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This blog describes the resource and size limits for JMS resources used in the JMS and AS2 adapter, that can be used in Cloud Platform Integration Enterprise Edition. It describes which limits apply and how to monitor them. It also gives some guidance on how to cleanup the resources.

JMS Resource and Size Limits

The connected JMS messaging instance, that is used in asynchronous messaging scenarios using with the JMS or AS2 Adapter has limited resources. The Enterprise License sets a limit on the queues, storage and connections that you can use in the messaging instance.

There are also technical restrictions on the size of the headers and exchange properties that can be stored in the JMS queue.

Resource Limits for CPI Enterprise Edition

In the CPI Enterprise Edition, a dedicated set of resources is available in the JMS instance. Keep this in mind when configuring and running your scenarios.

  • Maximum number of queues: 30
  • Queue Capacity: 9GB
  • Transactions: 150
  • Consumers: 150
  • Providers: 150
  • Message Volume: 150GB/month

JMS Resources

The JMS Resources are shown in the Queue Monitor at the top of the page, in the Manage Storages section in the Operations view with the June-10-2018 update:

If the JMS Resources get critical the message appears as a yellow warning message. If the JMS resources are exhausted, it appears as a red error message.

If the resources are exhausted, messages can no longer be processed, so you need to keep an eye on this value. Make sure that there are no messages stuck in queues!

Using the Details link you get the detailed overview of the JMS Resources:

How to activate alerting for the JMS Resources is described in the blog Automated Notification for Critical or Exhausted JMS Resources.

Number of Queues

JMS queues are used by the JMS, AS2 and XI adapter. When the first integration flow that uses a JMS queue is deployed, the queue is created in the messaging broker. The queue can then be used for sending messages into the queue and for consuming messages from the queue.

The status for Number of Queues gets Critical if only one queue is left. In the above case it would get the critical status when 32 queues are created and only one is left.

The status for Number of Queues does never get Exhausted because there is no impact in runtime. If you would deploy a new integration flow using a new queue you would get an error during deployment of the integration flow.

Queue Deletion

If you no longer need a specific queue, (for example if the integration flow has been undeployed), you have to delete the queue manually in the Queue Monitor. Unused queues, that do not contain messages will be deleted automatically.

If the queue limit has been reached, you can check for unused queues and delete them. For more information about checks for unused queues, see the blog ‘Checks in Queue Monitor’.

Queue Capacity

The total queue capacity used by all the scenarios is also shown in the JMS Resources.

The master view of the monitor shows how this capacity is distributed between the queues. The Size column displays the size of all messages in this queue.

If the capacity used reaches 80% of the total capacity available, the status gets Critical. If 98% of the available capacity is used, the status gets Exhausted/Error.

If the limit is reached, messages can no longer be processed, so you need to keep an eye on this value. Make sure that there are no messages stuck in queues!

Transactions, Consumers and Providers

To process a message during runtime always a consumer or provider and an open transaction are required. If a message is stored to JMS queue (JMS Receiver channel) a provider is required, for polling a message from JMS queue (JMS sender channel) a consumer is required.

If the JMS Resources get Critical you need to optimize the usage of transactions in consumers and providers. Think about the following technical details:

Consumers

Consumers are created in the JMS broker from JMS sender adapters to consume messages from a JMS queue. There is a minimum number of consumers that are always created for the deployed integration flows having JMS queues, independent of the message throughput, and a maximum number that is started when many messages are stored in the JMS queues and need to be consumed.

Minimum number of consumers:

For each JMS queue used in a JMS or AS2 sender channel a minimum of one consumer is created for each runtime node started in the Cloud Integration cluster.

In short, the minimum number of consumers for a tenant can be calculated like this:

Cmin = number of worker nodes * number of JMS queues

Maximum number of consumers:

If lots of messages are to be consumed from the JMS queue, the initially created consumer is dynamically increased up to the configured Number of Concurrent Processes in the JMS or AS2 channel to provide a higher message throughput. For each JMS queue used in a JMS or AS2 sender channel, a maximum of consumers is created as concurrent processes are configured in the JMS sender channel in parameter Number of Concurrent Processes. If several runtime nodes are started in the Cloud Integration cluster those many consumers are created from each runtime node.

In short, the maximum number of consumers for a tenant can be calculated like this:

Cmax = number of worker nodes * number of JMS queues * number of concurrent processes

Note that the numbers of worker nodes is currently not explicitly shown in the WebUI. The only option you have is to count the numbers of system log files (ljs_trace_*) written in parallel in your tenant. In the System Log Files monitor check how many ljs_trace* files are written at the same time. It’s one for each worker node.

Note, that additional consumers are created for monitoring (when the Queue Monitor is used) and in case large messages are processed.

To reduce the parallel consumers, you can either reduce the number of concurrent processes in the JMS sender channels or reduce the number of runtime nodes started in the cluster.

Providers

Providers are created by the JMS receiver adapter in the JMS broker to store messages in a JMS queue. As many providers are created as messages are send to the JMS queue in parallel. The number of providers created is dynamically increased as long as enough providers and transactions are available.

In short, the number of providers for a tenant cannot be calculated, but depend on the sender system:

P = number of parallel sender calls

Note, that additional providers are created in case large messages are processed.

To reduce the parallel providers, you need to reduce the parallelism of the inbound processing by reducing the number of parallel inbound calls from sender systems sending messages to scenarios using JMS queues.

Transactions

To consistently process messages, JMS transactions are required in the JMS broker to be able to consistently roll back the processing in case of errors. As many transactions are created in the JMS broker as consumers and providers are under processing in parallel. This means, that for every consumer and every provider a transaction is started.

In short, the minimum number of transactions for a tenant can be calculated like this:

Tmin = Cmin + P

And the maximum number of transactions for a tenant can be calculated like this:

Tmax = Cmax + P

There are 150 open transactions available in the JMS broker, they can be used for a consumer or for a provider. The transactions are distributed dynamically to providers and consumers. This means, if lots of messages are consumed in parallel in consumers (polling messages form JMS queues via JMS´or AS2 sender channels) most of the transactions will be used for those and the number of available transactions to store message to JMS queues is lower.

If the limit for transactions is reached (if you get a runtime error) you need to reduce the parallelism for the consumers and/or providers (see above).

If multiple JMS resources, like JMS, XI or AS2 Sender Adapters and/or one or more JMS Receiver Adapters are used in one integration flow you can optimizes the numbers of used transactions in the JMS instance using a JMS transaction handler because then only one transaction is opened for the whole processing. More details about this option you can find in blog ‘How to configure transaction handling in integration flow/‘.

Size Limits for Messages, Headers, Properties and Attachments

The following size limits apply when saving messages to JMS queues.

  • There are no size limits for the payload. The message is split internally when it is put into the queue
  • There are no size limits for the attachements. The message and attachment are split internally when put into the queue
  • Headers and exchange properties defined in the integration flow before the message is saved to queue must not exceed 4MB for headers and properties together.

Important: As mentioned, there are no hard size limits for payload and attachments, but you need to keep in mind that processing the message in the CPI runtime may limit the possible size of payload and attachments for your scenario. You as scenario developer have to test and restrict the limits your scenario can handle!

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3 Comments

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  1. Richard Kleibl

    Hello Mandy,

     

    thanks for the Blog. We just got the feedback from support that there is also a limit per queue (4GB). Is this still accurate or not?

    Thanks and kind regards

     

    (0) 
    1. Mandy Krimmel Post author

       

      No, there is such limit. Before the last takt release the overall queue capacity was 4GB, but this was increased to 8GB. There is no limit per queue, never was.

      BR,

      Mandy

      (0) 

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