Anh Le (Andy) anhldbk

LInux

Three system configuration parameters must be set to support a large number of open files and TCP connections with large bursts of messages. Changes can be made using the /etc/rc.d/rc.local or /etc/sysctl.conf script to preserve changes after reboot.

1. /proc/sys/fs/file-max: The maximum number of concurrently open files.

fs.file-max = 1000000

2. /proc/sys/net/ipv4/tcp_max_syn_backlog: Maximum number of remembered connection requests, which are still did not receive an acknowledgment from connecting client. The default value is 1024 for systems with more than 128Mb of memory, and 128 for low memory machines.

net.ipv4.tcp_max_syn_backlog = 3240000

3. /proc/sys/net/core/somaxconn: Limit of socket listen() backlog, known in userspace as SOMAXCONN. Defaults to 128.

net.core.somaxconn = 3240000

Converting a Word Document to Markdown in Two Moves

The Problem

A lot of important government documents are created and saved in Microsoft Word (*.docx). But Microsoft Word is a proprietary format, and it's not really useful for presenting documents on the web. So, I wanted to find a way to convert a .docx file into markdown.

The Solution

As it turns out, there are several open-source tools that allow for conversion between file types. Pandoc is one of them, and it's powerful. In fact, pandoc's website says "If you need to convert files from one markup format into another, pandoc is your swiss-army knife." But, although pandoc can convert from markdown into .docx, it doesn't work in the other direction.

Git Cheat Sheet

Initial Setup

Initialize a repo

Create an empty git repo or reinitialize an existing one

git init

From Meteor's documentation:

In Meteor, your server code runs in a single thread per request, not in the asynchronous callback style typical of Node. We find the linear execution model a better fit for the typical server code in a Meteor application.

This guide serves as a mini-tour of tools, trix and patterns that can be used to run async code in Meteor.

Basic async

Sometimes we need to run async code in Meteor.methods. For this we create a Future to block until the async code has finished. This pattern can be seen all over Meteor's own codebase:

This is a post by Joel Spolsky. The original post is linked at the bottom.

This is such a common question here and elsewhere that I will attempt to write the world's most canonical answer to this question. Hopefully in the future when someone on answers.onstartups asks how to split up the ownership of their new company, you can simply point to this answer.

The most important principle: Fairness, and the perception of fairness, is much more valuable than owning a large stake. Almost everything that can go wrong in a startup will go wrong, and one of the biggest things that can go wrong is huge, angry, shouting matches between the founders as to who worked harder, who owns more, whose idea was it anyway, etc. That is why I would always rather split a new company 50-50 with a friend than insist on owning 60% because "it was my idea," or because "I was more experienced" or anything else. Why? Because if I split the company 60-40, the company is going to fail when we argue ourselves to death. And if you ju

	# Feel free to change this path of course (and keys_zone value as well, but also change the usage of it below).
	proxy_cache_path /var/www/cache/resized levels=1:2 keys_zone=resizedimages:10m max_size=1G;

	# Gzip was on in another conf file of mine...You may need to uncomment the next line.
	#gzip on;
	gzip_disable msie6;
	gzip_static on;
	gzip_comp_level 4;
	gzip_proxied any;
	# Again, be careful that you aren't overwriting some other setting from another config's http {} section.

	import java.util.ArrayList;
	import java.util.Iterator;
	import java.util.List;
	import java.util.concurrent.Callable;
	import java.util.concurrent.ExecutorService;
	import java.util.concurrent.Future;
	import java.util.concurrent.LinkedBlockingQueue;
	import java.util.concurrent.ThreadPoolExecutor;
	import java.util.concurrent.TimeUnit;

	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

	# to generate your dhparam.pem file, run in the terminal
	openssl dhparam -out /etc/nginx/ssl/dhparam.pem 2048