fix(pubsub): prevent double reconnect in releaseConn#3833
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When a connection is both not usable and has a bad conn error, releaseConn would call reconnect twice — first establishing a new connection, then immediately closing it to create another. Add early return after the first reconnect to avoid the wasted connection.
ndyakov
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May 29, 2026
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This should not happen, but makes sense to have this.
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Thanks for the review! To be honest, I caught this potential edge case just by reading the code and found it really difficult to write a stable reproduction test. I wasn't entirely sure if it could be triggered in practice, so I submitted this as a defensive fix. |
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This PR contains the following updates: | Package | Change | [Age](https://docs.renovatebot.com/merge-confidence/) | [Confidence](https://docs.renovatebot.com/merge-confidence/) | |---|---|---|---| | [github.com/redis/go-redis/v9](https://github.com/redis/go-redis) | `v9.20.0` → `v9.20.1` |  |  | --- ### Release Notes <details> <summary>redis/go-redis (github.com/redis/go-redis/v9)</summary> ### [`v9.20.1`](https://github.com/redis/go-redis/releases/tag/v9.20.1): 9.20.1 [Compare Source](redis/go-redis@v9.20.0...v9.20.1) This is a patch release containing bug fixes only. There are no new features or breaking changes; upgrading from 9.20.0 is a drop-in replacement. #### 🚀 Highlights ##### RESP3 pub/sub message loss fixed `PeekPushNotificationName` previously inspected only the bytes already buffered by `bufio`, so when a push frame header straddled a buffer fill boundary it could return a **truncated** notification name (e.g. `"messa"` instead of `"message"`). The push processor then mis-routed the frame and `ReadReply` silently dropped it, causing intermittent RESP3 pub/sub message loss. The peek now grows its window (36 bytes → up to 4 KiB) and reads more from the connection until the header is complete, cleanly separating incomplete prefixes from corrupt frames (including overflow-safe bulk-length handling). Fixes [#​3839](redis/go-redis#3839). ([#​3842](redis/go-redis#3842)) by [@​ndyakov](https://github.com/ndyakov) #### 🐛 Bug Fixes - **RESP3 push peeking**: `PeekPushNotificationName` no longer returns a truncated notification name when a push frame header spans a buffer boundary, preventing silent RESP3 pub/sub message loss (fixes [#​3839](redis/go-redis#3839)) ([#​3842](redis/go-redis#3842)) by [@​ndyakov](https://github.com/ndyakov) - **`FT.HYBRID` vector params**: Vector data is now always sent via `PARAMS` with auto-generated param names (`__vector_param_N`, with collision avoidance) when `VectorParamName` is omitted, since Redis no longer accepts inline vector blobs; the `FTHybridOptions.Params` map is no longer mutated, so the same options struct can be reused across calls ([#​3844](redis/go-redis#3844)) by [@​ndyakov](https://github.com/ndyakov) - **`CLUSTER SHARDS` forward compatibility**: Unknown shard- and node-level attributes in the `CLUSTER SHARDS` reply are now skipped via `DiscardNext()` instead of erroring, so clients keep working when the server introduces new fields ([#​3843](redis/go-redis#3843)) by [@​madolson](https://github.com/madolson) - **PubSub double reconnect**: `PubSub.releaseConn` no longer reconnects twice when a connection is both unusable (or pending handoff) and reports a bad-connection error, avoiding a wasted connection establish-then-close cycle ([#​3833](redis/go-redis#3833)) by [@​cxljs](https://github.com/cxljs) #### 👥 Contributors We'd like to thank all the contributors who worked on this release! [@​cxljs](https://github.com/cxljs), [@​madolson](https://github.com/madolson), [@​ndyakov](https://github.com/ndyakov) *** **Full Changelog**: <redis/go-redis@v9.20.0...v9.20.1> </details> --- ### Configuration 📅 **Schedule**: (UTC) - Branch creation - Between 12:00 AM and 03:59 AM (`* 0-3 * * *`) - Automerge - Between 12:00 AM and 03:59 AM (`* 0-3 * * *`) 🚦 **Automerge**: Disabled by config. Please merge this manually once you are satisfied. ♻ **Rebasing**: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox. 🔕 **Ignore**: Close this PR and you won't be reminded about this update again. --- - [ ] <!-- rebase-check -->If you want to rebase/retry this PR, check this box --- This PR has been generated by [Mend Renovate](https://github.com/renovatebot/renovate). <!--renovate-debug:eyJjcmVhdGVkSW5WZXIiOiI0My4yMTQuNSIsInVwZGF0ZWRJblZlciI6IjQzLjIxNC41IiwidGFyZ2V0QnJhbmNoIjoiZm9yZ2VqbyIsImxhYmVscyI6WyJkZXBlbmRlbmN5LXVwZ3JhZGUiLCJ0ZXN0L25vdC1uZWVkZWQiXX0=--> Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/13061 Reviewed-by: Mathieu Fenniak <[email protected]>
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When a connection is both not usable and has a bad conn error, releaseConn would call reconnect twice — first establishing a new connection, then immediately closing it to create another. Add early return after the first reconnect to avoid the wasted connection.
Note
Low Risk
Single control-flow guard in pub/sub connection release; no API or security surface changes.
Overview
Fixes a bug in
PubSub.releaseConnwhere an unusable or handoff connection could triggerreconnecttwice in one call—once for!IsUsable()/ShouldHandoff(), and again ifisBadConn(err, …)was also true.Adds an early
returnafter the first reconnect so a bad-connection error on the same release path does not immediately tear down and reopen the connection again.Reviewed by Cursor Bugbot for commit 02ebca1. Bugbot is set up for automated code reviews on this repo. Configure here.