Progress
Installation and Configuration Guide
Version 9
for Windows
Shared Memory
Shared memory is an area in system memory that multiple users can access concurrently. Progress stores shared resources in the shared-memory area; more than one user and server can access each database. Progress uses semaphores and spin locks to synchronize the activities of server and self-service client processes that are connected to a database. Each process uses its semaphore or relies upon the spin lock when it must wait for a shared resource.
You can tune Progress performance by reconfiguring the size of the following shared-memory buffers:
- Database buffers — Progress reads database blocks into the database buffer pool. Larger buffers usually result in less disk I/O.
- Before-image (BI) buffers — Progress stores BI notes in memory before writing them to disk.
- After-image (AI) buffers — Progress stores AI notes in memory before writing them to disk.
Progress also creates shared-memory tables to provide essential information on the status of each process, server, transaction, and lock. These tables enable you to control all of the database activities from one shared area.
See the Progress Database Administration Guide and Reference for more information about managing and improving Progress performance.
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