Gerrit v3.4.0-rc1: weekly update

Starting from this week, GerritForge provides a weekly status update of how the Gerrit v3.4.0 release plan is progressing:

  1. List of merged changes since the previous RC
  2. List of issues fixed
  3. Result of the Gatling E2E tests on AWS

We hope that having these regular updates would help you focus on what is changing during the release plan execution and do more research, learning or specific investigation on the areas that are more pertinent to your use case.

Also, because the Gerrit release candidates do not come with an associated set of release notes, the list below would help people understand the new functionalities or fixes coming through every week.

Both Gatling-Git and the AWS-Gerrit project with a complete production-ready setup are projects started by GerritForge and contributed as OpenSource to the Gerrit community.

Merged changes

From Matthias Sohn:

    Log memory allocated per command in httpd_log 
    Change-Id: Ie0ce1382a8515e6dfb7d0d3fe10b3e64c0cf9aee

    Log cpu usage per http request   
    Change-Id: I9e78bed5219f9baf57a2b76f0f947efff334ffe5

    Log memory allocated per command in sshd_log
    Change-Id: Ifc1d274bf42eb3cb9b2cf46271b6be0117aa8b18

    Add metrics for monitoring Java memory pools
    Change-Id: I60e5960899c0cff8c05983d299b414d7a646bb07

    Log cpu usage in sshd_log
    Change-Id: I1c53f64caf982c2f85195e6bda4c6d790f79a810

    Encapsulate fields of SshScope.Context
    Change-Id: If989630425ad40922aaf8958c4335aab0bb5c2c9

    Log "-" for missing log fields in sshd_log
    Change-Id: I90adc7618864f702b42029ab596c6014bd4c6cfe

From Ben Rohlfs:

    Remove backend support for HTML UI plugins
    Change-Id: I44cc0d15910937de7e1f9b9780a799d4b85b0673

    Stop producing html version of plugins
    Change-Id: I1036f06e385f2997f7bea849755729df2789acaa

From Milutin Kristofic:

    A11y - show outline when focused on tab title in change view
    Change-Id: Ie9456a5d886e70a77dae8f055a54a3a1a0045daf

    A11y - show outline when focused on change subject in dashboard
    Change-Id: I9c73e49de661a17928c6f96a290c2069503bdfb4

    A11y - fix and improve label when navigating dashboard
    Change-Id: Id01302aea38c783687443401290995bdd0764126

From Hermann Loose:

    Allow setting image viewer max-width and max-weight externally
    Change-Id: Ie151a85d8ede5cb7fa0899d9367ca0dccd887538

From Han-Wen Nienhuys:

    Fix meta_diff documentation
    Change-Id: I9c59a4857724cdfd59b995a6dc255f77d29b017e

From Paladox:

    Update plugins/codemirror-editor and plugins/delete-project
    Change-Id: Ieca7d2e36b9eefffe5c830962109e1fa62134b5c

    gr-confirm-move-dialog: Fix _getProjectBranchesSuggestions
    Change-Id: I8d4ead0bf3a8c30d0ecefdc190e4ba4ea7ede29d

    Remove unused _handleDropdownTap
    Change-Id: Ie4a8effd6d814985cafa6dea9239903f503dae33

    Remove unused _handleDropdownTap
    Change-Id: Ie4a8effd6d814985cafa6dea9239903f503dae33

From Dhruv Srivastava:

    Clean up upload change help dialog
    Change-Id: I0c72450c37326ec2c2922b74928e0b059df0043e

From Saša Živkov:

    Fix binding of DELETE REST calls from plugins
    Change-Id: I9b9632e8f719937e5f7c61466996be79e6f29c14

Issues fixed

  • Issue 14335: CodeMirror plugin broken
  • Issue 14127: REST API DELETE query for delete-project plugin doesn’t work

Gatling E2E tests results

Git Protocol Simulation

Gatling full results:
https://gerrit-ci.gerritforge.com/job/gatling-gerrit-test/287/gatling/report/gerritgitsimulation-20210412213548212/source/index.html

Gatling simulation class:
https://github.com/GerritForge/gatling-sbt-gerrit-test/blob/master/src/test/scala/gerritforge/GerritGitSimulation.scala

Gerrit UI REST Simulation

Gatling full results:
https://gerrit-ci.gerritforge.com/job/gatling-gerrit-test/287/gatling/report/gerritrestsimulation-20210412213912089/source/index.html

Gatling simulation class:
https://github.com/GerritForge/gatling-sbt-gerrit-test/blob/master/src/test/scala/gerritforge/GerritRestSimulation.scala

2021: What’s cooking in GerritForge

Our mission is to improve the Gerrit Code Review platform, with the Open-Source community and in full transparency. Everything we do is published, is open, can be analysed and scrutinised by any member of the community at any time.

In this article, we are publishing what GerritForge is planning to do in the forthcoming 2021, a pivotal year that will see the entire world bouncing back and looking at the future of Technology with a different light.

