4.1.0-rc.1 release notes

Author: michaelklishin

release-notes/4.1.0.md

@@ -40,7 +40,7 @@ key in `rabbitmq.conf` and do not set it in the application code.
 
 [`amqplib`](https://github.com/amqp-node/amqplib/) is a popular client library that has been using
 a low `frame_max` default of `4096`. Its users must [upgrade to a compatible version](https://github.com/amqp-node/amqplib/pull/787)
-or explicitly use a higher `frame_max`.
+(starting with `0.10.7`) or explicitly use a higher `frame_max`.
 
 
 ### MQTT
@@ -117,6 +117,14 @@ This section can be incomplete and will be expanded as 4.1 approaches its releas
 
 #### Enhancements
 
+ * Quorum queue log reads are now offloaded to channels (sessions, connections).
+
+   In practical terms this means improved consumer throughput, lower interference of publishers
+   on queue delivery rate to consumers, and improved CPU core utilization by each quorum queue
+   (assuming there are enough cores available to the node).
+
+   GitHub issue: [#12713](https://github.com/rabbitmq/rabbitmq-server/pull/12713)
+
  * Feature flag quality of live improvements.
 
    Certain required feature flags will now be automatically required on node boot
@@ -136,6 +144,22 @@ This section can be incomplete and will be expanded as 4.1 approaches its releas
 
     GitHub issue: [#12415](https://github.com/rabbitmq/rabbitmq-server/pull/12415)
 
+ * Larger (up to 8192 bytes) [JWT tokens](https://www.rabbitmq.com/docs/oauth2) now can be used by AMQP 0-9-1 clients.
+
+   Before a client connection can negotiate a maximum frame size (`frame_max`), it must authenticate
+   successfully. Before the authenticated phase, a special lower `frame_max` value
+   is used.
+
+   Clients that do override `frame_max` now must use values of 8192 bytes or greater.
+   We recommend using the default server value of `131072`: do not override the `frame_max`
+   key in `rabbitmq.conf` and do not set it in the application code.
+
+   [`amqplib`](https://github.com/amqp-node/amqplib/) is a popular client library that has been using
+   a low `frame_max` default of `4096`. Its users must [upgrade to a compatible version](https://github.com/amqp-node/amqplib/pull/787)
+   (starting with `0.10.7`) or explicitly use a higher `frame_max`.
+
+   GitHub issue: [#13541](https://github.com/rabbitmq/rabbitmq-server/issues/13541)
+
  *  AMQP 1.0 connections that use OAuth 2.0 now can renew their JWT tokens
     This allows clients to set a new token proactively before the current one [expires](/docs/oauth2#token-expiration), ensuring uninterrupted connectivity.
     If a client does not set a new token before the existing one expires, RabbitMQ will automatically close the AMQP 1.0 connection.
@@ -162,6 +186,24 @@ This section can be incomplete and will be expanded as 4.1 approaches its releas
 
    GitHub issue: [#13231](https://github.com/rabbitmq/rabbitmq-server/pull/13231)
 
+ * Quorum queue checkpoint algorithm was tweaked to take checkpoints more frequently, thus
+   clearing older segment files more aggressively.
+
+   Workloads that use larger messages should continue following [the documented recommendations](https://www.rabbitmq.com/docs/quorum-queues#performance-tuning-large-messages) to
+   avoid large disk space footprint of segment files.
+
+   GitHub issue: [#13622](https://github.com/rabbitmq/rabbitmq-server/pull/13622)
+
+ * Previously a node that was a cluster member but then was [reset](https://www.rabbitmq.com/docs/clustering#restarting-with-hostname-changes) could not
+   rejoin the cluster if the [schema data store](https://www.rabbitmq.com/docs/metadata-store) was Mnesia.
+
+   Now the reset node will try to leave the cluster and retry rejoining again.
+   This was already the case for Khepri.
+
+   Contributed by @SimonUnge.
+
+   GitHub issue: [#13643](https://github.com/rabbitmq/rabbitmq-server/pull/13643)
+
  * Nodes will now fall back to system CA certificate list (if available) when no CA certificate
    is explicitly configured.
 
@@ -171,8 +213,6 @@ This section can be incomplete and will be expanded as 4.1 approaches its releas
 
  * AMQP 1.0 and AMQP 0-9-1 connections now dynamically adjust their TCP socket buffers.
 
-
-
    GitHub issue: [#13363](https://github.com/rabbitmq/rabbitmq-server/pull/13363)
 
  * Peer discovery resilience improvements.
@@ -203,6 +243,14 @@ This section can be incomplete and will be expanded as 4.1 approaches its releas
 
 #### Bug Fixes
 
+ * Quorum queue leadership transfer could take several seconds longer than necessary to complete.
+
+   GitHub issue: [#13190](https://github.com/rabbitmq/rabbitmq-server/pull/13190)
+
+ * Quorum queue follow replica's last index could lag behind that of the leader.
+
+   GitHub issue: [#13328](https://github.com/rabbitmq/rabbitmq-server/pull/13328)
+
  * AMQP 0-9-1 channel exception generator could not handle entity names (say, queue or stream names)
    that contained non-ASCII characters.
 
@@ -356,7 +404,7 @@ This section can be incomplete and will be expanded as 4.1 approaches its releas
    GitHub issue: [#12720](https://github.com/rabbitmq/rabbitmq-server/pull/12720)
 
 
-### Management UI
+### Management Plugin
 
 #### Breaking Changes and Deprecations
 
@@ -415,6 +463,30 @@ This section can be incomplete and will be expanded as 4.1 approaches its releas
 
    GitHub issues: [#13545](https://github.com/rabbitmq/rabbitmq-server/pull/13545), [#3478](https://github.com/rabbitmq/rabbitmq-server/issues/3478)
 
+ * New health check commands help detect quorum queues without an elected leader.
+
+   ```
+   # verifies all quorum queues across all virtual hosts
+   GET /health/checks/quorum-queues-without-elected-leaders/all-vhosts/
+   ```
+
+   ```
+   # verifies all quorum queues in the given virtual host
+   GET /health/checks/quorum-queues-without-elected-leaders/vhost/{vhost}
+   ```
+
+   ```
+   # verifies a subset of quorum queue that match the pattern across all virtual hosts
+   GET /health/checks/quorum-queues-without-elected-leaders/all-vhosts/pattern/{pattern}
+   ```
+
+   ```
+   # verifies a subset of quorum queue that match the pattern in the given virtual host
+   GET /health/checks/quorum-queues-without-elected-leaders/vhost/{vhost}/pattern/{pattern}
+   ```
+
+   Note that the values in the path must be percent-encoded, including the pattern.
+
  * Web app tab title now changes depending on the selected top-level tab.
 
    GitHub issue: [#13512](https://github.com/rabbitmq/rabbitmq-server/pull/13512)
@@ -438,6 +510,29 @@ This section can be incomplete and will be expanded as 4.1 approaches its releas
    GitHub issue: [#12818](https://github.com/rabbitmq/rabbitmq-server/pull/12818)
 
 
+### Stream Plugin
+
+#### Enhancements
+
+ * Stream replication connections now can be configured to use IPv6 using `advanced.config`:
+
+   ```erl
+   [
+     {osiris, [
+        {replica_ip_address_family, inet6}
+     ]}
+   ].
+   ```
+
+#### Bug Fixes
+
+ * When a connection of one or more consumers in a [Single Active Consumer](https://www.rabbitmq.com/docs/streams#single-active-consumer) group failed,
+   the group could try to activate (promote) one of the consumers are are no longer online. In practical terms
+   this means that other consumers were not getting any deliveries.
+
+   GitHub issue: [#13657](https://github.com/rabbitmq/rabbitmq-server/pull/13657)
+
+
 ### OAuth 2 AuthN and AuthZ Plugin
 
 #### Breaking Changes and Deprecations
@@ -483,6 +578,15 @@ This section can be incomplete and will be expanded as 4.1 approaches its releas
    GitHub issue: [#12598](https://github.com/rabbitmq/rabbitmq-server/issues/12598)
 
 
+### LDAP Plugin
+
+#### Enhancements
+
+ * The `in_group_nested` query now uses case-insensitive matching, which is more typical of the LDAP tooling.
+
+   GitHub issue: [#13629](https://github.com/rabbitmq/rabbitmq-server/pull/13629)
+
+
 ### Federation Plugin
 
 #### Enhancements
@@ -491,9 +595,21 @@ This section can be incomplete and will be expanded as 4.1 approaches its releas
 
    GitHub issue: [#13115](https://github.com/rabbitmq/rabbitmq-server/pull/13115)
 
+#### Bug Fixes
+
+ * Queue federation could cause a deadlock in a quorum queue replica process.
+
+   GitHub issue: [#12713](https://github.com/rabbitmq/rabbitmq-server/pull/12713)
+
 
 ### Shovel Plugin
 
+#### Enhancements
+
+ * New Shovel metric: the number of forwarded messages.
+
+   GitHub issue: [#13626](https://github.com/rabbitmq/rabbitmq-server/pull/13626)
+
 #### Bug Fixes
 
  * AMQP 0-9-1 channel exception generator could not handle entity names (say, queue or stream names)
@@ -600,11 +716,12 @@ This section can be incomplete and will be expanded as 4.1 approaches its releas
 
 ### Dependency Changes
 
- * `ra` was upgraded to [`2.16.3`](https://github.com/rabbitmq/ra/releases)
+ * `ra` was upgraded to [`2.16.6`](https://github.com/rabbitmq/ra/releases)
  * `osiris` was upgraded to [`1.8.6`](https://github.com/rabbitmq/osiris/releases)
  * `observer_cli` was upgraded to [`1.8.2`](https://github.com/zhongwencool/observer_cli/releases)
  * `eetcd` was upgraded to [`0.5.0`](https://github.com/zhongwencool/eetcd/releases)
  * `gun` was upgraded to [`2.1.0`](https://github.com/ninenines/gun/releases)
+ * `credentials_obfuscation` was upgraded to [`3.5.0`](https://github.com/rabbitmq/credentials-obfuscation/releases)
 
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