Edit report at https://bugs.php.net/bug.php?id=60274&edit=1
ID: 60274
Updated by: s...@php.net
Reported by: jwprice at georgiasouthern dot edu
Summary: cpu steady on httpd processes never clears
-Status: Feedback
+Status: No Feedback
Type: Bug
Package: OCI8 related
Operating System: Solaris 10
PHP Version: 5.3.8
Assigned To: sixd
Block user comment: N
Private report: N
Previous Comments:
------------------------------------------------------------------------
[2012-02-29 23:56:48] s...@php.net
The MaxRequestsPerChild setting will cause the httpd processes to restart after
a number of HTTP requests.
Your MaxClients looks inherently high; but only your application tuning can
determine the best value. It effectively means you could have up to 1200
connections open to the DB, which will cause problems in the DB tier.
I suggest:
- Do the PHP & Oracle client upgrade previously discussed.
- Bring the OS patch level up to date.
- Review the application for inefficiencies - fixing these should help
reduce load in each tier.
- Check for application errors and for Oracle trace files. using Oracle
Instant
Client 11g will create better client side trace files.
- Monitor if anything unexpected is causing load during "idle" times.
- Check that the number of httpd processes decreases when there is no load.
- Use truss, pstack etc to identify what any high CPU httpd process are doing
------------------------------------------------------------------------
[2012-02-29 13:42:44] jwprice at georgiasouthern dot edu
What do you mean by httpd process cycled? Do you be restarted every so often?
I was not aware there were and php.ini oci settings so we're using whatever the
defaults are. The database is on a separate machine.
These settings have been set for a couple of years now. We changed MaxClients
to
1200 an it solved couple of problems we were having and worked for one fall
registration. We only started having a problem when we upgraded php and apache
from php 5.2.11 and apache 2.0.63
<IfModule prefork.c>
ServerLimit 1200
StartServers 5
MinSpareServers 5
MaxSpareServers 10
MaxClients 1200
MaxRequestsPerChild 5000
</IfModule>
------------------------------------------------------------------------
[2012-02-29 00:09:59] s...@php.net
Are the httpd processes not being cycled by choice? What are the MaxClients
and
MaxRequestsPerChild values? (Are you using the prefork MPM?).
What are the php.ini oci8.* values?
Is the DB on a different host?
oci_pconnect will cause DB host memory contention unless you restrict
MaXClients
and/or have Oracle 11g and use its DRCP.
------------------------------------------------------------------------
[2012-02-28 19:46:39] jwprice at georgiasouthern dot edu
cpu load was measured with uptime and prstat. Note this is a 4 core 16 thread
16Gb SunFire T2000. Load is normally between 3 and 5, between 350 and 550
process. During the busy time load was > 200 and stayed there even after the
load on the database was gone. I would say that the httpd processes were
spinning at 3 to 4% of cpu each normally this is a lot lower .1%. They are not
being cycled. We are using an older version of the oracle client we will
definitely try to update it. We have since updated to apache 2.2.21 and php-
5.3.8. We will have another high load Mar 5th. We've stayed away from
persistent connections because it caused a high load on the database. We will
look into the performance tips you mentioned.
Apache was configured and compiled with the following:
./configure --enable-modules=most \
--prefix=${Home}/server \
--enable-mods-shared=most \
--enable-proxy \
--enable-proxy-http \
--enable-so
------------------------------------------------------------------------
[2012-02-28 18:39:15] s...@php.net
This bug just came to my attention and I've now changed the package from
"Performance" to "OCI8".
How are you measuring CPU load? How is Apache configured and what is the system
configuration? Are httpd process spinning? Are they being cycled? 600
processes
seems a large number for a single commodity machine. One old rule of thumb was
to set maxclients to 25 for a 1Gb, 2-core machine. Look at reducing maxclients
and using persistent OCI8 connections. If possible, use Oracle 11g DRCP
connections.
I'd recommend upgrading the Oracle client by using the free Oracle Instant
Client. Use the latest version that can still connect back to your DB.
The current PHP OCI8 hasn't had any particularly relevant changes since 5.3.4.
Make sure the code uses binds, prefetches, etc. effectively. Check the
performance tips in
http://www.oracle.com/technetwork/topics/php/underground-php-oracle-manual-
098250.html
------------------------------------------------------------------------
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