Goal: cloud-native Gerrit Code Review

Since our initial post in 2019 about our plans for the future, we have been making steady progress toward a unified global Gerrit platform, highly available and distributed across the globe. Since then, a lot of steps have been made, many of them happened in 2020.

Thanks to SAP and GerritForge, we have now two Open-Source standard deployments on the Cloud:

  1. K8s-Gerrit – Helm-charts for deploying Gerrit Code Review to a Kubernetes Cluster (beta)
  2. AWS-Gerrit – CloudFormation templates for creating a production-like setup of Gerrit HA and Multi-Site to ECS on the AWS platform.

Even if Gerrit can deployed now into a Cloud environment, that does not mean that Gerrit is cloud-native. The main requirements for making an application cloud-native is captured by the 12-factor principles. We will be tackling some of them in our 2021 roadmap.

Cloud-native backing services

Thanks to the advances in the Gerrit Multi-Site plugin in 2020, it is today possible to have a geographically distributed cluster of Gerrit servers around the globe. The services that are needed for coordinating the events across Gerrit nodes and ensuring global consistency are:

  1. Event-broker (Kafka)
  2. Global ref-db (Zookeeper)

The price to pay for a global Gerrit Multi-Site is currently quite high, because one may argue that actually managing a cluster of Kafka brokers or Zookeeper nodes can be even more challenging that managing Gerrit itself.

A cloud-native application should be fully independent from its backing services and be opened to swapping one specific implementation (e.g. Kafka) with a serviced off-the-shelf solution (e.g. AWS Kinesis, GCP PubSub).

As GerritForge we are joining the forces with the Gerrit Code Review community in 2021 for refactoring the Gerrit Event system and making it more Cloud-native, using open-standards for representing and publishing events across the network.

The immediate actions are:

  1. Build a new protobuf-based events representation in Gerrit v3.4
  2. Abstract the serialisation of events from their transport
  3. Implement different events brokers and listeners, other than the Kafka. (e.g. NATS)
  4. Provide a AWS Kinesis-stream event broker connector
  5. Provide a GCP PubSub broker connector in cooperation with Google

Gerrit performance across sites

Making a stateful application like Gerrit Code Review a truly cloud-native and distributed platform brings some challenges in terms of latency and performance.

The current Gerrit Multi-Site architecture still relies heavily on the traditional (push) replication plugin, which has been working nicely for over a decade for a Gerrit primary/replica setup. When the repository size increases and the need for global consistency becomes more stringent, relying on a traditional async git push is not enough anymore: you need a lot more tools at your service.

GerritForge has introduced in 2020 the pull-replication plugin, which enables to invert the replication logic: instead of having one Gerrit server to push everything to everyone else, you just tell the other nodes of what’s new in the repository, and it will be their responsibility to fetch only the stuff that has changed.

In 2021 we are going to improve the plugin with native JGit client protocol v2 support and features that will go well beyond the limits of the git protocol:

  1. BLOB and ref-update on remote git pulls. The remote Gerrit node can receive directly the content of what has changed, directly in its payload. That allows to avoid the expensive git pull operation especially for NoteDb related updates.
  2. Event broker integration for git pulls. Instead of relying on REST-API, the pull replication plugin can produce pull replication events in the event broker.

The implementation of those improvements will allow to drastically reduce the incidence of the traditional (push) replication activity and make the Gerrit user experience more seamless across sites.

CI integration

Integrate Gerrit in more seamlessly with other cloud-native services, such as CI/CD. Gerrit v3.4 is planning to introduce a brand-new style of integration which would not require anymore any 3rd party adaptation or API support.

GerritForge is committed to endorse this new module and allow Gerrit v3.4 to be fully connected with Jenkins on day-1 and potentially other cloud-based CI/CD systems.

Git reftable: provide more performance for mono-repos

GerritForge will experiment and test at scale the introduction of Google’s Git reftable, already included from Gerrit v3.2 onwards, to assess its performance impact on large mono-repos, with hundreds of thousands of refs.

Have your say on Gerrit future

This is our GerritForge shopping list for 2021, wide open for discussion, contributions, amendments, and voting.

Why should you care about what we do? Simply because the union of intents and cross-pollination of ideas make the Open-Source products and community stronger: if we join forces in building a solution that is a common interest for all of us, we will all benefit from it.

Your feedback is welcome and precious, feel free to have your say and comment this post with your ideas, likes and suggestions on how to make them even better.

The GerritForge Team.

GerritForge 2020 year in Review

Dear Gerrit Code Review fellow,

It has been a challenging year, a strange year, for everyone. Most of us confined in our homes and working remotely, finding new ways of dealing with old problems.

Still, we believe the Gerrit Community as a whole has demonstrated an outstanding level of resilience in the face of exceptional difficulties. As far as we are concerned, we have seen no lesser activity, interest, new projects, compared to the previous years. For this, we are thankful to the community we are so strongly proud of being a part of.

In sharing our most sincere vows for happy festivities and a fruitful new year, we wanted to take the opportunity to share with you some of the achievements that made this 2020 worth getting through.

