[JBoss JIRA] (MODCLUSTER-372) Number of registered contexts negatively affects mod_cluster performance
6:16 a.m.
[
https://issues.jboss.org/browse/MODCLUSTER-372?page=com.atlassian.jira.pl...
]
Michal Babacek resolved MODCLUSTER-372.
---------------------------------------
Resolution: Done
The fix has been ported to 1.2.x branch. This is the updated spreadsheet:
||natives||sessions||mean response time, {{ms}}||throughput, {{samples/s}}||CPU load,
{{%}}||
|m_c 1.2.6.Final|2000|1182|901.4|85|
|m_c 1.2.x HEAD:1d1512f|2000|1221|906.8|85|
|*m_c 1.2.x HEAD:6838624*|2000|417|1477|33|
|m_c 1.3.1 HEAD:88040c3|2000|1572|781.6|34|
|mod_jk/1.2.37|2000|651|1237.9|9|
||natives||sessions||mean response time, {{ms}}||throughput, {{samples/s}}||CPU load,
{{%}}||
|m_c 1.2.6.Final|1700|899|895.4|85|
|m_c 1.2.x HEAD:1d1512f|1700|853|924.4|85|
|*m_c 1.2.x HEAD:6838624*|1700|353|1203|23|
|m_c 1.3.1 HEAD:88040c3|1700|259|1345.9|53|
|mod_jk/1.2.37|1700|16|1672.9|10|
One may notice the suspiciously good results of *m_c 1.2.x HEAD:6838624* in comparison to
1.3.x branch. All the aforementioned results were obtained with the exactly same test on
the physically same set of bare metal machines. Given all this, it is still possible that
something has changed in a meantime, so I'll eventually re-run the 1.3.x branch and
1.2.x branch perf tests so as to verify the results.
Number of registered contexts negatively affects mod_cluster
performance
------------------------------------------------------------------------
Key: MODCLUSTER-372
URL: https://issues.jboss.org/browse/MODCLUSTER-372
Project: mod_cluster
Issue Type: Bug
Affects Versions: 1.2.4.Final, 1.2.6.Final
Environment: RHEL6, other platforms are to be confirmed.
Reporter: Michal Babacek
Assignee: Jean-Frederic Clere
Labels: mod_cluster, performace
Fix For: 1.2.8.Final, 1.3.0.Final
Attachments: 4-workers-1-context-balancer-cpu.png,
4-workers-61-context-accessing-1-balancer-cpu.png, 9-workers-1-context-balancer-cpu.png,
9-workers-31-context-accessing-1-balancer-cpu.png,
9-workers-31-context-round-robin-balancer-cpu.png, callgrind.zip, httpd.conf
There is a performance concern regarding CPU usage on the Apache HTTP Server with
mod_cluster set up as a load balancer. Perf tests revealed that the major variable
affecting the CPU usage is the overall number of registered contexts. It's noteworthy
that these contexts actually don't need to be accessed at all, it's enough that
they are present.
The first test [9 workers, 31 contexts, round
robin|https://issues.jboss.org/browse/MODCLUSTER-372#9workers,31contexts,...]
depicts a behavior where all contexts are being accessed in a round robin fashion. Note
the CPU usage. If we compare it to the [9 workers, 1
context|https://issues.jboss.org/browse/MODCLUSTER-372#9workers,1context] test, it becomes
apparent that there is something wrong with the CPU usage. As it is clear from the [9
workers, 31 contexts, access
1|https://issues.jboss.org/browse/MODCLUSTER-372#9workers,31contexts,acce...]
test, accessing only one of these contexts doesn't help much.
The last two tests, [4 workers, 61 contexts, accessing
1|https://issues.jboss.org/browse/MODCLUSTER-372#4workers,61contexts,acce...]
and [4 workers, 1
context|https://issues.jboss.org/browse/MODCLUSTER-372#4workers,1context] confirm the
results, environment differs only in number of nodes and number of contexts.
