## Description:
Pulsar is a highly scalable, low latency messaging platform running on
commodity hardware. It provides simple pub-sub semantics over topics,
guaranteed at-least-once delivery of messages, automatic cursor management for
subscribers, and cross-datacenter replication.
## Project Status:
- There are no issues requiring board attention at this time.
## Project Activity:
- Pulsar 5.0.0-M1, the first preview of Pulsar 5, was released on June
23rd 2026. It is a milestone build meant to gather early feedback ahead
of the 5.0 LTS release, and previews the major changes of 5.0:
- Scalable Topics: a new kind of topic (topic:// scheme) that sizes
itself to its actual load. The broker splits hot key-range segments
and merges cold ones at runtime, with no downtime and without
breaking per-key ordering, so there is no partition count to choose
up front (PIP-460, 466, 468, 473, 475, 483).
- A new V5 Java client (pulsar-client-v5): a clean-slate redesign with
three purpose-built consumers (Stream, Queue, Checkpoint). It works
against existing topics and can subscribe to an entire namespace.
- Oxia is now the recommended metadata store for new clusters, with a
live, zero-downtime migration from ZooKeeper (PIP-454, 469). The etcd
backend is removed (PIP-462).
- Structured logging (PIP-467), IO connectors moved to a dedicated
repository (PIP-465), the javax.* to jakarta.* migration (PIP-472)
and the move from Maven to Gradle (PIP-463).
- The second milestone, 5.0.0-M2, is under vote as of this writing
(release candidate published September 12th). Pulsar 5.0.0, the next
LTS release, is targeted for this fall.
- Pulsar 4.2.0 remains the latest feature release (March 31st 2026).
Maintenance releases across the 4.2.x and 4.0.x (LTS) lines continue on
a regular cadence; the 3.0.x LTS line has reached end of support:
- 4.2.4 was released on August 3rd 2026
- 4.0.13 was released on August 3rd 2026
- 4.2.3 was released on July 6th 2026
- 4.0.12 was released on July 6th 2026
- 5.0.0-M1 was released on June 23rd 2026
- Pulsar C++ releases:
- No new release this quarter (latest is 4.2.0, June 14th 2026)
- Pulsar Go releases:
- 0.21.0 on July 20th 2026
- 0.20.0 on June 15th 2026
- Pulsar Python releases:
- 3.13.0 on July 6th 2026
- Pulsar NodeJS releases:
- 1.18.0 on June 26th 2026
- Pulsar C# (DotPulsar) releases:
- 5.3.3 on August 26th 2026
- 5.3.2 on August 14th 2026
- Pulsar Helm Chart releases:
- 4.7.0 on July 13th 2026
- 4.6.1 on June 18th 2026
- The connectors repository, split out of the main repo under PIP-465,
saw a large integration-test and bug-fix pass in July (32 PRs merged),
adding real integration tests for a dozen connectors and fixing the
runtime bugs that surfaced as a result.
- The flow of "Pulsar Improvement Proposals" remains strong. After the
exceptional burst leading up to 5.0.0-M1, this quarter saw 17 PIPs with
activity, 9 of them new (PIP-486 through PIP-494). Themes include
follow-ups to the Scalable Topics initiative (PIP-486, 494), a set of
security and authentication proposals (PIP-478, 485, 488, 489, 490),
operability and metrics (PIP-470, 487, 492) and consumer delivery
semantics (PIP-491, 493):
PIP-486: Scalable Topic Key-Shared Consumption
PIP-487: Add event count metrics for InflightReadsLimiter acquire and
release operations
PIP-488: Pluggable authentication audit-event hook
PIP-489: FIPS 140-3 compliance mode for Apache Pulsar
PIP-490: Zero-downtime token signing-key rotation for the built-in JWT
provider
PIP-491: Prevent delivery stalls by making the client return exactly
the permits used by the broker
PIP-492: Add subscription-level storage backlog age metric and stats
field
PIP-493: Key-ordered negative acknowledgement for Key_Shared
subscriptions
PIP-494: Scalable Topics Client Specification — authoritative reference
and change process
- Pulsar has reached 732 contributors on the main GitHub repo
(It was 724 in June 2026)
## Health report:
- The community remains healthy. The first Pulsar 5 preview shipped in
June with a second milestone now under vote, maintenance releases
continue monthly on both supported lines, and PIP activity, while down
from the exceptional pre-5.0.0-M1 burst of last quarter, is in line
with its historical level. A new committer was added this quarter, the
first since July 2025. Most day-to-day user interaction continues to
happen on Slack and GitHub rather than on the users@ list.
## Membership Data:
Apache Pulsar was founded 2018-09-18 (8 years ago)
There are currently 86 committers and 47 PMC members in this project.
The Committer-to-PMC ratio is roughly 2:1.
Community changes, past quarter:
- No new PMC members. Last addition was Cong Zhao on 2025-09-16.
- Zhuohan Zhou was added as committer on 2026-08-05
## Community Health:
- Activity on the dev@ list returned to its typical level this quarter,
after the previous quarter's spike driven by the Scalable Topics PIPs
ahead of the 5.0.0-M1 release. Traffic is a mixture of release votes,
PIP discussions and design threads from both long-time and newer
contributors.
- [email protected]:
- 0% change in traffic in the past quarter (15 emails compared to 15)
- [email protected]:
- 48% decrease in traffic in the past quarter (166 emails compared to 319)
## Slack activity:
- 10917 Members (10910 in June 2026)
- 56 Active monthly users (133 in June 2026)
--
Matteo Merli
<[email protected]>
