¿Number of threads of JCA WorkManager in AS7?

[ignacio.marrero]

We are doing some performance tests of our application (REST API with Mysql) and find that with independency of the concurrency (no matters if we have 50 clients or only 3) the JCA subsystem uses only 2 threads. This brings into a bottleneck in the case of high concurrency as many DB requests are enqueued within the same JCA worker.

Our configuration is:

* CentOS 6, X64_86

* AS7.1

* 2 stateless balanced jboss nodes

* Standalone.xml (please refer to https://gist.github.com/4140899)

* NDB MySQL cluster with two nodes and maxconnections=150 per node

¿how can i increase de number of JCA threads? ¿why iraonjacamar instantiates only 2 threads?

any help will be apreciated

[jesper.pedersen]

The WorkManager has nothing to do with datasources - see <pool> / <xa-pool> - http://docs.jboss.org/ironjacamar/userguide/1.0/en-US/html/deployment.html#deployingds_descriptor

[ignacio.marrero]

Hi Jesper,

Unfortunately we have no success changing pool / xa-pool.

You are rigth, our problem aren't workers but we can't understand JCA behaviour, so we can't solve the bottleneck.

I would like to explain better the tests we are doing:

* We are using JMeter to stress our API with 50 threads and 30 iterations with 0 seconds "Ramp-up period"

* The tests are performed from a single host located outside the data center against our public ip

* Each thread does 5 HTTP requests

* Each HTTP request makes a few DB calls

* Due to an unknown reason our jboss only uses two "JCA threads" to enqueue all the DB requests of 150 HTTP threads

* This is a fragment of one of the two "JCA threads" (https://gist.github.com/4161046)

Thank you in advance

[ghilling]

Hi Ignacio,

Your application won't use "jca threads" to handle the db requests. These are handled by your application threads.

Example:

* Connection pool size is 10.

* You have a maximum of 20 http connections.

* Handling of an http requests will involve getting a connections from the pool.

If you fire up JMeter, a maxiumum of 20 connections will be allowed, each connection will try to get a DB connection from the pool and is blocked while none is available.

Eventually a connection will become available and the blocked thread can continue.

So typically you will have 10 of your 20 http threads blocked waiting for a db connections from the pool.

The blocked threads are those named "http--0.0.0.0-8080-"x ...

Hope that helps.