomes difficult to figure out the optimal configuration for the entire application. It is ok to do this kind of optimization for a few specific steps - but not for all the endpoints (nothing in you questions suggests that you are doing it, just thought that I will raise it anyway.
Related
I need to receive 'n' number of messages per every second from IBM MQ. Example : I need to receive maximum 10 messages per second.
I want to use DefaultMessageListnerContainer of spring.
Can this be achieved by setting the below configurations?
<bean id="msgListenerContainer"
class="org.springframework.jms.listener.DefaultMessageListenerContainer"
p:connectionFactory-ref="mqConnectionFactory"
p:messageListener-ref="myMessageListener"
p:concurrentConsumers="1"
p:maxConcurrentConsumers="10"
p:receiveTimeout="1000"
p:maxMessagesPerTask = "10" />
You might be better using JmsTemplate.receiveAndConvert() instead of a message-driven architecture, if you want to control the rate of message consumption.
Spring DMLC doesn't have a throttle built in. Apache Camel is another option that is designed for JMS -> throttle -> data processing
I have a “listener-container” defined like this:
<listener-container concurrency="1" connection-factory="connectionFactory" prefetch="10"
message-converter="jsonMessageConverter"
error-handler="clientErrorHandler"
mismatched-queues-fatal="true"
xmlns="http://www.springframework.org/schema/rabbit">
<listener ref="clientHandler" method="handleMessage" queue-names="#{marketDataBroadcastQueue.name}" />
</listener-container>
I want to process the messages in sequential order, so I need to set concurrency to 1.
But the bean “clientHandler” has more than one “handleMessage” methods (with diferent java classes as parameters). I can see in the application logs that messages are not processed one by one. I have several messages processed in parallel. Can it be due to having multiple methods with the same name that processes those messages?
Thanks!
I have a huge xml that come as an input payload to my Spring integration flow. So I am using claim check in transformer instead of header enricher to retain my payload. I am using an in-memory message store.
Later on in my SI flow, I have a splitter that splits the payload into multiple threads and each thread will invoke different channel based on one of the attribute payload. I am using a router for achieve this. Each flow or each thread uses a claim check out transformer to retrieve the initial payload then us it for building the required response. Each thread will produce a response and I don't have to aggregate them. So I will have multiple responses coming out from my flow which will then be dropped into a queue.
I cannot remove the message during the check out as other thread will also try to check out the same message. What is the best way to remove the message from the message store?
Sample configuration
`<int:chain input-channel="myInputChannel"
output-channel="myOutputchannel">
<int:claim-check-in />
<int:header-enricher>
<int:header name="myClaimCheckID" expression="payload"/>
</int:header-enricher>
</int:chain>`
all the other components in the flow are invoked before the splitter
<int:splitter input-channel="mySplitterChannel" output-channel="myRouterChannel" expression="mySplitExpression">
</int:splitter>
`<int:router input-channel="myRouterChannel" expression="routerExpression"
resolution-required="true">
<int:mapping value="A" channel="aChannel" />
<int:mapping value="B" channel="bChannel" />
<int:mapping value="C" channel="cChannel" />
</int:router>`
Each channel has a claim check out transformer for the initial payload. So how do I make sure the message is removed after all the threads have been processed?
When you know you are done with the message you can simply invoke the message store's remove() method. You could use a service activator with
... expression="#store.remove(headers['myClaimCheckID'])" ...
However, if you are using an in-memory message store there is really no point in using the claim check pattern.
If you simply promote the payload to a header, it will use no more memory than putting it in a store.
Even if it ends up in multiple messages on multiple threads, it makes no difference since they'll all be pointing to the same object on the heap.
I have an integration flow where some of the steps are async and some of sync. I want to use the barrier to block the Main thread until all async tasks have completed. Based on the documentation, there are two ways to use the barrier.
Send a second trigger message to the input channel of the barrier.
