"record entire execution of your Java app; play it back on any machine". Other features: time-travelling debugger -- step backwards, jump to any point in execution, designed for long running programs; post-execution logging -- add log statements after the program has run, and see what it would have logged. Looks extremely nifty, but I wonder how big those recording files get...

via Toby DiPasquale. nice tip

'gcprof is a simple utility for profile allocation and garbage collection activity in the JVM [...] Profile allocation and garbage collection activity in the JVM. The gcprof command runs a java command under profiling. Allocation and collection statistics are printed periodically. If -n or -no are provided, statistics are also reported in terms of the given application metric. Total allocation, allocation rate, and a survival histogram is given. The intended use for this tool is twofold: (1) monitor and test garbage allocation and GC behavior, and (2) inform GC tuning.'

'GC Strategies for Event Processing Systems on the JVM'

Fascinating. Evading the Java GC by reimplementing a slab allocator, basically

'Backdoor that gives you a scala shell over ssh on your jvm. The shell is not sandboxed, anyone access the shell can touch anything in the jvm and do anything the jvm can do including modifying and deleting files, etc.' nifty!

a good intro from Bruce Eckel. We need a good excuse to deploy some Scala ;)

classic presentation from Paul Tyma of Mailinator regarding the java.nio (event-driven, non-threaded) vs java.io (threaded) model of server concurrency, backing up the scalability of threads on modern JVMs

'SoftReferences are the cheap, crappy caching mechanism [...] perfect for when you'd like your cache to be cleared at random times and in random order.'