mimirpb: fix RW2 write request splitting - #16295
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<!-- Thanks for sending a pull request! Before submitting: 1. Read our CONTRIBUTING.md guide 2. Rebase your PR if it gets out of sync with main --> #### What this PR does Remote ruler writes were previously sent as a single gRPC message, so large rule evaluation results could exceed `ruler.distributor.grpc_client_config.max_send_msg_size`. This PR derives a compression-safe effective payload limit, splits oversized Remote Write 1.0 requests at series boundaries, and sends the resulting requests sequentially. Each generated request has its own timeout and retry lifecycle. Successful earlier requests aren't rolled back if a later request fails, so a failed rule evaluation can leave partially written results. The ruler emits one float or native-histogram sample per result series for each evaluation. Consequently, an individual result series exceeding the effective split limit cannot be losslessly subdivided. If this occurs, increase `ruler.distributor.grpc_client_config.max_send_msg_size` and configure the distributor's `server.grpc_server_max_recv_msg_size` to be at least as large. When compression is enabled, a series above the conservative effective limit may still succeed if its compressed payload fits within the configured transport limit; otherwise gRPC returns `ResourceExhausted`. The implementation preserves request ownership and series ordering and reuses the RW1 write-request splitter already used by ingest storage to keep Kafka records within their configured size limit. The ruler adds compression-aware sizing, sequential gRPC sends, and per-request retries around that splitter. The `cortex_ruler_remote_distributor_requests_per_write_request` histogram reports how many remote requests each ruler write generates. This PR also fixes the RW1 splitter's protobuf embedded-message framing accounting and caps its initial preallocation for very small limits. The corresponding RW2 fixes are in #16295. #### Checklist - [x] Tests updated. - [x] Documentation added. - [x] `CHANGELOG.md` updated - the order of entries should be `[CHANGE]`, `[FEATURE]`, `[ENHANCEMENT]`, `[BUGFIX]`. If changelog entry is not needed, please add the `changelog-not-needed` label to the PR. - [ ] [`about-versioning.md`](https://github.com/grafana/mimir/blob/main/docs/sources/mimir/configure/about-versioning.md) updated with experimental features. Not applicable: this PR doesn't add an experimental feature or configuration surface. --------- Signed-off-by: Arve Knudsen <arve.knudsen@gmail.com> Co-authored-by: Julius Hinze <julius.hinze@grafana.com>
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Account for protobuf embedded-message framing when splitting Remote Write 2.0 requests, preserve request settings, and bound capacity estimates for small size limits.
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please rebase this PR on latest main, otherwise it can't merge — it's blocked on required checks that will never report. context: #16335 changed the unit test CI matrix and the required checks got renamed ( |
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What this PR does
It follows the Remote Write 2.0 Kafka record-splitting pattern introduced in #12166 and fixes the split size calculation. The splitter previously counted a series' protobuf message payload but omitted the surrounding field key and length prefix when deciding whether another series fit. Requests containing multiple series near the configured producer record limit could therefore still exceed it.
The splitter now includes that embedded-message framing, preserves write-request settings across generated requests, returns the original request for non-positive limits, and caps its initial allocation at the number of series. As before, splitting is best-effort: a single series larger than the limit remains intact and may produce an oversized record.
Checklist
CHANGELOG.mdupdated - the order of entries should be[CHANGE],[FEATURE],[ENHANCEMENT],[BUGFIX].about-versioning.mdupdated with experimental features. Not applicable: this PR doesn't add an experimental feature or configuration surface.