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7#
发表于 2013-12-23 23:50:06
Hang/Locking > Determine a Cause >Overview
At this point you should have identified if the issue you are experiencing is a "True" database hang, "Stuck" or "Locked" sessions, OS resource
problem, or slow database. The "Determine a Cause" portion of the guide will assist you in troubleshooting "True" database hang, or "Stuck" or
"Locked" session related issues.
Data Collection
To further troubleshoot "Stuck" sessions, you will have several choices. You can troubleshoot by taking a closer look at the traces previously
generated (hanganalyze, systemstate, and errorstack dumps), by using OEM, by using utllockt.sql, or by performing queries on some V$ views.
Hanganalyze, systemstate, and errorstack dumps are great for collecting hang related data quickly, but understanding how to read these files can be
complex. It is not really possible to present all methods for interpreting these files, but examples will be provided in the Determine a Cause >
Analysis portion of the guide.
The hanganalyze, systemstate, and errorstack dumps are very useful (if collected as previously requested) when logging a service request because
they generally provide a good picture of what the database is doing when the sessions are hung.
Troubleshooting "Stuck" session issues by collecting data from the V$ views is less complex than reading the dump files. However, in order for this
to be effective, the sessions must remain in a "stuck" state until all the data is collected. In some cases this is not possible due to time constraints.
Analysis Approach
Further troubleshooting will:
1. Determine which wait events are involved
2. Determine the active SQL involved in the blocking and waiting sessions
3. Look for common causes for "Stuck" sessions
4. Review possible solutions for the likely cause
5. Implement the best solution
6. Verify that the solution solved the problem or if more work is needed |
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