Can a single thread be shared among multiple processes ? If yes how?

Question

Each process can have multiple threads , but is it allowed that single thread can be shared among multiple processes ? I have confusion that i am relating this to tightly coupled multiprocessor where memory is shared among multiple processor.

In tightly coupled multiprocessor : memory is shared In loosely coupled multiprocessor : distributed memory

Correct me if i am thinking in wrong direction.

Answer 1

Yes, you are right that accidentally you were thinking in wrong direction.

Now, to start with answer to your confusion, whether it tightly coupled or loosely coupled multi-core or single-core processor etc. etc., in Java a thread will belong to the same process for its life time.

• The process to which the thread belongs may be parked by the processor to give time to some other process, which would mean that thread is also not active.
• The thread may be parked by the process to give priority over some other thread. This is exactly what you call as thread priorities.

You can take advantage of multi-core processors using Java's fork/join framework by using all available processors for thread execution. But in this case as well, whether a thread is being executed by one processor or other, thread will stick tightly to the process in which it started it life.