What is the vamessages.log used for?

SourceForge records just about everything it's doing to this file. You can use this log to debug startup issues, performance issues, system errors, exid backtraces, JVM issues, SQL issues, etc.

The log can be found at /usr/local/sourceforge/log/vamessages.log. Since this log contains so many different types of log messages, it grows extremely rapidly, so the file is automatically rotated by SourceForge when it reaches 100M, and SourceForge will keep the previous ten copies of the log. If you are having any kind of issue, this is probably the log to look at.