Load tests for the real world

The gold standard for systems performance measurement is a load test, which is a deterministic process of putting a demand on a system to establish its capacity. For example, you might load test a web search cluster by playing back actual logged user requests at a controlled rate. Load tests make great benchmarks for performance tuning exactly because they are deterministic and repeatable. Unfortunately, they just don’t work for some of us.

At Foursquare, we push new versions of our application code at master/HEAD to production at least daily. We are constantly adding features, tweaking how old features work, doing A/B tests on experimental features, and doing behind-the-scenes work like refactoring and optimization to boot. So any load test we might create would have to be constantly updated to keep up with new features and new code. This hypothetical situation is reminiscent of bad unittests that basically repeat the code being tested — duplicated effort for dubious gain.

To make things even worse, a lot of our features rely on a lot of data. For example, to surface insights after you check in to a location on Foursquare we have to consider all your previous check-ins, your friends’ check-ins, popular tips at the venue, nearby venues that are popular right now, etc. etc. Creating an environment in which we might run a meaningful load test would require us to duplicate a lot of data, maybe as much as the whole site. A lot of data means a lot of RAM to serve it from, and RAM is expensive.

So we usually choose not to attempt these “canned” load tests. In lieu of a classic load test, our go-to pre-launch performance test is what we call a “dark test.” A dark test involves generating extra work in the system in response to actual requests from users.

For example, in June 2012, we rolled out a major Foursquare redesign in which we switched the main view of the app from a simple list of recent friend check-ins to an activity stream which included other types of content like tips and likes. Behind the scenes, the activity stream implementation was much more complex than the old check-in list. This was in part because we wanted to support advanced behavior like collapsing (your friend just added 50 tips to her to-do list, we should collapse them all into a single stream item).


Before and after the redesign

Perhaps surprisingly, the biggest driver of additional complexity was the requirement for infinite scroll, which meant we needed to be ready to materialize any range of activity for all users. Since the intention was for the activity stream to be the main view a user sees upon opening the Foursquare app, we knew that the activity stream API endpoint would receive many, many requests as soon as users started to download and use the new version of the app. Above all, we did not want to make a big fuss about this great new feature and then give our users a bad experience by serving errors to them when they tried to use it. Dark testing was a key factor in making the launch a success.

The first version of the dark test was very simple: whenever a Foursquare client makes a request for the recent check-ins list, generate an activity stream response in parallel with the recent check-ins response, then throw the activity stream response away. We then hooked this up to a runtime control in our application which permitted it to be invoked on an arbitrary percentage of requests, so we were able to generate this work for one percent, five percent, 20 percent, etc. of all check-in list requests. By the time we were a few weeks out from redesign launch, we were running this test 24/7 for one-hundred percent of requests, which gave us pretty good confidence that we could launch this feature without overloading our systems.

Click here to read the full post.

- Cooper Bethea (@cooperb)

Native app integration like never before: The Foursquare for BlackBerry 10 SDK

Yesterday, BlackBerry announced their first BB10 devices. We here on the BlackBerry team at Foursquare are really excited about the launch and wanted to give our awesome third party developers something to help them get the most out of Foursquare and BlackBerry 10. With the help of the amazing Invocation Framework (learn more here) we have opened up a few parts of the Foursquare for BlackBerry 10 app to developers to enrich their native apps with Foursquare content easier than ever before. Check out the two examples below and then head over to GitHub to check out our sample app and get started.

Foursquare Single Sign On (SSO)
The first thing we’ve opened up, and a personal favorite, is the ability for your users to connect their Foursquare accounts with the click of a button. Instead of every app having to make their own WebView wrapper solution to the OAuth flow for obtaining an access token, we’ve built it right into the native Foursquare app for everyone to use. You can now let a user login to your app through Foursquare in 6 lines of code, and the user never has to leave the context of your app.

It is up to the user whether to approve or deny your app. We will send their action back to you, along with the access token if they decided to link their Foursquare account with your app.


Easy as that! So be sure to include a “connect with Foursquare” option in your app to reduce friction for new users signing up!

Foursquare Place Picker
More and more often the most engaging content that users can create comes with a location attached to it, whether that’s a picture posted on Instagram or a beer being checked into on Untappd. With the place picker api, you can build this rich content into your app built on the power of the over 50 million places in the Foursquare database. The best part about this is that just like the SSO api, you get the native Foursquare UI, network requests and GPS functionality built into your app without having to write any of it. Just use the invocation framework to launch it. If you know what your user is looking for already, you can pass in a query to prime the search with and if you have already authenticated a user, just pass in their token for personalize results!

