Bug 1861948

Summary:	add a parameter enable/disable the locking mechanism introduced in bz 1435663
Product:	Red Hat Enterprise Linux 8	Reporter:	Marc Sauton <msauton>
Component:	slapi-nis	Assignee:	Alexander Bokovoy <abokovoy>
Status:	CLOSED MIGRATED	QA Contact:	ipa-qe <ipa-qe>
Severity:	high	Docs Contact:
Priority:	unspecified
Version:	8.2	Keywords:	MigratedToJIRA, Triaged
Target Milestone:	rc	Flags:	pm-rhel: mirror+
Target Release:	8.0
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2023-09-18 18:42:38 UTC	Type:	Bug
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description Marc Sauton 2020-07-30 01:54:32 UTC

Description of problem:

This is a request to add a performance tuning parameter to enable/disable the newer locking mechanism added as described in the bug report 1435663.
For example, similar to the 389-ds's nsslapd-db-deadlock-policy configuration parameter and performance trade offs.

The newer locking mechanism is related to the message
ERR - schemacompat - map rdlock: old way MAP_MONITOR_DISABLED

The issue is the IPA LDAP service can "hang" or appear as "hanged" for more than 20 seconds, in the slapi-nis plug-in , usually in scenario with "high" LDAP traffic.
This used to be a corner case in 2017, but we see more accurances of the dead locks, more chances of this to happen:
  a LDAP search or mod operation acquire a slapi-nis map lock and a DB page lock
  another thread does an update, holding hold DB page lock and need a slapi-nis map lock
Adding this new config knob in the plug-in could also be interpreted as a workaround to avoid a full deadlock in favor of a "long" transient slowdown.

The existing related bug reports are

bz 1724761 - Entry cache contention during base search
bz 1435663 - deadlock in modify operation with schema-compat plugin
https://pagure.io/389-ds-base/issue/50542 [CLOSED] / Entry cache contention during base search
https://bugzilla.redhat.com/1724761 [VERIFIED] [RHEL-7.9]
https://bugzilla.redhat.com/1435663 [CLOSED ERRATA] slapi-nis-0.56.0-10.el7
https://bugzilla.redhat.com/1435663#c18 - the short term solution / workaround
https://bugzilla.redhat.com/1435663#c30 - test script


Version-Release number of selected component (if applicable):

slapi-nis component for RHEL-7 and RHEL-8


How reproducible:

not trivial, not always on demand:
https://bugzilla.redhat.com/show_bug.cgi?id=1435663#c22


Steps to Reproduce:
1.
2.
3.

Actual results:


Expected results:


Additional info:

Comment 4 RHEL Program Management 2023-09-18 18:37:36 UTC

Issue migration from Bugzilla to Jira is in process at this time. This will be the last message in Jira copied from the Bugzilla bug.

Comment 5 RHEL Program Management 2023-09-18 18:42:38 UTC

This BZ has been automatically migrated to the issues.redhat.com Red Hat Issue Tracker. All future work related to this report will be managed there.

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