On Wed, 8 Feb 2023 16:36:16 GMT, Eirik Bjorsnos <d...@openjdk.org> wrote:
>> After finding a hash match, getEntryPos needs to compare the lookup name up >> to the encoded entry name in the CEN. This comparison is done by decoding >> the entry name into a String. The names can then be compared using the >> String API. This decoding step adds a significat cost to this method. >> >> This PR suggest to update the string comparison such that in the common case >> where both the lookup name and the entry name are encoded in >> ASCII-compatible UTF-8, decoding can be avoided and the byte arrays can >> instead be compared direcly. >> >> ZipCoder is updated with a new method to compare a string with an encoded >> byte array range. The default implementation decodes to string (like the >> current code), while the UTF-8 implementation uses >> JavaLangAccess.getBytesNoRepl to get the bytes. Both methods thes uses >> Arrays.mismatch for comparison with or without matching trailing slashes. >> >> Additionally, this PR suggest to make the following updates to getEntryPos: >> >> - The try/catch for IAE is redundant and can be safely removed. (initCEN >> already checks this and will throws IAE for invalid UTF-8). This seems to >> give a 3-4% speedup on micros) >> - A new test InvalidBytesInEntryNameOrComment is a added to verify that >> initCEN does in fact reject invalid UTF-8 in CEN file names and comments. (I >> found no existing test coverage for this) >> - The recursion when looking for "name/" matches is replaced with iteration. >> We keep track of any "name/" match and return it at the end of the search. >> (I feel this is easier to follow and it also gives a ~30% speedup for >> addSlash lookups with no regression on regular lookups) >> >> (My though is that including these additional updates in this PR might >> reduce reviewer overhead given that it touches the exact same code. I might >> be wrong on this, please advise :) >> >> I'm seeing a ~17% saving on the micro ZipFileGetEntry.getEntryHit (modified >> to use xalan.jar): >> >> Baseline: >> >> Benchmark (size) Mode Cnt Score Error >> Units >> ZipFileGetEntry.getEntryHit 512 avgt 15 74.941 ± 1.004 >> ns/op >> ZipFileGetEntry.getEntryHit 1024 avgt 15 84.943 ± 1.320 >> ns/op >> ZipFileGetEntry.getEntryHitUncached 512 avgt 15 120.371 ± 2.386 >> ns/op >> ZipFileGetEntry.getEntryHitUncached 1024 avgt 15 126.128 ± 1.075 >> ns/op >> ZipFileGetEntry.getEntryMiss 512 avgt 15 23.818 ± 0.838 >> ns/op >> ZipFileGetEntry.getEntryMiss 1024 avgt 15 29.762 ± 5.998 >> ns/op >> ZipFileGetEntry.getEntryMissUncached 512 avgt 15 59.405 ± 0.545 >> ns/op >> ZipFileGetEntry.getEntryMissUncached 1024 avgt 15 71.840 ± 2.455 >> ns/op >> ZipFileGetEntry.getEntrySlash 512 avgt 15 135.621 ± 4.341 >> ns/op >> ZipFileGetEntry.getEntrySlash 1024 avgt 15 134.190 ± 2.141 >> ns/op >> >> >> >> PR: >> >> >> Benchmark (size) Mode Cnt Score Error >> Units >> ZipFileGetEntry.getEntryHit 512 avgt 15 62.267 ± 1.329 >> ns/op >> ZipFileGetEntry.getEntryHit 1024 avgt 15 72.916 ± 2.428 >> ns/op >> ZipFileGetEntry.getEntryHitUncached 512 avgt 15 101.630 ± 1.154 >> ns/op >> ZipFileGetEntry.getEntryHitUncached 1024 avgt 15 113.161 ± 0.502 >> ns/op >> ZipFileGetEntry.getEntryMiss 512 avgt 15 23.003 ± 1.191 >> ns/op >> ZipFileGetEntry.getEntryMiss 1024 avgt 15 23.236 ± 1.114 >> ns/op >> ZipFileGetEntry.getEntryMissUncached 512 avgt 15 56.781 ± 1.505 >> ns/op >> ZipFileGetEntry.getEntryMissUncached 1024 avgt 15 67.767 ± 1.963 >> ns/op >> ZipFileGetEntry.getEntrySlash 512 avgt 15 73.745 ± 2.717 >> ns/op >> ZipFileGetEntry.getEntrySlash 1024 avgt 15 75.784 ± 1.051 >> ns/op >> >> >> To assess the impact on startup/warmup, I made a main method class which >> measures the total time of calling ZipFile.getEntry for all entries in the >> 109 JAR file dependenies of spring-petclinic. The shows a nice improvement >> (time in micros): >> >> >> Percentile Baseline Patch >> 50 % 23155 21149 >> 75 % 23598 21454 >> 90 % 23989 21691 >> 95 % 24238 21973 >> 99 % 25270 22446 >> STDEV 792 549 >> Count 500 500 > > Eirik Bjorsnos has updated the pull request incrementally with one additional > commit since the last revision: > > Update the sameHashAndLengthDirLookup to use ASCII example colliding paths, > allowing the test to run over all charsets Yes, I'll file a PR to see if we can make `startsWith` a bit sharper. In addition to - or instead of - an `equals` shortcut then if coders are the same we could use `ArraysSupport.mismatch` which should get similar speed and help more generally. ------------- PR: https://git.openjdk.org/jdk/pull/12290
