Increasing the Maximum Simultaneous Requests

The Denodo Platform embeds the Apache Tomcat Web container that Virtual DataPort uses, among other things, to deploy SOAP and REST Web services. If you expect these Web services to receive a high number of concurrent requests, consider increasing the maximum number of threads that Tomcat will create to attend requests. To do this, follow these steps:

  1. Open the file <DENODO_HOME>/resources/apache-tomcat/conf/server.xml

  2. Look for the attribute maxThreads and replace its default value (150) with a higher one. For example, 300.

    There are two occurrences of the maxThreads attribute, one for the non-SSL Connector and another one for the SSL Connector. You can have a different value for each one.

  3. From the Administration Tool, do the following:

    1. Open the wizard “Concurrent Requests” on the menu “Administration > Server configuration”.

    2. Make sure that if “Limit concurrent requests” is “On”, the value of “Max concurrent requests” is greater than or equal to the maxThreads attribute. Otherwise, Tomcat will process the requests, but Virtual DataPort will not be able to attend them.

      If you have enabled SSL on Tomcat (explained in the section Enabling HTTPS in the Embedded Apache Tomcat), “Max concurrent requests” has to be greater than or equal to the sum of the maxThreads attribute of the non-SSL connector and the SSL connector.

  4. To apply these changes, stop the Virtual DataPort server and all the Denodo administration tools. Once they are all stopped, start them again.

Each incoming request requires a thread for the duration of that request. If Tomcat receives more simultaneous requests than the number of available request processing threads, Tomcat creates additional threads up to maxThreads. If Tomcat still receives more simultaneous requests, they are stacked up, up to the value of the acceptCount attribute of the Connector element. Any further simultaneous requests will receive “connection refused” errors.

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