Archive for 2009

Multi-Process Plugins

Tuesday, December 15th, 2009

Yesterday I landed multi-process plugin support in mozilla-central. By default, this capability is disabled, because there are still some serious bugs. But if you are willing to suffer some temporary instability, we could really use some help testing Minefield nightlies with out-of-process plugins (OOPP).

Currently only Windows and Linux support multi-process plugins: mac support requires additional work. To turn OOPP on, visit about:config, find the pref dom.ipc.plugins.enabled, set it to true, and restart your browser. Please report any crashes or instability in bugzilla: product “Core” component “Plug-Ins”. Where possible, please be as detailed as possible in bug reports:

  • Operating system: please be specific about Windows versions, since Windows XP and Windows Vista deliver some Windows events differently;
  • Page visited;
  • Plugin data from about:plugins;
  • Whether turning IPC off fixes the problem (Note: flipping the pref usually requires restarting the browser to take effect).

There is one major known bug right now: any plugin which is installed in a path with spaces fails to load. On Windows, this affects almost everything except Flash. I hope to have this fixed in tomorrow’s nightly. There is a tracking bug for all the known issues which prevent us from turning on OOPP by default.

Please direct any questions about this work to the discussion list.

Mozilla Status Updates

Tuesday, December 15th, 2009

If you work on Mozilla, how do you coordinate with other people? How do you let people know what you’re working on and ask for help without burdening your coworkers with unwanted email? As part of coordinating the Electrolysis project, I created a webtool which allows people to post status reports in a low-touch way. The Mozilla Status Board allows members of the Mozilla community to post status updates which will be distributed to other people on their teams, and to the public.

A status report is simple: you list items that have been accomplished, what you plan to work on next. Finally, you can list items that other members of your team may need to see, such as review requests, links to posted designs, or even vacation days.

One of the important design considerations was not forcing users into one communication medium. Users group themselves into teams, and each user can decide whether to receive email updates from their team or subscribe to a web feed. For example, if you wanted to see my personal status updates, you can visit my status page or subscribe to my personal feed. And if I wanted to use a feed reader, I could subscribe to the posts of everyone on my team. Hint: to change your email settings, visit the preferences page linked from the header.

Everyone in the Mozilla community is invited to use the status board. In order to keep spammers away, registrations require a password: ask somebody who has already registered, or ask in #developers, or ask any Mozilla employee.

The status board was written in python cherrypy+genshi. The code is hosted at and I am happy to take patches or suggestions. At some point I will probably try to transfer the site from my own server to some Mozilla server, but I’ll make sure that links keep working and data is migrated.

If you’ve been using the status board already, note that I just fixed a bug in the email system: daily/weekly emails were being delivered incorrectly, so starting tonight it should work correctly.

Update: Fixed an issue where Firefox wouldn’t remember your username correctly; renamed “Tags” to “Coordination” to make its intended purpose more obvious, and enabled markdown.

Choose To Shave

Wednesday, December 2nd, 2009

Johnathan Nightingale, an otherwise upright and honorable man, is leading our world astray. In the name of freedom, adventure, and independence from societal mores, he encourages NSID: No Shaving in December.

Anyone has the freedom to shave or not-shave as they see fit, and I would not dare to take away their right. But do not be hoodwinked by this movement! At its core is not fun-loving independence and adventure. Beneath the surface, behind unshaved faces, lies a sinister purpose: to destroy the conventions upon which proper functioning of society is maintained. It may seem at first glance that shaving is merely a choice, an aspect of personal decoration. But looking deeper, we see that decoration is nothing trivial: the word “decoration” derives from the Latin “decorus”, meaning “fit” or “proper”. Abstaining from shaving is neither fit nor proper in public society, and those who choose this lifestyle should be shunned. Take a stand for decency, wholesomeness, and civic life, and shave regularly and with passion.

Freedom is good. Use it wisely. Choose to shave.

Multi-Process Fennec

Friday, October 30th, 2009

Today Joe Drew, Olli Pettay, and I have gotten Mobile Firefox (Fennec) working with a separate process for rendering. It’s a significant achievement, because even though we had to hack out some Fennec features, it’s already a fairly functional browser. Olli made a screencast showing the browser in action:

Getting Fennec working was difficult partly because the mobile Firefox code uses a different drawing system: instead of displaying a native scrollable widget, the mobile code uses a cache of “tiles” to display the web page. This allows them to display certain kinds of content over the web page, as well has have better control and speed when scrolling, zooming, and performing other interactions.

