Project: RabbitMQ (App Definition and Development / Streaming & Messaging)
File: 3.6.0.md

This is the release notes for RabbitMQ 3.6.0 RC3. This is a preview of a feature release. Key improvements in this release are: Lazy queues Much better queue synchronisation throughput Lower RAM use, tunable flow control Stronger password encryption with pluggable algorithms Development moved to GitHub; build system now uses erlang.mk Significant improvements to Web STOMP Experimental WinRT-compatible .NET client, SQL CLR compatibility in the "regular" one Pagination in management UI Cluster-wide alarm state is not updated when alarmed node goes down. Contributed by Alexey Lebedeff (@binarin). GitHub issue: Blocked connections could be unblocked too early. When multiple resource alarms were in effect, clearing just one of them would unblock all publishers prematurely. Contributed by Alexey Lebedeff (@binarin). GitHub issue: Blocked connections that are closed by clients are now expired and cleaned up by the heartbeat mechanism. Contributed by Alexey Lebedeff (@binarin). GitHub issue: If `RABBITMQMNESIADIR` was set to a value with a trailing slash, it could prevent automatic clustering (and other operations that assume pristine node state) from starting. GitHub issue: Standard output and error redirection in package scripts not respects `RABBITMQLOGBASE`. GitHub issue: Properly seed pseudo-random number generator when picking client port Contributed by Alexey Lebedeff (@binarin). GitHub issue: `RABBITMQALLOWINPUT` was ignored on Windows GitHub issue: Lazy queues. Lazy queues is a new feature that can significantly reduce RAM use of queues that can grow very long (e.g. don't have consumers online for hours or day). Such queues page messages to disk as they enter the queue. This feature is opt-in and has virtually no overhead for consumers in most cases, making throughput for publishers much more even and reducing RAM use. GitHub issue: Queue synchronisation to mirrors now happens in batches of configurable size, 4096 messages by default. This can improve sync throughput by an order of magnitude. GitHub issue: queue leader-to-node distribution is now more flexible: there are several strategies to choose from. GitHub issue: Stronger password encryption algorithm. SHA-256 is the hashing function used by default now, with SHA-512 being an option provided out of the box. Support for more options (Scrypt, bcrypt, etc) can be added with plugins. Existing user records will continue using MD5. To force re-hashing/encryption, change user password using `rabbitmqctl` or management UI/HTTP API. This should improve FIPS-180 compatibility. GitHub issue: Lower RAM use thanks to disabled in-process caching. RabbitMQ's in-process read buffers are now disabled by default. This often significantly reduces RAM usage at effectively no throughput or latency cost because the OS and file system do the same job fairly well. GitHub issue: Note that larger values will not necessarily lead to higher throughput or lower latency. They can also result in larger RAM use and therefore can be dangerous. GitHub issue: Build system switched to erlang.mk. is a modern build system for Erlang projects. RabbitMQ and all of its sub-projects have been switched to

This yields several benefits for RabbitMQ maintainers and plugin developers, for example, dependency management for plugins is much more straightforward, build times are significantly improved, there is no need to depend on `rabbitmq-server` for most plugins. Various 3rd party plugins need to migrate to erlang.mk in order to be built against RabbitMQ 3.6.0 (`rabbit_common`). GitHub issue: Streaming `rabbitmqctl`: `rabbitmqctl` list operations now stream results instead of waiting for the entire result set to arrive. This both improves responsiveness and makes it possible to list individual items, including those which did not respond in time. GitHub issue: (More) standard exit codes for command line tools `rabbitmqctl` and `rabbitmq-plugins` now use more standard, or at least distinctive, error codes for various failures. Contributed by Alexey Lebedeff (@binarin). GitHub issue: Improved log message for channel exceptions. GitHub issues: Improved log message when a client's TCP connection is closed unexpectedly. GitHub issue: Improved log message when a client connects to a non-existent vhost GitHub issue: Improved log message for `access_refused` connection errors. GitHub issue: Improved log message for `command_invalid` connection errors. GitHub issue: More sensible error code when a client connects to a non-existent vhost (or vhost it has no permissions for). The code returned is now `530`. GitHub issue: Memory monitoring interval is now configurable. GitHub issue: Prevent background GC interval from becoming too large due to backoff. Contributed by Dallas Marlow (@dallasmarlow). GitHub issue: Windows installer now supports "unattended" NSIS installs. Contributed by Ryan Zink (@ryanzink). GitHub issue: Windows package name now includes RabbitMQ version it provides. GitHub issue: `kernel.net_ticktime` is now included into `rabbitmqctl status` output. GitHub issue: `rabbitmqctl` now has a command for setting up free disk space limit at runtime. GitHub issue: Backup directory location is now mentioned in failed upgrade messages. GitHub issue: `rabbitdiagnostics:maybestuck/0` now includes date and time in its output. GitHub issue: Erlang R16B03 is now required. 17.5 or 18.x are recommended. GitHub issue: Use/support new Erlang/OTP 18 date and time API. Only when it is available, of course. GitHub issue: RabbitMQ server now supports tracing of credit flow events (e.g. when a process is blocked by credit flow). This is currently a compile-time flag aimed to be used in development environments. GitHub issue: Shutdown threads can use an executor. In environments with very constrainted per-process thread reasources, e.g. basic PaaS plans, temporary threads created during connection shutdown may make the app run over the limit. It is now possible to use a user-provided executor for shutdown operations instead. GitHub issue: ChannelManager now can use an executor. Similar to the above but for `ChannelManager` operations. GitHub issue: `Channel#consumerCount(string)` is a new convenience method for retrieving number of consumers on a queue. GitHub issue: `Channel#messageCount(string)` is a new convenience method for retrieving number of messages in a queue. GitHub issue: `LongString#toString` is part of the API GitHub issue: Host/address list support is back. Host selection strategy (when recovering a connection) is now pluggable. GitHub issue: Experimental

