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Tree Sheriffs

I'm a new sheriff, now what?

  1. Read the tour of the waterfall to understand what you are doing.
  2. This page
  3. The relevant page for your sheriffing type:
    1. Chromium sheriff
    2. Blink sheriff (aka "gardeners")
    3. Memory sheriff
    4. Chromium OS sheriff
    5. NaCl sheriff
    6. GPU pixel wrangler
    7. Chromium Perf sheriff

What is a sheriff?

  • Closes, throttles, and opens the tree
  • Tracks down people responsible for breakage
  • Backs out broken changes
  • When idle, the sheriff:
    • improves the tools,
    • updates the doc,
    • fix flaky tests,
    • remove reliability signatures
Sheriffs should have a strong bias towards actions that keep the tree green and then open; if a simple revert can fix the problem, the sheriff should revert first and ask questions later

What is a trooper?

Troopers know more about maintaining the buildbot masters and slaves themselves. They're the people to look for when the bots need an OS update, a machine goes offline, checkouts are failing repeatedly, and so on.
  • Chromium troopers: Please email chrome-troopers [at] google.com
    • Refer to the rotation calendar to find the current trooper (look in "more details"->"Guests").
  • Chromium OS troopers:
    • Same list as Chromium troopers (see above)
  • NaCl troopers: bradnelson, noelallen, ncbray, TBD

What is a gardener?

Gardeners are watchers of particular component interactions. They generally watch a component's release or development and move the version included forward when it is compatible. This is called "rolling DEPS", and consists of committing a CL that changes the (Subversion) revision number in some DEPS file, particularly the root DEPS, and then seeing if anything breaks. In some cases the DEPS roll also needs to have a landmine to force a full rebuild (clobber).

Of particular interest to the Chromium projects are the gardeners who watch the interaction between Blink, Skia and Chromium, and those who watch the interaction of Chromium and ChromiumOS.

Our 7 out of 8 goal

  • We have a goal of keeping the tree open 7 hours out of every 8. To achieve this goal, sheriffs need to resolve issues as they arise.
  • If the tree is closed automatically by the gatekeeper, the sheriff needs to change the status within a few minutes to let other people know that someone is looking at the failures.
  • If the sheriff can keep track of the failures on the tree, and those failures are not preventing the code from being tested correctly, then the tree should stay open.
  • Want to know how you did? Check the status viewer for ChromiumChromium OS or NaCl. (7/8 = 87.5%)

Sheriffing Details

See Sheriff Details: Chromium to revert changes, disable tests, etc.

Common tasks

Closing, throttling, or opening the tree

The tree status can be closed, throttled, or open. These status levels control the activity of the commit queue. If the tree is open, the commit queue run as normal. If the tree is closed or throttled, the commit queue will not submit any changes.
Warning: before opening the tree for one failure, make sure that all the bots are green. if the tree's already closed then subsequent failures don't "reclose" so it can be easy to miss them.
  1. Go to chromium-status.appspot.com (Chromium) or chromiumos-status.appspot.com (Chromium OS).
  2. Change the status.
    • To close the tree, include the word "closed" in the status.
    • To open the tree, include the word "open" in the status.
    • To throttle the tree, include the word "throttled" in the status.

Effectively communicating tree closure

Annotate the tree status with information about what is known about the status of build failures. For example, automatic closure messages such as...

Tree is closed (Automatic: "compile" on "Mac Builder" from 12345: foo@chromium.org)

... should be changed to:

Tree is closed (compile -> johnd)

... to indicate that committer 'johnd' has been notified of the problem and is looking into it. Once a fix has been checked in, sheriffs often use status:

Tree is closed (cycling green)

... to indicate that a fix/revert has been checked in and the tree will likely be opened soon. Alternatively, if the sheriffs decided to revert first and ask questions later, then the tree status should be changed to:

Tree is open (reverted r54321)

Effectively communicating tree repairs

If the tree has been closed for an extended time, particularly if the breakage covered more than one working timezone (US Pacific, US Eastern, Europe, Asia), it is considered best practice to communicate what was needed to fix the breakage. That way the next sheriff knows what's been happening, and people in other timezones know what to do next time it breaks the same way.

If the fix was simple, it can be listed in the tree-open status message, such as...

Tree open (rebooted Chromium (dbg) to clear tempfiles)

Tree open (svn server came back)

Tree open (reverted r54321)

If a more detailed fix was needed, send email to the chromium-dev mailing list explaining what happened. It's a good idea to CC the current and upcoming sheriffs too.

Tips and tricks

It's clobberin' time!

Sometimes you just need to clobber some class of bots (win, mac+ninja, linux asan using make, etc.). You can do this by landing a landmine change. Docs are here: Chromium Clobber Landmines.

