High Log File Sync Wait Due to LGWR with Slow io_submit()
(Doc ID 2400987.1)
Last updated on JUNE 21, 2021
Applies to:
Oracle Database - Enterprise Edition - Version 11.2.0.4 to 11.2.0.4 [Release 11.2]Oracle Database Cloud Schema Service - Version N/A and later
Oracle Database Exadata 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
Red Hat Advanced Server
Symptoms
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- LGWR process is blocking many sessions with following error stack and status:
and is blocked by
=> Oracle session identified by:
{
instance: 1 (instance1.instance1)
os id: 118998
process id: 46, username@instance1 (LGWR)
session id: 691
session serial #: 1
}
which is not in a wait: <<~~~~~~~~~~~
{
last wait: 13.169313 sec ago
blocking: 387 sessions
current sql: <none>
short stack: ksedsts()+465<-ksdxfstk()+32<-ksdxcb()+1927<-sspuser()+112<-__sighandler()<-io_submit()+7<-skgfqio()+1246<-ksfd_skgfqio()+894<-ksfdgo()+423<-ksfdwtio()+795<-ksfdgo()+405<-ksfdwtio()+795<-ksfdgo()+405<-ksfdwtio()+795<-ksfdgo()+405<-ksfdwtio()+795<-ksfdgo()+405<-ksfdwtio()+795<-ksfdgo()+405<-ksfdwtio()+795<-ksfdgo()+405<-ksfdwtio()+795<-ksfdgo()+405<-ksfdwtio()+795<-ksfdgo()+405<-ksfdwtio()+795<-ksfdgo()+405<-ksfdaio()+2296<-kfk_ufs_async_io()+696<-kfk_submit_ufs_io()+211<-kfk_submit_io()+90<-kfk_io1()+1089<-kfkRequ
wait history:
1. event: 'latch: redo allocation'
time waited: 0.001150 sec
wait id: 113258 p1: 'address'=0x2a6bf1c578
p2: 'number'=0xd1
p3: 'tries'=0x0
* time between wait #1 and #2: 0.022980 sec
2. event: 'LGWR wait for redo copy'
time waited: 0.011874 sec
wait id: 113257 p1: 'copy latch #'=0x20b
* time between wait #2 and #3: 0.004795 sec
3. event: 'latch: redo allocation'
time waited: 0.001398 sec
wait id: 113256 p1: 'address'=0x2a6bf1be98
p2: 'number'=0xd1
p3: 'tries'=0x0
}
To get the errorrstack of LGWR, you may refer the doc below. Both actions should be taken while the issue is happening..
How to Collect Errorstacks for use in Diagnosing Performance Issues. (Doc ID 1364257.1)
Steps to generate HANGANALYZE trace files (9i and below) (Doc ID 175006.1)
Steps to generate HANGANALYZE trace files (9i and below) (Doc ID 175006.1)
Changes
DB server has been moved to other data center.
Cause
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In this Document
Symptoms |
Changes |
Cause |
Solution |