Question

1. Name one advantage of associating user threads with kernel thread?
2. Suggest an advantage and disadvantage of using mailboxes over shared memory for inter-process communication.

Answer 1

<A> Advantage of associating user threads with kernel thread :

The kernel knows and manages the threads.

In this case no runtime system is needed. rather than thread table in each process, the kernel has a thread table that always keeps track of all threads in the system.

Also, the kernel maintains the "traditional process table "to keep track of processes.

Operating Systems kernel provides system call to create and manage threads(s).

<B> Advantage and disadvantage of using mailboxes over shared memory for inter-process communication :

# Advantages :

@ Sender and receivers can be on different machines(s).

@ It is relatively secure :Receiver can inspect the messages it has received before processing them,which increases the security .

# Disadvantages:

@ It is difficult to use : Each and every data transfer requires a " send() " and a " receive() " which is a drawback.

@ Receiving process must also expect the send() : This  might require forking a special thread ,which is not good.