eZSessionGarbageCollector run by PHP during user http request

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Kevin Gaudin	Monday 17 May 2010 5:57:45 am Hello there, The method eZSessionGarbageCollector() is set by eZ as a PHP handler for cleaning sessions (session_set_save_handler php function) in eZ 4.0. While investigating performance issues on our Intranet production clustered RHEL servers, it appears that an important amount of slow queries (from 3 to 6 seconds) are generated by the "DELETE * FROM ezsession... " which is launched by eZSessionGarbageCollector(). With these execution time, having the session garbage collection run during users http request is a nonsense... Is this setting a recent addition to eZ Publish ? Do you know of performance "best practices" about eZ Publish which would advise to deactivate session garbage collection in php.ini or a configuration item in eZ Publish which would have the same effect ? My own analyse would be to set in php.ini the item session.gc_probability to 0 and run ez's cleanup.php as a daily cronjob script, as it was advised for Debian setups. Any experience on this subject is welcome, Thanks ! Kevin Twitter: @kevingaudin
Gaetano Giunta	Monday 17 May 2010 9:08:01 am - that query was altered in 4.2 so that it would not slow down db too much. Now it deletes 100 (or 50?) rows at a time. It's your best bet to fix the problem - doing it randomly on a statistical basis is the way of php (not just the way of ez) - you can increase in php.ini gc_probability and lower gc_divisor to have gc happen more frequently. That should make the queries faster if you have a site with lots of traffic (more frequency = fewer rows to delete) - also diminishing session timeout (3 days by default!) can have a positive impact, as there will be fewer sessions in the db at any given time - you can set in php.ini gc_probability = 0 and run the query via cronjob, so at least slow queries are not hitting live pages (see the cronjob session_gc.php, added in 4.1) Principal Consultant International Business Member of the Community Project Board

Author

Message

Kevin Gaudin

Monday 17 May 2010 5:57:45 am

Hello there,

The method eZSessionGarbageCollector() is set by eZ as a PHP handler for cleaning sessions (session_set_save_handler php function) in eZ 4.0.

While investigating performance issues on our Intranet production clustered RHEL servers, it appears that an important amount of slow queries (from 3 to 6 seconds) are generated by the "DELETE * FROM ezsession... " which is launched by eZSessionGarbageCollector().

With these execution time, having the session garbage collection run during users http request is a nonsense...

Is this setting a recent addition to eZ Publish ?

Do you know of performance "best practices" about eZ Publish which would advise to deactivate session garbage collection in php.ini or a configuration item in eZ Publish which would have the same effect ?

My own analyse would be to set in php.ini the item session.gc_probability to 0 and run ez's cleanup.php as a daily cronjob script, as it was advised for Debian setups.

Any experience on this subject is welcome,

Thanks !

Kevin

Twitter: @kevingaudin

Gaetano Giunta

Monday 17 May 2010 9:08:01 am

- that query was altered in 4.2 so that it would not slow down db too much. Now it deletes 100 (or 50?) rows at a time. It's your best bet to fix the problem

- doing it randomly on a statistical basis is the way of php (not just the way of ez)

- you can increase in php.ini gc_probability and lower gc_divisor to have gc happen more frequently. That should make the queries faster if you have a site with lots of traffic (more frequency = fewer rows to delete)

- also diminishing session timeout (3 days by default!) can have a positive impact, as there will be fewer sessions in the db at any given time

- you can set in php.ini gc_probability = 0 and run the query via cronjob, so at least slow queries are not hitting live pages (see the cronjob session_gc.php, added in 4.1)

Principal Consultant International Business
Member of the Community Project Board

eZ debug

Timing:	Jan 18 2025 02:14:52
Script start
Timing:	Jan 18 2025 02:14:52
Module start 'layout'
Timing:	Jan 18 2025 02:14:52
Module start 'content'
Timing:	Jan 18 2025 02:14:53
Module end 'content'
Timing:	Jan 18 2025 02:14:53
Script end

Main resources:

Total runtime	0.7732 sec
Peak memory usage	4,096.0000 KB
Database Queries	55

Timing points:

Checkpoint	Start (sec)	Duration (sec)	Memory at start (KB)	Memory used (KB)
Script start	0.0000	0.0077	589.5391	153.8906
Module start 'layout'	0.0077	0.0042	743.4297	39.4531
Module start 'content'	0.0119	0.7599	782.8828	534.5938
Module end 'content'	0.7718	0.0013	1,317.4766	12.0938
Script end	0.7731		1,329.5703

Time accumulators:

Accumulator	Duration (sec)	Duration (%)	Count	Average (sec)
Ini load
Load cache	0.0036	0.4649	16	0.0002
Check MTime	0.0013	0.1731	16	0.0001
Mysql Total
Database connection	0.0007	0.0936	1	0.0007
Mysqli_queries	0.7241	93.6510	55	0.0132
Looping result	0.0005	0.0636	53	0.0000
Template Total	0.7423	96.0	2	0.3711
Template load	0.0019	0.2452	2	0.0009
Template processing	0.7404	95.7596	2	0.3702
Template load and register function	0.0001	0.0115	1	0.0001
states
state_id_array	0.0008	0.0982	1	0.0008
state_identifier_array	0.0016	0.2020	2	0.0008
Override
Cache load	0.0016	0.2088	23	0.0001
Sytem overhead
Fetch class attribute can translate value	0.0006	0.0835	2	0.0003
Fetch class attribute name	0.0012	0.1524	4	0.0003
XML
Image XML parsing	0.0009	0.1118	2	0.0004
class_abstraction
Instantiating content class attribute	0.0000	0.0009	4	0.0000
General
dbfile	0.0010	0.1255	22	0.0000
String conversion	0.0000	0.0013	4	0.0000
Note: percentages do not add up to 100% because some accumulators overlap

Templates used to render the page:

Usage	Requested template	Template	Template loaded
1	node/view/full.tpl	full/forum_topic.tpl	extension/sevenx/design/simple/override/templates/full/forum_topic.tpl
2	content/datatype/view/ezimage.tpl	<No override>	extension/sevenx/design/simple/templates/content/datatype/view/ezimage.tpl
2	content/datatype/view/ezxmltext.tpl	<No override>	extension/community_design/design/suncana/templates/content/datatype/view/ezxmltext.tpl
4	content/datatype/view/ezxmltags/paragraph.tpl	<No override>	extension/ezwebin/design/ezwebin/templates/content/datatype/view/ezxmltags/paragraph.tpl
2	content/datatype/view/ezxmltags/link.tpl	<No override>	design/standard/templates/content/datatype/view/ezxmltags/link.tpl
1	print_pagelayout.tpl	<No override>	extension/community/design/community/templates/print_pagelayout.tpl
Number of times templates used: 12 Number of unique templates used: 6

Time used to render debug report: 0.0001 secs