Count the connection failure as the condition of quarantine#4727
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zymap wants to merge 2 commits intoapache:masterfrom
Open
Count the connection failure as the condition of quarantine#4727zymap wants to merge 2 commits intoapache:masterfrom
zymap wants to merge 2 commits intoapache:masterfrom
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--- ### Motivation Currently, the BookieClient quarantine mechanism primarily triggers based on read and write error responses from Bookies. However, in multi-region deployments, a common failure mode is the Network Partition or DNS Resolution Failure at the Region level. In such scenarios: A Bookie remains registered in ZooKeeper (it can still heartbeat to its local ZK observer). The Client (Broker) cannot resolve the Bookie's IP or establish a TCP connection. The EnsemblePlacementPolicy (especially RegionAwareEnsemblePlacementPolicy) sees the Bookie as "Available" and repeatedly selects it to satisfy minRack or E/Qw constraints. The LedgerHandle fails to write because it cannot initialize a connection handle, triggering an Ensemble Change. Because the connection failure didn't trigger a quarantine, the placement policy picks the same problematic Bookie again in the next iteration. This creates an infinite Ensemble Change loop, causing the Ledger write to hang indefinitely and bloating the Ledger metadata in ZooKeeper with thousands of segments.
lhotari
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Mar 13, 2026
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suggesting a new name for the config. It seems that getBoolean would throw an exception if the setting is missing and when the default value isn't provided.
| protected static final String BOOKIE_ERROR_THRESHOLD_PER_INTERVAL = "bookieErrorThresholdPerInterval"; | ||
| protected static final String BOOKIE_QUARANTINE_TIME_SECONDS = "bookieQuarantineTimeSeconds"; | ||
| protected static final String BOOKIE_QUARANTINE_RATIO = "bookieQuarantineRatio"; | ||
| protected static final String BOOKIE_CONNECTING_ERROR_COUNTED_INTO_QUARANTINE = "bookieConnectingErrorCountedIntoQuarantine"; |
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Could we call this bookieConnectionErrorQuarantineEnabled instead? The "counted into" part is slightly confusing.
Suggested change
| protected static final String BOOKIE_CONNECTING_ERROR_COUNTED_INTO_QUARANTINE = "bookieConnectingErrorCountedIntoQuarantine"; | |
| protected static final String BOOKIE_CONNECTING_ERROR_QUARANTINE_ENABLED = "bookieConnectionErrorQuarantineEnabled"; |
| * @return | ||
| */ | ||
| public boolean getBookieConnectingErrorCountedIntoQuarantine() { | ||
| return getBoolean(BOOKIE_CONNECTING_ERROR_COUNTED_INTO_QUARANTINE); |
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Default value should be provided as the 2nd argument, for example getBoolean(BOOKIE_CONNECTING_ERROR_QUARANTINE_ENABLED, false) (example with the suggested name of the config)
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Motivation
Currently, the bookie client quarantine mechanism primarily triggers based on
readandwriteerror responses from Bookies. However, in multi-region deployments, a common failure mode is the Network Partition or DNS Resolution Failure at the Region level.In such scenarios:
EnsemblePlacementPolicy(especiallyRegionAwareEnsemblePlacementPolicy) sees the Bookie as "Available" and repeatedly selects it to satisfyminRackorE/Qwconstraints.LedgerHandlefails to write because it cannot initialize a connection handle, triggering an Ensemble Change.This creates an infinite Ensemble Change loop, causing the Ledger write to hang indefinitely and bloating the Ledger metadata in ZooKeeper with thousands of segments.