We currently have issues after connecting a new MQ Server (IBM MQ v9) to our service.
The current expectation is that we have two issues:
The connection establishment at MQ-Server takes too much time
We assume that on every message send a new physical connection is established instead of using the payara pool
Especially to prove No. 2 - is there any possibility to find out or log every Connection establishment that is done by the Resource Adapter?
You can use the Application activity trace of IBM MQ.
There is also a very nice presentation available to find out more about how to use the Activity Trace.
Related
I have a Spring Boot based messaging app sending/receiving JMS messages to/from IBM MQ queue manager.
Basically, it uses MQConnectionFactory to organize connection to IBM MQ and a JmsPoolConnectionFactory from messaginghub:pooledjms to enable JMS connection pool, which is removed from MQConnectionFactory in IBM MQ 7.x
The app uses two different appoach to work with JMS. A "correct" one runs a JMSListener to receive messages and then sends a response on each message using JmsTemplate.send(). And there is a second "troubling" approach, where the app sends requests using JmsTemplate.send() and waits for response using JmsTemplate.readByCorrelId() until received or timed out.
I say troubling because this makes JMS sessions last longer if the response is delayed and could easily exhaust IBM MQ connection limit. Unfortunately, I cannot rewrite the app at the moment to the first approach to resolve the issue.
Now I want to restrict the number of connections in the pool. Of course, the delayed requests will fail but IBM MQ connection limit is more important at the moment, so this is kind of appropriate. The problem is that even if I disable the JmsPoolConnectionFactory, it seems that MQConnectionFactory still opens multiple connections to the query manager.
While profiling the app I see multiple threads RvcThread: com.ibm.mq.jmmqi.remote.impl.RemoteTCPConnection#12433875[...] created by JMSCCMasterThreadPool and corresponding connections to the query manager in MQ Explorer. I wonder why there are many of them in spite of the connection pooling is removed from MQConnectionFactory? I suppose it should open and reuse a single connection then but it is not true in my test.
Disabling "troubling" JmsTemplate.readByCorrelId() and leaving only "correct" way in the app removes these multiple connections (and the waiting threads of course).
Replacing JmsPoolConnectionFactory with SingleConnectionFactory has not effect on the issue.
Is there any way to limit those connections? Is it possible to control max threads in the JMSCCMasterThreadPool as a workaround?
Because it affects other applications your MQ admins probably want you to not exhaust the overall Queue Manager's connection limit (MaxChannels and MaxActiveChannels parameters in qm.ini). They can help you by defining an MQ channel exclusively used by your application. By this, they can limit the number of connections of your application with the MAXINST / MAXINSTC channel parameter. You will get an exception when this number is exhausted which is appropriate as you say. Other applications won’t be affected anymore.
I am looking for detailed description on how IBM MQ Client or listener get the messages from MQ Server when new messages are placed on MQ Queue or Topic.
How the connection between MQ Client and MQ Server are created?
Does MQ Client initiates the connection with Server or does server initiates the connection to its consumer?
In case we have connection pool defined on MQ Client, how client knows that it has to create more connections with Server as the messages are increasing on Server? How Client know about the messages on Server?
Is there a communication from Server to Client which tells client that new messages have arrived?
I am looking for these details not the details on how this is setup or how to setup MQ Channels or Listeners. I am looking for how it works behind the scene.
If someone can point me to the right direction or documentation, it would be great.
It's hard to speak definitively about how the IBM WebSphereMQ client & server work since they're closed source, but based on my experience with other messaging implementations I can provide a general explanation.
A JMS connection is initiated by a client to a server. A JMS client uses a javax.jms.ConnectionFactory to create a javax.jms.Connection which is the connection between the client and server.
Typically when a client uses a pool the pool is either filled "eagerly" (which means a certain number of connections are created when the pool is initialized to fill it to a certain level) or "lazily" (which means the pool is filled with connections one-by-one as clients request them from the pool). If a client requests a connection from the pool and if all the connections in the pool are being used and the maximum size of connections allowed by the pool hasn't been reached then another connection will be created. If the pool has reached its maximum allowed size (i.e no more connections can be created) then the client requesting a connection will have to wait for another client to return their connection to the pool at which point the pool will then give it to the waiting client.
A JMS client can find out about messages on the server in a few different ways.
If the JMS client wants to ask the server occasionally about the messages it has on a particular queue it can create a javax.jms.Consumer and use the receive() method. This method can wait forever for a message to arrive on the queue or it can take a timeout parameter so that if a message doesn't arrive in the specified timeout the call to receive() will return.
If the JMS client wants to receive a message from a particular queue as soon as the message arrives on the queue then it can create a javax.jms.MessageListener implementation and register it on the queue. When such a listener is registered on a queue then when a message arrives on the queue the server will send the message to the listener. This is sometimes referred to as a "callback" since the server is "calling back" to the client.
The first thing you should do is take a course on JMS/IBM MQ or go to the new IBM conference called: Integration Technical Conference
Ok, now to your questions:
How the connection between MQ Client and MQ Server are created?
You simply issue the createQueueConnection method of QueueConnectionFactory class and specify the credentials.
