Lock Management Enhancements

SAP ASE version 16.0 and later includes several enhancements to lock management.

Spinlocks in versions of SAP ASE earlier than 16.0 occasionally result in lock contention. SAP ASE version 16.0 reduces lock contention by optimizing the following areas:

Engine lock transfer – Improves the transfers of locks between global pool and engine local caches.
Engine lock caching – Optimizes the number of locks an engine can cache locally by:
- Increasing the default engine local cache size
- Increasing the transfer size of locks from global to local caches.
- Improves lock transfers between local and global by using of blocks of locks instead of individual locks
- Draining or reclaiming locks from local to global caches less frequently
LOCK_VERIFY operations – Optimizes LOCK_VERIFY operations to deploy an optimistic approach when possible and avoid taking locks.
Lock promotion - Tracks repeatedly failed lock promotion attempts, and disables lock promotion for the DML statement incurring the failed lock promotion after a number of attempts.
Log semaphore locks - Avoids taking locks for log semaphores since only one lock can be held by the semawait.
Deadlock checking - Ensures that specifying a small value for the deadlock checking period never results in a value less than 1, and that deadlock checks are performed on a dedicated service thread
Hot DOL tables - Allows DOL tables to be hot tables, which alleviates high table lock contention

These features are intended to enhance performance: you should not notice any performance degradation when SAP ASE uses these enhancements. The lock management enhancements are enabled by default, and you need not to perform any configuration to enable these enhancements.