[JavaSpecialists] Issue 235 - Talk Recording in Warsaw, Poland

Good day,

I presented a talk to a bunch of Polish Java enthusiasts last Tuesday, based in part on the newsletter that I wrote last month. I made a recording, which I have uploaded on Vimeo. To avoid your SPAM filters, here is a link that hopefully won't get caught in the net:

vimeo[dot]com/160219051

Sorry for the trouble with the URL. I trust you will figure out what to do :-)

Here is description for the talk:

Title: Using Java Reflection to Debug Performance Issues

Abstract: Java reflection allows us to peek inside objects that we don't know, find their classes and then call methods and set fields. Great, but how can we use this practically in the "real world"? In this talk, we start by showing how we find performance bottlenecks in Java using a profiler. We check the profiler has found the mother lode by looking at the objects with reflection. In our first example, we profile an open source tool that exhibited CPU bound performance issues. We discover a typical bad coding paradigm and use Java reflection to test whether this bottleneck could be eliminated with a better hashing mechanism. Our second example is a look at the new Java 8 hash function inside HashMap. Debuggers hide the gory details of a HashMap from our prying eyes, so we use reflection to output the contents of the array of buckets. This shows us essential data about the effects of the new hash function. Java 8 HashMaps can perform 3x slower than previous versions! Usin
g reflection we show why that is. This talk is mostly live coding, with a few slides explaining how we find performance bottlenecks quickly.

Author: Dr Heinz Kabutz writes the popular "The Java Specialists' Newsletter" read by tens of thousands of enthusiastic fans in over 134 countries. To sign up, visit http://www.javaspecialists.eu

Kind regards from Crete. Yesterday we had a dust storm from the Sahara which was fun. Airport was closed for the day as it was also too windy to land. Today is beautiful again - blue skies and not too hot.

Heinz

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