Chrome Network Bug Triage : Suggested Workflow

Looking for new crashers

  1. Go to go/chromecrash.

  2. For each platform, look through the releases for which releases to investigate. As per bug-triage.txt, this should be the most recent canary, the previous canary (if the most recent is less than a day old), and any of dev/beta/stable that were released in the last couple of days.

  3. For each release, in the “Process Type” frame, click on “browser”.

  4. At the bottom of the “Magic Signature” frame, click “limit 1000”. Reported crashers are sorted in decreasing order of the number of reports for that crash signature.

  5. Search the page for “net::”.

  6. For each found signature:

    • If there is a bug already filed, make sure it is correctly describing the current bug (e.g. not closed, or not describing a long-past issue), and make sure that if it is a net bug, that it is labeled as such.
    • Ignore signatures that only occur once, as memory corruption can easily cause one-off failures when the sample size is large enough.
    • Ignore signatures that only come from a single client ID, as individual machine malware and breakage can also easily cause one-off failures.
    • Click on the number of reports field to see details of crash. Ignore it if it doesn't appear to be a network bug.
    • Otherwise, file a new bug directly from chromecrash. Note that this may result in filing bugs for low- and very-low- frequency crashes. That's ok; the bug tracker is a better tool to figure out whether or not we put resources into those crashes than a snap judgement when filing bugs.
    • For each bug you file, include the following information:
      • The backtrace. Note that the backtrace should not be added to the bug if Restrict-View-Google isn't set on the bug as it may contain PII. Filing the bug from the crash reporter should do this automatically, but check.
      • The channel in which the bug is seen (canary/dev/beta/stable), its frequency in that channel, and its rank among crashers in the channel.
      • The frequency of this signature in recent releases. This information is available by:
        1. Clicking on the signature in the “Magic Signature” list
        2. Clicking “Edit” on the dremel query at the top of the page
        3. Removing the “product.version=‘X.Y.Z.W’ AND” string and clicking “Update”.
        4. Clicking “Limit 1000” in the Product Version list in the resulting page (without this, the listing will be restricted to the releases in which the signature is most common, which will often not include the canary/dev release being investigated).
        5. Choose some subset of that list, or all of it, to include in the bug. Make sure to indicate if there is a defined point in the past before which the signature is not present.

Identifying unlabeled network bugs on the tracker

  • Look at new uncomfirmed bugs since noon PST on the last triager's rotation. Use this issue tracker query.

  • Press h to bring up a preview of the bug text.

  • Use j and k to advance through bugs.

  • If a bug looks like it might be network/download/safe-browsing related, middle click (or command-click on OSX) to open in new tab.

  • If a user provides a crash ID for a crasher for a bug that could be net-related, look at the crash stack at go/crash, and see if it looks to be network related. Be sure to check if other bug reports have that stack trace, and mark as a dupe if so. Even if the bug isn't network related, paste the stack trace in the bug, so no one else has to look up the crash stack from the ID.

    • If there's no other information than the crash ID, ask for more details and add the Needs-Feedback label.
  • If network causes are possible, ask for a net-internals log (If it‘s not a browser crash) and attach the most specific internals-network label that’s applicable. If there isn't an applicable narrower label, a clear owner for the issue, or there are multiple possibilities, attach the internals-network label and proceed with further investigation.

  • If non-network causes also seem possible, attach those labels as well.

Investigating Cr-Internals-Network bugs

  • It's recommended that while on triage duty, you subscribe to the Cr-Internals-Network label. To do this, go to and click on “Subscriptions”. Enter “Cr-Internals-Network” and click submit.

  • Look through uncomfirmed and untriaged Cr-Internals-Network bugs, prioritizing those updated within the last week. Use this issue tracker query.

  • If more information is needed from the reporter, ask for it and add the Needs-Feedback label. If the reporter has answered an earlier request for information, remove that label.

  • While investigating a new issue, change the status to Untriaged.

  • If a bug is a potential security issue (Allows for code execution from remote site, allows crossing security boundaries, unchecked array bounds, etc) mark it Type-Bug-Security. If it has privacy implication (History, cookies discoverable by an entity that shouldn't be able to do so, incognito state being saved in memory or on disk beyond the lifetime of incognito tabs, etc), mark it Cr-Privacy.

