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backfill: fetch thread replies one at a time #141

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iFixRobots wants to merge 1 commit into from
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backfill: fetch thread replies one at a time #141

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2 changes: 2 additions & 0 deletions pkg/connector/backfill.go
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Original file line number Diff line number Diff line change
Expand Up @@ -84,10 +84,12 @@ func (s *SlackClient) FetchMessages(ctx context.Context, params bridgev2.FetchMe
if !ok {
return nil, fmt.Errorf("invalid thread root ID")
}
s.threadFetchLock.Lock()

@indent indent Bot Nov 1, 2026

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🟡 Bug · Global thread lock stalls every portal's event loop, and waiters ignore ctx

bridgev2 runs thread backfill inside forward backfill, in the portal event loop (createMatrixRoomInLoop with roomCreateLock held, and handleChatResync). With this per-login lock, every portal's loop blocks until all threads queued ahead of it, in any channel, are fetched. The holder keeps the lock through slackgo's retry loop (OptionRetry(5)), which sleeps for each 429's Retry-After (60s default if missing), so one call can hold it for minutes and late channels can't process live messages, edits or reactions. sync.Mutex.Lock also ignores ctx, so a waiter whose context was cancelled (portal deleted, shutdown) keeps waiting and then makes a request anyway. Use a ctx-aware semaphore or a rate limiter (Wait(ctx)) instead.

Found by Indent Review Agent

chunk, err = s.Client.GetConversationRepliesContext(ctx, &slack.GetConversationRepliesParameters{
GetConversationHistoryParameters: *slackParams,
Timestamp: threadTS,
})
s.threadFetchLock.Unlock()
} else {
chunk, err = s.Client.GetConversationHistoryContext(ctx, slackParams)
if chunk != nil {
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1 change: 1 addition & 0 deletions pkg/connector/client.go
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Expand Up @@ -164,6 +164,7 @@ type SlackClient struct {
userGroupInfoCacheLock sync.Mutex
lastReadCache map[string]string
lastReadCacheLock sync.Mutex
threadFetchLock sync.Mutex
}

var (
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