Median JIRA Resolution Latency
established15.0 days Sep 2026
Based on: CHAOSS: Issue Resolution Duration, CHAOSS: Change Request Closure Ratio (adjacent)
Code and contributor health metrics: sustainability, review capacity, and responsiveness — computed from Git, ASF JIRA and GitHub PR history.
Faint points mark a month flagged low-n or insufficient data —
its statistic (a rate, an HHI, a median) comes from too few underlying events to be
reliable on its own. Hover a point for its exact n and flag; the value itself is unchanged.
Responsiveness
CHAOSS practitioner guide
-
Time to First Response (JIRA)
1.8 days
Sep 2026 · n=48
-
Stale PR Rate
25.5%
Oct 2026 · n=650
-
Open PR backlog
549
Sep 2026 · n=549
-
Median JIRA Resolution Latency
15.0 days
Sep 2026 · n=66
Responsiveness
Median JIRA Resolution Latency (12m cohort)
established11.8 days Sep 2026
Based on: CHAOSS: Issue Resolution Duration
Stale JIRA Issue Rate
established69.9% Oct 2026
Based on: CHAOSS: Change Requests (adjacent), CHAOSS: Change Requests Declined (adjacent)
PR Merge Lead Time
proxy1.1 days Aug 2026
PR Time to Close
proxy4.8 days Sep 2026
Based on: CHAOSS: Change Requests (adjacent)
Time to First Response (JIRA)
established1.8 days Sep 2026 backfill pending
Based on: CHAOSS: Time to First Response, CHAOSS: Responsiveness practitioner guide
Stale PR Rate
established25.5% Oct 2026
Based on: CHAOSS: Change Requests (adjacent), CHAOSS: Change Requests Declined (adjacent)
Change Request Closure Ratio — GitHub PR
proxy0.541 Sep 2026
Based on: CHAOSS: Change Request Closure Ratio
Change Request Closure Ratio — JIRA Patch Submissions
established0.667 Sep 2026
Based on: CHAOSS: Change Request Closure Ratio
Time to First Response (GitHub issues)
establishedn/a
insufficient data
Based on: CHAOSS: Issue Response Time, CHAOSS: Time to First Response
Issue Closure Ratio — GitHub Issues
proxyn/a
insufficient data
Based on: CHAOSS: Issues Closed (adapted)
Reviewer Capacity
PR Time to First Review
proxy17.4 h Sep 2026
Based on: CHAOSS: Time to First Response (GitHub-only variant)
Review responsiveness
How quickly a patch submission gets its first visible review response, split by how many
prior submissions the same contributor has -- a first-time submitter, a 2nd-5th submission, or
a 6th+ submission. A "submission" is one JIRA issue that ever reached
Patch Available, together with any linked GitHub pull request. "First visible
response" is the earliest of a JIRA comment, a JIRA status change to
Review In Progress/Ready to Commit, or a GitHub PR review/comment,
from someone other than the submission's own author -- review that happened somewhere this
project doesn't track (a private message, an in-person conversation) is invisible to this
section, so "no visible response" means exactly that, not "no response at all."
Methodology and caveats. The submission's author is reconstructed from JIRA's assignee-change history, which is a best-effort proxy, not a confirmed identity. Shares for "response within 7/30 days" and "no visible response" only count submissions old enough to judge (right-censoring: a submission newer than 7, 30, or 365 days is left out of that share's count entirely, not counted as a miss). These figures are informational only, shown with their own sample size (n) for context. Full definitions: METRICS.md.
First-time submitters
| Year | Submissions | Median days to first response | ≤7d | ≤30d | No visible response | Committed ≤365d |
|---|---|---|---|---|---|---|
| 2009 | 42 | 0.2 | 93% | 98% | 2% | 90% |
| 2010 | 75 | 0.4 | 92% | 95% | 1% | 72% |
| 2011 | 80 | 0.3 | 84% | 89% | 0% | 78% |
| 2012 | 54 | 0.8 | 83% | 91% | 6% | 65% |
| 2013 | 61 | 0.7 | 85% | 95% | 2% | 93% |
| 2014 | 103 | 0.7 | 83% | 94% | 0% | 83% |
| 2015 | 102 | 1.3 | 68% | 85% | 2% | 81% |
| 2016 | 83 | 3.2 | 60% | 82% | 6% | 67% |
| 2017 | 68 | 1.3 | 63% | 81% | 4% | 51% |
| 2018 | 58 | 1.8 | 62% | 76% | 0% | 43% |
| 2019 | 29 | 1.8 | 62% | 72% | 3% | 76% |
| 2020 | 44 | 0.3 | 75% | 89% | 0% | 84% |
| 2021 | 46 | 0.1 | 87% | 96% | 0% | 80% |
| 2022 | 54 | 0.1 | 87% | 98% | 0% | 87% |
| 2023 | 40 | 0.0 | 78% | 92% | 2% | 82% |
| 2024 | 32 | 0.0 | 81% | 88% | 6% | 78% |
| 2025 | 31 | 0.2 | 77% | 87% | 3% | 92% |
2nd-5th submission
| Year | Submissions | Median days to first response | ≤7d | ≤30d | No visible response | Committed ≤365d |
|---|---|---|---|---|---|---|
| 2009 | 68 | 0.2 | 91% | 97% | 3% | 91% |
| 2010 | 111 | 0.4 | 94% | 97% | 2% | 91% |
| 2011 | 118 | 0.4 | 78% | 88% | 4% | 82% |
| 2012 | 80 | 0.7 | 82% | 94% | 1% | 74% |
| 2013 | 56 | 0.4 | 82% | 95% | 2% | 93% |
| 2014 | 131 | 0.5 | 73% | 88% | 5% | 82% |
| 2015 | 122 | 0.9 | 75% | 88% | 4% | 80% |
| 2016 | 141 | 3.5 | 61% | 77% | 9% | 79% |
| 2017 | 77 | 0.9 | 71% | 83% | 3% | 57% |
| 2018 | 68 | 3.3 | 62% | 71% | 3% | 46% |
| 2019 | 37 | 0.7 | 68% | 78% | 0% | 78% |
| 2020 | 67 | 0.3 | 82% | 91% | 0% | 87% |
| 2021 | 53 | 0.3 | 79% | 89% | 0% | 85% |
| 2022 | 70 | 0.4 | 81% | 93% | 1% | 94% |
| 2023 | 67 | 0.2 | 81% | 91% | 0% | 85% |
| 2024 | 54 | 0.2 | 83% | 89% | 2% | 80% |
| 2025 | 40 | 1.3 | 72% | 95% | 0% | 93% |
6th+ submission
| Year | Submissions | Median days to first response | ≤7d | ≤30d | No visible response | Committed ≤365d |
|---|---|---|---|---|---|---|
| 2009 | 200 | 0.2 | 96% | 98% | 2% | 97% |
| 2010 | 525 | 0.2 | 92% | 95% | 4% | 95% |
| 2011 | 791 | 0.2 | 88% | 95% | 3% | 95% |
| 2012 | 626 | 0.5 | 85% | 95% | 2% | 95% |
| 2013 | 609 | 0.2 | 89% | 96% | 3% | 95% |
| 2014 | 794 | 0.5 | 84% | 94% | 4% | 93% |
| 2015 | 989 | 1.0 | 77% | 91% | 3% | 95% |
| 2016 | 769 | 1.4 | 64% | 81% | 13% | 94% |
| 2017 | 393 | 1.1 | 69% | 84% | 3% | 87% |
| 2018 | 314 | 1.6 | 68% | 82% | 4% | 87% |
| 2019 | 144 | 3.4 | 60% | 72% | 5% | 81% |
| 2020 | 461 | 0.7 | 77% | 90% | 4% | 95% |
| 2021 | 486 | 0.4 | 81% | 88% | 5% | 94% |
| 2022 | 486 | 0.5 | 82% | 90% | 4% | 92% |
| 2023 | 569 | 0.4 | 81% | 90% | 7% | 91% |
| 2024 | 430 | 0.5 | 75% | 85% | 10% | 94% |
| 2025 | 403 | 0.6 | 69% | 80% | 16% | 92% |
Trailing 12-month response-within-30-days share, by tier
Source of first response (2025 and later tiers combined)
| Source | Count | Share |
|---|---|---|
| JIRA comment | 135 | 33% |
| GitHub review | 100 | 24% |
| JIRA status change | 98 | 24% |
| GitHub PR comment | 77 | 19% |
Open PR backlog
The open apache/cassandra PR backlog by age and by linked-JIRA-ticket state, reconstructed monthly. Scoped to apache/cassandra: other configured repos use their own issue tracker or none, so ticket-key state isn't meaningful for them — see the table below instead.
