I am using RabbitMQ 3.1.3 to handle Celery tasks, and have discovered a task that is locking up my workers. It is one of two messages in a queue, and I would love to see the content of the message to debug what is breaking my process flow. How can I dump the message body for debugging purposes? I have tried rabbitmqadmin, but get "Connection reset" errors on login attempt (and the logs show a cryptic "{bad_header,<<"POST /ap">>}
").
Login to the web managemnet gui at the RabbitMQ server to view the status of your server in an easy way. You can see exchanges, queues etc. And the status of the messages.
I would also recommend you to check out the tutorials at the RabbitMq website. They explain how everything works in a compact way it is also code examples for several programming languages. Php, Java, Ruby etc
You can easily write small programs to test queues, sending test messages etc from the examples.
Related
I am NOT talking about Cloudera or Yarn system level logs. I am talking about applications running on Cloudera/Yarn infrastructure.
We have tens of Java and Python applications running on our Cloudera Infra, and all of them generate application logs. I am looking for the best way to monitor these logs for any errors and warnings. If it is a pure stand alone Java application, traditionally we can use one of these log scraper tools that send emails based on an expression matching (to detect error/warning/any other special situation). I am looking for something similar, that can monitor our application logs and emails us in real time for better production application support.
If thinking about this like a traditional application log monitoring is not the right way, then I am happy to know if there are any better industry standard approaches. Thanks!
I guess the ElasticStack (https://www.elastic.co/de/) could be one approach to solve this. You could use FileBeats to send your application logs to Logstash which forwards it to ElasticSearch. You could then create a Watcher in Kibana which sends i.e. Emails based on some triggering condition (we use a webhook to send notifications into a MS Teams channel).
This solution should work at least in near-realtime (~1-2 minutes delay, but this also depends on your watcher configuration).
Currently, we plan to upgrade our product to use MQ(RabbitMQ or ActiveMQ) for message transfer between server and client. And now we are using a network lib(evpp) for doing so.
Because I don't use MQ before, so excpet for a lot of new features of MQ, I can't figure out the essential difference between them, and don't know exactly when and where should we use MQ or just use network library is fine.
And the purpose that we want to use MQ is that we want to solve the unreliability of communication, such as message loss or other problems caused by unstable network environment.
Hope there is someone familiar with both of them could release my confusion. Thanks for advance.
Message queuing systems (MQ, Qpid, RabbitMQ, Kafka, etc.) are higher-layer systems purpose-built for handling messages reliably and flexibly.
Network programming libraries/frameworks (ACE, asio, etc.) are helpful tools for building message queueing (and many other types of) systems.
Note that in the case of ACE, which encompasses much more than just networking, you can use a message queuing system like the above and drive it with a program that also uses ACE's classes for thread management, OS abstraction, event handling, etc.
Like in any network-programming, when a client sends a request to the server, the server responds with a response. But for this to happen the following conditions must be met
The server must be UP and running
The client should be able to make some sort of connection between them
The connection should not break while the server is sending the response to the client or vice-versa
But in case of a message queue, whatever the server wants to tell the client, the message is placed in a message-queue i.e., separate server/instance. The client listens to the message-queue and processes the message. On a positive acknowledgement from the client, the message is removed from the message queue. Obviously a connection has to made by the server to push a message to the message-queue instance. Even if the client is down, the message stays in the queue.
Being new to the RabbitMQ I was wondering how to deal with an offline target node.
As an example this scenario:
1 log recording application that stores logs to some persistent storage
N log publishing applications that want their logs to be written to the persistent storage via the log recording server.
There would be two options:
Each publishing application publishes it's log messages to it's local RabbitMQ instance and the log recording server must subscribe to each of these
The log recording application has it's local RabbitMQ instance on which each log publishing application delivers it's messages.
Option 1 would require me to reconfigure/recode/notify the recording application each time a new application appears or moves. Therefore I would think Option 2 is the right one, each new publishing application simply writes to the RabbitMQ Node of the recording application.
The only thing I am struggling with is how to deal with a situation in which the Node of the recording application is down. Do I need to build my own system to store the messages until it's back online or can I use some functionality of RabbitMQ to deal with that? I.e. could the local RabbitMQ of each of the publishing applications just receive the messages and forward them to the recording application RabbitMQ as soon as it's back online?
I found something about the Federated plugin be couldn't understand if that's the solution. Maybe I need something different or maybe I have to write my own local queueing system (which I hope I don't have to) to queue messages when the target Node is offline.
Any links to architectural examples or solutions are more than welcome.
BTW: https://groups.google.com/forum/#!topic/easynetq/nILIKSjxyMg states that you shouldn't be installing a RabbitMQ Node for each application, so maybe I should resort to something like MSQM or ZeroMQ (?)
From experience in what sounds like a similar situation, I would suggest using something other than a queue to store the messages locally, when offline.
Years ago, I built a system that had to work offline - no network connection at all - and then had to push messages through a message queue to the central server, when the laptop was brought back to the office.
I solved this by using a local database (sqlite at the time) to store my messages when the message queue was not available.
You should do something similar. Use a local database or even a plain text file or CSV file to store your messages when RabbitMQ is offline. When it reconnects, read the messages from your local file system and send them through RabbitMQ.
This is a good strategy to use, even if you do not expect RabbitMQ to go offline. Frankly, it will go offline at some point and you will have to deal with it. You should be prepared for that situation, and having a local store for your messages will help that.
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regarding rqm node per application: bad idea. this adds a ton of complexity to your system. You want as few RabbitMQ nodes as you can get away with. Meaning, 1 per system (a system being comprised of many applications) when possible... with the exception of RabbitMQ clusters for availability - but that's another line of questions and design, entirely.
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I did an interview with Aria Stewart about designing for failure with RabbitMQ and messaging systems, and have a small excerpt where she talks about how networks fail.
The point is, the network or RabbitMQ or something will fail and you will need a solution like a local datastore so that you can recover when RabbitMQ comes back online.
Right now we have a queuing system(activemq) which is storing the messages. And we have written a separate java application that will read the queue and then trigger a exe to do some processing. But we want to do away with this extra application that is linking our activemq and exe. So i want to know whether any queuing system houses a code which will help me run the exe without any extra code written by me.
Any inputs regarding which queuing system can get me this done will be greatly appreciated.
This isn't really how Message Brokers work. You could however embed a broker inside your own application or create a broker plugin to do something. In the end though the best way to do this is to create your own client that can implement your business logic and let the Message Broker do what it was designed to do, route message traffic.
If you want more of a 'push' solution rather than a producer-consumer solution (which sounds to me like you are) you could look into the use of WebSockets. That would be another way of dealing with messages.
As others have said it doesn't look like using a message broker is the solution you want if you don't want to have some additional middleware to provide asynchronous communication.
So you just need something to launch an EXE on message arrival?
Message Queuing Triggers
Just some additional information for you... Triggered applications are natively supported in IBM Websphere MQ via a Trigger Monitor application that runs as a service (in windows implementations) or a daemon (in UNixish implementations).
When a message arrives in a queue, the MQ software will generate another message ("Trigger" message and send it to the "Trigger" queue, which is being monitored by the Trigger Manager app. The app then starts the required application.
So your implementation of an "app to start an app" is not odd ball or strange at all.. IBM do it in their implementation. I see nothing wrong with your implementation and if you can integrate it tighter to activeMQ then you are on a winner.
What about IBM MQ's triggering feature ?
WebSphere MQ provides a feature that enables an application or channel to be started automatically when there are messages available to retrieve from a queue. A message is put to a queue defined as triggered. If a series of conditions are met, the queue manager sends a trigger message to an initiation queue.
https://www.ibm.com/support/knowledgecenter/en/SSFKSJ_9.0.0/com.ibm.mq.dev.doc/q026940_.htm
I have multiple components connected with RabbitMQ. Some are producers and consumers. I need to benchmark/load test my system. I need to ensure that the consumers can handle N messages/second. I've done some searching on the internet but haven't really found anything. Does anyone have any experience with benchmarking RabbitMQ? Ideally I'd like to just spam the network with messages without having to create a new producer.
Do you know the tool JMeter? With this tool you can simply simulate a heavy load on a server. I use it normaly for web applications, but i saw a JMeter-RabbitMQ-plugin to test AMQP message broker like RabbitMQ with JMeter. I think you should have a look on it.
If you have a web application in the front of RabbitMQ, then you can also test directly this application with JMeter.