Top-Ten achievements in 2020

1. GerritForge has confirmed to be the world’s largest non-Google contributor to the Gerrit Code Review project.

GerritForge contributed almost a thousand changes merged, over 47 different components in the past 12 months. That is an outstanding achievement confirming the commitment and dedication of the company to the Gerrit Code Review platform and community.

2. Improved Gerrit DevOps Analytics with the ability to process Changes hashtags

The Gerrit DevOps Analytics platform continued to expand its possibilities, with the full support of the parsing of the NoteDb changes and the extractions of precious meta-data, such as the changes hashtags.

3. Driven two major releases of Gerrit Code Review

GerritForge helped driving the release of two major Gerrit Code Review version: Gerrit v3.2 – 1st June and with Ericsson making the Gerrit v3.3 – 1st December. GerritForge is also providing the CI/CD pipeline for the build and validation of the releases and helped the migration to Java 11.

4. Released major security fixes for the whole Gerrit Community, of all Gerrit versions dating back to v2.14

GerritForge coordinated together with Ericsson the release of critical security fixes across 6 different versions of the Gerrit Code Review platform, showing a continued commitment to a secure and scalable adoption of Gerrit in the enterprise.

5. Brand-new Gerrit module cache-chroniclemap, a new high-performance persistent cache in Gerrit v3.3

GerritForge continued its efforts in improving Gerrit’s scalability and performance with the development of a brand-new persistent cache backend powered by ChronicleMap, showing unprecedented low latency and performance on Gerrit v3.3.

6. Introduced the world-first official Open-Source AWS-based Gerrit Code Review Deployment

In a year of remote working and flexible environments, GerritForge provided its contribution to the whole community to help adopting Gerrit in the cloud. The aws-gerrit project is a brand-new production-ready AWS deployment now available for everyone and fully Open-Source. The new project is based on the GitOps best-practices and has been successfully adopted for the testing and validation of Gerrit v3.3.

7. New read-write scalability for Gerrit in High-Availability

GerritForge’s mission to scalability and high-availability (HA) plugin continued with the ability to scale horizontally with multiple R/W Gerrit Servers behind the same load balancer.

8. Improved reliability and flexibility of Gerrit Multi-Site

The Gerrit Multi-Site (MS) plugin has received exciting improvements with the support for geographically distributed R/W Gerrit servers across the globe.

9. Brand-new pull-replication plugin for improving latency and performance of large mono-repos replication.

The need to have Gerrit multi-site brought the request to have faster replication, especially for large mono-repos. GerritForge introduced a new pull-replication plugin project that, used in conjunction with Git Protocol v2, assure top-notch performance in replicating repositories with large number of refs.

10. Helped large-scale OpenSource Community migrating to Gerrit v3

The Eclipse Foundation and the OpenDev platform (by OpenStack), upgraded to the latest version of Gerrit Code Review, thanks to the continuous help and support from GerritForge and the rest of the Gerrit Code Review community.


All the best, Stay Safe, and we will shake hands again soon!

The GerritForge Team

What’s new in Gerrit Code Review v3.2

gerrit-code-review-3.2-intro

Gerrit Code Review is unstoppable: despite the recent COVID-19 pandemic and the cancellation of the Spring Hackathon 2020, the community has made an extraordinary effort to deliver remotely and on-time the Gerrit v3.2 release on the 1st of June.

GerritForge has already migrated GerritHub.io on the day-1 of the release and is happy to share with you the highlights of this new release. If you need help to assess your current setup and migrating, please get in touch with us at https://gerritforge.com/contact.

Get ready to migrate: get rid of zombie comments

The migration process performs the cleanup of the zombie draft comments in the All-Users.git repository that has been left behind since the introduction of NoteDb back in v2.16.
Every user commenting on any change was creating a series of commits on the All-Users.git repository, where the draft comments are stored. Once the comments were finalised and applied to the change, they were not fully removed from the All-Users.git. That created a backlog of zombie comments on All-Users.git that are now being completely removed during the Gerrit v3.2 migration process.

Since Gerrit v2.16.16, there is a standalone utility to remove the zombie draft comments. You may want to do that operation upfront to make sure that the migration to v3.2 does not have a lot of processing during the init step. Also, make sure that the All-Users.git resides on a fast access local filesystem for minimizing the migration time.

If you do nothing, the cleanup utility will be automatically executed when migrating to Gerrit v3.2, bearing in mind that it may take quite a long time to complete. In our tests, it took around 10 minutes for 10k zombie comments.

WARNING: the execution time is not linear and it may take up to 48h of processing time for a staggering number of 1M zombie comments.

Migrate with zero-downtime

If you have on Gerrit v3.1.x in a high-availability configuration, you can upgrade seamlessly to Gerrit v3.2, without having to suspend or degrading the service in any way. GerritForge has a record number of installations done in high-availability and multi-site: if you are running a single Gerrit master today, you should get in touch with the GerritForge Team to help moving to high-availability.

For the very first time, the whole Gerrit Community can benefit from the ability to perform a rolling upgrade without any downtime.