By age — apache/cassandra (last 36 months)
By linked-ticket state — apache/cassandra (last 36 months)
Current month — apache/cassandra
| Month | Open PRs | Drafts | No GitHub response |
|---|---|---|---|
| 2026-09-30 | 549 | 20 | 57% (n=549) |
Other project repositories
| Repo | Open PRs | Drafts | <30d | 30-90d | 90d-1y | 1-3y | >3y |
|---|---|---|---|---|---|---|---|
| cassandra-builds | 12 | 0 | 0 | 0 | 2 | 1 | 9 |
| cassandra-diff | 4 | 0 | 0 | 0 | 1 | 0 | 3 |
| cassandra-dtest | 49 | 0 | 0 | 1 | 4 | 12 | 32 |
| cassandra-harry | 1 | 0 | 0 | 0 | 1 | 0 | 0 |
| cassandra-in-jvm-dtest-api | 1 | 0 | 0 | 0 | 1 | 0 | 0 |
| cassandra-website | 15 | 0 | 1 | 1 | 1 | 3 | 9 |
Based on: CHAOSS: Change Requests (adapted), CHAOSS: Issue Age (adapted, applied to change requests)
Base branch (trunk vs. release branches) is not collected yet, so it is not shown here.
Contributor sustainability
CHAOSS practitioner guide
-
Active Contributors
16
Sep 2026 · n=16
-
New Contributors
3
Sep 2026 · n=3
-
Contributor Dependency (N for 50%)
7
Sep 2026 · n=97
-
Unique Reviewers
43
Sep 2026 · n=43
Contributor Sustainability
Active Contributors
established16 Sep 2026
Based on: CHAOSS: Contributors
New Contributors
established3 Sep 2026
Based on: CHAOSS: New Contributors
First → Second Contribution Conversion
proxy42.9% Jan 2026 backfill pending
Based on: CHAOSS: Conversion Rate
Contributor Funnel Conversion
proxy0.0% Jun 2026 backfill pending
Based on: CHAOSS: Conversion Rate (adjacent), CHAOSS: New Contributors (adjacent)
Contributor Tenure (Kaplan–Meier)
experimental54.4% Sep 2026
Based on: Lin, Robles & Serebrenik (2017), Developer Turnover in Global, Industrial Open Source Projects, Foucault et al. (2015), Impact of Developer Turnover on Quality in Open-Source Software
Contributor Churn Rate
proxy54.3% Aug 2025 backfill pending
Based on: project-specific (no established CHAOSS/literature equivalent)
Sustained Contributors
established18 Sep 2026
Based on: CHAOSS: Contributors (adjacent)
Truck Factor (DOA)
experimental14 Sep 2026
Based on: CHAOSS: Contributor Absence Factor / Bus Factor (adjacent), Avelino, Passos, Hora & Valente (2016), A Novel Approach for Estimating Truck Factors
Contributor Dependency (N for 50%)
established7 Sep 2026
Based on: CHAOSS: Contributor Absence Factor
Contributor Concentration (HHI)
established0.053 Sep 2026
Based on: DOJ/FTC: Herfindahl-Hirschman Index
Reviewer Capacity
Unique Reviewers
proxy43 Sep 2026
Reviewer Concentration (HHI)
proxy0.063 Sep 2026
Based on: project-specific (no established CHAOSS/literature equivalent)
PR Review Engagement (Reviewers/PR)
proxy1.5 Sep 2026
Contributor pipeline
Two additional views of the cards above: a Kaplan–Meier survival curve over contributor tenure, and a per-stage breakdown of the latest completed first-time-contributor cohort's funnel. Both are computed from git commit history only; the committer and PMC funnel stages are not available (no confirmed identity link between the ASF roster and this project's git/JIRA identities exists yet).
Tenure survival (Oct 2024 – Sep 2026 cohort intake, n=83)
median tenure not reached
36 churn event(s), 47 still-active (censored), 21.16 months max follow-up
Tick marks show right-censored (still-active) contributors at the time they were last observed. The curve beyond the point where fewer than 10 contributors remain at risk is shown at reduced opacity -- it rests on very few people and is noisier than the rest of the line.
Funnel, pooled across the last 12 horizon-elapsed cohorts (Feb 2022 – Sep 2024, n=66)
Pooled rather than shown as a single cohort month: at this cohort size, one month's bars are noisy enough on their own to be misleading, and the 730-day observation horizon means only cohorts old enough to be fully resolved are included here (no "in flight" segment).
