Fix directory stream leak in FileCache.restoreFromDirectory - #22994
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Files.list returns a Stream backed by a DirectoryStream that has to be closed explicitly to release its file descriptor. The flatMap chain here opened one of these streams per data path (local store location and indices folder) but never closed any of them, since the whole pipeline was a single expression with no try with resources block anywhere in it. Restructured the scan to open and close one Files.list stream per directory instead of flattening them into the outer stream, so each one is released as soon as its directory has been read. Behavior and exception messages are unchanged, verified against the existing FileCacheTests suite (27 tests, all passing). Signed-off-by: Akanksha Trehun <akankshatrehun@gmail.com>
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September 10, 2026 04:59
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Description
FileCache.restoreFromDirectoryrebuilds the file cache from disk at node startup by scanning the local store location and indices folder under each file cache data path. It did this withStream.concat(...).flatMap(dir -> Files.list(dir))...forEach(...), one long expression with no try with resources anywhere in it.Files.list()opens aDirectoryStreamunder the hood that has to be closed explicitly to release its file descriptor, and flatMap does not close the inner streams it consumes, so every directory scanned during startup leaked one.This restructures the scan to iterate the candidate directories with a plain forEach and open one
Files.liststream per directory inside a try with resources block, so each directory's handle is released as soon as its contents have been read. Exception messages, put/decRef behavior, and the set of files processed are all unchanged.Verified against the existing
FileCacheTestssuite (27 tests, all passing).Related Issues
Resolves #
No existing issue; found by inspection while reviewing FileCache's startup path.
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