High 'Cursor: Pin S Wait On X', 'Library Cache Lock' And "Latch: Shared Pool" Waits due to Shared Pool/Buffer Cache Resize Activity
(Doc ID 742599.1)
Last updated on JANUARY 14, 2023
Applies to:
Oracle Database Cloud Schema Service - Version N/A and laterOracle Database Exadata Express Cloud Service - Version N/A and later
Gen 1 Exadata Cloud at Customer (Oracle Exadata Database Cloud Machine) - Version N/A and later
Oracle Cloud Infrastructure - Database Service - Version N/A and later
Oracle Database Backup Service - Version N/A and later
Information in this document applies to any platform.
Symptoms
- A spike in "cursor: pin S wait on X" ,"library cache lock" or "latch: shared pool" waits may be seen.
This is more likely to be seen in an OLTP environment where both shared pool and buffer cache are in demand. - The problem will happen randomly and intermittently.
- In extreme examples the database can appear to hang and you may receive related timeout symptoms such as "WAITED TOO LONG FOR A ROW CACHE ENQUEUE LOCK!" if no movement occurs for a threshold period. See:
<Document 278316.1> Troubleshooting: "WAITED TOO LONG FOR A ROW CACHE ENQUEUE LOCK! "
Changes
- Automatic Shared Memory Management is used. This is actively resizing the shared pool
- The characteristics of the workload has changed. For example a batch Job has been added in an OLTP environment or there has been an increase of activity in a certain application area that requires memory changes.
Cause
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In this Document
| Symptoms |
| Changes |
| Cause |
| Solution |
| References |