wernerdv commented on code in PR #13554:
URL: https://github.com/apache/ignite/pull/13554#discussion_r4004787189
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modules/core/src/main/java/org/apache/ignite/internal/processors/cache/persistence/freelist/AbstractFreeList.java:
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@@ -701,10 +713,29 @@ private int writeWholePages(T row, IoStatisticsHolder
statHolder) throws IgniteC
* @throws IgniteCheckedException If failed.
*/
private int writeSinglePage(T row, int written, IoStatisticsHolder
statHolder) throws IgniteCheckedException {
+ // TOCTOU closure: the size-aware reserve (ensureFreeSpaceForInsert,
invoked from RowStore.addRow/addRows
+ // before this write) accumulates enough real empty pages but does not
pin them to this thread - a concurrent
+ // writer can consume them between the reserve and this allocation.
When the free list cannot hand out a page,
+ // re-reserve on the remaining size and retry before allocating a
brand-new page; otherwise the race surfaces
+ // as a raw IgniteOutOfMemoryException (wrapped into
CorruptedFreeListException in the batch path).
+ //
+ // The re-reserve is an inline demand-eviction: reached from the
BPlusTree.invoke row-creation closure, it may
+ // re-entrantly remove other entries from the same data tree. That is
safe because the closure runs with no
Review Comment:
Partially correct.
The premise — "BPlusTree.invoke holds the leaf write lock while running the
closure" — is not supported by the code: BPlusTree.invokeDown releases the leaf
read lock when read(...) returns and takes the leaf write lock only afterwards
(in tryInsert/tryReplace/tryRemoveFromLeaf). Your broader point stands: entry
tryLock covers only entry-level ordering and does not make eviction page-level
lock-free.
The cross-tree (data→pending vs pending→data) residual risk with the TTL
worker is real and documented in the code comment; a full fix is out of scope.
Please correct me if I'm wrong.
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