Building Carousel, Part I: How we made our networked mobile app feel fast and local

When we began the journey of building a mobile app for Dropbox a few years ago, we started simple — our Android and iOS apps allowed our users to view their files on the go, and cache them for offline access. As smartphones became more popular, we realized we could provide another great service on mobile: automatic backup of all the photos and videos taken on these devices, so they’d be safe forever in Dropbox.

Last Wednesday, on April 9, we took another giant leap forward with the introduction of Carousel. Carousel is a single home for all your photos and videos,

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Introducing Pyston: an upcoming, JIT-based Python implementation

Hello everyone, I’m very excited to announce Pyston, a new open-source implementation of Python, currently under development at Dropbox.  The goal of the project is to produce a high-performance Python implementation that can push Python into domains dominated by traditional systems languages like C++.

Here at Dropbox, we love Python and try to use it for as much as we can.  As we scale and the problems we tackle grow, though, we’re starting to find that hitting our performance targets can sometimes become prohibitively difficult when staying on Python.  Sometimes, it can be less work to do a rewrite in another language.  

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Video Processing at Dropbox

Every day millions of people upload videos to Dropbox. Besides wanting their memories safe forever, they also want to be able to watch them at any time and on any device. The playout experience should feel instant, despite the fact that the content is actually stored remotely. Low latency playback of content poses interesting technical challenges because of the three main factors below.

1. Codec diversity

Most end users are familiar with extensions like .mp4, .avi, .flv, but not everybody is familiar with the fact that the file extension does not necessarily match the internal encoding of the content.

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Improving Dropbox Performance: Retrieving Thumbnails

Dropbox brings your photos, videos, documents, and other files to any platform: mobile, web, desktop, or API. Over time, through automatic camera uploads on iOS and Android, you might save thousands of photos, and this presents a performance challenge: photo thumbnails need to be accessible on all devices, instantly.

We pre-generate thumbnails at various resolutions for the different devices at upload time, to reduce the cost of scaling photos at rendering time. But when users are quickly scrolling through many photos, we need to request a large number of thumbnails. Since most platforms have limitations on the number of concurrent requests,

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Outage post-mortem

On Friday evening our service went down during scheduled maintenance. The service was back up and running about three hours later, with core service fully restored by 4:40 PM PT on Sunday.

For the past couple of days, we’ve been working around the clock to restore full access as soon as possible. Though we’ve shared some brief updates along the way, we owe you a detailed explanation of what happened and what we’ve learned.

What happened?

We use thousands of databases to run Dropbox. Each database has one master and two replica machines for redundancy.

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Dropbox Status Update

UPDATE 1/12 at 7:23pm PT: Dropbox should now be up and running for all of you, but we’re working through a few last issues with the Dropbox photos tab.  More info on our main blog and the latest post here.

UPDATE 1/12 at 1:59pm PT: Hi everyone, we wanted to give an update on where things stand.

As of this morning at 4:10am PT, nearly all users (over 99%) can access their files on The Photos tab is still turned off, but you can access your photos via the Files tab on or the desktop client.

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