Windows Server 2012
MSMQ 6 Workgroup Mode
We've had issues trying to recover MSMQ messages that were sent to the transaction dead letter queue. We've tried moving them to the outbound queue, the message seems to send fine (even the Event Log says so) however it never gets to the destination queue.
After trial and error we've figured out how to get them to another queue on the same server but not to the destination queue on a remote server. We don't want to lose anymore messages. Does anyone have any suggestion on how we can deliver these messages?
Thank you,
David
As I understood your question, it's a one time problem with some number of messages you already have in MSMQ, and not general connectivity issue between machines? If so, you should be able to solve it with some MSMQ management tool. Disclaimer: I'm the author of one such tool - QueueExplorer. I don't know what other tools can do, but with QueueExplorer you can copy/paste or drag/drop messages to another machine opened in separate tab/window. In order to do that QueueExplorer has to perform MSMQ Send operation, so messages will have to pass through MSMQ between these two machines.
So if there's still that issue that prevented original delivery you'll still be stuck. In that case you can save all messages to a file, transfer it to another machine through file system and load it there to whichever queue they should go. This is obviusly just a manual workaround for one time situation. Btw. this could be done in QueueExplore's trial mode.
If however problem is with connectivity and messages always end up in dead letter queue, it's better to check them from Computer Management. It's one area where it's better than our tool - you can turn on "Class" column and see reason why messages couldn't be delivered. For instance if you see "The time-to-be-received has elapsed" you'll know what's the problem.
Related
I use NServiceBus with MSMQ on Windows Server 2008.
In one of our scenario we send a command to another server queue but sometimes the message never arrives in the queue and MSQM doesn't throw an exception.
I have written a small application that sends a message directly to the queue without NServiceBus and I have encountered the same problem.
I think it isn't a nservicebus problem but a MSMQ problem : windows security, network,...
How can I force MSMQ to return an error when the message can't be saved in queue ?
What are the possible reasons of this behavior ?
Where are the messages that have disappeared ?
In the MSMQ Management snap-in take a look at the system queues and look at transactional dead letter and non-transactional dead letter queues.
Also be sure to have setup queue ACL correctly.
I have a transactional private message queue (among other message queues on which I have not seen this problem) on a Windows Server 2008 R2 server.
This particular queue has a recurring problem happening every few weeks where the console shows a nonzero count of messages in the queue, but it does not have any messages in the queue itself or any subqueue. Queue Explorer shows the same thing. Performance counters indicate there are messages like the count in the built-in msmq console and queue explorer.
I cannot find any messages. I understand that I could see a situation like this for outgoing queues with dead letter tracking such that it may have been delivered to a remote machine but not yet processed. This is not an outgoing queue, though. Messages are sourced from remote machines and have landed here on this machine.
Also, I am certain that the count I'm seeing are not journal messages or subqueues.
Does this make any sense? Is there a logical explanation for this and under some circumstance this is expected? If so, what is it?
EDIT: Removed info about purging queue removing the count - that was incorrect. Purging actually does nothing and leaves me in the same state as before with a count reflected, but no messages showing.
As you noted, you can see a message count on an outgoing queue if source journaling is in use. The invisible messages are there in case they need to be moved to the DLQ.I would expect your problem to be similar - there should be a visible message in the outgoing queue and an invisible message in the destination queue because delivery hasn't completed. I assume a handshaking or storage acknowledgement has been lost along the way. Or maybe the message has been processed and removed from the queue but MSMQ couldn't update the sender of the fact. Check the outgoing queues on the remote machines sending TO this queue.
Is there some standard configuration setting, service, or tool that accepts messages from one queue and moves them on to another one? Automatically handling the dead message problem, and providing some of retry capability? I was thinking this is what "MSMQ Message Routing" does but can't seem to find documentation on it (except for on Windows Mobile 6, and I don't know if that's relevant).
Context:
I understand that when using MSMQ you should always write to a local queue so that failure is unlikely, and then X should move that message to a remote queue. Is my understanding wrong? Is this where messaging infrastructure like Biztalk comes in? Is it unnecessary to write to a local queue first to absolutely ensure success? Am I supposed to build X myself?
As Hugh points out, you need only one MSMQ Queue to Send messages in one direction from a source to a destination. Source and destination can be on the same server, same network or across the internet, however, both source and destination must have the MSMQ service running.
If you need to do 'message' routing (e.g. a switch which processes messages from several source or destination queues, or routing a message to one or more subscribers based on the type of message etc) you would need more than just MSMQ queue.
Although you certainly can use BizTalk to do message routing, this would be expensive / overkill if you didn't need to use other features of BizTalk. Would recommend you look at open source, or building something custom yourself.
But by "Routing" you might be referring to the queue redirection capability when using HTTP as the transport e.g. over the internet (e.g. here and here).
Re : Failed delivery and retry
I think you have most of the concepts - generally the message DELIVERY retry functionality should be implicit in MSMQ. If MSMQ cannot deliver the message before the defined expiry, then it will be returned on the Dead Letter Queue, and the source can then process messages from the DLQ and then 'compensate' for them (e.g. reverse the actions of the 'send', indicate failure to the user, etc).
However 'processing' type Retries in the destination will need to be performed by the destination application / listener (e.g. if the destination system is down, deadlocks, etc)
Common ways to do this include:
Using 2 Phase commit - under a distributed unit of work, pull the message off MSMQ and process it (e.g. insert data into a database, change the status of some records etc), and if any failure is encountered, then leave the message back onto the queue and the DB changes will be rolled back.
Application level retries - i.e. on the destination system, in the event of 'retryable' type errors (timeout due to load, deadlocks etc) then to sleep for a few seconds and then retry the same transaction.
However, in most cases, indefinite processing retries are not desirable and you would ultimately need to admit defeat and implement a mechanism to log the message and the error and remove it from the queue.
But I wouldn't 'retry' business failures (e.g. Business Rules, Validation etc) and the behaviour should be defined in your requirements of how to handle these (e.g. account is overdrawn, message is not in a correct format or not valid, etc), e.g. by returning a "NACK" type message back to the source.
HTH
MSMQ sends messages from one queue to another queue.
Let's say you have a queue on a remote machine. You want to send a message to that queue.
So you create a sender. A sender is an application that can use the MSMQ transport to send a message. This can be a .Net queue client (System.Messaging), a WCF service consumer (either over netMsmqBinding or msmqIntegrationBinding, BizTalk using the MSMQ adapter, etc etc.
When you send the message, what actually happens is:
The MSMQ queue manager on the sender machine writes the message to a temporary local queue.
The MSMQ queue manager on the sender machine connects to the MSMQ manager on the receiving machine and transmits the message.
The MSMQ queue manager on the receivers machine puts the message onto the destination queue.
In certain situations MSMQ will encounter messages which for some reason or another cannot be received on the destination queue. In these situations, if you have indicated that a message will use the dead-letter queue then MSMQ will make sure that the message is forwarded to the dead-letter queue.
We have a Pub / Sub system based on NServiceBus, where we have intermittent issues with messages getting stuck on the Publishers outgoing queue indefinitely, rather than being transmitted to the Subscribers input queues.
Points to note:
When we restart the Publisher Service and Subscriber services, message flow resumes normally for a while.
The problem seems to occur more often if a sustained period of time between messages occurs.
The publisher service resides on the LAN, the subscribers on the otherside of a firewall.
Some messages get through! As mentioned after service restarts, things go fine for a while.
Using QueueExplorer, I can see the messages on the Outgoing queue have a state of WAITING.
Annoyingly our development environment does not exhibit this behaviour, but then again the publisher and subscribers all reside on the same LAN in this environment.
