Bryan DwordPtr

Quick Tips for Fast Code on the JVM

I was talking to a coworker recently about general techniques that almost always form the core of any effort to write very fast, down-to-the-metal hot path code on the JVM, and they pointed out that there really isn't a particularly good place to go for this information. It occurred to me that, really, I had more or less picked up all of it by word of mouth and experience, and there just aren't any good reference sources on the topic. So… here's my word of mouth.

This is by no means a comprehensive gist. It's also important to understand that the techniques that I outline in here are not 100% absolute either. Performance on the JVM is an incredibly complicated subject, and while there are rules that almost always hold true, the "almost" remains very salient. Also, for many or even most applications, there will be other techniques that I'm not mentioning which will have a greater impact. JMH, Java Flight Recorder, and a good profiler are your very best friend! Mea

How to convert markdown to PDF:

This post reviews several methods for converting a Markdown (.md) formatted file to PDF, from UNIX or Linux machines.

Using `Pandoc`:

$ pandoc How_I_got_svg-resizer_working_on_Mac_OSX.md -s -o test1.pdf

FWIW: I (@rondy) am not the creator of the content shared here, which is an excerpt from Edmond Lau's book. I simply copied and pasted it from another location and saved it as a personal note, before it gained popularity on news.ycombinator.com. Unfortunately, I cannot recall the exact origin of the original source, nor was I able to find the author's name, so I am can't provide the appropriate credits.

Effective Engineer - Notes

By Edmond Lau
Highly Recommended 👍
http://www.theeffectiveengineer.com/

What's an Effective Engineer?

Common Options

-#, --progress-bar Make curl display a simple progress bar instead of the more informational standard meter.

-b, --cookie <name=data> Supply cookie with request. If no =, then specifies the cookie file to use (see -c).

-c, --cookie-jar <file name> File to save response cookies to.

	#!/bin/bash
	# Who23 Github

	# A script to display current spotify track info in a small terminal window
	# this includes art, track name, and artist. All art/text centered

	# BUILT TO WORK WITH MACOS, iTERM, & SPA (https://gist.github.com/Who23/8ff45f0f2c2c3ae8a95582178a5c92ec)
	# for linux:
	# iTerm is needed for the image display protocol, can work with another terminal if you change the image protocol to one
	# supported by that terminal

	function logColor(color, args) {
	console.log(`%c ${args.join(' ')}`, `color: ${color}`);
	}

	const log = {
	aliceblue: (...args) => { logColor('aliceblue', args)},
	antiquewhite: (...args) => { logColor('antiquewhite', args)},
	aqua: (...args) => { logColor('aqua', args)},
	aquamarine: (...args) => { logColor('aquamarine', args)},
	azure: (...args) => { logColor('azure', args)},

	# Directories #
	/build/
	bin/
	repos/
	/repos/
	doc/
	/doc/
	.gradle/
	/bin/
	target/


	git log --author="Linus Torvalds" --date=iso \| perl -nalE 'if (/^Date:\s+[\d-]{10}\s(\d{2})/) { say $1+0 }' \| sort \| uniq -c\|perl -MList::Util=max -nalE '$h{$F[1]} = $F[0]; }{ $m = max values %h; foreach (0..23) { $h{$_} = 0 if not exists $h{$_} } foreach (sort {$a <=> $b } keys %h) { say sprintf "%02d - %4d %s", $_, $h{$_}, ""x ($h{$_} / $m 50); }'