client with Windows RT support is now available. GitHub issue: SQL CLR compatibility. GitHub issue: `IModel#ConsumerCount(string)` is a new convenience method for retrieving number of consumers on a queue. GitHub issue: `IModel#MessageCount(string)` is a new convenience method for retrieving number of messages in a queue. GitHub issue: Continuation timeout is now configurable. GitHub issue: `RabbitMQ.Client.Headers` is a new class that contains constants for commonly used headers. Contributed by Yury Pliner (@Pliner). GitHub issue: .NET 4.5 is now required by the library. GitHub issue: Code examples are removed from the .NET client repository. All examples belong to `rabbitmq-tutorials` now. GitHub issue: Pagination for connections, channels, exchanges, and queues. Management UI now supports pagination, making the UI much more responsive in environments with many connections, queues, etc. GitHub issue: Queue information objects in responses now has a boolean property for queue exclusivity instead of a confusing `owner_pid`. GitHub issue: Connection and channel filtering should respect active vhost. GitHub issue: GET requests to `/api/queues/{vhost}/{name}/get` now accept/provide `application/json` GitHub issue: Pluggable retained message stores. Since MQTT 3.1.1 spec doesn't dictate any consistency or availability from the store in clustered environments, we only provide an in-memory implementation suitable for development environments with a single node. For production environments, plugins that provide stores with specific consistency guarantees are expected to be developed. GitHub issue: Default subscription (queue) TTL for non-clean sessions is now 24 hours GitHub issue: Socket-based authentication plugins now can work with plugins such as MQTT and STOMP (those using direct Erlang client). Contributed by Petr Gotthard (@gotthardp). GitHub issue: Control over queue properties. It is now possible to control queue properties (durable, auto-delete, exclusive plus several supported x-arguments) for all STOMP destinations. When using durable topics, it is now necessary to configure queue auto-deletion to `false` explicitly via a header. GitHub issue: Socket-based authentication plugins now can work with plugins such as MQTT and STOMP (those using direct Erlang client). Contributed by Petr Gotthard (@gotthardp). GitHub issue: Raw WebSocket endpoint. The plugin now supports a new endpoint, `/ws`, which supports WebSocket connections directly without the need to use SockJS. GitHub issue: . Support for binary data streams. Thanks to the new direct WebSocket support, binary data now can be transferred over Web STOMP connections. GitHub issue: STOMP heartbeat support. GitHub issue: Heartbeats are disabled for SockJS. GitHub issue: CORS headers support GitHub issue: Cowboy configuration. Key settings of Cowboy, the HTTP/WebSocket server powering the plugin, now can be fine tuned via this plugin. GitHub issue: Cowboy is upgraded to `1.0.3` GitHub issue: SockJS is upgraded to `1.0.3`. GitHub issue: Queue parameters now can be configured via headers (just like in the regular STOMP plugin). GitHub issue: Address Web STOMP listener binds to now can be configured. Previously only port was configurable. GitHub issue: LDAP server connections are now pooled. This significantly reduces the load on LDAP servers. Contributed by . GitHub issue: . Routing key policy is now optional. GitHub issue: Initial public release. GitHub issue: