Database Hang with Contention on 'latch: enqueue hash chains' and 'latch free'
(Doc ID 2729839.1)
Last updated on JULY 20, 2024
Applies to:
Oracle Database - Enterprise Edition - Version 19.1.0.0.0 to 19.8.0.0.0 [Release 19]Information in this document applies to any platform.
Symptoms
- The database encountered a high percentage of database time, spending on wait events belonging to the Other Class (primarily, 'latch: enqueue hash chains' and 'latch free'):
Top 10 Foreground Events by Total Wait Time
Event Waits Total Wait Time (sec) Avg Wait % DB time Wait Class
latch: enqueue hash chains 294,883 1.2M 4168.74ms 44.3 Other
latch free 8,893,044 825.3K 92.80ms 29.7 Other
enq: US - contention 31,015 149.4K 4815.74ms 5.4 Other
library cache lock 7,509 117.5K 15.65 s 4.2 Concurrency
db file sequential read 201,447 23K 114.27ms .8 User I/O
enq: HW - contention 574 12.5K 21.72 s .4 Configuration - An AWR report from the time of incident indicates a high number of session sleeps on the 'resmgr:resource group CPU method' latch from the kgkprrpicknext() function:
Latch Miss Sources
Latch Name Where NoWait Misses Sleeps Waiter Sleeps
resmgr:resource group CPU method kgkprrpicknext 0 15,210,415 15,159,220 ◄◄◄
resmgr:resource group CPU method kgkprraddtorl 0 8,198 47,690
resmgr:resource group CPU method kgkpgcremovefrl 0 7,411 21,481
Changes
N/A
Cause
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In this Document
| Symptoms |
| Changes |
| Cause |
| Solution |
| References |