  • For bugs that already have a more specific network label, go ahead and remove the Cr-Internals-Network label and move on.

  • Try to figure out if it's really a network bug. See common non-network labels section for description of common labels needed for issues incorrectly tagged as Cr-Internals-Network.

  • If it's not, attach appropriate labels and go no further.

  • If it may be a network bug, attach additional possibly relevant labels if any, and continue investigating. Once you either determine it's a non-network bug, or figure out accurate more specific network labels, your job is done, though you should still ask for a net-internals dump if it seems likely to be useful.

  • Note that ChromeOS-specific network-related code (Captive portal detection, connectivity detection, login, etc) may not all have appropriate more specific labels, but are not in areas handled by the network stack team. Just make sure those have the OS-Chrome label, and any more specific labels if applicable, and then move on.

  • Gather data and investigate.

    • Remember to add the Needs-Feedback label whenever waiting for the user to respond with more information, and remove it when not waiting on the user.
    • Try to reproduce locally. If you can, and it's a regression, use src/tools/ to figure out when it regressed.
    • Ask more data from the user as needed (net-internals dumps, repro case, crash ID from about:crashes, run tests, etc).
    • If asking for an about:net-internals dump, provide this link: Can just grab the link from about:net-internals, as needed.
  • Try to figure out what's going on, and which more specific network label is most appropriate.

  • If it's a regression, browse through the git history of relevant files to try and figure out when it regressed. CC authors / primary reviewers of any strongly suspect CLs.

  • If you are having trouble with an issue, particularly for help understanding net-internals logs, email the public list for help debugging. If it's a crasher, or for some other reason discussion needs to be done in private, use TODO(mmenke): Write up a net-internals tips and tricks docs.

  • If it appears to be a bug in the unowned core of the network stack (i.e. no sublabel applies, or only the Cr-Internals-Network-HTTP sublabel applies, and there's no clear owner), try to figure out the exact cause.

Monitoring UMA histograms and gasper alerts

For each Gasper alert that fires, determine if it's a real alert and file a bug if so.

  • Don't file if the alert is coincident with a major volume change. The volume at a particular date can be determined by hovering the mouse over the appropriate location on the alert line.

  • Don‘t file if the alert is on a graph with very low volume (< ~200 data points); it’s probably noise, and we probably don‘t care even if it isn’t.

  • Don't file if the graph is really noisy (but eyeball it to decide if there is an underlying important shift under the noise).

  • Don't file if the alert is in the “Known Ignorable” list:

    • SimpleCache on Windows
    • DiskCache on Android.

For each Gasper alert, respond to with a summary of the action you've taken and why, including issue link if an issue was filed.

Investigating crashers

  • Only investigate crashers that are still occurring, as identified by above section. If a search on go/crash indicates a crasher is no longer occurring, mark it as WontFix.

  • Particularly for Windows, look for weird dlls associated with the crashes. If there are some, it may be caused by malware. You can often figure out if a dll is malware by a search, though it's harder to figure out if a dll is definitively not malware.

  • See if the same users are repeatedly running into the same issue. This can be accomplished by search for (Or clicking on) the client ID associated with a crash report, and seeing if there are multiple reports for the same crash. If this is the case, it may be also be malware, or an issue with an unusual system/chrome/network config.

  • Dig through crash reports to figure out when the crash first appeared, and dig through revision history in related files to try and locate a suspect CL. TODO(mmenke): Add more detail here.

  • Load crash dumps, try to figure out a cause. See for more information

Dealing with old bugs

  • For all network issues (Even those with owners, or a more specific labels):

    • If the issue has had the Needs-Feedback label for over a month, verify it is waiting on feedback from the user. If not, remove the label. Otherwise, go ahead and mark the issue WontFix due to lack of response and suggest the user file a new bug if the issue is still present. Use this issue tracker query for old Needs-Feedback issues.

    • If a bug is over 2 months old, and the underlying problem was never reproduced or really understood:

      • If it's over a year old, go ahead and mark the issue as Archived.
      • Otherwise, ask reporters if the issue is still present, and attach the Needs-Feedback label.
  • Old unconfirmed or untriaged Cr-Internals-Network issues can be investigated just like newer ones. Crashers should generally be given higher priority, since we can verify if they still occur, and then newer issues, as they're more likely to still be present, and more likely to have a still responsive bug reporter.