TaopaiC TaopaiC

On Tue Oct 27, 2015, history.state.gov began buckling under load, intermittently issuing 500 errors. Nginx's error log was sprinkled with the following errors:

2015/10/27 21:48:36 [crit] 2475#0: accept4() failed (24: Too many open files)

2015/10/27 21:48:36 [alert] 2475#0: *7163915 socket() failed (24: Too many open files) while connecting to upstream...

An article at http://www.cyberciti.biz/faq/linux-unix-nginx-too-many-open-files/ provided directions that mostly worked. Below are the steps we followed. The steps that diverged from the article's directions are marked with an *.

* Instead of using su to run ulimit on the nginx account, use ps aux | grep nginx to locate nginx's process IDs. Then query each process's file handle limits using cat /proc/pid/limits (where pid is the process id retrieved from ps). (Note: sudo may be necessary on your system for the cat command here, depending on your system.)
Added fs.file-max = 70000 to /etc/sysctl.conf

What forces layout / reflow

All of the below properties or methods, when requested/called in JavaScript, will trigger the browser to synchronously calculate the style and layout*. This is also called reflow or layout thrashing, and is common performance bottleneck.

Generally, all APIs that synchronously provide layout metrics will trigger forced reflow / layout. Read on for additional cases and details.

Element APIs

Getting box metrics

elem.offsetLeft, elem.offsetTop, elem.offsetWidth, elem.offsetHeight, elem.offsetParent

Get Git log in JSON format

git log --pretty=format:'{%n  "commit": "%H",%n  "abbreviated_commit": "%h",%n  "tree": "%T",%n  "abbreviated_tree": "%t",%n  "parent": "%P",%n  "abbreviated_parent": "%p",%n  "refs": "%D",%n  "encoding": "%e",%n  "subject": "%s",%n  "sanitized_subject_line": "%f",%n  "body": "%b",%n  "commit_notes": "%N",%n  "verification_flag": "%G?",%n  "signer": "%GS",%n  "signer_key": "%GK",%n  "author": {%n    "name": "%aN",%n    "email": "%aE",%n    "date": "%aD"%n  },%n  "commiter": {%n    "name": "%cN",%n    "email": "%cE",%n    "date": "%cD"%n  }%n},'

The only information that aren't fetched are:

%B: raw body (unwrapped subject and body)
%GG: raw verification message from GPG for a signed commit

Jenkins CI on OSX

Instructions on how to setup a secured Jenkins CI on a Mac.

Download & Install dependencies

All of these operations are done with your admin user.

Developer tools

Install the command line developer tools.

2015-01-29 Unofficial Relay FAQ

Compilation of questions and answers about Relay from React.js Conf.

Disclaimer: I work on Relay at Facebook. Relay is a complex system on which we're iterating aggressively. I'll do my best here to provide accurate, useful answers, but the details are subject to change. I may also be wrong. Feedback and additional questions are welcome.

What is Relay?

Relay is a new framework from Facebook that provides data-fetching functionality for React applications. It was announced at React.js Conf (January 2015).

##TUNING##

Configuration

System: set file descriptors to 32K or 64K

vim /etc/security/limit.conf

	Disclaimer: The instructions are the collective efforts from a few places online.
	Nothing here is my original. But I want to put them together in one place to save people from spending the same time as I did.

	First off, bundle.
	==================

	1. cd to the project directory
	2. Start the react-native packager if not started
	3. Download the bundle to the asset folder:
	curl "http://localhost:8081/index.android.bundle?platform=android" -o "android/app/src/main/assets/index.android.bundle"

	user web;

	# One worker process per CPU core.
	worker_processes 8;

	# Also set
	# /etc/security/limits.conf
	# web soft nofile 65535
	# web hard nofile 65535
	# /etc/default/nginx

	var https = require('https');
	var util = require('util');

	exports.handler = function(event, context) {
	console.log(JSON.stringify(event, null, 2));
	console.log('From SNS:', event.Records[0].Sns.Message);

	var postData = {
	"channel": "#aws-sns",
	"username": "AWS SNS via Lamda :: DevQa Cloud",

	console.log('Loading function');

	const https = require('https');
	const url = require('url');
	// to get the slack hook url, go into slack admin and create a new "Incoming Webhook" integration
	const slack_url = 'https://hooks.slack.com/services/...';
	const slack_req_opts = url.parse(slack_url);
	slack_req_opts.method = 'POST';
	slack_req_opts.headers = {'Content-Type': 'application/json'};