Claes,
It loogsk good. One minor nit is that the "hashCode" check in Name.equals() might not be really necessary, given in most/normal use scenario the "Name" is used as a key in Attributes.map, which is a LinkedHashMap. Arguably the hashcode should be check already during lookup. Agreed what you suggested in previously email regarding equalsIgnoreCase vs CASE_INSENSITIVE_ORDER. It appears equalsIgnoreCase() at least can take advantage of "intern()" and "length()" match. Thanks, Sherman On 04/20/2018 07:07 AM, Claes Redestad wrote:
Hi, please review this patch to address some of the legacy performance concerns arising when dealing extensively with java.util.jar.Attributes.Name (mainly when parsing jar Webrev: http://cr.openjdk.java.net/~redestad/6805750/open.02/ Bug: https://bugs.openjdk.java.net/browse/JDK-6805750 While also picking up a few of the micro-optimizations suggested (eagerly calculate the hashCode since it will always be used), the main approach is to set up a small map of commonly used manifest attributes, including but not limited to (non-deprecated) ones declared as constants of Attributes.Name. For known strings, this can see speed-ups of ~10x of Attributes.putValue(String, String) and 25x on Attributes.get(String), while reducing the footprint of typical Manifest objects[1]. I've also done a few experiments with a concurrent and dynamic backing storage[2][3], each of which have some elegant properties (mainly getting similar benefits on arbitrary attributes), but adding too much complexity to improve performance of uncommon attributes while slightly reducing the efficiency for common ones doesn't really seem worthwhile. Thanks! /Claes [1] http://cr.openjdk.java.net/~redestad/6805750/Attributes.java [2] http://cr.openjdk.java.net/~redestad/6805750/open.00/ -- reuse MethodType$ConcurrentWeakInternSet. Nice to reuse some code, but only gets a 2.5x improvement since we can't avoid allocation. [3] http://cr.openjdk.java.net/~redestad/6805750/open.01/ -- create a custom interning map from String to WeakEntry<Name>: ~15x get and ~8x putValue perf for any repeatedly used attribute name.