The zero-downtime upgrade consists of the following steps:

  1. Have Gerrit masters upgraded to v3.1.6 (or later) in a high-availability configuration, healthy and able to handle the incoming traffic properly.
  2. Set gerrit.experimentalRollingUpgrade to true in gerrit.config on both Gerrit masters.
  3. Set the first Gerrit master unhealthy.
  4. Shutdown the first Gerrit master and then upgrade to v3.2.
  5. Startup the first Gerrit master and wait for the on-line reindex to complete.
  6. Please verify that the first Gerrit master is working correctly and then make it healthy again.
  7. Wait for the first Gerrit master to start serving traffic regularly.
  8. Repeat steps 3. to 7. for the second Gerrit master.
  9. Remove gerrit.experimentalRollingUpgrade from gerrit.config on both Gerrit masters.

NOTE: Gerrit v3.1.6 has not been released yet. However, if you want to perform a rolling upgrade today, you can download the latest build on the stable-3.1 branch from the GerritForge’s CI at https://gerrit-ci.gerritforge.com/job/Gerrit-bazel-stable-3.1/

GerritHub.io has been successfully upgraded on the 1st of June without any interruption of any kind using the above procedure.

Java 11 official support

Gerrit is now officially supported on Java 11, in addition to Java 8. Running on Java 11 was already possible from v2.16.13, v3.0.4 and v3.1.0, but not officially supported because of the lack of a CI validation on Java 11 for stable-2.16, stable-3.0 and stable-3.1 branches.

Gerrit v3.2 has been validated with Java 11, with the following known issues:

  • Issue 11567: Java 11 runtime & startTLS LDAP broken: ‘error code 8 – BindSimple: Transport encryption’.
  • Issue 12639: WARNING: An illegal reflective access operation has occurred, when starting Gerrit.

After 24h of adoption of Gerrit v3.2 on GerritHub.io, we have seen two major benefits from the migration to Java 11: overall reduction of the “old generation” build up in the JVM heap and massive reduction of GC cycles times and full-GCs.

screenshot-2020-06-02-at-11.48.30

Before the 29th of May, all GerritHub.io nodes were on Gerrit v3.1 / Java8. The old-generation JVM heap keeps on building up constantly until it reaches the 60GB and triggers a full GC cycle. After the upgrade to Gerrit v3.2 / Java11, memory consumption is very much under control. There are still possibilities of peaks with associated full GCs (see the one on the 30th of May around 12:00 BST) but there isn’t build up of old-generation objects anymore.

screenshot-2020-06-02-at-11.52.43

Java11 brings a lot of benefits also in reducing the latency of the individual GC cycles, showing much better performance with large heaps.
After the migration on the 29th of May, the GC graph is pretty much flat. The only full GC peak that is noticeable on the 30th of May lasted for just 5 msecs while the normal GC cycles are well below 1 msec, barely noticeable.

Performance is a feature

Shawn Pearce, the Gerrit Code Review project founder, used to say “performance is a feature”, which is very true. Any software nowadays can provide some basic out of the box features, thanks to the plethora of open-source components available out of the box. However, designing architecture and making it scale and perform to the levels that an Enterprise Code Review system needs, it is not easy.

Gerrit v3.2 is yet another significant milestone in the continued effort of the Gerrit maintainers and contributors in making Gerrit Code Review faster, more stable and available than ever before.

Performance tuning isn’t a “one-off task” but is a continuous improvement on thousands of little details ranging from the front-end javascript tuning down to the backend of the platform.

New accounts cache

From the data collected on googlesource.com Patrick Hiesel (Google) has identified the accounts loading from NoteDb as a significant cause of the delay of backend calls. That is true for all Gerrit installations, but especially for distributed setups or setups that restart often.

Gerrit v3.2 introduces a brand-new AccountCache decomposed into smaller chunks that can be cached individually:

  1. External IDs + user name (cached in ExternalIdCache)
  2. CachedAccountDetails (newly cached)
  3. Gerrit’s default settings CachedAccountDetails – a new class representing all information stored under the user’s ref (refs/users/<sharded-id>).

The new structure is cleverly designed to require a lot less I/O when an entry needs to be reloaded and lowering the ratio of cache-miss in case of user’s details updates.

The new structure has the following advantages:

  1. CachedAccountDetails contains only details from refs/users/<sharded-id>. By that, we can use the SHA1 of that ref as cache key and start serializing the cache to eliminate cold start penalty as well as router assignment change penalty (for distributed setups). It also means that we don’t have to do invalidation ourselves anymore.
  2. When the server’s default preferences change, we don’t have to invalidate all accounts anymore.
  3. The projected speed improvements that come from persisting the cache makes it so that we can remove the logic to load accounts in parallel.

