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edf7d2a074
* fix(filer): eliminate redundant disk reads causing memory/CPU regression (#9035) Since 4.18, LocalMetaLogBuffer's ReadFromDiskFn was set to readPersistedLogBufferPosition, causing LoopProcessLogData to call ReadPersistedLogBuffer on every 250ms health-check tick when a subscriber encounters ResumeFromDiskError. Each call creates an OrderedLogVisitor (ListDirectoryEntries on the filer store), spawns a readahead goroutine with a 1024-element channel, finds no data, and returns — 4 times per second even on an idle filer. This is redundant because SubscribeLocalMetadata already manages disk reads explicitly with its own shouldReadFromDisk / lastCheckedFlushTsNs tracking in the outer loop. Set ReadFromDiskFn back to nil for LocalMetaLogBuffer. When LoopProcessLogData encounters ResumeFromDiskError with nil ReadFromDiskFn, the HasData() guard returns ResumeFromDiskError to the caller (SubscribeLocalMetadata), which blocks efficiently on listenersCond.Wait() instead of polling. * fix(filer): add gap detection for slow consumers after disk-read stall When a slow consumer falls behind and LoopProcessLogData returns ResumeFromDiskError with no flush or read-position progress, there may be a gap between persisted data and in-memory data (e.g. writes stopped while consumer was still catching up). Without this, the consumer would block on listenersCond.Wait() forever. Skip forward to the earliest in-memory time to resume progress, matching the gap-handling pattern already used in the shouldReadFromDisk path. * fix(filer): clear stale ResumeFromDiskError after gap-skip to avoid stall The gap-detection block added in the previous commit skips lastReadTime forward to GetEarliestTime() and continues the outer loop. On the next iteration, shouldReadFromDisk becomes true (currentReadTsNs > lastDiskReadTsNs), the disk read returns processedTsNs == 0, and the existing gap handler at the top of the loop runs its own gap check. That check uses readInMemoryLogErr == ResumeFromDiskError as the entry condition — but readInMemoryLogErr is still the stale error from two iterations ago. GetEarliestTime() now equals lastReadTime.Time (we already advanced to it), so earliestTime.After(lastReadTime.Time) is false and the handler falls into listenersCond.Wait() — stuck. Clear readInMemoryLogErr at the gap-skip point, matching the existing pattern at the earlier gap handler that already clears it for the same reason. * fix(log_buffer): GetEarliestTime must include sealed prev buffers GetEarliestTime previously returned only logBuffer.startTime (the active buffer's first timestamp). That is narrower than ReadFromBuffer's tsMemory, which is the min across active + prev buffers. Callers using GetEarliestTime for gap detection after ResumeFromDiskError (the SubscribeLocalMetadata outer loop's disk-read path, the new gap-skip in the in-memory ResumeFromDiskError handler, and MQ HasData) saw a time that was *newer* than the real earliest in-memory data. Impact in SubscribeLocalMetadata's slow-consumer path: - tsMemory = earliest prev buffer time (T_prev) - GetEarliestTime() = active startTime (T_active, later than T_prev) - Consumer position = T1, with T_prev < T1 < T_active - ReadFromBuffer returns ResumeFromDiskError (T1 < tsMemory) - Gap detect: GetEarliestTime().After(T1) = T_active.After(T1) = true - Skip forward to T_active -- silently drops the prev-buffer data - And when T_active happens to equal the stuck position, gap detect evaluates false, and the subscriber stalls on listenersCond.Wait() This reproduces the TestMetadataSubscribeSlowConsumerKeepsProgressing failure in CI where the consumer stalled at 10220/20000 after writing stopped -- the buffer still had data in prev[0..3], but gap detection was comparing against the active buffer's startTime. Fix: scan all sealed prev buffers under RLock, return the true minimum startTime. Matches the min-of-buffers logic in ReadFromBuffer. * test(log_buffer): make DiskReadRetry test deterministic The previous test added the message via AddToBuffer + ForceFlush and relied on a race: the second disk read had to happen before the data was delivered through the in-memory path. Under the race detector or on a slow CI runner, the reader is woken by AddToBuffer's notification, finds the data in the active buffer or its prev slot, and returns after exactly one disk read — failing the >= 2 disk reads assertion even though the loop behaved correctly. Reproduced on master with race detector (2/5 failures). Rewrite the test to deliver the data exclusively through the disk-read path: no AddToBuffer, no ForceFlush. The test waits until the reader has issued at least one no-op disk read, then atomically flips a "dataReady" flag. The reader's next iteration through readFromDiskFn returns the entry. This deterministically exercises the retry-loop behavior the test was originally written to protect, and removes the in-memory delivery race entirely.