Probably not an issue you run into much with high speed trading, but when you are running multiple vmware/virtualbox instances and each is running a glassfish app ... PermGen taming becomes a serious concern.
Introduction Measuring an object’s size in Java is not straightforward. The platform encourages you to consider references and abstractions rather than raw memory usage. Still, understanding how objects fit into memory can yield significant benefits, especially for high-performance, low-latency systems. Over time, the JVM has introduced optimisations like Compressed Ordinary Object Pointers (Compressed Oops) and, more recently, Compact Object Headers. Each of these can influence how large or small your objects appear. Understanding these factors helps you reason about memory usage more concretely. Measuring Object Sizes In principle, you can estimate an object’s size by creating instances and observing changes in the JVM’s free memory. However, you must neutralise certain factors to get consistent results. For example, turning off TLAB allocation ( -XX:-UseTLAB ) makes memory usage more directly observable. Repeated measurements and median calculations can reduce the im...
As different AIs are implemented differently, they don't all provide the same answer, nor do they consistently outperform one another. The best approach is to use multiple AI and pick the one you like best. My goal here is not to declare a winner based on one example, but instead to show the variety of answers you can get with different AI. I asked each AI to Suggest how to implement this more optimally private static String formatOffset(int millis) { String sign = millis < 0 ? "-" : "+"; int saveSecs = Math.abs(millis) / 1000; int hours = saveSecs / 3600; int mins = ((saveSecs / 60) % 60); int secs = (saveSecs % 60); if (secs == 0) { if (mins == 0) { return sign + twoDigitString(hours); } return sign + twoDigitString(hours) + twoDigitString(mins); } return sign + twoDigitString(hours) + twoDigitString(mins) + twoDigitString(secs); } private static String twoDigitString(int value) { ...
Peter Lawrey is an Australian/British software engineer and entrepreneur best known for work on ultra-low-latency Java systems and for leading the open-source OpenHFT libraries. He is the founder and chief executive of Chronicle Software, a London-based company whose technology is used in trading and market-infrastructure workloads. Lawrey is also a recognised Java community figure: he was named a Java Champion in 2015, has been described by conference organisers as having provided the most answers for the Java and JVM tags on Stack Overflow, and writes the long-running Vanilla Java blog. ( Chronicle Software , javachampions.org , qconnewyork.com , blog.vanillajava.blog ) Career Lawrey founded and leads Chronicle Software, which builds enabling technology for event-driven trading and market-data platforms. The company states that its software underpins systems at several tier-one banks; a 2024 press announcement similarly described Chronicle as supplying "8 of the t...
Happy New Year to you too.
ReplyDeleteIt has been a pleasure to read your blog during this year. I've learnt a lot.
Please, keep on writting ;)
Hi Peter,
ReplyDeleteThanks for a great Year ful of interesting posts!
Keep up the good work!
Thanks,
Markus
keep up !!!
ReplyDeleteThanks Peter. Happy New Year to you also and all the best for a prosperous year of blogging ahead
ReplyDeleteHappy New Year! Keep up the good work!
ReplyDeleteAlso, if you need a topic... PermGen profiling :)
Probably not an issue you run into much with high speed trading, but when you are running multiple vmware/virtualbox instances and each is running a glassfish app ... PermGen taming becomes a serious concern.