[GitHub] [pulsar] codelipenghui commented on a change in pull request #11621: fix getPreviousPosition npe

[GitBox <gi...@apache.org>]

codelipenghui commented on a change in pull request #11621:
URL: https://github.com/apache/pulsar/pull/11621#discussion_r686085678



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File path: managed-ledger/src/main/java/org/apache/bookkeeper/mledger/impl/ManagedLedgerImpl.java
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@@ -3202,8 +3203,9 @@ public PositionImpl getPreviousPosition(PositionImpl position) {
             return PositionImpl.get(position.getLedgerId(), position.getEntryId() - 1);
         }
 
+        final NavigableMap<Long, LedgerInfo> ledgersCopied = new TreeMap<>(ledgers);
         // The previous position will be the last position of an earlier ledgers
-        NavigableMap<Long, LedgerInfo> headMap = ledgers.headMap(position.getLedgerId(), false);
+        NavigableMap<Long, LedgerInfo> headMap = ledgersCopied.headMap(position.getLedgerId(), false);

Review comment:
       We may have many ledgers if users keep long-term data, copy here might be expensive here, as you can see we have many places that uses the `getPreviousPosition` method, can we catch the NPE and retry the execution?




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