DDevelopment & Design

Glimpse on Tomcat performance tuning.

  • byRafal P
  • August 23, 2010
  • 3 minute read

Production environment ;-)

Have You ever wondered about Tomcat configuration in production environment, or just let “this things” to the admins, or even worse, don’t care at all about it? If the answer is “Tomcat configuration ? I/We/Our client just installs tomcat and deploy our application. Why border about any additional configuration ?” You should read this post.

I will not write about all Tomcat’s configuration. It’s pointless. I just want to show some problems with performance with default Tomcat’s configuration in production enviroment. Especially if You are using Tomcat in as web server in internet, with many simultaneous clients and connections. In such cases performance and high responsivity is important.

1. Let’s start from logs. Standard Tomcat’s logs are configured to appear in two places: file and console. In production it’s pointless to have duplicate logs so first thing to gain some speed boost is to replace following line from logging.properties:

.handlers = 1catalina.org.apache.juli.FileHandler, java.util.logging.ConsoleHandler with this one: .handlers = 1catalina.org.apache.juli.FileHandler

2. Second thing to do with logs is to set max file size and protection from overflow. It’s also very easy. Just add new handler like following one:

catalina.java.util.logging.FileHandler

and configure it like this (max 4 filesx10Mb):

1catalina.java.util.logging.FileHandler.pattern = ${catalina.base}/logs/catalina.%g.log 1catalina.java.util.logging.FileHandler.limit = 10000000 1catalina.java.util.logging.FileHandler.count = 4

3. Last thing You have TO HAVE in production environment are asynchronous logs. Synchronous logging is far more time consuming then asynchronous one. Especially when You have numerous clients. Check if Your Tomcat is configured in proper way (I won’t write about this. Just search in web about log4j configuration. It’s lot of this there.)

4. That’s all about logging. Now something much more influent on connection speed-connectors. They are configured in server.xml under node.

Tomcat have 3 main connectors:

– BIO – Blocking Java connector which is default one

– APR – Uses native C code fo IO (very fast)

– NIO – Non blocking connectror in Java (also faster than default)

The first BIO connector (“org.apache.coyote.http11.Http11Protocol”) is set as default one. Why ? Becouse in many cases such configuration it’s enough. Tomcat usually is used in intranets where it’s not required to handle high traffic volume. Moreover BIO connector is very stable.

But if our applications have to serve many http requests the blocking connector isn’t the best choice. So here comes ARP and NIO connector.

The first one (org.apache.coyote.http11.Http11AprProtocol) requires to compile native library (just search in google for ARP) and could be less stable than BIO connector. In exchange ARP connector is very fast, could handle requests simultanously in non blocking mode, have pooling of unlimited size and could handle unlimited threads (in theory, becouse threads are limited with CPU power)

Last connector – NIO (org.apache.coyote.http11.Http11NioProtocol) is something between ARP and BIO. It’s good choice if You don’t want to compile native libraries. NIO connector is also non blocking, little slower in reading static content than ARP, but far more configurable (pool size, no of threads etc).

5. Ok, so now We know, which connector should we choose, but every connector have to be set up in proper way. There are several parameters but the important ones are:

– maxThreads – typical from 150-800 (For BIO this is max nr of open connections)

– maxKeepAliveRequests – typical 1 or 100-250. For BIO this should be set to 1 to disable keep alive (only if we have high concurency and not using SSL). BIO connector automatically disables keep alive for high connection traffic

– connectionTimeout – typical 2000-60000 WARNING: default Tomcat has it set to 20 000! It’s to high for production environment. Good choice is to decrese it to 3000-5000 unless Your production env is working with slow clients. This parameters describes max time between TCP packets during blocking read/write

6. This is “almost” the end of tunning Tomcat for production. The last thing is to configure cache. Default cache is configured to 10 MB. You can set this a little more if You have a lot of static content. Also cache revalidation (standard 5 sec) should be tuned. How ? It’s difficult to say. The best way is to tune this parameters by own during tests.

That’s all. I hope I realized to everyone why not rely on standard Tomcat configuration.

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DDevelopment & Design

Spock, Java and Maven

Few months ago I've came across Groovy - powerful language for JVM platform which combines the power of Java with abilities typical for scripting languages (dynamic typing, metaprogramming).

