Release notes

Release notes for the Prom++ module. Each entry follows a unified structure: a release date, an optional short summary and highlights, and sections ordered as Highlights → New features → Improvements → Fixes → Security updates → Breaking changes → Upgrade notes → Known issues → Docs → Dependencies. Empty sections are omitted.

v3.8.11

Release date: 2026-08-07

Summary: fixed metadata loss on scrapes over 4 GiB, lower query memory, faster scrape parsing, and better behaviour with a large number of rule groups.

Highlights

• Scrapes larger than 4 GiB no longer fail with “invalid metric type” and lose the whole metadata batch.
• Better performance with a large number of rule groups (1000+), where the memory allocator itself used to slow down.

Improvements

• Lower memory use for queries with many label matchers.
• Faster scrape parsing.
• Short-lived storages no longer create memory arenas that brought them no benefit and only slowed the allocator down.
• C++ memory is now reclaimed earlier under growing load.

Fixes

• Fixed metadata handling for very large scrapes: buffer offsets are now 64-bit, so a /federate response over 4 GiB is parsed correctly.

Security updates

• Updated the web UI packages postcss and sanitize-html with upstream security fixes.

Docs

• Fixed broken links in the module documentation and added the configuration reference pages.

v3.8.10

Release date: 2026-07-31

Summary: lower query-path memory usage, crash fixes for the active query log and DataStorage metrics path, and faster WAL segment reads.

Highlights

• Query results no longer keep large off-heap buffers alive until GC, reducing memory growth under query load.
• Fixed SIGBUS crashes related to the active query log on some filesystems.

Improvements

• Lower memory usage when executing queries by releasing query result buffers as soon as the response is built.
• Faster WAL segment reads through pooled buffer reuse.

Fixes

• Fixed SIGBUS in ActiveQueryTracker when the active query log was created as a sparse file.
• Fixed a race condition during static object initialization that could cause startup errors on older processors.

Security updates

• Updated Go dependencies (github.com/klauspost/compress, go.opentelemetry.io/otel) and the web UI postcss package with upstream security fixes.

v3.8.9

Release date: 2026-07-24

Summary: correct CPU feature detection for better out-of-the-box performance, faster scrape parsing, lower ingestion memory, and stability and security fixes.

Highlights

• Fixed CPU feature detection so the engine selects the right instruction set on modern CPUs instead of always falling back to the baseline, improving performance out of the box.
• Faster scrape parsing.

Improvements

• Faster scrape parsing through a reworked scraper write-ahead-log encoding.
• Lower peak memory during ingestion: the transaction snapshot is now released as soon as the transaction is committed.
• The module image now uses a statically-linked curl, reducing runtime dependencies.
• Module release notes are now shipped with the release and shown in the Deckhouse UI (unified changelog format).

Fixes

• Fixed CPU feature detection that always selected baseline instruction bindings even on modern CPUs, degrading performance.

Security updates

• Updated Go dependencies (golang.org/x/text, golang.org/x/net, google.golang.org/grpc) and web UI packages (body-parser, webpack-dev-server, immutable) with upstream security fixes.

v3.8.8

Release date: 2026-07-17

Summary: incident-recovery tooling and observability improvements, lower memory usage when writing blocks, and stability and security fixes.

Highlights

• Added a persist-head command to prompptool for recovering an individual head to TSDB blocks during incident handling.
• Reduced memory consumption when writing blocks over wide or sparse time ranges.
• Added on-demand jemalloc heap profiling over HTTP for troubleshooting memory usage.

Improvements

• The block writer now skips blocks that already fall entirely outside the retention period, avoiding wasted disk writes.
• Added a /debug/jemalloc HTTP endpoint to capture a jemalloc heap profile on demand (requires profiling enabled at startup).
• Added a metric for the total size of unknown objects in local storage, making disk leftovers visible.
• Reduced memory consumption when writing blocks over wide or sparse time ranges.

Fixes

• Fixed a rare crash (heap-buffer-overflow) in the outdated chunk merger.
• Leftover temporary block directories from an interrupted compaction or persist are now cleaned up on startup.

Security updates

• Updated the Go toolchain, addressing known security vulnerabilities.

v3.8.7

Release date: 2026-07-16

Fixes

• Removed internal C++ metrics registration because it led to a memory leak.

v3.8.6

Release date: 2026-07-15

Fixes

• Disabled the internal C++ metrics collector by default to prevent a rare crash (use-after-free) that could occur during metrics collection.

v3.8.5

Release date: 2026-07-09

Improvements

• Reworked historical block storage with a new block-manager engine, improving compaction planning and adding block layout diagnostics metrics.
• Core dumps are no longer written on crash, preventing unexpected disk usage in constrained environments such as Kubernetes.
• Added metrics for observing the internal data storage.
• Improved performance of label processing and index writing.

Security updates

• Updated the build toolchain and dependencies, addressing known security vulnerabilities.

v3.8.4

Release date: 2026-06-11

Improvements

• Improved instant query performance.
• Reduced memory consumption during head rotation and when processing high-cardinality metrics through the federation API.

Security updates

• Updated base images and security-related components.

v3.8.3

Release date: 2026-06-02

Fixes

• Fixed a chunk encoder issue that could, in rare cases, lead to historical data corruption.
• Updated PromQL range query behavior to match the current Prometheus implementation. As a result, the output of the rate, sum_over_time, and count_over_time functions may differ slightly from previous versions.

Security updates

• Fixed a vulnerability that could lead to memory exhaustion when processing remote read queries.
• Fixed multiple XSS vulnerabilities in the web interface.

v3.8.1

Release date: 2026-05-15

Improvements

• Improved data processing performance and reduced memory consumption when executing queries in sharded environments.

Fixes

• Fixed WAL processing during shard rotation.

Security updates

• Updated dependencies and addressed known security vulnerabilities.

v3.8.0

Release date: 2026-04-22

Improvements

• Added metrics for analyzing mutex and semaphore contention in the Go runtime.
• Added a metric for jemalloc resident memory usage.
• Improved resource cleanup during WAL rotation.

v3.7.11

Release date: 2026-05-15

Improvements

• Added metrics for monitoring jemalloc arena reuse efficiency.

v3.7.10

Release date: 2026-04-22

Improvements

• Added support for WAL v2 format in remote write.

Fixes

• Fixed false positives for the PrometheusRemoteWriteDesiredShards alert.
• Resolved potential issues affecting remote write under high load.

v3.7.9

Release date: 2026-03-30

New features

• Added new PromQL functions: op_defined, op_replace_nan, op_smoothie, op_zero_if_none, and op_top.

Improvements

• Improved remote write performance.
• Added a data age limit for remote write to prevent WAL file accumulation when external systems are unavailable.

Fixes

• Fixed ingestion metric calculations.
• Resolved increasing memory consumption when using custom jemalloc arenas.

Security updates

• Updated dependencies and addressed known security vulnerabilities.

v3.7.6

Release date: 2026-02-20

Improvements

• Improved rule evaluation and remote write performance.

Security updates

• Updated security-related dependencies.

v3.7.5

Release date: 2026-01-23

Improvements

• Optimized data ingestion and processing workflows.

v3.7.4

Release date: 2026-01-12

Improvements

• Added support for splitting high-cardinality metrics when using the federation API, reducing peak memory consumption.

v3.7.2

Release date: 2025-12-08

Improvements

• Improved rule evaluation and query execution performance.

Fixes

• Fixed stability issues that could cause intermittent failures.
• Fixed handling of empty labels in OTLP Protobuf.

v3.7.0

Release date: 2025-11-05

Improvements

• Data copying during rotation is now performed in the background, reducing the impact of rotation on system responsiveness.
• Improved query execution and rule evaluation performance.

Fixes

• Fixed handling of StaleNaN values during data rotation.

v3.6.5

Release date: 2025-10-22

Improvements

• Added a mechanism for offloading infrequently used time series to disk, significantly reducing memory consumption in large-scale deployments.
• Reduced memory consumption during metrics collection and processing.

Fixes

• Fixed regular expression handling in matchers.
• Improved resilience to corrupted WAL files and invalid data.
• Fixed handling of StaleNaN values for backfilled data.

v3.5.0

Release date: 2025-08-25

Improvements

• Upgraded the underlying Prometheus version to 2.55.1.
• Added support for the Prometheus 3.x storage format.

Security updates

• Updated dependencies and addressed known security vulnerabilities.