The Cocoon Performance Tips in this version is a loose collection of
usenet articles regarding how to improve the Apache Cocoon performance.
As in the real world, it needs some kind of evolution to get better.
If you have suggestions how to make it better or new kool tips, then be brave and
send it to the
Cocoon Mailing Lists!
|Sometimes the tips maybe doubled or contradictory. If you notice something
like that, then send a note to the
Cocoon Mailing Lists.
Caching and Pooling
Logging kills performance. Consider disabling logging entirely from
Cocoon (leave only the ERROR channel) and let Apache or the servlet
container log accesses and stuff.
Use a transparent proxy in front of your web server! The fastest
response is the one that is not even processed. Cocoon is very slow
(compared to a proxy server) to read resources such as stylesheets and
images. A transparent proxy (SQUID, for example, don't use Apache's
mod_proxy because it is not fully compatible with HTTP/1.1 and disables
connection keep-alive). Make sure you tune how long the static resources
that Cocoon "read"s from the sitemap are cached (look into the readers
code to find out more).
Consider prerendering or time-based batch-process the static parts
of your site. PDF reports, rasterized SVG graphs or things that change
For optimum performance with Tomcat 4 and Cocoon 2,
use the HTTP/1.0 connector.
Move static content out of Cocoon's control. Move your static content out of the
Cocoon servlet context and into its own context (just letting Tomcat serve directly).
An even better approach would be to use a front-end webserver to serve the static, but
installing Apache + Tomcat + our Cocoon app would be a bit much when Tomcat + our Cocoon
app is doing fine.
Disable resource reloading. The disk I/O system could become the
Search for messages such as "decommissioning instance of...". This reveals some
undersized pools which are corrected by tuning cocoon.xconf and sitemap.xmap.
Undersized pools act like an object factory, plus the ComponentManager
Fine-tune the pool sizes for components in the files cocoon.xconf and
sitemap.xmap. If the pools are too small for the load this will have a great
impact on your performance. The goal is to achieve such a configuration that for
every request there is a free component in the pool. Suppose, you have up
to 100 simultaneous requests and your pipelines have up to 2 xslt
transformers, then you need to set the maximum pool size to 200 xslt
transformers. They will be created when needed and retained to the pool
for future use.
Fine-tune the Cocoon settings for the store and the other stuff.
Important is the size of the documents that will be cached, because
caching appears to be very time consuming process.
If you are using the Caching Pipeline, you should be able to experience
better performance each time you request it. However, if your cache is set
too small to keep the entire XML in memory, the cache will be of no benefit.
Watch the cachability in the log files, and make sure that things
are being fed from the cache.
Only use dynamic data when it is needed. Dynamic pages can't be
Don't put Cocoon webapp too deep into directory structure. Cache
keys contain absolute file names (or hash values of the absolute file
names - in 2.0.X series), and the deeper cocoon is located in the
filesystem, the longer keys are becoming. Obviously, longer keys will
take more time to process them. In worst case scenario, slowdown up to
10% could be achieved (unscientifical observations, do your own
Utilize the pipeline
expires parameter to dramatically reduce
redundand requests. Even the most dynamic application pages have a
reasonable period of time during which they are static.
Even if a page doesn't change for just one minute, still use the
expires parameter. Here is an example:
<map:parameter name="expires" value="access plus 1 minutes"/>
The value of the parameter is in a format borrowed from the Apache HTTP module mod_expires.
Examples of other possible values are:
access plus 1 hours
access plus 1 month
access plus 4 weeks
access plus 30 days
access plus 1 month 15 days 2 hours
Imagine 1'000 users hitting your web site at the same time.
Say that they are split into 5 groups, each of which has the same ISP.
Most ISPs use intermediate proxy servers to reduce traffic, hense
improving their end user experience and also reducing their operating costs.
In our case the 1'000 end user requests will result in just 5 requests to Cocoon.
After the first request from each group reaches the server, the expires header will
be recognized by the proxy servers which will serve the following requests from their cache.
Keep in mind however that most proxies cache HTTP GET requests, but will not cache HTTP POST requests.
To feel the difference, set an expires parameter on one of your pipelines and
load the page with the browser. Notice that after the first time, there are no
access records in the server logs until the specified time expires.
JVM and OS
Consider using a good JVM on a good OS. Scalability is a very
different beast than pure speed. An Apple DualG4 866 seems to run faster
than a Sun Enterprise 4500 (and costs a fraction), but try hitting them
with 2000 concurrent Cocoon requests.
Fine-tune your JVM settings (max heap-size, initial memory, s.o.).
Please read the Java Performance
FAQ's and the Tuning
Garbage Collection Document.
Don't specify the -Xms parameter.
-Xnoclassgc parameter on the Sun JDK 1.3.1!
It reduces the frequency of need for garbage collection by permitting the
memory allocated to unused classes to be reused (instead of having to be
collected and/or compacted). Less fragmentation means less collection
means better response times.
Consider following formula for Pipeline Processing:
Number_of_simultaneous_users * depth_of_content_aggregation
Consider following formula for Generators/Transformers/Serializers:
Amount_required_to_process_one_request * Number_of_simultaneous_users
Consider following formula for Connectors:
Keep an eye on the overall complexity of pipelines.
Try to keep the size of the documents going through the pipeline
small. To big documents slows down translation.
expires parameter (see above) as frequently as you can.
It improves the end user experience dramatically. Browsers and intermediate
proxy servers love the HTTP
Consider turning your XSPs into Generators by hand and call them
directly. Of course you don't need to do this for all pages, but it's
recommended to it for those which are heavy loaded.
You can try it this way:
Cocoon will compile your XSP's into Java classes
(see tomcat/work/..../org/apache/cocoon/www/my_xsp.class). After that, add
the generated Generator to the Sitemap:
<map:generator type="myXSP" src="org.apache.cocoon.www.my_xsp"/>
And use it:
XSLT and XSL
|For more tips and information about XSL and XSLT grep the Internet and the
Try to keep the number of templates in the XSL translation small.
There are several ways of doing the same stuff in XSLT, test the
difference between them.
Consider browser-dependent targetting to perform client-side XSLT.
Cocoon is very fast if it doesn't do transformations. IE 5.5 and 6 are
pretty compliant and might be something around 30% of your hits
(probably more on some popular public web sites like Nasa's). Reducing
one/third of the transformations might speed up a LOT.
How complicated are the XSLT stylesheets? If you are not using global
variables or parameters this will speeds things up.
Consider using XSLTC instead of Xalan. XSLTC compiles XSLT to bytecode (translets)
the first time a stylesheet is used. Consequently it uses the compiled code
which is faster by a magnitude than the interpreted one.