BewareMyPower opened a new pull request, #25119:
URL: https://github.com/apache/pulsar/pull/25119

   Fixes #25118
   
   ### Motivation
   
   The steps of compaction phase two are:
   1. Seek the compacted reader to the position of the 1st retained entry
   2. Read to latest
   3. Acknowledge the last compacted message id (horizon) as well as the 
compacted ledger's id in properties
   
   However, if broker is closing during phase two, the pending `readNextAsync` 
call could fail with `CancellationException`. In this case, when the managed 
ledger is closed, the position of the 1st retained entry will be persisted as 
the `__compaction` cursor's mark-delete position.
   
   As a result, during the next compaction, the horizon will be very early, and 
phase one will read too many entries from original ledgers. This issue could 
get into a bad state when the original ledgers are not deleted, typically due 
to improper retention policy or unexpected large backlog from another durable 
subscription.
   
   ### Modifications
   
   Specially for `__compaction` cursor, do not modify the mark-delete position 
in `internalResetCursor` (triggered by client seek API).
   
   Add `testPhaseTwoInterruption` to reproduce this issue by injecting topic 
close in compaction phase two. Additionally, speed up the whole 
`CompactionTest`.
   
   It should be noted that the original behavior also makes 
`testCompactorReadsCompacted` incorrect. This test sends two messages to two 
ledgers and compacted them. Then it sends the third message and trigger the 
compaction. However, it assumes the 2nd ledger will be opened. Technically, the 
2nd ledger has only 1 entry that has been compacted, so it should not be 
opened. The entries from first two ledgers should be read directly from the 
compacted ledger. This test is fixed by adding another more message before 
creating the 3rd ledger.
   
   ### Documentation
   
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