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Open Source Bridge: the aftermath

By Selena Deckelmann
June 24, 2009

Open Source Bridge Opening Day

I’ve been planning the Open Source Bridge conference in my spare time over the past 9 months here in Portland, OR. We finally made it happen June 17-19, 2009 at the Oregon Convention Center. I had the pleasure of co-chairing the event with Audrey Eschright, and was extremely happy that End Point decided to also sponsor the event.

The conference was organized around the idea of “open source citizenship”, and what things we as individual contributors, companies and users of free and open source software do to participate. We came together to share how we do things, what we’ve already done, and what we might be doing in the future.

The conference held 76 sessions, from over 100 speakers and panelists and 475 total participants over three days. There were 8 rooms full of talks for about 9 hours every day. We had a 24-hour hacker lounge at the conference hotel, and it was packed every evening—​including our closing night, when we wrapped right at midnight.

Above, are my slides for the opening remarks, and there’s even a video of the opening session, the keynotes and all the sessions that happened in the Fremont room will be available at osbridge.blip.tv. …

Getting Started with Demand Attach

By Steven Jenkins
June 23, 2009

As OpenAFS moves towards a 1.6 release that has Demand Attach Fileservers (DAFS), there is a need to thoroughly test Demand Attach. Getting started can be tricky, so this article highlights the important steps to configuring a Demand Attach fileserver.

OpenAFS CVS HEAD does not come with Demand Attach enabled by default, so you’ll need to build your own binaries. You should consult the official documentation, but the major requirement is to pass the –enable-demand-attach-fs option to configure. You should also note that DAFS is only supported on namei fileservers, not inode.

Once you’ve built and installed the binaries, you need to be careful to remove your existing fileserver’s bos configuration (i.e., fs) and put a dafs one in place; e.g.,

$ bos stop localhost fs -localauth
$ bos delete localhost fs -localauth

Once the fs bnode is deleted, you need to install the new binaries and create the dafs entry. You should pass your normal command line arguments to the fileserver and volserver processes:

$ bos create localhost dafs dafs "/usr/afs/bin/fileserver -my-usual-options" \
    /usr/afs/bin/volserver \
    /usr/afs/bin/salvageserver /usr/afs/bin/salvager

Once the …

Packaging Ruby Enterprise Edition into RPM

By Adam Vollrath
June 16, 2009

It’s unfortunate that past versions of Ruby have gained a reputation of performing poorly, consuming too much memory, or otherwise being “unfit for the enterprise.” According to the fine folks at Phusion, this is partly due to the way Ruby does memory management. And they’ve created an alternative branch of Ruby 1.8 called “Ruby Enterprise Edition.” This code base includes many significant patches to the stock Ruby code which dramatically improve performance.

Phusion advertises an average memory savings of 33% when combined with Passenger, their Apache module for serving Rails apps. We did some testing of our own, using virtualized Xen servers from our Spreecamps.com offering. These servers use the DevCamps system to run several separate instances of httpd for each developer, so reducing the usage of Passenger was crucial to fitting into less than a gigabyte of memory. Our findings were dramatic: one instance dropped 100MB down to 40MB. (The status tools included with Passenger were very helpful in confirming this.)

There has been some discussion on the Phusion Passenger and other mailing lists about packaging Ruby Enterprise Edition for Red Hat Enterprise Linux and its derivatives …

Inside PostgreSQL - Clause selectivity

By Josh Tolley
June 5, 2009

One of the more valuable features of any conference is the so-called “hall track”, or in other words, the opportunity to talk to all sorts of people about all sorts of things. PGCon was no exception, and I found the hall track particularly interesting because of suggestions I was able to gather regarding multi-column statistics, not all of which boiled down to “You’re dreaming—​give it a rest”. One of the problems I’d been trying to solve was where, precisely, to put the code that actually applies the statistics to a useful problem. There are several candidate locations, and certainly quite a few places where we could make use of such statistics. The lowest-hanging fruit, however, seems to be finding groups of query clauses that aren’t as independent as we would normally assume. Between PGCon sessions one day, Tom Lane pointed me to a place where we already do something very similar: clausesel.c

