Bug 241945

Summary: RHEL 4.4 nscd not (apparently) caching anything
Product: Red Hat Enterprise Linux 4 Reporter: Neil Doane <ndoane>
Component: glibcAssignee: Jakub Jelinek <jakub>
Status: CLOSED NOTABUG QA Contact: Brian Brock <bbrock>
Severity: medium Docs Contact:
Priority: medium    
Version: 4.4CC: fweimer, tao
Target Milestone: ---   
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2007-05-31 21:07:52 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Attachments:
Description Flags
a script to exercise nscd by repeatedly querying the passwd & group tables none

Description Neil Doane 2007-05-31 20:55:08 UTC 
Description of problem:
nscd does not appear to be caching anything in RHEL 4.4.

Version-Release number of selected component (if applicable):
nscd-2.3.4-2.25

How reproducible:
Every time.

Steps to Reproduce:
1.In /etc/nscd.conf, enable logging to /var/log/nscd.log and set debug level to 99
2. Restart nscd
3. Run attched perl script
  
Actual results:
grep 'GETPWBYNAME' /var/log/nscd.log | wc -l
...will show positive values after running script, however...
The output of 'nscd -g' will show 
 0% cache hit rate

Expected results:
'nscd -g' should show a 99% (or 100%) cache hit rate 

Additional info:
This works fine on RHEL 3
Comment 1 Neil Doane 2007-05-31 20:55:09 UTC 
Created attachment 155842 [details]
a script to exercise nscd by repeatedly querying the passwd & group tables
Comment 2 Neil Doane 2007-05-31 21:04:54 UTC 
Same results with nscd-2.3.4-2.36 as well.
Comment 3 Jakub Jelinek 2007-05-31 21:07:52 UTC 
In RHEL4 nscd.conf defaults to shared yes and persistent yes for all databases.
This means that nscd's cache is read-only mapped in applications and they
search the cache directly instead of asking nscd to do the cache search
for them.  Only when a request (or a negative search entry) is not found in
the cache, apps ask nscd over the socket and nscd does the search and adds it to
the cache.  nscd -g stats only report requests that actually made it to nscd,
it can't see requests answered just by cache search within the applications.