Contributor leaderboard
Top contributors by one activity type at a time — commits, reviews, and JIRA issues resolved — over the trailing 12 completed months (2025-10-01 to 2026-09-30). These are ranked counts of deterministic, public activity, never a blended "contribution score" and never based on any classified label (DECISIONS.md — D19).
Identity-resolution limits. Counts are grouped by resolved identity (normalize/identity.py), not by human being. M0's identity resolution only merges an exact-matching git email or JIRA username; a commit-trailer reviewer name (a bare handle or display name, not an email) is never automatically linked to that same person's git email or JIRA username, so one contributor active under more than one raw identifier can appear more than once, or under a handle rather than their full name. Manual merges are reviewed, evidenced entries in identity_overrides.yaml -- see the corrections link below to request one. Request an identity correction (every row's own "Report an issue" link below uses this same form) — see /corrections/ for what happens next.
Commits
| # | Contributor | Organization | Count | |
|---|---|---|---|---|
| 1 | Stefan Miklosovic | Instaclustr | 57 | Report an issue |
| 2 | Dmitry Konstantinov | NetCracker | 54 | Report an issue |
| 3 | Mick Semb Wever | unknown | 44 | Report an issue |
| 4 | Benedict Elliott Smith | Apple | 22 | Report an issue |
| 5 | Sam Tunnicliffe | Apple | 22 | Report an issue |
| 6 | Marcus Eriksson | Apple | 21 | Report an issue |
| 7 | Francisco Guerrero | unknown | 21 | Report an issue |
| 8 | Arvind Kandpal | Ksolves | 20 | Report an issue |
| 9 | David Capwell | unknown | 12 | Report an issue |
| 10 | Caleb Rackliffe | Apple | 11 | Report an issue |
| 11 | Maxim Muzafarov | Aiven | 11 | Report an issue |
| 12 | Patrick McFadin | DataStax | 10 | Report an issue |
| 13 | Nivy Kani | Apple | 9 | Report an issue |
| 14 | samlightfoot | unknown | 8 | Report an issue |
| 15 | Minal Kyada | unknown | 6 | Report an issue |
| 16 | Alan Wang | unknown | 6 | Report an issue |
| 17 | Paulo Motta | unknown | 5 | Report an issue |
| 18 | Matt Byrd | Apple | 5 | Report an issue |
| 19 | Sunil Ramchandra Pawar | Apple | 4 | Report an issue |
| 20 | Brandon Williams | DataStax | 4 | Report an issue |
| 21 | Aleksey Yeschenko | Apple | 3 | Report an issue |
| 22 | Jon Meredith | unknown | 3 | Report an issue |
| 23 | Mohammad Suhel | Ksolves | 3 | Report an issue |
| 24 | Isaac Reath | Bloomberg | 3 | Report an issue |
| 25 | Jyothsna Konisa | Apple | 3 | Report an issue |
Reviews
| # | Contributor | Organization | Count | |
|---|---|---|---|---|
| 1 | Stefan Miklosovic | unknown | 88 | Report an issue |
| 2 | Dmitry Konstantinov | unknown | 58 | Report an issue |
| 3 | Caleb Rackliffe | unknown | 38 | Report an issue |
| 4 | Francisco Guerrero | unknown | 38 | Report an issue |
| 5 | Sam Tunnicliffe | unknown | 33 | Report an issue |
| 6 | Brandon Williams | unknown | 29 | Report an issue |
| 7 | Michael Semb Wever | unknown | 26 | Report an issue |
| 8 | David Capwell | unknown | 25 | Report an issue |
| 9 | Yifan Cai | unknown | 24 | Report an issue |
| 10 | Marcus Eriksson | unknown | 22 | Report an issue |
| 11 | Jyothsna Konisa | unknown | 21 | Report an issue |
| 12 | Alex Petrov | unknown | 19 | Report an issue |
| 13 | Ariel Weisberg | unknown | 12 | Report an issue |
| 14 | Benedict Elliott Smith | unknown | 10 | Report an issue |
| 15 | Brad Schoening | unknown | 8 | Report an issue |
| 16 | Branimir Lambov | unknown | 7 | Report an issue |
| 17 | Mick Semb Wever | unknown | 7 | Report an issue |
| 18 | Bernardo Botella | unknown | 7 | Report an issue |
| 19 | Aleksey Yeschenko | unknown | 6 | Report an issue |
