CORBA 2.3.3 Programmer's Guide for Java

Chapter 8. Writing Multithreaded Applications

Table of Contents

Overview of Multithreading

Multithreading in Client Applications

Multithreading in Server Implementations

This section describes how to make appropriate threading decisions and write multithreaded NonStop

CORBA applications.

Java programmers should use standard Java multithreading in NonStop CORBA applications.

For several examples of explicit multithreading in a NonStop CORBA application, refer to the Bank

sample application. The client wrapper uses mutexes. The feed program includes several uses of

multithreading. Multithreading in the feed program reduces the number of processes that are needed to

generate workload for the application.

Overview of Multithreading

Multithreading is a programming paradigm that enables logically concurrent execution. A thread is a

sequence of running code that coexists with other threads in the same address space. Each thread has its

own execution stack, but shares the process instruction space with other threads. Having multiple threads

in a process means that there are many apparently simultaneous points of execution. Multithreading

simplifies programming tasks by allowing you to write a single code sequence as if it were alone and

have it run as many threads. By writing different threads to handle different tasks, you can easily divide

the problem space. Multithreading can also increase the throughput of a process without incurring the

overhead of creating multiple processes.

The NonStop CORBA ORB itself is multithreaded, and it provides automatic multithreaded dispatching

of requests to servants through its implementation of the default POA threading policy,

ORB_CTRL_MODEL. The same servant can be accessed by multiple threads. You can also explicitly

create additional threads in your applications. In a distributed NonStop CORBA application, you can use

multithreading in the client, the server, or both. You can use multithreading with or without server pools.

Some applications lend themselves better to multithreading than others. Multithreading can be useful

when:

Interacting with another object or process that may be slow in responding●

Interacting with a user who may not respond immediately●