Gerrit User Summit 2021: how to tackle big mono-repos

GerritForge keeps working to improve performance using Gerrit with very large mono-repos with millions of refs, hundreds of GBs and tens of millions of objects.

On the second day of the virtual Gerrit User Summit 2021, Luca will present the work done over the past two years to overcome significant difficulties when:

  • Reducing the overhead of refs advertisement
  • Speeding-up clones by a 10x factor
  • Reducing the system load when accessing change notes
  • Increasing performance of replication
  • Surviving the deadly “search-for-reuse” phase during git-upload-pack

Register here to join the user summit on December 2nd and 3rd.

Happy New Year, Gerrit Code Review

It has been a hectic and productive year for ourselves at GerritForge and the Gerrit Code Review Community.
We want to take this opportunity to recap some of the milestones of the 2019 and the exciting perspectives for 2020 and beyond.

Gerrit Code Review, 2019 in numbers

gerrit-2019-commits.png

Gerrit had over 120+ contributors from all around the world coming from 33 different companies and organisations, which is excellent. There is a robust 6% increase in the number of commits (+231 commits) but a reduction in the number of contributors (-7 authors).

With regards to the overall trend of commits during the year, the success of the Gerrit User Summit 2019 in Sunnyvale is visible, with an increase of the rate of commits around October/November.

Top-three projects of the 2019

  1. Gerrit (1,626 commits) is, of course, the most active project. However, it is visibly down in terms of number of commits from 2018 (-19%). That is a consequence of the shift of focus to the other two key components listed below, which are available as plugins and then not accounted for the overall gerrit core repository statistics.
  2. Checks (315 commits) is the brand-new 1st class CI integration API for external build systems, such as Jenkins and Zuul. It is incredible how in just 12 months it has become robust and fully mature. It is currently used for the validation of all changes on the Gerrit project.
  3. Multi-site (234 commits) is the long-awaited support for Gerrit that everyone has been waiting for years. It is finally available for all active and supported versions (from 2.16+ onwards).

Top-three companies contributing to Gerrit

gerrit-contributors-2019.png

  1. Google is, with no surprise, still the top contributor of the Gerrit project overall. It is basically stable from 2018 (around 43%) as a confirmation of the continued commitment to the project.
  2. GerritForge is growing significantly in the contribution to the project, with exactly half of the contributions of Google. This is a significant result from 2018 with a 7% growth of involvement.
  3. CollabNet is sliding to the 3rd position (it was 2nd in 2018) with a 3% decrease of contributions. As noticeable mention, however, David Pursehouse from CollabNet is still the number #1 maintainer in terms of number of commits.

Even if it is outside the top#3 contributors companies, SAP deserves a special mention for its continuous involvement in the JGit project, which is at the basis of Gerrit engine, and its fantastic engagement in improving the Gerrit CI system and integrating it with the checks plugin.

Top-three achievements from GerritForge

The outstanding results of contributions of GerritForge in 2019 have been focused on three major topics.

Gerrit multi-site, released and production ready

We released the Gerrit Multi-Site plugin, allowing seamless balancing in a distributed environment, a technologically highly advanced development, crucial for very distributed companies. See https://gerrit.googlesource.com/plugins/multi-site for more information.

Gerrit User Summits in Europe, USA and streaming

We successfully organised and executed the Gerrit User Group in Europe and the US. The event was very well received by the community with an overall attendance of some 87 on-site and 38 in streaming. Have a look at https://gitenterprise.me/2019/12/23/gerrit-user-summit-survey/ for interesting feedback on those from the attendees.
We opened our own local office in Sunnyvale, in the heart of Silicon Valley. A crucial move to better serve our ever-expanding US customer base.

Gerrit Analytics for the Android Open-Source Project

We kickstarted the Gerrit Analytics for the Android open-source project initiative: after the successful adoption of the automatic collection of code metrics on the Gerrit project (see https://analytics.gerrithub.io) the Android team asked GerritForge to start working on extracting the same metrics from their code.

