What is the system-dependent default thread pool?

Question

From the AsynchronousFileChannel API:

When an AsynchronousFileChannel is created without specifying a thread pool, then the channel is associated with a system-dependent default thread pool that can be shared with other channels.

I have not seen this terminology anywhere, and I have not found any specific explanation through web search. What is the system-dependent default thread pool? What are its characteristics? And how can they vary between systems?

Answer 1

Just read the documentation a little more:

The default thread pool is configured using the specific system properties of the AsynchronousChannelGroup class.

And if you jump there , you will see:

In addition to groups created explicitly, the Java virtual machine supports a default common default group, which is built automatically. Asynchronous channels that do not indicate a group at construction time are tied to the group by default. The group by default has an associated thread pool, which, if necessary, creates new threads. The default group can be configured using specific system properties in the table below. Where the ThreadFactory for the group is not configured by default, then the group merged threads are by default daemon threads.

... then a list of configuration options.