INF: Detecting Deadlocks

Last reviewed: April 25, 1997
Article ID: Q45548

The information in this article applies to:

  - Microsoft SQL Server version 4.2 for OS/2

SQL Server cannot detect deadlocks by simple timeout. SQL Server keeps track of which locks belong to which processes. When a request for a lock is blocked by another process that already holds a lock on that object, SQL Server checks to see if that other process is waiting for a lock that belongs to this process. In fact, it checks all waiting processes so that even transitive deadlocks are detected.

Deadlock does not refer to one transaction waiting for another to release a lock; it refers to a closed loop of waiting processes. Because it is impossible for any of the processes to ever complete, a timeout period makes no sense. Once the condition is detected, the process with the least amount of time invested is terminated.

Additional query words:
Keywords : kbusage SSrvServer
Version : 4.2
Platform : OS/2

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Last reviewed: April 25, 1997
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