MediaWiki: Define new metric type - Histogram
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Description

Task to implement proposal found in T344751#9247383

In T344751#9175304, @Krinkle wrote:

The handful of timing metrics we have (and actively make use of) vary a lot in their range. I'm not sure a single set can be of much use. The size and range of timing measures vary a lot throughout the platform, from job measures in the range between whole seconds and hours, to WANCache callbacks that are measures between 0.1 and 100 milliseconds.

To handle cases where a custom range of histogram buckets are needed, there should be a metric type that generates histograms based on a hardcoded set of buckets.

This task is complete when MediaWiki StatsLib can produce histograms in a set of counters following guidance provided by the Prometheus team.

Details

Related Changes in Gerrit:

Subject	Repo	Branch	Lines +/-
Stats: Encourage start() or observeNanoseconds()	mediawiki/core	master	+60 -30
Stats: implement HistogramMetric	mediawiki/core	master	+268 -1
Stats: Allow specifying histogram buckets via a mean value and skip	mediawiki/core	master	+156 -1
update isSubclassOf_entities_total to Histogram type	mediawiki/extensions/WikibaseQualityConstraints	master	+1 -4
stats: limit number of definable buckets for Histograms	mediawiki/core	master	+15 -1
Stats: add special bucket attribute to MetricTrait	mediawiki/core	master	+108 -10

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Related Objects
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Status	Assigned	Task
Open	None	T343020 Converting MediaWiki Metrics to StatsLib
Resolved	herron	T350591 Audit legacy mediawiki stats used in production dashboards
Open	None	T350592 EPIC: migrate in use metrics and dashboards to statslib
Open	Jgiannelos	T354908 evaluate and migrate in-use parsoid metrics to statslib
Resolved	colewhite	T348796 MediaWiki: Define new metric type - Histogram

Event Timeline

colewhite created this task.Oct 12 2023, 6:11 PM

Restricted Application added a subscriber: Aklapper. · View Herald TranscriptOct 12 2023, 6:11 PM

colewhite updated the task description. (Show Details)Oct 12 2023, 6:12 PM

colewhite mentioned this in T348806: Rethink how metric label values are sanitized.Oct 12 2023, 9:10 PM

Scheduling this into the future unless there's a need to address this now. Please advise otherwise.

colewhite mentioned this in T344751: Decide on default histogram buckets for MediaWiki timers.Oct 16 2023, 11:54 PM

• lmata removed a project: SRE Observability (FY2023/2024-Q3).Mar 12 2024, 3:03 PM

• lmata moved this task from Inbox to Backlog on the Observability-Metrics board.

Change #1063064 had a related patch set uploaded (by Cwhite; author: Cwhite):

[mediawiki/core@master] Stats: add special bucket attribute to CounterMetric

https://gerrit.wikimedia.org/r/1063064

Change #1063065 had a related patch set uploaded (by Cwhite; author: Cwhite):

[mediawiki/core@master] Stats: implement HistogramMetric

https://gerrit.wikimedia.org/r/1063065

colewhite changed the task status from Open to In Progress.Aug 16 2024, 5:07 PM

colewhite claimed this task.

colewhite triaged this task as Medium priority.

• lmata added a project: SRE Observability (FY2024/2025-Q1).Aug 19 2024, 2:33 AM

• lmata moved this task from Backlog to Prioritized on the Observability-Metrics board.

• lmata edited projects, added SRE Observability (FY2024/2025-Q2); removed SRE Observability (FY2024/2025-Q1).Nov 5 2024, 5:11 PM

colewhite moved this task from Backlog to Epics in Progress on the MediaWiki-libs-Stats board.Jan 9 2025, 6:29 PM

colewhite merged a task: T383563: mw.track: support for histogram metrics.Jan 13 2025, 5:09 PM

colewhite added subscribers: Michael, Ottomata.

Adding this as a blocker for T382003: (mw.track) Migrate timing.growthExperiments.* to statslib as we have one metric there that is tracking bytes and used to use timing with Graphite.

• lmata edited projects, added SRE Observability (FY2024/2025-Q3); removed SRE Observability (FY2024/2025-Q2).Jan 14 2025, 3:59 PM

Michael mentioned this in T383953: Statsv support for timer metrics.Jan 28 2025, 9:14 AM

Change #1115973 had a related patch set uploaded (by Cwhite; author: Cwhite):

[mediawiki/extensions/WikibaseQualityConstraints@master] update isSubclassOf_entities_total to Histogram type

https://gerrit.wikimedia.org/r/1115973

Michael mentioned this in T383563: mw.track: support for histogram metrics.Feb 7 2025, 12:50 PM

In T348796#10458111, @Michael wrote:

Adding this as a blocker for T382003: (mw.track) Migrate timing.growthExperiments.* to statslib as we have one metric there that is tracking bytes and used to use timing with Graphite.

Parsoid also has a number of bytes-bases metrics (wikitext size, html size, etc). We use a "fake timing" method for these right now, but it would be nice to be able to shift these to a more appropriate type.

Krinkle removed a parent task: T382003: (mw.track) Migrate timing.growthExperiments.* to statslib.Apr 10 2025, 2:44 PM

Is this task stalled? Parsoid is having trouble migrating its byte-count metrics to prometheus so this is a blocker for us at this time. I note that @Michael's blocker seems to have been solved by adding bucket support to the JavaScript side in mw.track, but we really need PHP-side support.

cscott added a parent task: T354908: evaluate and migrate in-use parsoid metrics to statslib.Apr 15 2025, 7:48 PM

In T348796#10745299, @cscott wrote:

Is this task stalled? Parsoid is having trouble migrating its byte-count metrics to prometheus so this is a blocker for us at this time. I note that @Michael's blocker seems to have been solved by adding bucket support to the JavaScript side in mw.track, but we really need PHP-side support.

Yes, still waiting on code review for the linked patches.

Change #1063064 merged by jenkins-bot:

[mediawiki/core@master] Stats: add special bucket attribute to MetricTrait

https://gerrit.wikimedia.org/r/1063064

ReleaseTaggerBot added a project: MW-1.44-notes (1.44.0-wmf.27; 2025-04-29).Apr 17 2025, 2:00 AM

Change #1137332 had a related patch set uploaded (by Cwhite; author: Cwhite):

[mediawiki/core@master] stats: limit number of definable buckets for Histograms

https://gerrit.wikimedia.org/r/1137332

Change #1063065 merged by jenkins-bot:

[mediawiki/core@master] Stats: implement HistogramMetric

https://gerrit.wikimedia.org/r/1063065

Change #1137332 merged by jenkins-bot: