This section covers the most relevant information for performance and size tuning the Tomcat 4.1.29 Servlet/JSP Container. Most of this information is available at the Apache Software Foundation Web site, http://jakarta.apache.org/tomcat/tomcat-4.1-doc/index.html.
A Connector is the representation of a communications endpoint by which requests are received from a Tomcat client. This object and its attributes are defined in the server.xml file, located in SYBASE\tomcat\conf. The following configurable properties are available for the HTTP/1.1 connector protocol. For simplicity only sizing relevant properties are included.
acceptCount – defines the maximum queue length of incoming connections that have not yet been accepted. The default for this attribute is 10 connections. This parameter corresponds to the TCP parameter backlog. The TCP parameter backlog dictates the number of requests that are allowed to queue up on the TCP stack waiting to be accepted. Once a client reaches the server and is placed in the backlog, the client side browser indicates that the server has been contacted and that the current request is in progress. If the backlog has been exceeded or is set to 0, the browser indicates that the server cannot be reached.
In general, modifying the backlog parameter is unnecessary; data has shown that a moderately busy Web server has an empty completed connection queue most of the time, while the incomplete connection queue needs 15 or fewer entries 98% of the time.
bufferSize – defines the input buffer size created by this Connector. The default for this attribute is 2048 Bytes. Increasing the buffer size improves performance, but at the expense of higher memory usage.
maxProcessors – defines the maximum number of request processing threads to be created by this Connector. Each incoming request requires a thread for the duration of that request. If more simultaneous requests are received than can be handled by the currently available request processing threads, additional threads are created up to the configured value of maxProcessors. Once the maxProcessors attribute is exceeded, any additional simultaneous requests are stacked inside the server socket created by the Connector, up to the configured maximum acceptCount attribute. Once the acceptCount value is exceeded, additional simultaneous requests receive “connection refused” errors, until resources are available to process them. The configuration of the property should reflect the maximum average load expected. Use the acceptCount property to handle any additional load spikes.
minProcessors – defines the number of request processing threads that are created upon server startup when this Connector is first initialized. The default value for this attribute is 5. This value should always be less than the value defined by maxProcessors.
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