In order to get all this working with multiple processes, the group attacked pieces of the problem separately. Joe Drew implemented a new method on the canvas element: asyncDrawXULElement. This call, very similar to drawWindow, will asynchronously ask the content process to draw a tile (or part of a tile).

Olli implement various interaction fixes: forwarding mouse events from the tiles to the content process, forwarding some important events such as MozAfterPaint from the content process back to the chrome process, and fixing widget focus in the embedded browser so that keystrokes are sent to it correctly.

Finally, I modified the Mozilla frame loader and subdocument frame such that “remote frames” could work correctly even without a docshell. I then hacked up the Fennec sources so that it would also work without a docshell, mainly by commenting out the security UI and zoom-to-element features which require additional information from the content process.

Now that it’s working, we hope to be able to bring additional developers in to fix up the features which we hacked around, fix DOM features which are currently broken such as link targeting, and start getting much better measurements for interactive performance and memory usage.

Mousewheel Zoom Eureka!

Wednesday, October 28th, 2009

In Firefox, you can make the page text larger and smaller by holding down the Control key and rolling your mouse scroll wheel up and down. Before continuing to read, I want you to think about which direction makes more sense: should scrolling down make the page get bigger or smaller?


The Best Part of Being a Sister

Thursday, September 10th, 2009

A project Ellie made at school, drawing her sisters

Ellie drew this in kindergarten today. Her younger siblings, from left to right: Claire (curly hair, 4), Maddie (1), Micah (2), Ellie (5), Abigail (3), and Bekah (4 months). I love how she drew Bekah lying down, since she can’t walk yet, and how everyone else is in height order.

IPDL: The Inter-Process Protocol Definition Language

Tuesday, September 8th, 2009

IPDL is the language that Mozilla is using to describe all the messages between processes. Invented by Chris Jones, the IPDL language makes it easier for us to write type-safe and secure code by generating a lot of the basic validation code involved with messages.

When Chris was at Mozilla Headquarters a few weeks ago, he presented a tech-talk on IPDL which has been recorded and is available for download or viewing:

In the presentation, Chris explains the motivations for IPDL, demonstrates basic usage, and answers many questions about the limitations and benefits of using IPDL. I encourage anyone who is interested in Mozilla’s Multi-Process work to watch the presentation.

There are also some IPDL protocols in the tree if you’d like to read them: see the dom/ipc directory in the Electrolysis branch.

Taras Owns libjar

Wednesday, August 19th, 2009

When Taras Glek stepped up and made major improvements to the performance of libjar, we couldn’t resist making him the module owner. libjar hasn’t had an official owner for as long as I can remember. I would occasionally do reviews, as would the networking owners (biesi/bz), but the code was really orphaned code that was unmaintained. Taras is already changing that in a big way. In a quick IRC convention with Brendan today, Taras became the new owner of the JAR code. Congratulations Taras!

Why Bother With Standards?

Wednesday, August 19th, 2009

Mozilla, as an organization and product, has made implementing and developing open standards a core part of its mission from the beginning. But what is so important about standards?

I was listening to a presentation by Mitchell the other day, and one phrase in particular stood out: “Standards compliance is important because it ensures the portability of my data”. We don’t expend huge amounts of time and effort on open standards and standards compliance because of marketplace pressure. Open standards are a guarantee that the documents and data that our users are reading and writing today will continue to be available to us permanently in the future. Open standards are an essential service to the users of Firefox and to the web as a whole.

This is why Mozilla has spent so much effort implementing open video and the <video> element in HTML. And this is why open video is fundamentally better for users than Flash video or even patent-encumbered formats such as H.264.

What’s Most Important?

Wednesday, August 19th, 2009

David Brooks’ Advice for High School Graduates:

The most important decision any of us make is who we marry. Yet there are no courses on how to choose a spouse. There’s no graduate department in spouse selection studies. Institutions of higher learning devote more resources to semiotics than love.

The most important talent any person can possess is the ability to make and keep friends. And yet here too there is no curriculum for this.

The most important skill a person can possess is the ability to control one’s impulses. Here too, we’re pretty much on our own.

These are all things with a provable relationship to human happiness. Instead, society is busy preparing us for all the decisions that have a marginal effect on human happiness. There are guidance offices to help people in the monumental task of selecting a college. There are business schools offering lavish career placement services. There is a vast media apparatus offering minute advice on how to furnish your home or expand your deck.

I’ve never heard it put so succinctly.