Migration to Polymer 3

PolyGerrit UX roadmap continues with yet another important milestone: the migration to Polymer 3. The result is visible with an improved polishing of the GUI and significant speedup of rendering and reduction of page loading times.
There are a significant amount of small refinements to the GUI as well, coming from a meticulous work of fixes included in this release.
Not by surprise, the number of issues fixed in v3.2 on the PolyGerrit UX outnumbers by far the overall changes in the release notes.

gerrit-3.2-findings

PolyGerrit is giving special attention to the classification of the feedback coming from robots rather than humans.
Most of the efforts made in the past 12 months target the improvement the support for robot-comments and giving some extra dedicated space for them.
In Gerrit v3.2 there is a special place for them in a brand-new “Findings” tab. It is currently empty on GerritHub.io as people did not start using them much. However, I do see a lot of space of adoption of this new feature, giving the ability for more integration of linters and automatic validation feedback in this tab.

A flooding of fixes and small improvements

The list of fixes and improvements in Gerrit v3.2 is really huge. Please check the release notes on the Gerrit Code Review release page for all the details.

There are a lot of reasons to migrate to Gerrit v3.2, the fastest, more stable and scalable release of Gerrit Code Review ever.


Thanks a lot to the whole Gerrit Code Review Community of maintainers and contributors for making this release happen. Thanks to Patrick Hiesel for the technical description of the account cache improvements and the replication clustering.

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

 

How to enable Git v2 in Gerrit Code Review

git-2-26

(c) Shutterstock / spainter_vfx

Git protocol v2 landed in Gerrit 3.1 on the 11th of October 2019. This is the last email from David Ostrovsky concluding a thread of discussion about it:

It is done now. Git wire protocol v2 is a part of open source Gerrit and will be
shipped in upcoming Gerrit 3.1 release.

And, it is even enabled per default!

Huge thank to everyone who helped to make it a reality!

A big thanks to David and the whole community for the hard work in getting this done!

This was the 3rd attempt to get the feature in Gerrit after a couple of issues encountered along the path.

Why Git protocol v2?

The Git protocol v2 introduces a big optimization in the way client and server communicate during clones and fetches.

The big change has been the possibility of filtering server-side the refs not required by the client. In the previous version of the protocol, whenever a client was issuing a fetch, all the references were sent from the server to the client, even if the client was fetching a single ref!

In Gerrit this issue was even more evident, since, as you might know, Gerrit leverages a lot the refs for its internal functionality, even more with the introduction of NoteDb.

Whenever you are creating a Change in Gerrit you are updating/creating at least 3 refs:

  • refs/changes/NN/<change-num>/<patch-set>
  • refs/changes/NN/<change-num>/meta
  • refs/sequences/changes

In the Gerrit project itself, there are currently about 104K refs/change and 24K refs/change/*/meta. Imagine you are updating a repo which is behind just a couple of commits, you will get all those references which will take up most of your bandwidth.

Git protocol v2 will avoid this, just sending you back the references that the Git client requested.

Is it really faster?

Let’s see if it really does what is written on the tin. We have enabled Gerrit v2 at the end of 2019 on GerritHub.io, so let’s test it there. You will need a Git client from version 2.18 onwards.

> git clone "ssh://barbasa@review.gerrithub.io:29418/GerritCodeReview/gerrit"
> cd gerrit
> export GIT_TRACE_PACKET=1
> git -c protocol.version=2 fetch --no-tags origin master
19:16:34.583720 pkt-line.c:80           packet:        fetch< version 2
19:16:34.585050 pkt-line.c:80           packet:        fetch< ls-refs
19:16:34.585064 pkt-line.c:80           packet:        fetch< fetch=shallow
19:16:34.585076 pkt-line.c:80           packet:        fetch< server-option
19:16:34.585084 pkt-line.c:80           packet:        fetch< 0000
19:16:34.585094 pkt-line.c:80           packet:        fetch> command=ls-refs
19:16:34.585107 pkt-line.c:80           packet:        fetch> 0001
19:16:34.585116 pkt-line.c:80           packet:        fetch> peel
19:16:34.585124 pkt-line.c:80           packet:        fetch> symrefs
19:16:34.585133 pkt-line.c:80           packet:        fetch> ref-prefix master
19:16:34.585142 pkt-line.c:80           packet:        fetch> ref-prefix refs/master
19:16:34.585151 pkt-line.c:80           packet:        fetch> ref-prefix refs/tags/master
19:16:34.585160 pkt-line.c:80           packet:        fetch> ref-prefix refs/heads/master
19:16:34.585168 pkt-line.c:80           packet:        fetch> ref-prefix refs/remotes/master
19:16:34.585177 pkt-line.c:80           packet:        fetch> ref-prefix refs/remotes/master/HEAD
19:16:34.585186 pkt-line.c:80           packet:        fetch> 0000
19:16:35.052622 pkt-line.c:80           packet:        fetch< d21ee1980f6db7a0845e6f9732471909993a205c refs/heads/master
19:16:35.052687 pkt-line.c:80           packet:        fetch< 0000
From ssh://review.gerrithub.io:29418/GerritCodeReview/gerrit
 * branch                  master     -> FETCH_HEAD
19:16:35.175324 pkt-line.c:80           packet:        fetch> 0000