Note: if a specific CL is causing bots to break unless they are clobbered, that CL should be reverted first and fixed to avoid this.

Forcing a build

To retry the last build, you can force a build.
  1. Navigate to builder on internal waterfall
    • From an existing builder URL, you can replace:
      • build.chromium.org/p 
      • to:
      • chromegw.corp.google.com/i
  2. Click the name of the builder in the top gray row
  3. Enter your username and an optional reason
  4. Click "Force Build".
For Chromium only, if you check the "Clobber" checkbox, it will also delete the build output directory before redoing the compile.
 
Note: If this is not a builder (no compile step), then doing a clobber won't do anything. You need to clobber the "Builder" first.

Stopping a build

There is an option to stop a build, but do not use it! If you stop the build during the update step, the bot is going to be hosed for sure. Again, don't use this option, and if you feel like using it, talk to the troopers first.

Use chromium extensions to annotate buildbot error pages

Install the buildbot error extension to more quickly isolate errors on stdio pages. See Useful extensions for chromium developers for more information.

PFQ Builds

Documentation is here in the Pre Flight Queue documentation

Sheriff schedule

Build sheriff calendar (authoritative)

The authoritative list is the on Google Calendar. Here's how to add the sheriff calendar to yours:
  1. Sign in to Google Calendar.
  2. Where it says "Other calendars - Add a friend's calendar" add the address for the calendar you want:
To see who the sheriff is, click an event and look at the guest list. (Yes, it would be nice if it showed the people in the event title, but then there's the issue of the event title and the guest list getting out of sync -- no easy answer.)  To find when a specific person is going to be sheriff, use google calendar's advanced search box (click the down-triangle in the main search box), select the appropriate sheriff calendar, and type the person's username into the "Who" box.

The script/process that updates the calendars can be found in svn://svn.chromium.org/chrome-internal/trunk/tools/build/scripts/tools/sheriff.

How to swap

If you need to swap shifts with someone, add them to the rotation so that the buildbot and other tools display the proper people as sheriffs. To do this:
  1. Find the "meeting" on your calendar for when you are sheriff. Click it so you can edit the details. (Make sure you click the event on your calendar and not the event on the sheriff calendar).
  2. On the upper right, where Calendar indicates your response, choose "No" for "Are you coming?". Below that, where Guests are listed, click "Add Guest" and "invite" your replacement.
  3. Finally, hit "Save" at the top.
  4. Have your replacement repeat this process on their calendar for the days you are taking.
  • Every committer is empowered and encouraged to do any of those things when needed, but the sheriff has overall responsibility in case somebody else is away or not paying attention.
  • The sheriffs receive gatekeeper emails when the tree is being closed automatically. Please take action on these as soon as you can.
  • Everyone helps! Everyone has been signed up to be a sheriff. If you're new, and therefore should be added to the team, submit a code review to add yourself (svn://svn.chromium.org/chrome-internal/trunk/tools/build/scripts/tools/sheriff/rotations) or ping mmoss. You can find your time as sheriff at the "Upcoming sheriffs" list at the end of the Sheriff details pages (e.g., for Chromium). If you need to change the schedule (you're out sick or on vacation), it's your responsibility to find a replacement for your time slot.

Time Zones

PST(CA, WA) EST(NY, Montreal) UTC(London) CET(Munich) JST(Tokyo)
4PM 7PM 0AM 1AM 9AM
5PM 8PM 1AM 2AM 10AM
6PM 9PM 2AM 3AM 11AM
7PM 10PM 3AM 4AM 12PM
8PM 11PM 4AM 5AM 1PM
9PM 0AM 5AM 6AM 2PM
10PM 1AM 6AM 7AM 3PM
11PM 2AM 7AM 8AM 4PM
0AM 3AM 8AM 9AM 5PM
1AM 4AM 9AM 10AM 6PM
2AM 5AM 10AM 11AM 7PM
3AM 6AM 11AM 12PM 8PM
4AM 7AM 12PM 1PM 9PM
5AM 8AM 1PM 2PM 10PM
6AM 9AM 2PM 3PM 11PM
7AM 10AM 3PM 4PM 12PM
8AM 11AM 4PM 5PM 1AM
9AM 12PM 5PM 6PM 2AM
10AM 1PM 6PM 7PM 3AM
11AM 2PM 7PM 8PM 4AM
12PM 3PM 8PM 9PM 5AM
1PM 4PM 9PM 10PM 6AM
2PM 5PM 10PM 11PM 7AM
3PM 6PM 11PM 12PM 8AM
See also IRC commands:
trungl-bot: offices
List office names for "time" command
trungl-bot: time office
Display local time of specified office, e.g. trungl-bot: time NYC