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Background documentation Special Threads Locate the document in its SAP Library structure

A database instance has the following special threads, among others:

Clock Thread

The clock thread computes internal times; for example, to determine the time needed to execute an SQL statement. It is only used under Microsoft Windows NT.

Console Thread

The console thread processes requests from the Database Console.

Coordinator

The coordinator monitors all threads of the database instance. It is the first active thread when the database instance is started and coordinates the start processes of the other threads. If operating errors occur, the coordinator can stop other database threads.

Dev Threads

Dev threads are responsible for processing reads and writes requested by tasks on the volumes.

The number of dev threads is primarily dependent on the number of volumes in the database instance. Under normal circumstances, two dev threads are activated for every data volume and every log volume. Only one dev thread is activated for writing the database trace, if it is enabled.

The dev thread dev0 plays a special role here. It coordinates and monitors the other dev threads.

Requester

The Requester accepts user process logons to the database and assigns them to a User Kernel Thread.

temporary dev threads

To make data backups, temporary dev threads ( asdev<i>) are activated for reading and writing data.

Timer

Timer are used to monitor time for timeout control.

 

 

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