In IE8 and Chrome, Processes Are the New Threads

SenFo writes "To many of the people who downloaded Google Chrome last week, it was a surprise to observe that each opened tab runs in a separate process rather than a separate thread. Scott Hanselman, Lead Program Manager at Microsoft, discusses some of the benefits of running in separate processes as opposed to separate threads. A quote: 'Ah! But they're slow! They're slow to start up, and they are slow to communicate between, right? Well, kind of, not really anymore.'"

Comments

Re:Processes in Vista

[bluefoxlucid]

The basic reasoning goes that Linux has an awesome processes model because its thread model sucks,

NPTL has scaled to hundreds of millions of threads created in under 10 seconds on common hardware....

Re:Chrome = slow as hell

[B3ryllium]

"to load 8 sites" ... 8 sites that you visit frequently and thus have cached on your Firefox installation, perchance?

Don't be so rash to judge. Chrome has many other areas where it lacks compared to Firefox, speed isn't generally one of them. I've heard many users say that it loads pages more than twice as fast as Firefox, and also scrolls much faster on graphical/data-intensive pages.

The lack of extensions (such as adblock, firebug/firephp, flash block, noscript, coloured tabs) is the main reason why I've barely used it since I installed it.

Re:Could someone give the gory details

[Shin-LaC]

I went looking for the same information earlier today. Surprisingly, the design document titled "How Chromium Displays Web Pages" doesn't shed any light on that, at least at this time. You have to dive into the source to find out.

Basically, a single process (the one main browser process) owns the window and draws to it. Renderer processes draw their web content into shared memory; the browser process then transfers the data into a backing store, which it uses to paint the window. The process is coordinated via inter-process message-passing (using pipes, it seems), but the rendering output travels via shared memory.

Re:Processes

[jc42]

Running each instance in a seperate process is NOT new technology

Well of course. It isn't even new in the browser world. In fact it's where we started.

And, as us old-timers know, this architecture was the basis of the original Bell Labs unix system, back in the 1970s. Lots of little, single-task processes communicating via that newfangled sort of file called a "pipe". That was before the advent of our fancy graphical displays, of course.

Somewhat later, in the mid-1980s when we had graphical displays, the tcl language's tk graphics package encouraged the same design by adding to the usual unix-style pipes and forked processes. The language had a simple, elegant "send" command that would let a sub-process run arbitrary commands (typically function calls) inside the parent process using the sub-process's data. The idea was that you have a main process that is responsible for maintaining the on-screen window(s), but the work is done by the sub-processes. This design prevented blocking in the GUI, because the actions that would block were done in the other processes. The result was a language in which GUI tools could be developed very quickly, and would take maximal advantage of any parallelism supplied by the OS.

But that was all decades ago, before most of our current programmers had ever touched a computer. Imagine if we only knew how to design things that way today. Is it possible that current software developers are rediscovering this decades-old sort of design?