Hi, undertow has completely different semantics to what jboss web had before. Undertow uses XNIO worker(s) which are the ones handling the thread pool and few other things. You can configure workers in IO subsystem and tell http listener which one to use. By default in configuration we ship we have one worker named "default" defined and all listeners use it. But if you want to have separate workers (thread pools) per worker, all you need to do is define new worker in IO subsystem and then reference it in http-listener worker="name-of-your-worker-in-io-subsystem" Just bit of note, we did mistake with default values for default worker in 8.0.0.Final release and will fix that in 8.0.1 In our testing we got best performance when io-threads ware set to number of logical cpus * 2 and task-max-threads set to number of cpus * 16. This will be defaults we will probably have in 8.0.1 as they perform optimal. -- tomaz On Tue, Feb 18, 2014 at 9:37 AM, Hamed Hatami <hamedhatami2012(a)gmail.com&gt;wrote: