October 2025 (2025-10): Focused on reliability, observability, and scalable cluster operations in emqx/emqx. Delivered key features to stabilize API configuration and tracing, fixed critical leader routing and replication issues, and strengthened backward-compatibility and test coverage. These changes improve deployment safety, error visibility, and performance of core broker operations.

September 2025 monthly summary: This period delivered significant improvements across EMQX core and docs with a strong emphasis on observability, reliability, and maintainability. Key work spanned API tracing and DS API enhancements, DSraft and DS-OTX robustness, startup and readiness reliability, and expanded testing and documentation. The combined efforts reduced operational risk, improved troubleshooting speed, and laid groundwork for smoother upgrades and scaling.

August 2025 performance-focused monthly summary for emqx/emqx: Consolidated and modernized the tracing subsystem to improve observability, reliability, and data quality. Delivered major tracing and streaming capabilities, reduced fragmentation of the tracing codebase, and completed important maintenance to lower long-term risk. The month also included improved test coverage for tracing, and API/stability enhancements that align with updated streaming semantics.

July 2025 monthly summary for emqx/emqx focusing on business value, reliability, and performance improvements. This month delivered stability and observability enhancements across the core broker, client subs, and socket/transport layers, along with targeted test and documentation improvements that reduce risk in production and streamline release cycles. Key changes included version bumps to keep dependencies current, improved test suites with mocks aligned to esockd_socket listeners, and connmod-aware session state and eviction logic. Major code cleanups reduced dead code and clarified maintenance tasks. Socket/connection paths were hardened with async sends, proper send_timeout handling, and error signaling. Observability and tracing were strengthened with connmod annotations, frame serialization optimizations, and CI improvements around OpenTelemetry. A set of targeted bug fixes and reliability improvements reduce races, prevent invalid state during restarts, and stabilize test suites for faster, safer deployments.

June 2025 — Key business value delivered: scalable broker dispatch, improved performance, and better observability across emqx/emqx and emqx/emqx-docs. Highlights include: (1) Async shard dispatch via broker pool with a concurrent-dispatch feature flag to scale fan-out; (2) Ensured shard subscribers are dispatched first for correct ordering; (3) Performance and efficiency improvements such as reusing the dispatch tuple and minifying the connection state, plus reducing the number of subscriber shards; (4) Observability enhancements with broker and connection timing instrumentation and explicit GC tracking; (5) Reliability and maintainability gains through code cleanup, test stabilization, environment-driven config fixes (EMQX_BROKER_INSTR), and documentation updates; (6) Documentation updates for durable session features and DS Raft metrics to improve developer experience and observability. The work spans both repos: emqx/emqx and emqx/emqx-docs, including WSConn/Cowboy upgrades and several test fixes.

May 2025 monthly summary for EMQX development. Focused on delivering core features, performance optimizations, and reliability improvements across EMQX core, WebSocket subsystem, and related tooling. Key outcomes include substantial feature delivery, targeted bug fixes, and improvements that translate into higher throughput, lower latency, and more robust observability. Key features delivered: - EMQX topic predicate optimization: use simple union for topic predicate in max QoS rules (commit 45d3762fca41c30a854844ff6eed79952a8d172b). - WebSocket performance enhancements: linear control flow implemented to improve throughput; active_n passed as Cowboy option; and Cowboy upgraded to 2.13.0-emqx-1 (commits 790287a85713eb66f7c5582a540c09adc2515f74, 163f41d9e577c34963517027f57dbcffdb67e82b, be48426ebbd6ad604fea41895c06a01e953a65d2). - Broker performance improvement: ETS accessors to reduce overhead and boost throughput (commit 85fd321c195eef430987001140439bf0877f1587). Major bugs fixed: - WebSocket: reply with HTTP 429 early if connection limit is hit (commit 028c9762b68600addc22bfcf8a9442b1ad3fe1b8). - Prometheus: anticipate empty DS Raft metric families and ensure unstable Mria metrics do not crash Prometheus (commits 718679ba4ca58c6ae12a71c986130ea381aeec2b, c29eb25d95dd6fefceed86e4e1982167559f7ee1). - Sessds: recreate subscription on upgrade/downgrade and maintain backward compatibility (commits 2900cfc9e1f39ed67f913487f8cfe4241b287a09, 0afd31d1ebd1c9a2088be34db9cd799a5498031e). Overall impact and accomplishments: - Increased reliability under load, with earlier feedback on connection limits and more stable metrics reporting; improved upgrade/downgrade handling for subscriptions; clearer performance characteristics of broker components; better observability and diagnosability through sturdier metrics. Technologies/skills demonstrated: - Proficiency with Erlang/OTP and Cowboy-based WebSocket pipelines; performance tuning of ETS-backed data paths; Gen_RPC usage; robust test and release processes including changelog and breaking change notes; emphasis on upgrade/downgrade safety and observability."

April 2025 — EMQX monthly notes for emqx/emqx highlight stability and value delivered across TLS integration, DSraft metrics, routing, and observability. The work focused on delivering business value through reliable upgrades, better visibility, and measurable performance gains while tightening security and test coverage. Key features delivered: - Dependency and maintenance: Bumped ekka to 0.21.2 to align cluster tooling and refreshed maintenance tasks to reduce technical debt (e.g., dropping unused test profiles, updating esockd, and simplifying SSL config workarounds). - TLS and security hardening: Consolidated CRL options in emqx_tls_lib, merged emqx_auth_ext into emqx_tls_lib, and fixed sni_fun injection to ensure correct OCSP/CRL behavior; expanded code comments for TLS semantics to aid future maintenance. - DSraft and routing enhancements: Expanded DSraft capabilities with local shard listing via gproc, added metrics for DB/shard transitions, bumped proto version, and cleaned up module naming; improved router stability with explicit routerepl state transitions and better handling of unexpected events; added smoke tests for route repl. - Observability, metrics, and testing: Exposed DSRAFT metrics at the primary endpoint, instrumented snapshot transfers, and added basic replication metrics; improved test coverage for router live connections and TLS listener constraints; reduced test noise by avoiding unnecessary mocking and fixing metric naming issues. - Performance and configurability: Implemented optimizations to avoid boxing in hot paths and introduced an option to tune max allowed QoS per client subscription; improved baseline metrics reporting and labels for accurate observability. Major bugs fixed: - Routing and stability: Postponed reconcile routing until the cluster is stable; hardening routerepl transitions and handling of unexpected events. - TLS integration: Correctly injects sni_fun and consolidates TLS options under emqx_tls_lib; removed default user_lookup_fun in favor of emqx_tls_lib. - System reliability: Tuning supervisor crash handling to reduce spammy crashes; fixes to bootstrap of shared routes; fixes for empty defaults in Helm charts; enhanced safety in SessDS test invariants. - Observability correctness: Fixed metric label base handling and corrected typos in metric names; ensured replication metrics are reported. Overall impact and accomplishments: - Significantly improved upgrade safety and cluster stability through targeted routing and TLS consolidations; added end-to-end visibility for DSraft and core metrics, enabling faster root-cause analysis and performance tuning. The changes reduce operational risk while delivering more predictable performance and security, with broader test coverage to support ongoing delivery velocity. Technologies and skills demonstrated: - Erlang/OTP engineering, TLS library integration, DSraft internals, gproc usage for local shard discovery, Prometheus metrics exposition, and robust test design. Demonstrated end-to-end maintenance capability including dependency management, code refactoring, and thorough release documentation.

Month: 2025-03 — Performance-focused monthly summary highlighting delivered features, fixed defects, and business value across EMQX repos. Key outcomes include robust DSRaft shard allocation and lost-site cleanup, routing table integrity via orphaned routing node purge, improved takeover/session reliability, broker test stability improvements, and dependency/docs maintenance that streamline releases and clarity for users. Key features delivered: - DSRaft shard allocation robustness and lost-site cleanup: Avoid allocating shards on lost sites, startup cleanup to forget lost sites, with tests verifying correct behavior. Commits include b6a2f8dd6ccac935756b0794a04cfe25e01341c6, bb213083d32d30e99b02860993aefd8992e70029, 0c41d1528d3b242c2ce3201b0b1867a3011f0285. - Routing reconciliation: purge orphaned routing nodes to ensure routing table reflects active cluster membership. Commits include 6795fda9f6fc48646cd644c68cb4df82847e00be, a7cc812bdd35824fcd00e81f899ccc0a9129bfe8. - Takeover/session reliability improvements: Reset expiry timers during takeover and tune takeover timeout for faster, more reliable takeovers. Commits include 084b4c83b77358dcb9763a69bb848361dcc11e69, de0da97e4bf00d85235fafed7ab04f240ac763b1, 9599a8b542d602a571ecfbb3bc8d4c66e68d65ad. - Broker test stability and tracing improvements: Reduce test flakiness and improve reliability of broker tests by adjusting client connection/disconnection handling and tracepoint usage. Commits include 032e1fffbee9cc4b508cbd33df88bd2c360dc4b0, 3cce897ae55ea3352d21d061f6a7c142a3cfcff0. - Dependency updates and documentation maintenance: Update dependencies (EMQX/emqtt to 1.14.2, Mria to 0.8.12.1) and add changelog entries documenting the fixes and improvements. Commits include 6d2851c288eff359733078389f2a5834be00a5f8, 4123ca220f3e5cd22375c5eebe5ddee68cdc55fb, caa3e76c29b525810928dcfd6371963ef57cfd7a, 9a0916c7aed26597a8b6a2afb654d090c9d492ce, 27a0ec42754de9dd57a9d3044fa649f08c092d47. Major bug fixes: - Routing reconciliation: purge orphaned routing nodes during reconcile to prevent routing table drift. - Broker test stability: reduced flakiness in broker tests via simplified tracepoints and connection handling. - Listener/config resilience and online updates improvements were also shipped as quality-of-life fixes to reduce operational risk. Overall impact and accomplishments: - Significantly improved cluster stability, routing correctness, and session takeover reliability. - Reduced test flakiness enabling safer releases and faster iteration. - Streamlined dependencies and added changelog/docs to aid operators and developers. - Demonstrated strong ownership of distributed systems concerns (DSRaft, routing, session lifecycle) and documentation discipline.

February 2025 monthly summary: Delivered substantial DSraft stabilization and reliability improvements, strengthened observability and test quality, upgraded the CI/OT stack, and introduced developer tooling to accelerate safe deployments. The work reduces operational risk during membership changes and shard rebalances, improves failure visibility, and accelerates release readiness, while documenting disaster recovery guidance for known issues.

January 2025 monthly summary for EMQX (emqx/emqx and emqx/emqx-docs). The team delivered OTP-27 readiness and a broad set of dependency upgrades, code quality improvements, reliability fixes, and release/packaging enhancements. The work positively impacts stability, security, and time-to-upgrade for customers moving to Erlang/OTP 27, while improving developer experience and CI reliability.

December 2024 monthly summary focusing on delivering measurable business value and robust technical achievements across the EMQX repository. Highlights include feature delivery with improved configurability, stability improvements in routing and storage subsystems, and strengthened testing/infrastructure to support maintainability and future growth.

November 2024 (EMQX) focused on stability, maintainability, and performance improvements across core engine, routing, and S3 integration. Delivered codebase hygiene and defaults simplification, reinforced reliability with targeted hook/order fixes and test stability, and unlocked performance gains through per-hookpoint caching, selective routing lookups, and framing optimizations. Strengthened S3 support with schema exposure and per-profile pooling, plus vhost-style access and test coverage. These efforts improve end-user latency, cluster scalability, and developer velocity.

October 2024 (2024-10) EMQX repo delivered a set of robustness and performance improvements focused on test coverage, documentation, and MQTT packet parsing. Key work reduced test flakiness, stabilized durable storage/queue behavior, clarified special topic matching rules, and improved runtime parsing performance by leveraging BEAM's native MQTT parser and streamlined framing.