Progress
Installation and Configuration Guide
Version 9
for UNIX


Shared-memory Architecture

Figure 7–3 shows the shared-memory Progress architecture.

Figure 7–3: Shared-memory Progress Architecture

The following sections explain the components of the architecture that are specific to shared-memory systems.

Progress Database Monitor Utility

The Progress Database Monitor utility displays performance and usage information about database status and activity.

For more information about the Database Monitor utility, see the description of the PROMON utility in the Progress Database Administration Guide and Reference .

Progress Watchdog Utility

If a process terminates improperly, it can maintain a lock on a record or shared-memory structure. This can impact database concurrency. The Progress Watchdog utility detects processes that have terminated improperly and cleans up after them.

At regular intervals, the Watchdog utility checks for processes that have terminated unexpectedly. If it finds one, it releases any locks or shared-memory structures that the process might hold.

The Watchdog utility checks for inactive processes approximately once every 10 seconds. It also checks for self-service clients that are no longer active, releases all the appropriate record locks, backs out of any live transactions, and releases any shared-memory locks. If a server process terminates unexpectedly, the Watchdog utility disconnects and cleans up the server’s remote clients.

For more information about the Watchdog utility, see the description of the PROWDOG utility in the Progress Startup Command and Parameter Reference .

Background Writers

Shared-memory Progress offers three background writer processes that improve performance. These processes continually perform certain housekeeping functions in the background. Because these functions are performed regularly by the dedicated background writer processes, client and server processes rarely have to wait for these functions to be performed.

The three types of background writers (asynchronous page writers, before-image writers, and after-image writers) are described in the "Processes" section in Memory and System Configuration."

For more information about background writers, see the Progress Database Administration Guide and Reference . You must manually start the background writers. For instructions, see Starting and Running Progress."


Copyright © 2004 Progress Software Corporation
www.progress.com
Voice: (781) 280-4000
Fax: (781) 280-4095