The journey of a Symfony API from 150ms to 20ms

I have been involved in the development of an app based on symfony 2.8 which also used solr, Mongo and redis.

The problem at hand: response times were slow (see table below). With some bold objectives we went down the road.

OriginalTargetCurrent
Median15010014
Average200??20
95%200018060
99%3000300150

Start

Best practices says to enable caching, but before going there let’s try to see what can we optimize, as caching may make some things harder to discover.

At this point you should make sure that you have the proper measuring tools (APM and load testing). For this we have used jmeter and free new relic. Get some numbers before starting the process and have patience (some results will start be seen after days).

Use your DB engine properly

What i mean is for mysql/mongo for example put in place proper indexes and analyse the queries your run.
Think about that a query that you runs every few hours could lock your tables/collections for a few seconds and this could increase your response time. Our particular case was in regards to missing indexes in mongo.

Another bottleneck were the Solr query. We have made some tweaks to both schema and config of the solr it self and boom…. from calls that took 2-3 seconds… we don’t have any above 500ms (the 99% at 3000 was mostly generated by solr calls)

Use the latest versions

Or at least somewhere around :). For example our upgrade from

php5.6 to php70 has helped us with a boost of 25% (and some headaches dues to required upgrade of Mongo driver and doctrine missing native support for the new driver).

Update 2016.12.1: Someone asked about the upgrade of doctrine+mongo to PHP 7. As many may have observed already, the old driver is deprecated and doctrine-mongo-odm is not compatible with the new driver. But someone made a cool transition package (https://github.com/alcaeus/mongo-php-adapter) that worked great for us.
Another problem encountered during the upgrade of ODM was related to the field annotation, that we had to migrate from @MongoDB\String @MongoDB\Int to @MongoDB\Field(type=”string”)

upgrade Mongo from 2.4 to 3.2 – well… someone used a very old version of Mongo when the cluster was made. This was a bit tricky as we had to take the whole app down for about 1 hour as we couldn’t migrate from 2.4 to 3.2 without taking a full backup and restoring it on a new cluster.

Bundles

If you don’t need it, remove it! If you need it in development, load it just in dev/test env.

Some examples of bundles disabled on our app were:

  • SecurityBundle – our API is read-only and it’s nothing that needs to be protected (or at least you could declare a dedicated firewall for the public API sections)
  • SwiftMailerBundle
  • SensioFrameworkExtraBundle
  • TwigBundle
  • AsseticBundle

Configs

Make sure all configs are in production mode. Some examples would be:

  • make as little as possible IO (also consider logs in the process)
  • Doctrine makes a lot of cache files for metadata. Put it in APC/APCU.
    doctrine_mongodb:
        connections:
            default:
                server: mongodb://%mongo_servers%
                options:
                    connect: true
                    connectTimeoutMS: 300
        default_database: %database_name%
        document_managers:
            default:
                metadata_cache_driver: apc
                retry_connect:              1
                retry_query:                1
                auto_mapping: true
  • persistent connections where possible (we had some problems with redis after doing this, because we were using 2 databases for different purposes and switching dbs… was a nightmare)
  • Make sure you read from slaves. (we were killing the Mongo master because of this)
    • Here we need to control when to read from slave… so we haven’t allowed it by default, but we enabled it on demand:
      $container->get('doctrine_mongodb')->getManager()->getClassMetadata('<Entity Name>')->slaveOkay = true
  • Try to consider what the timeout of the clients are and use them in your app. If you know your client is ignoring your response, why bother completing the entire request (example: timeout -300ms, but a internal http call takes 3000ms. This would keep you busy for nothing )

Queue it!

If you don’t need something now, just put in a queue and continue with serving requests. Write operations (to db or disk) are usually heavier than putting it on a queue and handling it on a separate server.

We use RabbitMQ with this bundle: https://github.com/php-amqplib/RabbitMqBundle

Twig

It’s an API and we chose to have twig enabled only in dev environment (so that we can have the profiler work). 🙂

Try to use php directly, but if you can’t live without it, at least install php twig extension (brings some boost in performance)

Container / DI

Here we also did a little comparison with other bare frameworks like slilex. We choose to stay with symfony as the performance penalty was minor compared with the advantages:

  • yml configs were actually cached as php code at deploy
  • yml errors were caught during deploy phase (at cache warmup) and faulty containers can not be released live
  • Personally I started to use a lot ContainerPass’es and also “tags”
  • We already knew how to define and use services in symfony and brining a new framework make lead to some beginner mistakes.

