Canonical Voices

Posts tagged with 'launchpad'

Vincent Ladeuil

The package importer is an important piece of the Ubuntu Distributed Development. It mirrors source packages and Bazaar branches and relies heavily on Launchpad to achieve that.

The past

During Launchpad downtimes, many (>1000) imports failed and they had to be re-queued semi-manually. The importer would have been better inspired by making tea instead of queuing imports that were bound to fail.

The circuit breaker

An automatically operated electrical switch designed to protect an electrical circuit <…> a circuit breaker can be reset (either manually or automatically) to resume normal operation.

This looks like a good candidate to avoid import failures while Launchpad is down.

In this automaton representing the behaviour of a circuit breaker, three events are used (remember that here closed == works ;)):

  • attempt: we try to use the circuit,
  • failure: an undesired event has occurred,
  • success: the circuit is working.

The main scenario here is:

closed — failure –> open — attempt –> half open — success –> closed

The reality test

A Launchpad rollout happened Friday 30 September 08:32. The importer log file said:

2011-09-30 08:32:02,308 – __main__ – INFO – Launchpad is down, re-trying jcifs

2011-09-30 08:34:09,337 – __main__ – INFO – Launchpad *is* back

The successful import took 27″, so the importer knew Launchpad was down for 1’40″ (back – down – duration(import)). I asked the Launchpad admins how long it took them and their log said:

2011-09-30 08:33:41 INFO    Outage complete. 0:01:40.919527

Make tea… or not

Another interesting number here is that we retried 498 times during this downtime. This is probably excessive and can be fixed by reducing the importer concurrency while Launchpad is down. These 498 attempts were previously seen as failures for 498 different packages.

In the end, not only did we avoid these 498 spurious failures but the imports were only suspended for as long as Launchpad was down, up to the second !

But that’s a bit short to make tea…

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Martin Pool

I’ve worked with Robert Collins for the last 5 years or so at Canonical, and it’s been a real pleasure. Now Robert’s moving on to a great new rôle at Canonical, as technical architect of Launchpad. I can’t think of a better job for him, or a better person for the role, and it’s already paying off through Launchpad becoming faster (shorter page timeouts and hitting them less often) and I think more fun to work on. (See also his stump speech.)

Now we’re looking for a very good software engineer to join the Bazaar team at Canonical, working both on the core tool itself and on how it’s used by Ubuntu developers. We would love to get more applications from people with packaging or distro experience. I want to work with someone who’s very driven, who’ll reach out to their users and not wait to be told what to do, someone who knows the whole environment we work in, and someone who cares about doing good things.


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Martin Pool

Review of Launchpad and Bazaar on ArsTechnica by the lead developer of gwibber.

  • Likes the way the bzr client feeds into the web ui, by setting bug links etc
  • Easy automatic imports from cvs, svn, git and hg, either for a one-shot cutover or continuing tracking
  • More powerful bug tracking than github
  • Loggerhead feels slow and poorly integrated with Launchpad, but qbzr is brilliant
  • Merge proposals good for tracking contributions

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Ian Clatworthy

One of the primary reasons why Bazaar exists is that Canonical wants to make it as easy as possible for more people to contribute to FOSS (Free and Open Source Software) projects. After many years of development, the pieces of the puzzle are really falling into place nicely. See the tutorial I put together last week to see just how easy it can be.


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