This may be a bit out of scope for this post, but at Google I used to get a lot of mileage out of a system I worked on called Dapper: http://static.googleuserc

This may be a bit out of scope for this post, but at Google I used to get a lot of mileage out of a system I worked on called Dapper: http://static.googleusercontent.com/external_content/untrusted_dlcp/research.google.com/en/us/pubs/archive/36356.pdf http://static.googleusercontent.com/external_content/untrust... It uses thread-local storage and RPC library instrumentation to thread a fixed request-id through every RPC call and thread handling a particular user request. Then you can do things like automatically adding the request ID to log messages, transparently to the request-handling code. And when you visualize logged RPCs, you can include (some subset of) the logged messages in your visualization.