Ayose C. ayosec

About `PrintCompilation`

This note tries to document the output of PrintCompilation flag in HotSpot VM. It was originally intended to be a reply to a blog post on PrintCompilation from Stephen Colebourne. It's kind of grown too big to fit as a reply, so I'm putting it here.

Written by: Kris Mok [email protected]

Most of the contents in this note are based on my reading of HotSpot source code from OpenJDK and experimenting with the VM flags; otheres come from HotSpot mailing lists and other reading materials listed in the "References" section.

This

Xvnc

The scripts in this gist will start an Xvnc server with a basic window manager (IceWM). This is intended to use in a virtual machine, where we can need to start a browser to run a test suite.

Installation on Debian

All commands have to be run as root

apt-get install icewm vnc4server

Too much for teh twitterz :)

JVM + invokedynamic is in a completely different class than CLR + DLR, for the same reasons that JVM is in a different class than CLR to begin with.

CLR can only do its optimization up-front, before executing code. This is a large part of the reason why C# is designed the way it is: methods are non-virtual by default so they can be statically inlined, types can be specified as value-based so their allocation can be elided, and so on. But even with those language features CLR simply cannot optimize code to the level of a good, warmed-up JVM.

The JVM, on the other hand, optimizes and reoptimizes code while it runs. Regardless of whether methods are virtual/interface-dispatched, whether objects are transient, whether exception-handling is used heavily...the JVM sees through the surface and optimizes code appropriate for how it actually runs. This gives it optimization opportunities that CLR will never have without adding a comparable profiling JIT.

So how does this affect dynamic

OpenSSL and RSA

You can encrpt files using a private/public keys.

First, create the keys:

openssl req -x509 -nodes -days 100000 -newkey rsa:2048 \
  -keyout private.pem -out public.pem -subj /

Scala macros tutorial, using sbt

The following steps executed in order will;

create the project file structure
set the sbt version
add the gen-idea sbt plugin (if you want to import your project into intellij)
create an sbt build, that builds the macros project prior to the macrostest project (so the regex macro is usable in the macrostest project)
create the macros project scala file
create the macrostest project scala file

List for PivotalTracker stories

Get the stories for your PitalTracker project.

Installation

Install httparty and term-ansicolor gems
Download the pt-list.rb file in this gist.
Set execution flag with chmod +x
Put it in some directory in your $PATH

	Latency Comparison Numbers (~2012)
	----------------------------------
	L1 cache reference 0.5 ns
	Branch mispredict 5 ns
	L2 cache reference 7 ns 14x L1 cache
	Mutex lock/unlock 25 ns
	Main memory reference 100 ns 20x L2 cache, 200x L1 cache
	Compress 1K bytes with Zippy 3,000 ns 3 us
	Send 1K bytes over 1 Gbps network 10,000 ns 10 us
	Read 4K randomly from SSD* 150,000 ns 150 us ~1GB/sec SSD

	#!/usr/bin/python
	#
	# Usage: python paste_img.py dest_file.png
	#
	# This program readd the image stored in the clipboard, and dumps it into a file

	import gtk, pygtk
	pygtk.require('2.0')
	import sys

	package: myapp.foo.locales

	en:
	mailbox:
	header:
	title: "Your mailbox"
	subtitle: "Read and send messages"
	welcome: "Welcome %{user}!"

	actions:

	// Steve Phillips / elimisteve
	// 2013.01.03

	// Programming Challenge: Launch 4 threads, goroutines, coroutines, or whatever your language uses for concurrency,
	// in addition to the main thread. In the first 3, add numbers together (see sample code below) and pass the results
	// to the 4th thread. That 4th thread should receive the 3 results, add the numbers together, format the results as
	// a string (see sample code), and pass the result back to `main` to be printed.
	//
	// Do this as succinctly and readably as possible. _Go!_ #golang #programming #concurrency #challenge
	package main