Invoke the trigger method manually of the barrier
In my use case a message comes in the flow and then goes through several components until it reaches the completed channel. I want the main thread to be blocked until the original messages reaches the completed channel. So it seems appropriate to use the option #2 and invoke the barrier trigger method after reaching the completed state. This doesnt seem to work. Here is a simplified version of my flow.
<int:gateway
service-interface="...BarrierGateway"
id="barrierGateway" default-request-channel="input">
</int:gateway>
<int:channel id="input">
<int:dispatcher task-executor="executor" />
</int:channel>
<int:service-activator input-channel="input" output-channel="completed">
<bean class="...BarrierSA" />
</int:service-activator>
<int:channel id="completed" />
<int:service-activator input-channel="completed"
ref="barrier1.handler" method="trigger" />
<int:barrier id="barrier1" input-channel="input" timeout="10000" />
I am sending a message to the gateway which passes it to the input channel which is using a dispatcher so a new thread is started to pass the message forward. At this point, I want to block the main thread while the Executor-1 thread goes through the flow. The rest of the flow is simple. My service-activator sleeps for 3 seconds before returning the message to simulate a delay. Once the message is received in the completed channel, the service-activator should invoke the barrier trigger method and only at this point, the main thread should be released. Instead, the main thread is released right after the dispatcher starts a new thread. I have tried specifying a constant correlation id ('abc') but that didnt help.
I see you're caught in a trap.
The <int:barrier> suspends the Thread just on the message message, but only that Thread which brings that message to him. Looking to your config it is the same input channel with Executor. The purpose of the ExecutorChannel to shift message to a different thread, but not suspend the caller's thread.
From other side you have one more mistake around that input. You declare two subscribers for him, where only one of them will be called by the round-robin balancing strategy.
To fix your task we should have one more top-level channel as <publish-subscribe-channel>. And right, already now you can have two subscribers.
One of them should be a <bridge> to your input ExecutorChannel. And another the desired <barrier>. And only now it can suspend (block in your terms) the main thread from the <gateway>.
From other side the more simpler solution would be don't use the <barrier> at all. The <gateway> has an ability to to block the caller's thread and wait for reply. Of course, that works when the gateway methods isn't void.
And one more point to your config: if you don't wait for reply in the gateway, the <barrier> will fail with the
throw new DestinationResolutionException("no output-channel or replyChannel header available");
So, consider to use something as an output-channel there a well.
I am using the Spring DefaultMessageListenerContainer to gain some dynamic benefits in setting the MessageSelector value since I am using the Glassfish OpenMQ which is not that advanced in that regards.
Let's have a JMS message. The listener issues a specific failure that means: retry after x seconds. It tries again with failure: retry after x*y seconds, and so on the time grows exponentially. If you cannot handle it after z retries, consider it as a poison JMS message.
DefaultMessageListenerContainer dmlc;
dmlc.stop();
dmlc.setMessageSelector(String.format("retries < %d AND retryTime <= %d", z, System.currentTimeMillis()));
dmlc.start();
I am not that satisfied with this solution, especially, when the Spring docs raise warning here:-). However, for the moment things meet our needs.
Now, I have a number of EJBs message consumers on different applications. Some of them need such dynamic changes of the messageSelector. Unfortunately, and to-my-best-knowledge, EJB MDBs do not support such dynamic "features". For example, see this.
Is that correct? is there a workaround for an EJB solution? I would appreciate any help.
To achieve dynamic changes to the message selector, you'd need to implement it straight in JMS, e.g.
ConnectionFactory cf;
Connection connection = cf.createConnection();
session = connection.createSession(transactional, acknowledgeMode);
MessageConsumer messageConsumer = session.createConsumer(destination, "message selector");
Additionally, you'd need to place this code some place it executes on its own, perhaps in an asynchronous task? But you'd be reinventing the wheel, as Spring DMLC does that better.
I don't know why you're doing this:
for load balancing? The message broker should take care of this.
for handling temporary downtimes? The queue should be configured to be able to store appropriate number of messages, or switch delivery to other node in cluster.