WebSphere automatically rolls back transactions that do not complete in a certain number of seconds. The default setting is 120 seconds, which may be too short for compiling certain complex pages, especially pages that embed many page fragments.

When you are developing an application, a page must be recompiled each time you change it. If your application includes complex pages (particularly if you are developing a portal with ATG Portal), you can avoid transaction timeouts by raising the timeout setting to 600 seconds. Before deploying the application on a production site, you should pre-compile all of the pages. You can then lower the timeout setting.

To change the setting, go to Servers > Application Servers > server > Transaction Service in the console.