> git -c protocol.version=1 fetch --no-tags origin master
19:16:57.035135 pkt-line.c:80           packet:        fetch< d21ee1980f6db7a0845e6f9732471909993a205c HEAD\0 include-tag multi_ack_detailed multi_ack ofs-delta side-band side-band-64k thin-pack no-progress shallow agent=JGit/unknown symref=HEAD:refs/heads/master
19:16:57.037456 pkt-line.c:80           packet:        fetch< 07c8a169d6341c586a10163e895973f1bdccff92 refs/changes/00/100000/1
19:16:57.037489 pkt-line.c:80           packet:        fetch< 0014ca6443ac0af338e2677b45e538782bb7a12e refs/changes/00/100000/meta
19:16:57.037502 pkt-line.c:80           packet:        fetch< b4af8cad4d3982a0bba763a5e681d26078da5a0e refs/changes/00/100400/1
19:16:57.037513 pkt-line.c:80           packet:        fetch< 9ec6e507c493f4f1905cd090b47447e66b51b7e1 refs/changes/00/100400/meta
19:16:57.037523 pkt-line.c:80           packet:        fetch< a80359367529288eea3c283e7d542164bced1e2f refs/changes/00/100800/1
19:16:57.037533 pkt-line.c:80           packet:        fetch< 170cced6d81c25d1082d95e50b37883e113efd01 refs/changes/00/100800/meta
19:16:57.037544 pkt-line.c:80           packet:        fetch< 6cb616e0ad4b3274d4b728f8f7b641b6bd22dce4 refs/changes/00/100900/1
19:16:57.037554 pkt-line.c:80           packet:        fetch< 286d1ee1574127b76c4c1a6ef0f918ad4c61953a refs/changes/00/100900/meta
19:16:57.037606 pkt-line.c:80           packet:        fetch< 312ba566d2620b43fb90be3e7c406949edf6b6d9 refs/changes/00/10100/1
19:16:57.037619 pkt-line.c:80           packet:        fetch< dde4b73cb011178584aae4fb29a528018149d20b refs/changes/00/10100/meta

…. This will go on forever …. 

As you can see there is a massive difference in the data sent back on the wire!

How to enable it?

If you want to enable it, you just need to update you git config (etc/jgit.config in 3.1 and $HOME/.gitconfig in previous versions) with the protocol version to enable it and restart your server:

[protocol]
  version = 2

Enjoy your new blazing fast protocol!

If you are interested in more details about the Git v2 protocol you can find the specs here.

Fabio Ponciroli (GerritForge)
Gerrit Code Review Contributor

Crunch Code Review hashtags with Gerrit DevOps Analytics

Screenshot 2020-05-12 at 11.13.06.pngWe have already discussed in previous posts how important it is to speedup the feedback loop in your Software Development Lifecycle. Having early feedbacks gives you the chance of evaluating your hypothesis and eventually change direction if needed. 

The more information you have, the smarter can be your decisions.

We recently added in our Gerrit DevOps Analytics the possibility of extracting data coming from Code Reviews’ metadata to extend the knowledge we can get out of Gerrit.

Furthermore, it is possible to extract meta-data from repositories not necessarily hosted on the Gerrit instance running the analytics processing. This is a big improvement since it allows to fully analyse repositories coming from any Gerrit server.

For example, the Gerrit analytics we are providing on https://analytics.gerrithub.io are coming from the Gerrit repository hosted on the gerrit-review.googlesource.com, the Gerrit server hosted by Google.

Hashtags aggregation

One important type of meta-data contained in the Code Reviews is the hashtag.

Hashtags are freeform strings associated with a change, like on social media platforms. In Gerrit, you explicitly associate hashtags with changes using a dedicated area of the UI; they are not parsed from commit messages or comments.

Similar to topics, hashtags can be used to group related changes together and to search using the hashtag: operator. Unlike topics, a change can have multiple hashtags, and they are only used for informational grouping; changes with the same hashtags are not necessarily submitted together.

You can use them, for example, to mark and easily search all the changes blocking a particular release:

Screenshot 2020-05-12 at 10.43.00.png

Hashtags can also be used to aggregate all the changes people have been working on during a particular event, for example, the Gerrit User Summit 2019 hackathon:

Screenshot 2020-05-12 at 10.44.39.png

The latest version of the Gerrit Analytics plugin exposes the hashtags attached to their respecting Git commit data. Let’s explore together some use cases:

The most popular Gerrit Code Review hashtags over the last 12 months

Screenshot 2020-05-12 at 10.47.49.png

Throughput of changes created during an event

see for example the Palo alto hackathon (#palo-alto-2018). We can see at the end of the week the spike of changes to release Gerrit 2.16.

Screenshot 2020-05-12 at 10.56.44.png

The extend of time for a feature

Removing GWT was an extensive effort which started in 2017 and ended in 2019. It took several hackathons to tackle the removal as shown by the hashtags distribution. Some changes were started in one hackathon and finalised in the next one.

Screenshot 2020-05-12 at 11.05.51.png

Those were some example of useful information on how to leverage the power of GDA.

The above examples are taken from the GDA dashboard provided and hosted by GerritForge on https://analytics.gerrithub.io which mirror commits and reviews on a regular basis from the Gerrit project and its plugin ecosystem.