[^httpd.conf] attached, stay tuned for some profiler outputs...
h3. 9 workers, 31 contexts, round robin
!9-workers-31-context-round-robin-balancer-cpu.png|thumbnail!
||Nodes||Sessions||Ses.Active||Samples||samples/s||mean resp. ms||max resp. ms||conn.
errors||valid samples||%||
|9|150|150|8843|147.4|15|60|0|8843|100%|
|9|250|250|14422|240.3|37|215|0|14422|100%|
|9|350|350|17551|292.5|196|443|0|17551|100%|
|9|450|450|21303|355.0|269|603|0|21303|100%|
|9|550|550|24818|413.6|325|686|0|24818|100%|
|9|650|650|26804|446.7|469|800|0|26804|100%|
|9|750|750|29930|498.8|507|985|0|29930|100%|
|9|850|850|30665|511.0|665|1185|0|30665|100%|
|9|950|950|34421|573.6|647|1316|0|34421|100%|
|9|1050|1050|35067|584.4|800|1487|0|35067|100%|
|9|1150|1150|36024|600.4|925|1612|0|36024|100%|
|9|1250|1250|36635|610.5|1030|1815|0|36635|100%|
|9|1350|1350|38395|639.9|1096|1942|0|38395|100%|
|9|1450|1450|39713|661.8|1170|2466|0|39713|100%|
|9|1550|1550|39455|657.5|1392|2340|0|39455|100%|
|9|1650|1650|39849|664.1|1465|4240|0|39849|100%|
|9|1750|1750|42435|707.2|1454|6511|0|42435|100%|
|9|1850|1850|44714|745.2|1498|4866|0|44714|100%|
|9|1950|1911|46072|767.8|1554|43016|0|46072|100%|
|9|2050|1911|44496|741.5|1617|4953|39|44457|99%|
|9|2150|1911|43715|728.5|1632|5348|125|43590|99%|
|9|2250|1911|41112|685.1|1764|9800|155|40957|99%|
h3. 9 workers, 31 contexts, accessing only one of them
!9-workers-31-context-accessing-1-balancer-cpu.png|thumbnail!
||Nodes||Sessions||Ses.Active||Samples||samples/s||mean resp. ms||max resp. ms||conn.
errors||valid samples||%||
|9|150|150|8954|149.2|4|42|0|8954|100%|
|9|250|250|14897|248.3|7|33|0|14897|100%|
|9|350|350|20784|346.4|8|68|0|20784|100%|
|9|450|450|26748|445.8|8|69|0|26748|100%|
|9|550|550|32553|542.5|11|92|0|32553|100%|
|9|650|650|38558|642.6|10|60|0|38558|100%|
|9|750|750|43571|726.1|29|329|0|43571|100%|
|9|850|850|46133|768.8|99|494|0|46133|100%|
|9|950|950|50854|847.5|120|501|0|50854|100%|
|9|1050|1050|54451|907.4|154|584|0|54451|100%|
|9|1150|1150|59961|999.3|138|674|0|59961|100%|
|9|1250|1250|62567|1,042.6|198|675|0|62567|100%|
|9|1350|1350|61939|1,032.2|301|799|0|61939|100%|
|9|1450|1450|67920|1,131.9|276|844|0|67920|100%|
|9|1550|1550|73151|1,219.1|261|861|0|73151|100%|
|9|1650|1650|73937|1,232.2|332|955|0|73937|100%|
|9|1750|1750|73516|1,225.2|423|1046|0|73516|100%|
|9|1850|1850|72556|1,209.1|515|1264|0|72556|100%|
|9|1950|1911|78613|1,310.1|454|50273|0|78613|100%|
|9|2050|1911|80141|1,335.6|431|1225|39|80102|99%|
|9|2150|1911|76979|1,282.9|490|1338|127|76852|99%|
|9|2250|1911|78048|1,300.7|464|1305|136|77912|99%|
h3. 9 workers, 1 context
!9-workers-1-context-balancer-cpu.png|thumbnail!
||Nodes||Sessions||Ses.Active||Samples||samples/s||mean resp. ms||max resp. ms||conn.
