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Status

Current state: "Under Discussion"

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Please keep the discussion on the mailing list rather than commenting on the wiki (wiki discussions get unwieldy fast).

Motivation

Log recovery is a process when a broker start up, if it has previous unclean shutdown, it'll be triggered to make sure the log is in a good state and not get corrupted. The process of log recovery is as below:

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So far, we have no way to know the log recovery progress. All we can do is checking the broker log and know it is busy on doing recovery. In this KIP, we're going to expose a "remainingLogsToRecovery" metric to allow the admin have a way to monitor the progress of log recovery.

Public Interfaces

"remainingLogsToRecovery" metric will be added into "kafka.log" → LogManager

Proposed Changes

The proposal is to propose a remainingLogsToRecovery  metric to keep the remaining logs number to be recovered. The total number of logs to be recovered will be added in step (b) described in "motivation" section. When each log completes the recovery for all the segments under the log, the remainingLogsToRecovery will be decremented, and in the end, it'll be 0. When broker is not under log recovery state, the number will always be 0.

Compatibility, Deprecation, and Migration Plan

No compatibility issue and no migration plan needed because this KIP only adds a metric for log recovery.

Rejected Alternatives

1. output the log recovery progress in logs

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