low latency logging with rabbitmq (php london - 4th sep 2014)

Low Latency Loggingwith RabbitMQ

PHP London4th September 2014

James Titcumbwww.jamestitcumb.comwww.protected.co.ukwww.phphants.co.uk@asgrim

Who is this guy?

Let’s go back to basics...

Errors

source: http://www.dpaddbags.com/blog/episode-119-technology-sucks/

error_reporting(0);

They look rubbish!

@

Log to file only

Ways Around// Will raise E_WARNING

fopen($somefile, 'r');

Ways Around// No error! :)

if (file_exists($somefile)) {

fopen($somefile, 'r');

} else {

// nice handling...

// maybe throw exception...

}

Exceptions

Jargon Buster

● throwTriggering

● tryTry to run

● catchHandle it

● finallyRun code after try/catch

source: http://www.dpaddbags.com/blog/episode-119-technology-sucks/

C♯/C++

Catchable

Turn into fatal errorsif not caught

Classy

Descriptive exceptions

Example (exception class)class DivisionByZeroException

extends LogicException

{

}

Example (throw)class Mathematics {

public function divide($a, $b) {

if ($b == 0) {

$msg = sprintf(“Divide %s by zero”, $a);

throw new DivisionByZeroException($msg);

}

return ($a / $b);

}

}

Example (catch)$maths = new Mathematics();

try

{

$result = $maths->divide(5, 0);

}

catch (DivisionByZeroException $exception)

{

$logger->warning($exception->getMessage());

}

Logging

What is “logging”?

What is “logging”?Keeping a record of all events...

What is “logging”?Keeping a record of all events...

exceptions, errors, warnings, info, debug

Logging is a paper trail

Log like you just don’t care

Log wherever you like

What about Apache’s error_log?

source: http://up-ship.com/blog/?p=20903

Doin’ it rightwrong… // Magic file that makes your entire project work perfectly

@ini_set('display_errors', 0);

@error_reporting(0);

function __globalErrorHandler() {

return true;

}

@set_error_handler('__globalErrorHandler');

@set_exception_handler('__globalErrorHandler');

@register_shutdown_function(function() {

if(error_get_last())

echo "Script executed successfully!";

}); https://github.com/webarto/boostrap.php

Requirements (for everyone)

● Fire & forget● Minimum or zero latency● Highly available● Log everything● PSR-3 compatible

PSR-3

● monolog (PSR-3)● Drupal - PSR-3 Watchdog● phpconsole● log4php● RavenPHP + Sentry● FirePHP (dev environment)● Roll your own

Logging Options

source: http://mirror-sg-wv1.gallery.hd.org/_c/natural-science/cogs-with-meshed-teeth-AJHD.jpg.html

Capturing Logging

Use “capture methods”, send to $logger

● set_exception_handler()○ Handles all uncaught exceptions

● set_error_handler()○ Handles most errors

● register_shutdown_function()○ Handles fatal errors

Sending Log Messages

● Handler/Adapter translates● However you want…● Monolog has loads:

○ syslog-compatible / error_log○ Email, HipChat○ AMQP, Sentry, Zend Monitor, Graylog2○ Redis, MongoDB, CouchDB

Capture Method

Logger (PSR-3)

Handler / Adapter

Data Storage

Typical PSR-3 Compatible Design

Monolog\ErrorHandler->handleException()

Monolog\Logger->log()

Monolog\Handler->handle()

Monolog

Low LatencyHigh Performance

Slow Logging

ApplicationBrowser Log Server

HTTP request

Send log message to database

Error!

Acknowledge message

HTTP response to client

Zero Latency Logging (ideal)

ApplicationBrowser Log Server

HTTP request

Send log message to database

Error!

HTTP response to client

UDP?

Low Latency Logging (balance)

ApplicationBrowser Log Server

HTTP request

Send log message to database

Error!

HTTP response to client

…so how?

Say hello to RabbitMQ

RabbitMQ - Basic

source: http://www.rabbitmq.com/tutorials/tutorial-one-php.html

Producer Consumer

test_queue

1 2 3 4 5

RabbitMQ - Exchanges

source: http://www.rabbitmq.com/tutorials/tutorial-three-php.html

Exchange

Consumertest_queue

1 2 3 4 5

Consumer

Consumer

Consumer

Consumer

Using Queues === Fast!Add RabbitMQ to logging architecture...

Ed\Log\Handler\ErrorHandler->handleException()

Ed\Log\Logger->log()

Ed\Log\Publisher\AmqpPublisher->publish()

Logging Server

Low Latency (using AMQP)

RabbitMQ JSON payload

Fetch message

Low Latency Logging (with AMQP)

ApplicationBrowser Log Server

HTTP request

JSON via AMQP

Error!

HTTP response

RabbitMQ

Why bother?● Scalability

RabbitMQ

Application A

Application B

Application C

Log Worker

Log Worker

Log Worker

Log Worker

Single Point of Failure...

● RabbitMQ can do HA or clustering

RabbitMQNode 1

RabbitMQNode 3

RabbitMQNode 2

RabbitMQNode 4

RabbitMQNode 5

RabbitMQNode 6

Questions?

James Titcumbwww.jamestitcumb.comwww.protected.co.ukwww.phphants.co.uk@asgrim

Thanks for watching!