How the multithreaded architecture works in DB2 9.5

Brief introduction

To understand the new multithreaded functionality in DB2 9.5, this article first discusses the DB2 process model. The entire DB2 process model is controlled by the Base System Utilities (bsus). BSU allocates memory for instance and database, intercepts and processes signals, and handles exceptions sent to DB2. Figure 1 shows the old DB2 process model for Linux and UNIX platforms.

Figure 1. Old DB2 process model on Linux and UNIX

Figure 2 shows the new process model on Linux and UNIX.

Figure 2. New DB2 process model on Linux and UNIX

The communication between the database server, client, and application is handled by a framework. This framework is the process model that is used by all DB2 servers. It ensures that the database files used internally do not interfere with users or database applications.

The engine dispatch unit (engine dispatchable units,edu) is responsible for performing various tasks, such as processing database application requests, reading database log files, and refreshing log records from the log buffer to log files on disk. Typically, the DB2 server processes each task as a separate EDU. Prior to DB2 9.5, most of these EDU were processes in UNIX and Linux environments and were threads in the Windows environment. In 9.5, the DB2 process model is unified, and EDU is now a thread in Linux, UNIX, and Windows environments.

Here are some of the advantages of this new memory model:

This new memory model is simpler and easier to configure. See the following in DB2 information Center:

Configure memory and Memory heap

Memory Configuration Simplification