Programming Erlang, 2nd Edition

Tools for Profiling Erlang Code

The standard Erlang distribution comes with three profiling tools.

• cprof counts the number of times each function is called. This is a lightweight profiler. Running this on a live system adds from 5 to 10 percent to the system load.

• fprof displays the time for calling and called functions. Output is to a file. This is suitable for large system profiling in a lab or simulated system. It adds significant load to the system.

• eprof measures how time is used in Erlang programs. This is a predecessor of fprof, which is suitable for small-scale profiling.

Here’s how you run cprof; we’ll use it to profile the code that we wrote in ​A SHOUTcast Server​: