Q:

How many threads at most are allowed in a monitor?

I am trying to understand the concept of a monitor.
How many threads at most are allowed in a monitor at the same time? One or some   number specified by the program that uses the monitor?
Thanks.

A:

At most one thread can be inside monitor. This number cannot be changed in any way.
The number of threads waiting to enter the monitor, and the number of threads waiting for notification, are not limited, or, better say, are limited by overall number of threads.
Overall number of threads in a JVM instance is limited by underlying O/S and by amount of available core memory.

