the third could be method that the thread are running.
your assumptions seems good. but I can't answer with 100% certainty.

What you're seeing is the output of Thread.getName().  Set with
Thread.setName() or the Thread constructor.

So it could be anything, depending on what the web app container does.
It's not specified by the Java language.  Talk to the developer of the
web app container.

I'm guessing that it is the following:
Simple class name (e.g., Thread)
pool number (1)
thread number (8)
priority (5, or Thread.DEFAULT_PRIORITY)
thread name (main)

As others have said, I don't think there's any spec about this, so
there's no way to be sure without knowing specific details of the
system you're on.

However, I will say this:  when I write a toString() method, I often
include in the output some information which can also be retrieved
by getWhatever() methods.  Are there are any getWhatever() methods
on Thread that would possibly return an integer with a value of 5?
It turns out Thread.getId() and Thread.getPriority() both return
integer values.  And Thread.getState() returns an enum, which could
map to a small integral value.  I would try printing out all of
those alongside your toString() output and seeing if one of them
mysteriously happens to always correspond to what you see between
the first and second comma in the toString() output.

  - Logan