<div dir="ltr"><div dir="ltr">This is because of changes made in Bug 1353956.<br></div><div>The telemetry now includes the CRC32 integrity check while loading variable length prefix set.</div><div>The total loading time should be reduced because we replace SHA256 with CRC32. The SHA256 integrity verification</div><div>wasn't included in this telemetry before.</div><div><br></div><div>Dimi<br></div><div><br></div><div><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Mon, Mar 11, 2019 at 5:35 AM <<a href="mailto:telemetry-alerts@mozilla.com">telemetry-alerts@mozilla.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">We have detected a change in the Telemetry probe URLCLASSIFIER_VLPS_FILELOAD_TIME in Firefox Nightly builds from 2019-03-08.<br>
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Alert details: <a href="http://alerts.telemetry.mozilla.org/index.html#/detectors/1/metrics/2028/alerts/?from=2019-03-08&to=2019-03-08" rel="noreferrer" target="_blank">http://alerts.telemetry.mozilla.org/index.html#/detectors/1/metrics/2028/alerts/?from=2019-03-08&to=2019-03-08</a><br>
Changes new to Nightly builds on 2019-03-08: <a href="https://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=af29567ecdba5441117b3f01ac2559a3473c3d6a&tochange=67424fa758d40134fdca363ec9a7a992aa92403f" rel="noreferrer" target="_blank">https://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=af29567ecdba5441117b3f01ac2559a3473c3d6a&tochange=67424fa758d40134fdca363ec9a7a992aa92403f</a><br>
The value of URLCLASSIFIER_VLPS_FILELOAD_TIME over time: <a href="https://telemetry.mozilla.org/new-pipeline/evo.html#!measure=URLCLASSIFIER_VLPS_FILELOAD_TIME" rel="noreferrer" target="_blank">https://telemetry.mozilla.org/new-pipeline/evo.html#!measure=URLCLASSIFIER_VLPS_FILELOAD_TIME</a><br>
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What to do about this:<br>
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1. File a bug to track your investigation. You can just copy this email into the bug Description to get you started.<br>
2. Reply-All to this email to let the list know that you are investigating. Include the bug number so we can help out.<br>
3. Triage the alert. You can find instructions here: <a href="https://docs.telemetry.mozilla.org/tools/alerts.html#triaging-a-telemetry-alert-email" rel="noreferrer" target="_blank">https://docs.telemetry.mozilla.org/tools/alerts.html#triaging-a-telemetry-alert-email</a><br>
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If you have any problems, please ask for help on the #telemetry IRC channel or on Slack in #fx-metrics. We'll give you a hand.<br>
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What this is:<br>
We have a system called cerberus[1] that compares Telemetry collected on different Nightly builds and looks for sudden changed in value distributions using the Bhattacharyya Distance[2]. It found such a change in URLCLASSIFIER_VLPS_FILELOAD_TIME on 2019-03-08 so it asked its buddy medusa[3] to send this email to the dev-telemetry-alerts mailing list and to all email addresses listed in the alert_emails field of URLCLASSIFIER_VLPS_FILELOAD_TIME's definition.<br>
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You can do this!<br>
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Your Friendly, Neighbourhood Firefox Telemetry Team<br>
[1]: <a href="https://github.com/mozilla/cerberus" rel="noreferrer" target="_blank">https://github.com/mozilla/cerberus</a><br>
[2]: <a href="https://en.wikipedia.org/wiki/Bhattacharyya_distance" rel="noreferrer" target="_blank">https://en.wikipedia.org/wiki/Bhattacharyya_distance</a><br>
[3]: <a href="https://github.com/mozilla/medusa" rel="noreferrer" target="_blank">https://github.com/mozilla/medusa</a><br>
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