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tarantool-etcd-dh3 Watch header.revision can go backwards on a stream (progress vs event fiber interleave) Lined Up

status: open P2 bug etcd-changelog-sweep
bd update tarantool-etcd-dh3 --claim bd close tarantool-etcd-dh3
Created byEugene Blikh
Ownerbigbes@gmail.com
Created2026-07-17T13:20:16Z
Updated2026-07-17T13:20:16Z
Description
etcd 3.4.22/3.5.5 fixed this by routing progress through the stream's single sendLoop.

Our RequestProgress computes a header, then performs yielding per-watcher writes (app/etcd/grpc.lua:527-533); a concurrent event fiber (grpc.lua:304,338) can interleave a newer-revision response first, so the client observes header.revision going backwards — which clients treat as a hard invariant violation.

Race-shaped: argued from fiber structure, not observed. Reproducer first. Likely shares a root cause with the WatchProgressRequest synchronisation issue — consider fixing together via a single per-stream writer fiber.
Acceptance criteria
header.revision is monotonic per stream under concurrent progress+event load; stress reproducer exists.

Depends on

No outgoing dependencies.

Depended on by

Nothing depends on this issue.

No comments.

  • Eugene Blikh created the issue · 2026-07-17T16:20:15Z
  • Eugene Blikh added label etcd-changelog-sweep · 2026-07-17T16:20:15Z
Stored rows — what this pane was built from, as read
issues 1 row
id tarantool-etcd-dh3
content_hash 6a957612b50e5ee613585d98d570b2f43fa00a9265a5dad4d58971140cd39cb2
title Watch header.revision can go backwards on a stream (progress vs event fiber interleave)
description etcd 3.4.22/3.5.5 fixed this by routing progress through the stream's single sendLoop. Our RequestProgress computes a header, then performs yielding per-watcher writes (app/etcd/grpc.lua:527-533); a concurrent event fiber (grpc.lua:304,338) can interleave a newer-revision response first, so the client observes header.revision going backwards — which clients treat as a hard invariant violation. Race-shaped: argued from fiber structure, not observed. Reproducer first. Likely shares a root cause with the WatchProgressRequest synchronisation issue — consider fixing together via a single per-stream writer fiber.
design
acceptance_criteria header.revision is monotonic per stream under concurrent progress+event load; stress reproducer exists.
notes
status open
priority 2
issue_type bug
assignee NULL
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created_at 2026-07-17T13:20:16Z
created_by Eugene Blikh
owner bigbes@gmail.com
updated_at 2026-07-17T13:20:16Z
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created_at 2026-07-17T16:20:15Z
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comment Added label: etcd-changelog-sweep
created_at 2026-07-17T16:20:15Z