errors||valid samples||%||
|9|150|150|8965|149.4|2|12|0|8965|100%|
|9|250|250|14965|249.4|2|22|0|14965|100%|
|9|350|350|20950|349.1|2|23|0|20950|100%|
|9|450|450|26941|449.0|2|26|0|26941|100%|
|9|550|550|32937|548.9|1|26|0|32937|100%|
|9|650|650|38900|648.3|1|19|0|38900|100%|
|9|750|750|44918|748.6|1|11|0|44918|100%|
|9|850|850|50902|848.3|2|22|0|50902|100%|
|9|950|950|56878|947.9|1|14|0|56878|100%|
|9|1050|1050|62874|1,047.8|2|12|0|62874|100%|
|9|1150|1150|68845|1,147.3|2|99|0|68845|100%|
|9|1250|1250|74851|1,247.4|2|103|0|74851|100%|
|9|1350|1350|80826|1,347.0|2|100|0|80826|100%|
|9|1450|1450|86806|1,446.7|2|19|0|86806|100%|
|9|1550|1550|92817|1,546.8|2|52|0|92817|100%|
|9|1650|1650|98774|1,646.1|2|18|0|98774|100%|
|9|1750|1750|104755|1,745.8|2|18|0|104755|100%|
|9|1850|1850|110734|1,845.4|2|20|0|110734|100%|
|9|1950|1910|113419|1,890.2|9|41855|0|113419|100%|
|9|2050|1911|114437|1,907.1|2|77962|39|114397|99%|
|9|2150|1911|114481|1,907.9|2|15|128|114353|99%|
|9|2250|1911|114545|1,908.9|2|24|144|114401|99%|
h3. 4 workers, 61 contexts, accessing only one of them
!4-workers-61-context-accessing-1-balancer-cpu.png|thumbnail!
||Nodes||Sessions||Ses.Active||Samples||samples/s||mean resp. ms||max resp. ms||conn.
errors||valid samples||%||
|4|500|500|29796|496.6|6|52|0|29796|100%|
|4|650|650|38706|645.0|7|149|0|38706|100%|
|4|800|800|47585|793.0|8|129|0|47585|100%|
|4|950|950|54467|907.7|43|377|0|54467|100%|
|4|1100|1100|62500|1,041.6|54|396|0|62500|100%|
|4|1250|1250|69446|1,157.3|81|512|0|69446|100%|
|4|1400|1400|76217|1,270.2|97|517|0|76217|100%|
|4|1550|1550|80216|1,336.8|152|810|0|80216|100%|
|4|1700|1700|80797|1,346.5|271|864|0|80797|100%|
|4|1850|1850|94172|1,569.3|182|822|0|94172|100%|
|4|2000|1916|91014|1,516.8|253|48650|0|91014|100%|
|4|2150|1916|95852|1,597.4|205|848|83|95769|99%|
h3. 4 workers, 1 context
!4-workers-1-context-balancer-cpu.png|thumbnail!
||Nodes||Sessions||Ses.Active||Samples||samples/s||mean resp. ms||max resp. ms||conn.
errors||valid samples||%||
|4|500|500|29922|498.7|2|39|0|29922|100%|
|4|650|650|38923|648.7|1|39|0|38923|100%|
|4|800|800|47916|798.5|1|17|0|47916|100%|
|4|950|950|56896|948.2|1|17|0|56896|100%|
|4|1100|1100|65889|1,098.1|1|115|0|65889|100%|
|4|1250|1250|74874|1,247.8|1|101|0|74874|100%|
|4|1400|1400|83818|1,396.8|1|17|0|83818|100%|
|4|1550|1550|92830|1,547.0|1|17|0|92830|100%|
|4|1700|1700|101805|1,696.6|1|11|0|101805|100%|
|4|1850|1850|110785|1,846.3|1|11|0|110785|100%|
|4|2000|1916|113747|1,895.6|10|53108|0|113747|100%|
|4|2150|1916|114825|1,913.6|1|24|83|114742|99%|
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Michal Babacek (JIRA)