“Clause selectivity” means much the same thing as any other selectivity: it’s the proportion of rows from a relation that an operation will return. A “clause”, in this case, is a filter on a relation, such as the “X = 1” and the “Y < 10” in “WHERE X = 1 AND Y < 10”. PostgreSQL uses …

Using the new-style Google Analytics pageTracker functions in Interchange

By Richard Templet
June 5, 2009

For a while now there have been two different ways to setup the JavaScript calls to report traffic back to Google Analytics. The older method uses functions names that mention “urchin,” while the newer method uses a function named “pageTracker”. This post describes an approach for using the new method at a standard Interchange store.

You can see an example of the new method of reporting a page view here. Nothing Interchange-related is required for normal page tracking, but you may want to use a variable for the Google Account Number, of which more below.

If you have your Google Analytics account setup to treat the website as an E-commerce site, then you can also add the order tracking tags to your receipt page, so that it sends order data over to Google Analytics at the time of conversion. The order tracking tags can be viewed here. This gist shows the typical Interchange tags you might want to use to transmit the order specifics. Of course you might need to change the field used for the category for the products since not everyone uses the prod_group field from the products table to hold this information.

As you can see, both normal and the order-conversion scripts need to be …

The importance of offline community

By Selena Deckelmann
June 1, 2009

Today, the June issue of the Open Source Business Review debuts. It features nine women who are active in open source development—​as developers, organizers and business leaders.

I wrote about offline community, and how techies in Portland, OR manage to get connected to each other, and how they’ve encouraged participation from women. You don’t often find women at a user group or even a tech-focused meetup at a restaurant or bar. Portland, somehow, has managed to encourage the women in the community to participate and lead. I talk about what I think the factors were that led to the higher percentage of women involved in the community today.

Let me know what you think!

Git rebase: Just-Workingness Baked Right In (If you’re cool enough)

By Ethan Rowe
May 28, 2009

Reading about rebase makes it seem somewhat abstract and frightening, but it’s really pretty intuitive when you use it a bit. In terms of how you deal with merging work and addressing conflicts, rebase and merge are very similar.

Given branch “foo” with a sequence of commits:

foo: D --> C --> B --> A

I can make a branch “bar” off of foo: (git branch bar foo)

foo: D --> C --> B --> A
bar: D --> C --> B --> A

Then I do some development on bar, and commit. Meanwhile, somebody else develops on foo, and commits. Introducing new, unrelated commit structures.

foo: E --> D --> C --> B --> A
bar: X --> D --> C --> B --> A

Now I want to take my “bar” work (in commit X) and put it back upstream in “foo”.

• I can’t push from local bar to upstream foo directly because it is not a fast-forward operation; foo has a commit (E) that bar does not.
• I therefore have to either merge local bar into local foo and then push local foo upstream, or rebase bar to foo and then push.

A merge will show up as a separate commit. Meaning, merging bar into foo will result in commit history:

foo: M --> X --> D --> C --> B --> A
      \
       E …

PostgreSQL with SystemTap

By Josh Tolley
May 28, 2009

Those familiar with PostgreSQL know it has supported DTrace since version 8.2. The 8.4beta2 includes support for several new DTrace probes. But for those of us using platforms on which DTrace doesn’t exist, this support hasn’t necessarily meant much. SystemTap is a relatively new, Linux-based package with similar purpose to DTrace, available on Linux, and is under heavy development. As luck would have it, PostgreSQL’s DTrace probes work with SystemTap as well.

A few caveats: it helps to run a very new SystemTap version (I used one I pulled from SystemTap’s git repository today), and in order for SystemTap to have access to userspace software, your kernel must support utrace. I don’t know precisely what kernel versions include the proper patches; my Ubuntu 8.04 laptop didn’t have the right kernel, but the Fedora 10 virtual machine I just set up does.

Step 1 was to build SystemTap. This was a straightforward ./configure, make, make install, once I got the correct packages in place. Step 2 was to build PostgreSQL, including the –enable-dtrace option. This also was straightforward. Note that PostgreSQL won’t build with the –enable-dtrace option unless you’ve already …