I recently stumbled across a useful presentation: “GC Tuning In the HotSpot JVM” from FISL 10, which provides a good overview of how to tune the ParNew, Paralell and CMS collectors…
Also quite useful is this blog entry which explains how to understand CMS GC logs.
Little gem from the Hotspot Internals wiki helping to solve puzzles such as is “X.class.isAssignableFrom(obj)” slower than “obj instanceof X“!
Performance techniques used in the Hotspot JVM.
Floating point arithmetic/rounding can be somewhat painful, made worse by the fact that the epsilon (error) in the machine representation of floating point varies depending on the exponent (i.e. how large/small the number being represented is):
Normalized numbers when Base = 2, Precision = 3, Exponents = -1 to 2 [Goldberg91]
A very comprehensive paper (from which [...]
Useful synopsis of the Java Memory Model from Doug Lea – in particular the clearest explanation I have found so far of the meaning of “happens-before”, and some useful definitions which helped to get a concrete idea of the semantics around safe-publication of variables through Thread.start()…
My home linux server (formerly my desktop PC), which has been sitting in the corner of my lounge for a few years (with all fans other than the CPU fan unplugged in order to keep the noise down), finally blew up a few weeks ago. The motherboard was loading the BIOS but failing to recognise [...]
A handy concurrency refcard from Alex Miller is now available on DZone. Most of this should be second nature for experienced Java developers, but it provides a handy summary of concurrency and reminders of some of the less frequently used (and hence more easily forgotten) classes like ConcurrentSkipListSet, Atomic*Array etc.
I have been having some problems with my employers’ remote access system which uses Aventail SonicWall. Unfortunately it seems that whilst it was previously working fine, some change to my PC means that the Aventail applet (used to verify the endpoint is running the Aventail system scanning agent) does not work correctly so access is [...]
After occasionally wondering over the past 2 years whether spending money on extra drives to build a RAID 5 array in my desktop PC was worthwhile, I now feel vindicated after one of my drives (a Western Digital WD5000YS) failed over the weekend. Upon restarting my PC, Intel Matrix Storage Console was able to identify [...]
After repeatedly retrying the upgrade for about 3 hours due to activation server errors I was finally able to upgrade by Wednesday evening.
Since then things have gone pretty smoothly. Finally having the ability to copy and paste is a godsend, as are basic things one would expect from a phone like sending contacts to other [...]
A quick guide to migrating contacts, calendar, email and email filters from GMail to Google Apps.