Together with Groovy I've discovered spock framework (https://code.google.com/p/spock/) - specification framework for Groovy (of course you can test Java classes too!). But spock is not only test/specification framework - it also contains powerful mocking tools.

Even though spock is dedicated for Groovy there is no problem with using it for Java classes tests. In this post I'm going to describe how to configure Maven project to build and run spock specifications together with traditional JUnit tests.


Firstly, we need to prepare pom.xml and add necessary dependencies and plugins.

Two obligatory libraries are:
<dependency>
    <groupid>org.spockframework</groupId>
    <artifactid>spock-core</artifactId>
    <version>0.7-groovy-2.0</version>
    <scope>test</scope>
</dependency>
<dependency>
    <groupid>org.codehaus.groovy</groupId>
    <artifactid>groovy-all</artifactId>
    <version>${groovy.version}</version>
    <scope>test</scope>
</dependency>
Where groovy.version is property defined in pom.xml for more convenient use and easy version change, just like this: 
<properties>
    <gmaven-plugin.version>1.4</gmaven-plugin.version>
    <groovy.version>2.1.5</groovy.version>
</properties>

I've added property for gmaven-plugin version for the same reason ;)

Besides these two dependencies, we can use few additional ones providing extra functionality:
  • cglib - for class mocking
  • objenesis - enables mocking classes without default constructor
To add them to the project put these lines in <dependencies> section of pom.xml:
<dependency>
    <groupid>cglib</groupId>
    <artifactid>cglib-nodep</artifactId>
    <version>3.0</version>
    <scope>test</scope>
</dependency>
<dependency>
    <groupid>org.objenesis</groupId>
    <artifactid>objenesis</artifactId>
    <version>1.3</version>
    <scope>test</scope>
</dependency>

And that's all for dependencies section. Now we will focus on plugins necessary to compile Groovy classes. We need to add gmaven-plugin with gmaven-runtime-2.0 dependency in plugins section:
<plugin>
    <groupid>org.codehaus.gmaven</groupId>
    <artifactid>gmaven-plugin</artifactId>
    <version>${gmaven-plugin.version}</version>
    <configuration>
        <providerselection>2.0</providerSelection>
    </configuration>
    <executions>
        <execution>
            <goals>
                <goal>compile</goal>
                <goal>testCompile</goal>
            </goals>
        </execution>
    </executions>
    <dependencies>
        <dependency>
            <groupid>org.codehaus.gmaven.runtime</groupId>
            <artifactid>gmaven-runtime-2.0</artifactId>
            <version>${gmaven-plugin.version}</version>
            <exclusions>
                <exclusion>
                    <groupid>org.codehaus.groovy</groupId>
                    <artifactid>groovy-all</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <dependency>
            <groupid>org.codehaus.groovy</groupId>
            <artifactid>groovy-all</artifactId>
            <version>${groovy.version}</version>
        </dependency>
    </dependencies>
</plugin>

With these configuration we can use spock and write our first specifications. But there is one issue: default settings for maven-surefire plugin demand that test classes must end with "..Test" postfix, which is ok when we want to use such naming scheme for our spock tests. But if we want to name them like CommentSpec.groovy or whatever with "..Spec" ending (what in my opinion is much more readable) we need to make little change in surefire plugin configuration:
<plugin>
    <groupid>org.apache.maven.plugins</groupId>
    <artifactid>maven-surefire-plugin</artifactId>
    <version>2.15</version>
    <configuration>
        <includes>
            <include>**/*Test.java</include>
            <include>**/*Spec.java</include>
        </includes>
    </configuration>
</plugin>

As you can see there is a little trick ;) We add include directive for standard Java JUnit test ending with "..Test" postfix, but there is also an entry for spock test ending with "..Spec". And there is a trick: we must write "**/*Spec.java", not "**/*Spec.groovy", otherwise Maven will not run spock tests (which is strange and I've spent some time to figure out why Maven can't run my specs).

Little update: instead of "*.java" postfix for both types of tests we can write "*.class" what is in my opinion more readable and clean:
<include>**/*Test.class</include>
<include>**/*Spec.class</include>
(thanks to Tomek Pęksa for pointing this out!)

With such configuration, we can write either traditional JUnit test and put them in src/test/java directory or groovy spock specifications and place them in src/test/groovy. And both will work together just fine :) In one of my next posts I'll write something about using spock and its mocking abilities in practice, so stay in tune.