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https://issues.apache.org/jira/browse/LOG4J2-1151?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14944226#comment-14944226
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Remko Popma commented on LOG4J2-1151:
-------------------------------------
I overlooked something: invalid input. The JDK code checks if the specified
characters are really single-byte, and if invalid they are represented with a
'?'.
I tried to accomodate for this but it impacts performance quite a bit.
Explanation of benchmarks below:
* "custom cast-to-byte": simply cast each char to a byte without checking if it
is a single byte char or not
* "ported JDK 8": copy of the JDK 8 code
* "verify and cast": attempt to do simple check in addition to cast-to-byte
(not a JDK 8 port)
*Conclusions*
* On JDK 8, it is better to simply use the built-in String.getBytes methods
* On JDK 7, the ported JDK 8 code gives best performance without sacrificing
functionality (invalid input is handled as with the built-in String.getBytes
methods)
*jdk 1.8.0_60 (64 bit Hotspot)*
{code}
Benchmark
Mode Samples Score Error Units
o.a.l.l.p.j.StringEncodingBenchmark.iso8859_1CustomCastToByte
sample 99563 87.159 ± 23.752 ns/op
o.a.l.l.p.j.StringEncodingBenchmark.iso8859_1CustomPortedJDK8
sample 153776 149.088 ± 2.656 ns/op
o.a.l.l.p.j.StringEncodingBenchmark.iso8859_1CustomVerifyAndCast
sample 99694 127.062 ± 2.692 ns/op
o.a.l.l.p.j.StringEncodingBenchmark.iso8859_1StringGetBytesCharSet
sample 112143 80.945 ± 2.699 ns/op
o.a.l.l.p.j.StringEncodingBenchmark.iso8859_1StringGetBytesString
sample 169835 94.945 ± 17.172 ns/op
o.a.l.l.p.j.StringEncodingBenchmark.usAsciiStringGetBytesCharSet
sample 174893 136.186 ± 2.051 ns/op
o.a.l.l.p.j.StringEncodingBenchmark.usAsciiStringGetBytesString
sample 151682 157.029 ± 13.066 ns/op
{code}
*jdk 1.7.0_55 (64 bit Hotspot)*
{code}
Benchmark
Mode Samples Score Error Units
o.a.l.l.p.j.StringEncodingBenchmark.iso8859_1CustomCastToByte
sample 101091 84.999 ± 3.336 ns/op
o.a.l.l.p.j.StringEncodingBenchmark.iso8859_1CustomPortedJDK8
sample 171849 149.490 ± 12.233 ns/op
o.a.l.l.p.j.StringEncodingBenchmark.iso8859_1CustomVerifyAndCast
sample 150746 302.352 ± 2.940 ns/op
o.a.l.l.p.j.StringEncodingBenchmark.iso8859_1StringGetBytesCharSet
sample 196531 244.018 ± 18.239 ns/op
o.a.l.l.p.j.StringEncodingBenchmark.iso8859_1StringGetBytesString
sample 146952 306.058 ± 2.919 ns/op
o.a.l.l.p.j.StringEncodingBenchmark.usAsciiStringGetBytesCharSet
sample 194692 250.779 ± 12.239 ns/op
o.a.l.l.p.j.StringEncodingBenchmark.usAsciiStringGetBytesString
sample 143561 316.768 ± 3.482 ns/op
{code}
> Performance improvement: backport fast Java 8 ISO-8859-1 String to byte[]
> encoder to AbstractStringLayout
> ---------------------------------------------------------------------------------------------------------
>
> Key: LOG4J2-1151
> URL: https://issues.apache.org/jira/browse/LOG4J2-1151
> Project: Log4j 2
> Issue Type: Improvement
> Components: Layouts
> Affects Versions: 2.4
> Reporter: Remko Popma
> Assignee: Remko Popma
> Fix For: 2.4.1
>
>
> Java 8 made large improvements to String encoding performance for all
> character sets. Especially for the ISO8859_1 encoding, Java 8 introduced
> logic that simply casts each char in the array to a byte, giving a huge
> performance increase.
> This ticket proposes to backport that logic into AbstractStringLayout to get
> the same performance in Java 7.
> Focussing on the results for ISO8859_1:
> {quote}
> Java 7 String.getBytes(): ~200-300 ns/op
> Java 8 String.getBytes(): ~70-80 ns/op
> Custom logic: ~90 ns/op (on both Java 7 and 8)
> {quote}
> Benchmarks below are with a representative message string of 100 characters,
> on 64 bit Windows 10, Dual Intel Core i5-3317U @1.70GHz with hyperthreading
> on (4 cores).
> *jdk 1.8.0_60 (64 bit Hotspot)*
> {code}
> Benchmark Mode
> Samples Score Error Units
> o.a.l.l.p.j.StringEncodingBenchmark.customIso8859_1 sample
> 156848 94.014 ± 2.362 ns/op <- custom
> o.a.l.l.p.j.StringEncodingBenchmark.encoderIso8859_1 sample
> 103773 859.529 ± 27.461 ns/op
> o.a.l.l.p.j.StringEncodingBenchmark.stringGetBytes sample
> 125785 363.129 ± 17.674 ns/op
> o.a.l.l.p.j.StringEncodingBenchmark.stringGetBytesCharSet88591 sample
> 117191 72.606 ± 2.771 ns/op <- variation 1
> o.a.l.l.p.j.StringEncodingBenchmark.stringGetBytesCharSetShiftJIS sample
> 102914 452.721 ± 21.274 ns/op
> o.a.l.l.p.j.StringEncodingBenchmark.stringGetBytesString88591 sample
> 181547 79.653 ± 1.735 ns/op <- variation 2
> o.a.l.l.p.j.StringEncodingBenchmark.stringGetBytesStringShiftJIS sample
> 125817 354.961 ± 4.072 ns/op
> {code}
> *jdk 1.7.0_55 (64 bit Hotspot)*
> {code}
> Benchmark Mode
> Samples Score Error Units
> o.a.l.l.p.j.StringEncodingBenchmark.customIso8859_1 sample
> 148456 93.248 ± 2.193 ns/op <- custom
> o.a.l.l.p.j.StringEncodingBenchmark.encoderIso8859_1 sample
> 176198 516.731 ± 24.054 ns/op
> o.a.l.l.p.j.StringEncodingBenchmark.stringGetBytes sample
> 121660 731.530 ± 27.116 ns/op
> o.a.l.l.p.j.StringEncodingBenchmark.stringGetBytesCharSet88591 sample
> 99636 234.709 ± 3.234 ns/op <- variation 1
> o.a.l.l.p.j.StringEncodingBenchmark.stringGetBytesCharSetShiftJIS sample
> 125754 1401.008 ± 25.385 ns/op
> o.a.l.l.p.j.StringEncodingBenchmark.stringGetBytesString88591 sample
> 147124 316.411 ± 21.454 ns/op <- variation 2
> o.a.l.l.p.j.StringEncodingBenchmark.stringGetBytesStringShiftJIS sample
> 114733 808.315 ± 27.177 ns/op
> {code}
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