JDK has heaps of extremely useful tools in the bin folder, which often make it possible to diagnose a problem without purchasing similar commercial products. Yes, for free and readily available!
What are they good for? To produce and analyse a heapdump, gather exceptions stack traces, see how GC works and what it spends so much time on, check memory content and much more, all from the command line. Does that mean that it will work on a server somewhere far far away, beyond 7 VPNs and without a graphics interface?
During the session, Andrzej presented many of the available tools and talked about what they can be used for and what they can do.