Hi, currently during ZipFile creation, we create an int[] array of pointers to META-INF entries. These are then retrieved from three different places in JarFile.
However, JarFile is only interested in some combination a few things: the existence of and name of the META-INF/MANIFEST file, the existence of and the names of various signature related files, i.e., files in META-INF that have a suffix such as .EC, .SF, .RSA and .DSA Refactoring the contract between JarFile and ZipFile means we can filter out such entries that we're not interested when opening the file, and also remove the need to create the String for each entries unless we actually want them: Bug: https://bugs.openjdk.java.net/browse/JDK-8244624 Webrev: http://cr.openjdk.java.net/~redestad/8244624/open.00/ This reduces retained footprint of Jar-/ZipFile by slimming down or removing the Source.metanames array entirely, and a significant speed-up in some cases. In the provided microbenchmark, getManifestFromJarWithManifest and getManifestFromJarWithSignatureFiles doesn't call JUZFA.getMetaInfEntryNames but still see small (~5%) speed-up decrease in allocations. getManifestFromJarWithNoManifest exercise JUZFA.getMetaInfEntryNames in the baseline, and now calls JUZFA.getManifestName. Result is a 1.25x speed-up and 30% reduction in allocations. While unrealistic (most JARs have a META-INF/MANIFEST.MF), this speed-up will translate to a few places - such as when loading classes from potentially-signed JAR files. Testing: tier1-2 Thanks! /Claes