MSMQ messages being stuck in an outgoing queue is purely an MSMQ issue. Restarting the Publisher and Subscriber services should make no difference as they are not directly involved in message delivery. If you can fix the problem by ONLY restarting the Pub/Sub services and NOT the Message Queuing services then it looks like a resources/memory leak problem.
I imagine something like this happening:
Messages flow to destination, which uses up kernel memory in storing them
For some reason, kernel memory runs out (too many messages, memory leak, whetever)
Destination now rejects new messages as they cannot be loaded into memory from the wire
Connection is reset and not re-connected until WaitTime value reached; Queue is "waiting" at this point
System loops through (3) and (4) until ...
Pub/Sub services are restarted and now there is sufficient resources for messages to be delivered
Goto (2)
Occasional messages get through when just enough kernel memory is temporarily freed up by one of the many services and device drivers that use it.
Item 4 of this blog post is the most likely culprit:
http://blogs.msdn.com/b/johnbreakwell/archive/2006/09/18/insufficient-resources-run-away-run-away.aspx
Cheers
John Breakwell
We had a similar scenario in production, it turned out we migrated one of our subscriber endpoints to a new physical host and forgot to unsubscribe before shutting down the old endpoint. Our publisher was trying to deliver messages to both the old and new endpoints but could only reach the new one. Eventually the publishers outbound queue grew so large that it started affecting all outgoing messages.
I have run into this issue as well, I know it is not Item 4, as I don't send anything to it before it gets stuck in the outgoing queue. If I let both publisher and subscriber sit for about 10 minutes before sending a message, it never leaves the outgoing queue. If I send a message before that amount of time, it flows fine. Also, if I restart the subscriber the message will then flow. This is reproducible every time I let them sit idle for 10 minutes.
I think I found the answer here, at least this fixed the issue I was having:
http://support.microsoft.com/kb/2554746
Also, in my case it had nothing to do with restarting, so don't let that throw you off, I did exhibit the symptoms in the netstat and messages would initially go through when the client was first started up.
Just to throw my 2p in:
We had an issue where the message queuing service had some kind of memory leak and would consume large amounts of memory which is did not release.
This lead to messages getting stuck for long periods of time - although they would eventually be delivered (sometimes after 3 days).
We have not bothered fixing this yet as it only happens when the service is under heavy load which does not happen often.
So, I am new to MSMQ and NServiceBus. I played around with demos and got a working scenario going with NServiceBus. (Getting my own up and running was even easier than following the demo thanks to the new Modeling tools!)
I then went and presented my plan (based off my work with the demo and my own model) to my co-workers. Two of them were versed in using MSMQ and started asking me questions about how I will handle "Dead Letters".
I had never heard of "Dead Letters". They explained that it is queue used for messages that things cannot be sent (either because the other end refuses them or if the other end is not there).
The concern of my co-workers is that if we don't have Dead Letter queues then how will we stop a message from blocking the queue? (If the queue is FIFO and the top message can't be sent, then it blocks the other messages behind it right?)
On the other hand, if we have "Dead Letter" queues how are they managed? (Do I get an event from NServiceBus that tells me a new message is in the Dead Letter queue? How do I configure when a message will go to the Dead Letter queue? How can I try to re-send a Dead Letter message?)
So basically, how does NServiceBus deal with undeliverable messages?
Typically, you specify an error queue as well, which is where messages that couldn't be sent will go. Look at their MSMQ example:
http://docs.particular.net/nservicebus/msmq/transportconfig &
http://docs.particular.net/nservicebus/msmq/connection-strings
<MsmqTransportConfig InputQueue="MyClient" ErrorQueue="error"
NumberOfWorkerThreads="1" MaxRetries="5"/>
In this scenario, the error queue will reside on the same machine as the input queue. This may also be a remote queue, if preferred. MaxRetries refers to the number of attempts to send before it gets put into the error queue. How you choose to handle the error queue is up to you, however.