Once a user selects a place, we’ll return back to you the JSON data for that place that you can process and then do whatever you need to do with it!


Kyle, Foursquare BlackBerry Engineer

The Opportunity Gap: learn about the public schools in your neighborhood with @ProPublica and Foursquare

As our recent hackathon showed, there are tons of ways that developers can use Foursquare to power amazing apps – from ones that shame you into going to the gym, to others that alert you to restaurants with health code violations.

Today, ProPublica, an award-winning investigative journalism site, is relaunching its Opportunity Gap news application, which helps people find and compare statistics about public schools across the nation. With their new Foursquare integration, you can connect your Foursquare account to instantly see statistics for schools you’ve checked in to before. And when you’re out, you can instantly get stats about a school on your phone whenever you check in to one. It’s a great example of how news organizations can use Foursquare to reach their readers with relevant information when they’re out in the real world.


Learn more about The Opportunity Gap and connect your Foursquare account here.

A Foursquare Hackathon for the new year – sign up and build the next amazing hack!

And take two! Although Sandy foiled our hackathon plans in November, we’re back and ready to hack it up with the best and brightest. On January 5, we’re inviting developers and designers in NYC, SF, and everywhere around the world to sign up and build some more amazing hacks using the Foursquare API. We’ll have prizes, swag, and (naturally) global glory for the best Foursquare hacks, no matter where in the world they originate.

Head over to our Meetup page and keep an eye on hackathon.foursquare.com for more details as the event draws nearer. If you’re in SF or NYC, sign up to work from our HQ, otherwise, you can use Meetup to connect with hackers in your area.

(Fun fact: back in 2010, two designer/developer friends got together and entered the first Foursquare hackathon. They built a snazzy little hack that took people’s Foursquare check-in histories and resurfaced them in the form of a daily email that showcased people’s check-ins from exactly one year ago. They dubbed their hack, “4SquareAnd7YearsAgo,” and today you might know it as Timehop.)

Now, go sign up for the Foursquare Hackathon 2013!

MongoDB at Foursquare: From the the cloud to bare metal

We’ve been running Mongo as our main storage engine for almost 3 years. For most of that time the Mongo servers and all the rest of our infrastructure were hosted on Amazon’s EC2. We recently migrated the Mongo servers onto our own hardware hosted in a datacenter and now have a hybrid environment with everything else still on EC2. I’ll be talking about why and how we did this at the upcoming MongoSV conference on Tuesday, December 4th, 2012.

The name of the talk is “MongoDB at Foursquare: From the the cloud to bare metal.” Come check it out!

For more information about the event, check out the agenda or 10gen’s blog post Get Ready for MongoSV. Register now with the discount code “foursquare20” and receive 20% off.

- Jon Hoffman (@hoffrocket)

Even more ways to personalize Foursquare – check out the latest additions to our app gallery

Want to know if there’s a teaser after the movie credits, or the healthiest dish to order at a restaurant? There are a bunch of apps you can connect to your Foursquare account to help you make the most of your check-ins. Our gallery keeps growing – check out some of the latest additions:

  • The Winester Square – it’s like Untappd for wine! Learn about the reds and whites on the menu after you check in.
  • YOLO tells you the most expensive item on the menu.
  • #mom helps you quickly let your mom know that you’re safe and sound with a call or text when you check in.
  • GeoPollster will tell you which political party the businesses you check in at support.

To connect these and other apps to your Foursquare account, go to our app gallery at Foursquare.com/apps or the settings screen in the Foursquare app on your phone. Got an idea for an app? Build one (and win prizes!) at our upcoming Global Hackathon on November 3.

Open-sourcing our dashboard for Apache Oozie

At Foursquare, we use Apache Oozie to manage the scheduling and control of our offline data processing workflows. We’ve had great success with the project, and we run upwards of 1000 Oozie workflows per day.

Despite the quality of Oozie’s core workflow engine, the web UI is a little clunky, and is franky unusable in a lot of circumstances, especially when you’re using it at a moderate scale.

Thankfully, every few months, Foursquare hosts internal hack days. The idea is that every engineer has 1-2 days to build something cool that they otherwise wouldn’t have a chance to work on.

This time, we decided to build a bunch of tooling for Oozie. One particular tool was a new web dashboard. It’s built using Scalatra and Twitter Bootstrap, and we unimaginatively called it “Oozie Web.”

The dashboard behaves like a normal website (unlike the default dashboard), so we could integrate a bunch of features that were unavailable to us in the bundled dashboard. Specifically:

  • Unique URL’s for coordinators, and workflows
  • Proper ordering of coordinator / workflow actions
  • Syntax highlighting of job definition and configuration files
  • Coordinator actions link to their corresponding workflows
  • Workflow actions link to their corresponding hadoop jobs
  • Re-run failed coordinator actions with a single click.
  • A better search implementation that matches substrings in workflow names

We’ve been using Oozie Web internally for a couple of months now, so we figured it was about time to make the project open-source and give back to the community. We’re releasing the project under the Apache 2.0 license, and it’s available right now on github: http://github.com/foursquare/oozie-web

- Joe Crobak (@joecrobak), Joe Ennever (@TDJoe), and Matthew Rathbone (@rathboma)

Big Data and the Big Apple: Understanding New York City using Millions of Check-ins

Last Friday, I spoke at DataGotham about how foursquare data can provide an unprecedented view into the behavior of cities. In this talk, I focus on what we can learn about New York City from aggregating the check-ins of millions of New Yorkers, and demonstrate tools that we are building to help make cities, like New York, easier to use.

- Blake (@metablake)

Connect all the apps! Dig into our new connected apps platform at our 2012 hackathon

You guys! The foursquare hackathon is back! And this year, we’re inviting you to hack foursquare itself. Our all-new Connected Apps platform enables you to wire new functionality directly into the core foursquare experience and make your app discoverable to the over 20 million people already on foursquare.

On November 3, we’ll open up our NYC & SF offices for an all-day Connected Apps hackathon. And like last year, we’re inviting developers all around the world to band together and hack up some awesome connected apps. We’ll have great prizes (last year one of the winning teams had their hack running on a giant screen in Times Square and even rang the closing bell for NASDAQ! Oh, and there’s a new title belt!), swag, and (naturally) global glory for the best foursquare hacks, no matter where in the world they come from.

To sign up, head over to our Meetup page and keep an eye on hackathon.foursquare.com for more details as the event draws nearer.

Ready? Set? Connect all the apps!

Developers, grow your numbers! Connected app success stories from our pilot partners

We’ve seen some amazing new apps built since we released the developer preview of our new connected apps framework two months ago. We’re continuing to make improvements, and we can’t wait for the official launch of our App Gallery to our entire community in the coming months.

Connected apps are great for both developers and the foursquare community. For people checking in, connected apps make foursquare more interesting and customized. For developers, connected apps provide an opportunity for more people to discover and engage with your timely and targeted content. 

The connected apps effect
Our connected apps launch partners have seen significant jumps in sign-ups and downloads, increased engagement, greater exposure to new audiences, and spikes in web traffic. Here’s what some of them had to say:

The Snoball connected app lets people set-up a donation to trigger when they check in to a specific place on foursquare. For example, a person can pledge $1 to charity:water when they check in to their favorite coffee house.

“Since the app’s July launch, the number of check in-based donations within Snoball has increased by 500%, while nonprofits within the platform saw a 40% increase in donations through Snoball with an average donation of $2 per check-in.” – Todd Graves, Software Developer at Snoball

Untappd gives beer recommendations to people who check in to a bar and makes it easy to track the beers they drink.

“Through the foursquare connected app, we saw a 10% increase in sign-ups for Untappd and that 10% of all replies sent to the user turned into a beer check-in. Most importantly, our users have told us how much they love getting great recommendations about beer choices while at their favorite establishments, without leaving the foursquare app.” – Greg Avola, Co-Founder of Untappd

Eat This, Not That
Eat This, Not That recommends the healthiest dishes to order when people check in to restaurants.

“Our goal in this partnership was to deliver quality information that is relevant to our viewers when they need it most. We provided the editorial content and foursquare provided the technology… Viewers are literally sitting at these restaurants, checking in, and looking at a list of menu options (usually without calorie counts); serving them helpful tips on what to order (and what to stay away from) is not only timely, but extremely useful.

We plan on launching a second connected app this year with Women’s Health, which will deliver content to its health-conscious readers in the nutrition/fitness category.” – Jackie Lebowitz, Special Projects Editor at Men’s Health

Sonar lets users know when their friends and other interesting people who share interests and connections are nearby.

“The impact of being a part of foursquare’s connected apps pilot has been fantastic. We’ve been able to attribute increases across all the standard metrics we track daily to our presence within foursquare, including downloads and engagement. On some days we’ve seen downloads from foursquare as much as doubling our daily download numbers, and we’ve seen a 6000% increase in website traffic sent from foursquare. We’ve also noticed a jump in downloads in new markets where foursquare has a high penetration, including Turkey, Russia and Brazil.” – Katie Smith-Adair, Vice President at Sonar

Want to build a connected app, or have one you’d like us to feature? Learn more or submit your app to be featured in our Connected Apps Gallery.