| 20 | marcuse | unknown | 5 | Report an issue |
| 21 | Maxwell Guo | unknown | 5 | Report an issue |
| 22 | Paulo Motta | unknown | 5 | Report an issue |
| 23 | Jaydeepkumar Chovatia | unknown | 4 | Report an issue |
| 24 | Nitsan Wakart | unknown | 4 | Report an issue |
| 25 | Doug Rohrer | unknown | 3 | Report an issue |
JIRA issues resolved
| # | Contributor | Organization | Count | |
|---|---|---|---|---|
| 1 | dnk | unknown | 58 | Report an issue |
| 2 | smiklosovic | unknown | 45 | Report an issue |
| 3 | mck | unknown | 35 | Report an issue |
| 4 | arvindk12 | unknown | 27 | Report an issue |
| 5 | samt | unknown | 23 | Report an issue |
| 6 | marcuse | unknown | 21 | Report an issue |
| 7 | frankgh | unknown | 21 | Report an issue |
| 8 | maedhroz | unknown | 15 | Report an issue |
| 9 | dcapwell | unknown | 12 | Report an issue |
| 10 | samueldlightfoot | unknown | 12 | Report an issue |
| 11 | bdeggleston | unknown | 12 | Report an issue |
| 12 | alanwang599 | unknown | 11 | Report an issue |
| 13 | mmuzaf | unknown | 11 | Report an issue |
| 14 | aleksey | unknown | 9 | Report an issue |
| 15 | aweisberg | unknown | 8 | Report an issue |
| 16 | minalkyada | unknown | 7 | Report an issue |
| 17 | nivy | unknown | 7 | Report an issue |
| 18 | mbyrd | unknown | 6 | Report an issue |
| 19 | rishabhsaraswat | unknown | 6 | Report an issue |
| 20 | anaik | unknown | 6 | Report an issue |
| 21 | paulo | unknown | 5 | Report an issue |
| 22 | Novice_P | unknown | 5 | Report an issue |
| 23 | rustyrazorblade | unknown | 5 | Report an issue |
| 24 | isaacreath | unknown | 4 | Report an issue |
| 25 | brandon.williams | unknown | 4 | Report an issue |
Organizational participation
CHAOSS practitioner guide
-
Elephant Factor
2
Sep 2026 · n=18
-
Organizational Concentration (HHI)
0.222
Sep 2026 · n=18
-
Single-Organization Share
24.7%
Sep 2026 · n=18
-
Unknown-Affiliation Rate
35.7%
Sep 2026 · n=462
Organizational Diversity
Elephant Factor
experimental2 Sep 2026
Based on: CHAOSS: Elephant Factor, CHAOSS wg-risk: Elephant Factor
Organizational Concentration (HHI)
established0.222 Sep 2026
Based on: CHAOSS: Organizational Diversity
Single-Organization Share
established24.7% Sep 2026
Based on: CHAOSS: Organizational Diversity
Unknown-Affiliation Rate
established35.7% Sep 2026
Based on: project-specific (no established CHAOSS/literature equivalent)
Leadership
CHAOSS practitioner guide
-
PMC Joins per Quarter
0
Sep 2026 · n=0
Releases
CHAOSS: Release Frequency
-
Release Frequency
24
Sep 2026 · n=24
-
Days Between Releases (median)
9.0 days
Sep 2026 · n=24
-
Time Since Last Release
75.0 days
Oct 2026 · n=1
Release Cadence
Release Frequency
established24 Sep 2026
Based on: CHAOSS: Release Frequency
Release Interval Regularity (CoV)
proxy1.406 Sep 2026
Based on: project-specific (no established CHAOSS/literature equivalent)
Time Since Last Release
established75.0 days Oct 2026
Based on: project-specific (no established CHAOSS/literature equivalent)
Days Between Releases (median)
proxy9.0 days Sep 2026
Based on: CHAOSS: Release Frequency
Conversation patterns
Conversation patterns
classifiedpreliminary
Classified dev@ mailing-list and JIRA-comment patterns — escalation, constructive resolution, newcomer treatment and message-level patterns, 2017–2025. Uncalibrated cutoffs, not yet reviewed by the PMC (D26).
- Venues covered dev@ mailing list, JIRA comments
- Classifier 1.0.0
- Quarters covered 2012Q1–2026Q3
Tone over time
dev@ mailing list
JIRA comments
Peer context
Peer context
CHAOSS does not set targets or rank projects. These numbers are shown for context only -- Cassandra and five comparable Apache Software Foundation projects, chosen by the project owner, computed with the same code and the same definitions.