How to setup GDA on Gerrit

Hashtag extraction is currently available from Gerrit 3.1 onwards. You can download the latest version released from the Gerrit CI.

To enable hashtag extraction you need to enable the feature extraction in the plugin config file as follow:

# analitycs.config
[contributors]
  extract-hashtags = true

For more information on how to configure and run the plugin, look at the analytics plugin documentation.

Conclusion

Data is the goldmine of your company. You need more and more of it for making smarter decision. The latest version of the GDA allows you to leverage even more data produced during the code review process.

You can explore the potential of the information held in Gerrit on the analytics dashboard provided by GerritForge on analytics.gerrithub.io.

If you would like your open source Gerrit hosted project to be added to our dashboard or would need help in setting up and supporting GDA for your organization, get in touch with GerritForge Sales Team and we can help you making smarter decisions today.

Summary of the Gerrit User Summit & Hackathon in Sunnyvale

sunnyvale-gerritforge-live.jpg

After months of reviews and contributions by different speakers and attendees, the summary of the last Gerrit User Summit & Hackathon in Sunnyvale CA has been published on the Gerrit Code Review News page.

High-performance Summit in numbers

The Gerrit User Summit 2019 has ended, with highest score of achievements
in the history of the 11 years of the entire Gerrit open-source project:

  • Two dates and locations in a 12-months period: Gothenburg (Sweden) and
    Sunnyvale (California).
  • Four Gerrit releases delivered: v2.15.16, v2.16.11, v3.0.2, v3.1.0
  • 127 people registered across the two locations,
    87 people attended on-site (70% turnout) and 38 people followed the event
    remotely at different times using the live streaming coverage
    provided by GerritForge.
  • 373 changes merged (204 in Gothenburg, 169 in Sunnyvale).
  • 32 developers attended the Hackathons, 8 of them have never contributed or
    attended an event before.
  • The highest performing version of Gerrit v3.1.0 released, with over
    2x git and REST-API performance compared to v3.0.x.
  • 22 talks presented across Gothenburg and Sunnyvale, with 6 new speakers
    that have never presented before at the Summit.

The performance of the Summit is yet again another evidence of the continuous
growth of the community and the increased synergies with the JGit, OpenStack/Zuul
and the Tuleap open-source projects.

Read the full Summit and Hackathon summary on the Gerrit Code Review web-site.

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.

 

Stress your Gerrit with Gatling

As a Gerrit administrator, making sure there is no performance impact while upgrading from one version to another can be difficult.

It is essential to:

  • have a smooth and maintainable way to reproduce traffic profiles to stress your server
  • easily interpret the results of your tests

Tools like wrk and ab are simple and good to run simple benchmarking tests, but when it comes to more complex scenarios and collection of client-side metrics, they are not the best tools to use.

Furthermore, they only support Close Workload Models, which might not always fit the behaviour of your system.

For those reasons in GerritForge we started to look at more sophisticated tools, and we started adopting Gatling, an open-source load testing framework.

The tool

The Gatling homepage describes it this way:

“Gatling is a highly capable load testing tool. It is designed for ease of use, maintainability and high performance…

Out of the box, Gatling comes with excellent support of the HTTP protocol…..

As the core engine is actually protocol-agnostic, it is perfectly possible to implement support for other protocols…

Based on an expressive DSL, the scenarios are self-explanatory. They are easy to maintain and can be kept in a version control system…”
In this article, we focus on the maintainability and protocol agnosticism of the tool.

What about Git?

Gatling natively supports HTTP protocol, but since the core engine is protocol-agnostic, it was easy to write an extension to implement the Git protocol. I started working on the Gatling git extension in August during a Gerrit hackathon in Sweden, and I am happy to see that is starting to get traction in the community.

This way we ended up among the official Gatling extension on the official Gatling homepage:

Screenshot 2019-12-16 at 15.03.32.png

The code of the git extension if opensource and free to use. It can be found here, and the library can be downloaded from Maven central. In case you want to raise a bug, you can do it here.

Maintainability

Gatling is written in Scala, and it expects the load tests scenarios to be written in Scala. Don’t be scared; there is no need to learn crazy functional programming paradigms, the Gatling DSL does a good job in abstracting the underneath framework. To write a scenario you just have to learn the building blocks made available by the DSL.
Here a couple of snippets extracted from a scenario to understand the DSL is:

class ReplayRecordsFromFeederScenario extends Simulation {
  // Boireplate to select the protocol and import the configuration
  val gitProtocol = GitProtocol()
  implicit val conf = GatlingGitConfiguration()

  // Feeder definition: the data used for the scenario will be loaded from "data/requests.json"
  val feeder = jsonFile("data/requests.json").circular

  // Scenario definition: 
  val replayCallsScenario: ScenarioBuilder =
    scenario("Git commands") // What's the scenario's name?
      .forever {  // How many time do I need to run though the feed?
        feed(feeder) // Where shall I get my data?
          .exec(new GitRequestBuilder(GitRequestSession("${cmd}", "${url}"))) // Build a Git request
      }

  setUp(
    replayCallsScenario.inject(
      // Traffic shape definition....pretty self explanatory
      nothingFor(4 seconds),
      atOnceUsers(10),
      rampUsers(10) during (5 seconds),
      constantUsersPerSec(20) during (15 seconds),
      constantUsersPerSec(20) during (15 seconds) randomized
    ))
    .protocols(gitProtocol) // Which protocol should I use?
    .maxDuration(60 seconds) // How long should I run the scenario for?
}

That is how the feeder looks like:

[
  {
    "url": "ssh://admin@localhost:29418/loadtest-repo.git",
    "cmd": "clone"
  },
  {
    "url": "http://localhost:8080/loadtest-repo.git",
    "cmd": "fetch"
  },
  {
    "url": "http://localhost:8080/loadtest-repo.git",
    "cmd": "push",
    "ref-spec": "HEAD:refs/for/master"
  }
]

Here another example reproducing the creation of a WIP change using the REST API:

class WIPWorkflow extends Simulation {

  // Configuration bolierplate
  implicit val conf: GatlingGitConfiguration = GatlingGitConfiguration()
  val baseUrl = "https://review.gerrithub.io"
  val username: String = conf.httpConfiguration.userName
  val password: String = conf.httpConfiguration.password
  val httpProtocol: HttpProtocolBuilder = http
    .baseUrl(baseUrl)
    .userAgentHeader("Gatling test")
  val request_headers: Map[String, String] = Map(
    "Content-Type" -> "application/json"
  )
  
  val scn = scenario("WIP Workflow") // What's the name of my scenario?
    .exec(
      http("Create WIP change")
        .post("/a/changes/") // Which url and which HTTP verb should I use? 
        .headers(request_headers) 
        .basicAuth(username, password) // How do I authenticate?
        .body( // What's the body of my request?
          StringBody("""{
            "project" : "GerritForge/sandbox/e2e-tests",
            "subject" : "Let's test this Gerrit! Create WIP changes!",
            "branch" : "master",
            "work_in_progress": "true",
            "status" : "NEW"
          }""")
        )
        .check(status.is(201)) // What's the response code I expect?
    )

  setUp(scn.inject(
    atOnceUsers(1) // Traffic profile
  )
  ).protocols(httpProtocol)
}

Jenkins integration

Running load tests can be tedious and time-consuming, but yet essential to spot any possible performance regression in your application.
Providing the least possible friction is essential to incentivize people in running them. If you are already using Jenkins in your company, you can leverage the Gatling plugin to scale your load quickly and provide easy access to metrics.

A real use case: Gerrit v3.0 Vs Gerrit v3.1 load test…in production!

Let’s go through a real case scenario to show how useful and easy to read are the metrics provided by Gatling.

The closest environment to your production one is…production!

gerrithub.io runs Gerrit in a multi-site configuration, and this gives us the luxury of doing canary releases, only upgrading a subset of the master nodes running Gerrit. One of the significant advantages is that we can run A/B tests in production.

That allows us also to run meaningful load tests against the production environment. See below a simplified picture of our Gerrit setup where it is possible to see the canary server with a higher Gerrit version.

Screenshot 2019-12-14 at 16.26.52.png

We ran against 2 servers in Germany the same load tests which:

  • Create 100 chained Change Sets via REST API
  • Submit all the changes together via REST API

We then compared the server-side and client-side metrics to see if a good job has been done with the latest Gerrit version.

Server-side metrics

Server-side metrics come from the Prometheus exporter plugin. The image is showing the HTTP requests mean time:

Screenshot 2019-12-14 at 16.32.12.png

We can see the improvement in the latest Gerrit version. The mean requests time is almost halved and, of course, the overall duration is decreased.

Client-side metrics

Let’s see what is going on on the client-side using the metrics provided by Gatling.

Among all the metrics we are going to focus on one step of the test, since we have more data points about it, the creation of the change:

Screenshot 2019-12-14 at 16.36.45.png

We can already see from the overall report the reduction of the response time in the latest Gerrit version:

Screenshot 2019-12-14 at 16.38.05.png

If we look in-depth to all the response times, we can see that the distribution of the response times is pretty much the same, but the scale is different….again we confirmed the result we previously encountered.

Screenshot 2019-12-14 at 16.39.17.png

What can we say…Good job Gerrit community!

Wrapping up

(You can see my presentation about Gatling in the last Gerrit User summit in Sunnyvale here <- add this when the talk will be sharable)

I have touched superficially several topics in this blog posts:

  • simplicity and maintainability provided by the Gatling DSL
  • Integration with Jenkins
  • Gatling extensions and reuse of the statistic engine
  • Example scenarios

I would like to write more in-depth about all these topics in some follow-up blog posts. Feel free to vote for the topic you are more interested in or suggest new ones in the comments section of this post.
If you need any help in setting up your scenario or understand how to run load tests against your Gerrit installation effectively, GerritForge can help you.

Fabio Ponciroli (aka Ponch) – GerritForge
Gerrit Code Review and Gatling Contributor