Analyze program isolation lock contention

Use the program isolation (PI) lock views to quickly analyze and resolve PI resource contention problems.

Program isolation lock contention analysis overview

You can use the program isolation views to answer the following questions:

  • Is there a contention problem?
  • How severe or widespread is the problem?
  • Which resources are most contended for?
  • How can I resolve the contention problem?

Four of the program isolation views (IPIRGLST, IPIRGWT, IPIRSWT, and IPIRSSUM) can be used for extensive analysis of PI lock contention. The other view (IPISTAT) shows overall PI resource use.

The PI Region Lock List view (IPIRGLST) shows the regions that are contending for PI locks, identifies the resource that each waiting region is waiting for, and provides a list of 'ultimate' holders that are causing lock contention.

The ultimate holder is not necessarily the immediate holder of a lock, which may itself be in a PI wait. The ultimate holder is the thread at the end of the wait chain. You can issue a line command in the IPIRGLST view to terminate the ultimate holder region if you decide that doing so is warranted.

Important

The line commands available in the PI views are described in Line-commands-Program-isolation-lock-views. For more information about ultimate holders, see Ultimate-lock-holder.

You can use the PI Resource Lock Summary view (IPIRSSUM) to quickly determine which database resources are in contention. The view lists all database resources that are in contention and shows the number of regions waiting for the resource and the number of regions holding locks on the resource.

The following PI lock views and menus are provided:

Tip

To access online Help for a view, position the cursor on the view name (in the window information line) and press the Help key. To access help for a field, place the cursor on the field and press the Help key.

 

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