Library Cache Lock

 

Issue: transactions hanged in Application for 2 hours

Analysis: after comparing last 7 days AWR and ASH reports for every 1 hour.

AWR report:


1. After checking top 5 timed foregrounds events, row lock contention caused in application and concurrency.


2. Load is very high 

3. found 3 tables from AWR report related to row lock contention.

ASH analysis:


4. after analyzing in blocking sessions, gather stats from SYS user ( library cache lock ) was blocked application session.

Solution:

after killing SYS user session ( library cache lock ), issue resolved. rescheduled stats gather for tovoid issue in future.







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