Groovy came in handy for me once again last week when I was tasked with aggregating performance data from application logs.  The logs were concatenated together into one file that totalled over 2 million lines.  Interspersed throughout the logs were performance timer entries.  Each entry included a timestamp, a string for tagging the line as a performance timer entry, the name of the object and method called, and the number of milliseconds elapsed for the method's execution.

Performance tests were run over a two-day period under various loads.  For analysis purposes we wanted to see each method's average run time for each set of conditions, so we needed a way to look at aggregated data for specified time periods.  The results would be output to a CSV format for easy integration with an Excel worksheet.  Finally, we didn't want to spend too much time on creating a script since it wouldn't really be reuseable outside the context of this project, due to the specific formatting of the performance timing entries.