Well, what if there was no log there to begin with? If you've got a bunch of logs labelled as INFO, WARN and ERROR in your system, and you tweak the debug leve

Well, what if there was no log there to begin with? If you've got a bunch of logs labelled as INFO, WARN and ERROR in your system, and you tweak the debug level - you get more detailed debug logs as need be. This will stream EXISTING logs to stdout and then to your favorite APM. However, if the exact bit of information you wanted isn't there (that variable isn't logged, that specific piece of code isn't instrumented so you can't know it was reached, etc...) you're stuck. In addition, sometimes (often) it's hard to correlate the exact path the code took, since it's not clear which condition or class or package or server were actually involved in the process of execution. This tool enables you to conditionally log just what you need in real time - basically "paint a path" through the code at runtime. Hope that's clearer, can elaborate more if need be.