Just to complement your statement: The default MMapDirectory uses MemorySegmentIndexInput. This one implements the close logic similar so Clones or slices cannot be closed: They do not get the Arena which controls lifetime of file mapping (it is null): <https://github.com/apache/lucene/blob/dba6c2c2fd98dce4a1348109ecad09cd3ba44e5f/lucene/core/src/java21/org/apache/lucene/store/MemorySegmentIndexInput.java#L699>
Here it is cloned or sliced: <https://github.com/apache/lucene/blob/dba6c2c2fd98dce4a1348109ecad09cd3ba44e5f/lucene/core/src/java21/org/apache/lucene/store/MemorySegmentIndexInput.java#L569> Uwe Am 31. März 2025 20:10:18 MESZ schrieb Michael Froh <msf...@gmail.com>: >Checking a few of the implementations, the general rule seems to be that >sliced IndexInput instances don't get closed or the close operation is a >no-op. > >For example, in NIOFSIndexInput, the slice constructor sets isClone to >true, which make the close() method a no-op: >https://github.com/apache/lucene/blob/7e20d5b3aad13739a2ae9fa36774e68ccae43ac4/lucene/core/src/java/org/apache/lucene/store/NIOFSDirectory.java#L123 > >Similarly, for DirectIOIndexInput, the slice constructor sets isClosable to >false, which makes close() a no-op: >https://github.com/apache/lucene/blob/f8fac44b321ee089571f1cee31fa1d90046d7c01/lucene/misc/src/java/org/apache/lucene/misc/store/DirectIODirectory.java#L330 > >ByteBuffersIndexInput has a close() method that doesn't close anything >(since ByteBuffersDataInput isn't closeable): >https://github.com/apache/lucene/blob/cfdd20f5bc8387ba24653ca2ba15aa5be10d0ae0/lucene/core/src/java/org/apache/lucene/store/ByteBuffersIndexInput.java#L37 > >So, the implicit contract seems to be that it's okay to close a sliced >IndexInput, but it's not necessary. > >Hope that helps, >Froh > > >On Fri, Mar 28, 2025 at 5:26 PM 기준 <0ctopus13pr...@gmail.com> wrote: > >> Hi all, hope you are doing great. >> >> Wondering what is the contract of `close` of sliced IndexInput? >> Could not find any related documents wrt this. >> >> I find many places in Lucene do not close sliced IndexInput, and when >> cleaning resources, it just close origin IndexInput. >> >> Would appreciate it if someone could help clarify the contract. >> Fundamental question is that can we skip calling `close` a sliced >> IndexInput?? >> >> Thank you >> -- Uwe Schindler Achterdiek 19, 28357 Bremen https://www.thetaphi.de
