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Chris LuandGitHub
0c95137528
* fix(filer): stop logging a held aggregated read as an error An aggregated subscriber may not read past the peers' low-watermark, and it stops at the first entry beyond it by returning a sentinel from the read callback. LoopProcessLogData logs every callback error, so on a cluster that keeps writing - where there is almost always an entry newer than the watermark - every read wrote an ERROR line naming the entry it stopped at, thousands per minute per filer. Mark the stop as control flow: an error wrapping StopReadingError is handed back to the caller unlogged, and the held-read sentinel wraps it. * fix(filer): release an aggregated watermark hold on peer progress A held read waited on the aggregated buffer's data channel, which the next write signalled - but a write cannot release a hold, only a peer reporting further progress can. On a cluster that keeps writing the loop therefore re-ran a whole pass per arriving event, log file listing and all, and held again on the same entry every time. Signal held readers from the meta aggregator instead, whenever a low-watermark rises: a peer reporting, or one dropped past its removal grace. The retry interval stays as the backstop for what no watermark covers. Count the holds so a parked subscriber stays visible. * fix(filer): floor how often an aggregated watermark hold releases Peers advance their delivery watermark on every event they stream, so releasing a hold on every advance is the same pass-per-event storm as releasing on every write, just without the log lines - and each pass lists a day of log files. Floor the release at 20ms. Advances inside the floor collapse into one release, which then delivers everything they covered. * fix(filer): pace a peer's delivery claim by what its subscribers hold at A filer's local metadata stream carries an idle heartbeat to its peer aggregators, and each peer turns it into that filer's delivery low-watermark. Aggregated subscribers hold at the minimum across peers, so a filer quiet enough to fall back on the heartbeat parked every subscriber in the cluster up to a keepalive interval - 5 seconds - behind live writes. With nine filers, most of them quiet at any moment, the minimum sat there permanently. Pace that heartbeat at 200ms once the filer has peers. It stays a keepalive, at the keepalive interval, for a filer with none. * fix(filer): wake each aggregated hold on its own watermark A persisted-log read is held by what the peers have flushed, an in-memory read by what they have delivered, but both parked on one channel closed whenever either minimum rose. Peers advance their delivery watermark on every event they stream, so a flush-held reader woke at the coalescing floor to re-list a day of log files and park again on the same entry - the storm this set out to fix, in the one place asymmetric peer progress still reached. Signal the two separately and park each read on the one that bounds it.