What’s coming in 2020

Gerrit v3.2 is currently under development and it is planned to be released around April/May 2020. It represents a major milestone for the Gerrit project with the support for Java 11 and large JVM heaps, up to hundreds of GBytes. Gerrit v3.2 is definitely the release that everyone that has a big repository (mono-repos) should target as next upgrade. See the Gerrit .roadmap at https://www.gerritcodereview.com/roadmap.html for more details about the planned features.

More work and improvements on the checks plugin, with the aim of fully integrating it into everyone’s user-journey and their CI/CD pipeline. Our first blog-post of 2020 will be how to use Jenkins and Checks plugin together with GerritHub.io.

Multi-site and HA will become more integrated with Gerrit, with the aim of moving parts of their technologies (e.g. global ref-db) into JGit and thus used in Gerrit core.

The Gerrit User Summit 2020 will continue the experiment of cross-pollination with other communities, after the success of the interactions with the JGit and OpenStack communities in 2019. Bazel is the next target, as it is used as the de-facto standard build system for Gerrit and its plugins.


 

Again, Best wishes from your friends at GerritForge and looking forward to a continuing successful partnership in the coming years.

Luca Milanesio
Gerrit Maintainer, Release Manager and member of the ESC.

Gerrit User Summit Survey

The 2019 has been an exceptional year, with the introduction of the next generation of Gerrit Code Review v3 releases and the largest ever Gerrit User Summit in the whole history of 11 years of the project.

As a community we want to improve even further and make the project and the community even better. Collecting metrics has been key for the improvements of the Gerrit product and its performance and, similarly, collecting feedback from the community events is the key to grow and increase the participation and sharing of the experiences about Gerrit Code Review.

Survey results

We have run a survey directed to all of those who have attended the two Gerrit User Summits this year, in Gothenburg and Sunnyvale. See below the executive summary of the results.

Did you achieve your objectives at the Summit?

Screenshot 2019-12-23 at 08.41.14

All of the attendees achieved their objective, which were different for the people, depending on their position and role in the community.

  • Getting the latest news of what’s happening in the Gerrit community and open-source product
  • Meeting the existing members of the community and welcome new contributors
  • Networking with the other Gerrit admin and users around the world
  • Influencing with ideas the future Gerrit roadmap

Overall, how would you rate the event?

Screenshot 2019-12-23 at 08.47.44

Over 76% of the people rated the event very good or excellent. However, as we strive for improvement, there is a substantial 24% of of people that are looking for a better event next year.

What did you like/dislike?

The positives of the event have been:

  • Presentation of the Gerrit roadmap and associated discussions
  • Successful mix of topics, including Zuul and JGit
  • People, atmosphere, friendship and networking
  • High quality of the talks and content

The not so positive sides where:

  • The summit covering the weekend
  • Too focused on Gerrit contributors and admins, no space for users
  • There was too much people for the chosen location
  • The talks and discussions went over the planned schedule

How organized was the event?

Screenshot 2019-12-23 at 08.56.17

89% of the people considered the event very well organized, whilst 11% are looking for improvement, possibly with a bigger venue and better timing.

What topics would you like to see covered next year?

  • Evolution of the User-Interface, roundtable with developers, user-journeys
  • Migration talks and discussions
  • CI/CD integration
  • Monitoring
  • Load testing
  • GitHub integration and pull-requests
  • Gerrit with large clusters
  • User-stories on using Gerrit

Would you like to have a workshop next year?

Screenshot 2019-12-23 at 09.02.56

The vast majority of people would like the next year event to be more informative, including a workshop for learning some of the features of Gerrit Code Review.

What would be the best time for the Summit next year?

Screenshot 2019-12-23 at 09.04.47

For the majority of people (75%) the best time for next year event would be two days during the week, rather than having it again over the weekend.


Thanks everyone again for attending the Gerrit User Summit 2019 in Gothenburg and Sunnyvale, and thanks to GerritForge, Volvo Cars and Google for sponsoring it. We are looking forward to seeing you next year.

Luca Milanesio (GerritForge)
Gerrit Code Review Maintainer, Release Manager and ESC Member.