How to Deal With Out Of Memory Errors

These errors are rather commonly seen during development phases, and even on production servers. These errors are even more annoying than others, because they do not show any stack trace. The reason for this is that a stack trace would not be of help for these errors. The code that fails with an Out Of Memory will be, in most cases, a "victim" of the problem, and not the problem itself.

Although it is very tempting to blame Tomcat on these errors, the fact is that many of them have their causes in "mistakes" in the webapps. These mistakes usually come from programming patterns and techniques perfectly legal and safe on standalone applications, but that are not correct in a managed environment like a servlet container (that is, Tomcat).

This page will maintain a list of those "well-known mistakes", so anyone experiencing these problems, or wanting to avoid them, could check their webapps and correct them.

The General Rule

The first thing to do is to set the basis for these patterns to be recognized. This way, the developer will be able to find even those mistakes that are not listed in this page, and why not, add them here

An Out Of Memory can be thrown by several causes:

• A servlet trying to load a several GBytes file into memory will surely kill the server. These kind of errors must be considered a simple bug in our program.