Cache

This was one of the final steps we added. A few tricks to be considered here:

  • Make sure your connection to the cache server is persistent
  • Consider with what TTL you should cache (depending on change freq). If you have a large data set and freq updates on various events, you can set a high TTL and make the update process to also flush the cache
  • you can try multi level caches if you need it (apc + memcache), but it will also generate some headaches
  • To avoid complicated logic inside your methods you could use a cool caching bundle: https://github.com/eMAGTechLabs/cachebundle
  • You might have a lot of cache evictions due to large cache.
    • Try to reduce the size of caches (is it really required that often?)
    • Add additional capacity to the caching server.

Nginx / FPM config

Here we did some changes after we discovered that under high load we had increased response time, but our servers were free (CPU and memory). We have increase the number of worker/child processes for both nginx and php-fpm and this allowed us higher load.

PHP 7

I have recently upgraded one of work project to PHP 7. What a bliss… Just by upgrading we have managed to reduce response time for Symfony based API from 100ms to 75ms (25% boost). (Note: responsibility of the decreased timing might also be from some updated libraries and drivers)
I have also managed to upgrade the present blog to the new PHP version and a similar improvement was observed.

Other major improvements from my perspective:

  • Strong type return methods (this can help increase the code quality and will help resolve some bugs in some early stages). I was a bit disappointed that overloading is still not available.
  • Syntax errors are now catchable

iPad from Apple

Recently Apple sent to market iPad, that wants to be a mobile device and most probably to replace Amazon’s Kindle. We can not state that it’s a computer or tablet pc as it’s operating system it’s almost the same as the one that is on iPhone.

At first look it looks nice, works great(as any other machine with OSX on it), has a bunch of great features, bit it will not replace desktop computers. If we look closer we can say that it’s a bigger iPhone(almost same features and interface, but with bigger screen, bigger processor and much more memory).

Power of farcry cms [Coldfusion post]

A few months ago i received the task for developing an website/webapplication for eeStec LC Bucharest. Altought is not ready yet i’m able to say the Farcry was able to help me very much.

First of all Farcry is CMS(Content Management System). This was very usefull b/c i’m able to have the static pages of the site quite quick ready.

We also needed to manage various information types (LCs, members, logins, events, news). Facry made my work very easy. How? All it was needed to be done was to create a cfcomponent(a class, a component). After that farcry created for me database structure, admin interface and some basic display ways for that objects.

You can have a look here. Don’t blame for the design.

Also if you are searching for an alternative to Coldfusion(it has a preety expensive license cost), you can always use Ralio.

Back to windows or upgrade to windows 7

From last time i wrote this many things have happended. Due to the fact it was neccesary to switch back to windows i decided to go with the lastest version: 7RC. It’s a decision that sometimes i regret (stupid firewall and the fact that it comes with IIS installed by default and i can’t use apache for developement on port 80), but it was a must.

I’m back

Missed me? I hope you did.
Some news about me and my activity in the past 2 months:
– i’m the newest employee of lunarpages.com. Last night i had to read the introduction part regarding the things i will have to do there and i am pretty tired.
– i also managed to convince my father that he should let me drive again, but not for a long time because i hope i will be able to take my own car.
– bumbacea.ro is not longer registered via mydomain.ro(aka Vodafone RO) and i succeed to drop all the restrictions i had there
– i’m thinking of buying a new desktop because i need it for work.
– i was the eestec-er of the week
That’s all for now… i don’t know when i will be back again, but i hope we’ll meet again in short time. 😉
Take care of you and see you soon. 😀

P.S. from now on i will be writing only in english

XSS

Azi am intrat pe blogul unui coleg care a descoperit niste brese in scriptul unui site…
tin sa il anunt ca atat timp cat nu are acces la DB, nu e chestie de securitate. Cateva dintre linkuri le-am verificat si eu, insa nu am reusit sa capat acces la db. Singura chestie care a uitat saracul programator sa o faca era un html_eneties();