How hystrix creates their thread pool

Question

My application is running in Websphere Application server. And I'm using Hystrix for some external service calls. The WAS server has a thread pool configuration, say a max thread pool size of 10 and the HystrixThreadPoolProperties maxCoreSize is set to 5.

I'm wondering how the threads are managed by hystrix. Does hystrix consumes 5 threads from the WAS server thread pool or will it create its own thread pool with 5 new threads which will result in a total of 15 threads.

In my case, I would want the hystrix to consume the threads from the WAS thread pool rather than creating new threads. Please advice.

Thanks in advance.

Answer 1

Hystrix, as all general purpose libraries, manages a thread pool on it's own, but provides a way to plug in a custom thread pool or executor.

In order to integrate Hystrix with a JavaEE server like WAS, you need to provide a concurrency strategy , which uses a managed executor to provide threads. In most JavaEE servers (I'm pretty sure that also in WAS), thread pool for a managed executor is different from the one used by HTTP threads by default - you still need to configure them separately or point both to use the same threadpool if the server supports it.