Aeron MeetUp Recording: What’s New – June 2025

Missed our latest Aeron Community MeetUps in June 2025? No problem. In this summary blog, based on our MeetUp presentation, we’ll dive into the additions and enhancements introduced in the latest Aeron releases, and what they mean for your applications. Please watch the talk recording for detailed explanations and further context.

What’s New in Aeron: Key Features and Enhancements over the past 6 months

Since the last Meetup in November, the Aeron team has maintained a steady pace, delivering two major releases (January and June)

Discover Aeron 1.47.0 and 1.48.0 enhancements including:

• Publication Revoke: immediate stream termination
• Image Reject: fine-grained control over subscriptions
• Handling dormant clients and preventing interference
• C/C++ Archive client API parity
• New Aeron Premium features

Watch the full recording here:

Publication Revoke: immediate stream termination

One of the headline features in the 1.48 release is Publication Revoke. This new capability allows exclusive publications to be stopped or closed immediately, with subscription images on the other side being notified and cleaned up without delay. Unlike the traditional close operation—which waits for all data to be delivered and acknowledged—revoke bypasses the draining state, instantly freeing resources and terminating the stream.

Key benefits:

• Faster resource cleanup: No more lingering states or waiting for subscribers to catch up.
• Immediate effect: Useful for scenarios like search-in-replay, where a client finds what it needs and wants to halt the stream right away.
• Robustness: Prevents resource leaks and makes the system more responsive to abrupt changes.

How does it work:

• The publisher issues a revoke command (either explicitly or using revokeOnClose).
• The media driver marks the publication as revoked, disconnects it, and notifies subscribers via a status message with a special flag.
• Subscribers drop the image immediately, and all resources are released—no need to consume the rest of the stream.

This feature is especially valuable for stopping archive replays and for terminating dormant or misbehaving client sessions efficiently.

Image Reject: fine-grained control over subscriptions

Building on previous work to limit the number of images a subscription can accept, Aeron now introduces an Image Reject API. This allows client-side logic to reject images dynamically, for reasons such as authentication failure, system overload, or business-specific rules.

Key benefits:

• Prevents resource exhaustion: Protects against DDoS or misconfiguration by limiting the number of active images.
• Dynamic control: Applications can reject images based on real-time conditions (e.g., high load, failed validation).
• Temporary state: Unlike revoke (which is terminal), rejected images can reappear if conditions change.

This mechanism is crucial for maintaining system stability and security, especially in large-scale or multi-tenant deployments.

Handling dormant clients and preventing interference

A recurring pain point for Aeron users has been dormant archive clients—sessions that are abandoned but still consume resources and can block active clients. The latest release addresses this by:

• Detecting dormant clients: The archive now sends periodic “ping” messages and, if unacknowledged, terminates the session.
• Preventing interference: By randomizing session IDs and encouraging the use of unique response channels, Aeron ensures that one client’s inactivity doesn’t block others on the same stream.

These improvements significantly enhance reliability, especially in environments with many clients or automated processes.

C/C++ Archive client API parity

A major milestone for the Aeron ecosystem is the full feature parity of the C and C++ Archive client APIs with the Java API. The new C++ wrapper (superseding the old pure C++ API, which is now deprecated) allows developers in non-Java environments to leverage all the latest archive features, broadening Aeron’s appeal and usability.

Aeron Premium features: Insights, Data Retention, SBE Domain Mapper

While Aeron remains a robust open source project, the team continues to also invest in premium features that address advanced operational needs. The latest additions include:

• Aeron Insights: More than just monitoring, Aeron Insights provides actionable intelligence, preempting issues before they impact availability. With curated metrics and integrations (e.g., Grafana), it helps teams achieve high reliability and rapid troubleshooting.
• Data Retention Regulator: Manages disk space by controlling data lifespan in archives and clusters, ensuring compliance and preventing storage exhaustion.
• SBE Domain Mapper: Simplifies and accelerates development with Aeron, making it safer and easier to use in complex environments.

These tools are available as commercial add-ons, but the lessons learned from their development benefit the entire community.

Looking ahead: future enhancements

The Aeron team is not resting on its laurels. Upcoming features include:

• Archive recovery improvements
• Replay Merge v2
• Non-blocking segment migration