uschindler commented on PR #13337: URL: https://github.com/apache/lucene/pull/13337#issuecomment-2096280645
Hi, give me some time to review. I got the concept! I also have some questions about the NIOFS one because I don't like to use twice as much file handles just for the prefetching. MMap: the pagesize problem is well known. You are not the first one hitting this. I worked aorund it with some hack, too: https://github.com/apache/lucene/blob/40cae087f71a875478309abfc4b1ab1e7b027cab/lucene/core/src/java21/org/apache/lucene/store/MemorySegmentIndexInputProvider.java#L117-L119 The problem with page size is: It is known everywhere in the JDK and available via Unsafe and various other places, but all are private. I temporarily tried to add a workaround to use another glibc call to retrieve the page size, but this failes due to differences in enum constants on different platforms (the SC_PAGESIZE constant has a different value on various linux/macos versions) because its a C enum and has no fixed value. So we cannot easily get the page size without hardcoding an integer constant which is not even defined in any header file. The alternative is to use the deprecated/outdated [getpagesize()](https://man7.org/linux/man-pages/man2/getpagesize.2.html) function on libc.... But I don't want to use it as its not posix standardized.... What do you think about this workaround: use 4 K as pagesize, but guard with try/catch and do nothing on IOExc (if unaliged)? I was about to open an issue on JDK to somehow allow to get page size from JVM in the MemorySegment API because you need it quite often when using them. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: issues-unsubscr...@lucene.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: issues-unsubscr...@lucene.apache.org For additional commands, e-mail: issues-h...@lucene.apache.org