QueueConnection conn = cf.createQueueConnection("myUserId", "myPwd");
Does MQ Client initiates the connection with Server or does server initiates the connection to its consumer?
MQ client application starts the connection - always.
In case we have connection pool defined on MQ Client, how client knows that it has to create more connections with Server as the messages are increasing on Server? How Client know about the messages on Server?
It is up to the team's architect or lead developer to understand message flow and message patterns. Hence, they will know what to set the pool count at. Also, lots and lots of testing too. Some client applications will only require a pool count of 10 whereas other applications may need a pool count of 50 because it is a heavy flow.
Is there a communication from Server to Client which tells client that new messages have arrived?
You use the createReceiver method of the QueueSession class to retrieve a message. Set a timeout value for the createReceiver method rather than continuously polling the queue manager.
Again, some training on the use of JMS/IBM MQ is strongly recommended.
I'm using IBM XMS v 9.0 .NET C# client library to connect IBM MQ.
Once connection are established, assigned MessageListener and OnXMSException.
Have set XMSC_WMQ_CLIENT_RECONNECT_TIMEOUT = 30.
We are getting messages on MessageListener and everything works fine.
When I disconnect the network after successful connection, I won’t get any exception delivered to OnXMSException listener method.
My intension is, if MQ connection is no longer valid / active , I should get back error ASAP, so that I can establish a new connection quickly to start reading the messages to avoid queue backlog.
Is XMSC_WMQ_CLIENT_RECONNECT_TIMEOUT, is the right one ? or any other setting exist for this?
I am trying network disconnect because sometimes we have noted that even when MQ connection in not active on MQ server, the client would get no CONNECTION BROKEN error. But sometime it works.)
I am trying to implement spring batch remote partitioning using spring integration. I am triggering the master using standalone app and slaves are running on jboss eap 6.1 cluster. I am able to trigger the job and i can see slaves also got triggered. but after some time master jms connection is timing out. can someone shed me a light, how can i configure this timeout settings..
2636699 21/11 16:59:55,580[org.springframework.jms.listener.DefaultMessageListenerContainer#0-378] WARN jms.listener.DefaultMessageListenerContainer.handleListenerSetupFailure - Setup of JMS message listener invoker failed for destination 'queue-screening-replies-partitioning' - trying to recover. Cause: Session is closed
2636699 21/11 16:59:55,580[org.springframework.jms.listener.DefaultMessageListenerContainer#0-378] INFO jms.listener.DefaultMessageListenerContainer.refreshConnectionUntilSuccessful - Successfully refreshed JMS Connection
I am getting this kind of errors..
Thanks in advance..
--M K
Either the network or your broker is timing out the connection.
Consult your broker documentation to enable some kind of heartbeats/timeouts to keep the connection open.
Or, it would be better to reduce your partition sizes (increase the number of partitions) so they complete in a reasonable time.
EDIT:
Also, configure the outbound gateway with a <reply-listener/> and use a fixed, named, reply queue and the gateway will be able to recover from the dropped connection.
But I would still recommend smaller partitions in general.
I have two clustered managed servers running on Weblogic, and seperate JMS server1 and server2 are running on each managed server. The problem is in application properties file, we only hardcoded and pass JMS server1 JNDI name to the application. So both applications running on each node actually only uses one fixed JMS server, which is not truly distributed and clustered. If JMS server 1 is down, the whole application will be down.
My question is how to let application dynamically find JMS server in above senario? Can you please point me a direction? Thanks!
It's in the Weblogic docs at: http://docs.oracle.com/cd/E14571_01/web.1111/e13738/best_practice.htm#CACDDFJD
Basically you created a comma separated list of servers and the JMS connection logic should be automatically able to handle to case when one of the servers is down:
e.g.
t3://hostA:7001,hostB:7001
When you use a property like jms.jndi.provider.url=t3://hostA:31122,hostA:31124
it tells wls to connect to either hostA:31122 or hostA:31124.
Note your JMS client is connected to only one Host at any given time.
when you shutdown hostA the connection between JMS client and server is cut abruptly resulting in an exception, your code will have to handle this exception gracefully and attempt to connect to WLS again periodically to ensure it connects to hostB.
WLS internally will round robin the request if more than 1 instance of the JMS client is running.
When using MDB as JMS client and deploying it to a cluster and using such a url 1 mdb instance would connect to one host and the other instance would connect to another host. MDB also inherently has the ability to reconnect periodically to the JMS destination.
A easy solution to your problem could be to
1) Set the jms.jndi.provider.url=t3://hostA:31122,hostA:31124
2) Have 2 instance of the JMS client code running, so one will connect to port 31122 and other to 31124
3) Set Forward-Delay on the JMS Queue so that message dont remain in queue without getting consumed for long and get forwarded to the other queue which has an active consumer.
I am updating my progress here instead of adding more comments. I have tested using a standalone JMS client by changing properties file from t3://hostA:7001 to t3://hostA:7001,hostB:7001 for JMS provider. The failover is automatically handled by WLS. No code change. The exception I got above is caused by using wlclient.jar, it is working after it changed to wlfullclient.jar.
I followed this link to generate wlfullclient.jar.
Thanks everyone!