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Created attachment 268326 [details] Caching lookups for jfs-rt resources When compiling a maven root project (~90 modules) with JDK8 and aspectj-maven-plugin, it takes less than 3 minutes. However, when using aspectj 1.9.0.BETA-5 the same operation takes over 22 minutes. The culprit is org.aspectj.weaver.bcel.ClassPathManager.JImageEnry::find. I changed the code in order to speed up this lookup by creating an 'index' file in user.home. The index takes less than 3 seconds to build and less than 1 sec to load. In order to not use a lot of memory, the index keeps only the mappings name->position on heap and the actual class file contents in a MemoryMapped Byte buffer (about 160MB). The impl can easily be adapted to use a RandomAccessFile instead. By employing this index, compilation time with JDK 9 dropped to ~2min:30s.
Created attachment 268342 [details] More Polished Version. Attaching a more polished version that is 100% based on a file index, which takes < 2ms to load. Lookup strategy can be selected by passing the -Dorg.aspectj.weaver.bcel.ClassPathManager.JIMAGE_CACHE_STRATEGY=<?> during build. Possible values for <?> are: 0-Don't use cache 1-Use cache and memory map the file (Default) 2-Use cache and FileChannel Performance for both 1 and 2 is quite similar on Linux. The implementation relies on the new JDK 9's java.util.Arrays.compare(byte[], int, int, byte[], int, int), which is vectorized/intrinsified, but can easily be backported. The index file will be created as a hidden file on user home, named .aj.cache.<java.vm.specification.vendor>.<java.runtime.version> e.g., .aj.cache.Oracle_Corporation.9_ea_165
I've created a version which just creates an in-memory-toc of all pathes of the module content. Bytes of classes are still read on demand. https://bugs.eclipse.org/bugs/show_bug.cgi?id=520597 This already brought up performance back for me.
