Sane defaults for Xnio.

[whitingjr]

Currently the configuration for Xnio is missing any settings for either io or worker pool sizes.
Resulting in hundred's of threads in a running server.

[whitingjr]

Here is a stack dump of the Indy process when idle after a stress test has stopped. It can be seen there are around 482 jvm threads.
For a jvm that is running in a shared resource environment (cloud) the thread count is seems excessively high. What it means is that the jvm will be overwhelmed as requests come in. Over time the jvm throughput may appear to decrease as the jvm threads start thrashing.
The setting of lower default values will throttle the number of threads. Unless these settings are over-riden for a system that is known to provide more compute resources.

[whitingjr]

A PR has been created to update the devel environment.