This is a rewrite (port) of Snappy writen in pure Java. This compression code produces a byte-for-byte exact copy of the output created by the original C++ code, and extremely fast.
The Snappy micro-benchmark has been ported, and can be used to measure the performance of this code against the excellent Snappy JNI wrapper from xerial. As you can see in the results below, the pure Java port is 20-30% faster for block compress, 0-10% slower for block uncompress, and 0-5% slower for round-trip block compression. These results were run with Java 7 on a Core i7, 64-bit Mac.
As a second more independent test, the performance has been measured using the Ning JVM compression benchmark against Snappy JNI, and the pure Java Ning LZF codec. The results show that the pure Java Snappy is 20-30% faster than JNI Snappy for compression, and is typically 10-20% slower for decompression. Both, the pure Java Snappy and JNI Snappy implementations are faster that the Ning LZF codec. These results were run with Java 6 on a Core i7, 64-bit Mac.
The difference in performance between these two tests is due to the difference in JVM version; Java 7 is consistently 5-10% faster than Java 6 in the compression code. As with all benchmarks your mileage will vary, so test with your actual use case.
JNI Java JNI Java
Input Size Compress Compress Throughput Throughput Change
---------------------------------------------------------------------
html 102400 76.4% 76.4% 294.9MB/s 384.8MB/s +30.5% html
urls 702087 49.1% 49.1% 178.7MB/s 226.5MB/s +26.8% urls
jpg 126958 0.1% 0.1% 2.7GB/s 3.2GB/s +17.4% jpg (not compressible)
pdf 94330 17.9% 17.9% 642.4MB/s 910.3MB/s +41.7% pdf
html4 409600 76.4% 76.4% 289.2MB/s 377.3MB/s +30.5% html4
cp 24603 51.9% 51.9% 166.4MB/s 233.7MB/s +40.5% cp
c 11150 57.6% 57.6% 177.1MB/s 295.4MB/s +66.8% c
lsp 3721 51.6% 51.6% 245.5MB/s 278.0MB/s +13.2% lsp
xls 1029744 58.7% 58.7% 263.0MB/s 292.5MB/s +11.2% xls
txt1 152089 40.2% 40.2% 116.8MB/s 163.1MB/s +39.7% txt1
txt2 125179 35.9% 35.9% 112.5MB/s 153.4MB/s +36.3% txt2
txt3 426754 42.9% 42.9% 123.3MB/s 169.8MB/s +37.6% txt3
txt4 481861 31.7% 31.7% 107.8MB/s 146.2MB/s +35.6% txt4
bin 513216 81.8% 81.8% 413.1MB/s 497.8MB/s +20.5% bin
sum 38240 48.1% 48.1% 162.4MB/s 213.9MB/s +31.7% sum
man 4227 40.6% 40.6% 194.6MB/s 241.7MB/s +24.2% man
pb 118588 76.8% 76.8% 363.7MB/s 450.3MB/s +23.8% pb
gaviota 184320 61.7% 61.7% 166.7MB/s 253.7MB/s +52.2% gaviota
JNI Java JNI Java
Input Size Compress Compress Throughput Throughput Change
---------------------------------------------------------------------
html 102400 76.4% 76.4% 1.5GB/s 1.3GB/s -12.2% html
urls 702087 49.1% 49.1% 969.2MB/s 827.5MB/s -14.6% urls
jpg 126958 0.1% 0.1% 18.6GB/s 19.4GB/s +4.2% jpg (not compressible)
pdf 94330 17.9% 17.9% 4.1GB/s 3.7GB/s -8.8% pdf
html4 409600 76.4% 76.4% 1.5GB/s 1.2GB/s -16.8% html4
cp 24603 51.9% 51.9% 965.2MB/s 956.0MB/s -1.0% cp
c 11150 57.6% 57.6% 989.1MB/s 924.9MB/s -6.5% c
lsp 3721 51.6% 51.6% 991.6MB/s 964.8MB/s -2.7% lsp
xls 1029744 58.7% 58.7% 798.4MB/s 747.3MB/s -6.4% xls
txt1 152089 40.2% 40.2% 643.8MB/s 580.8MB/s -9.8% txt1
txt2 125179 35.9% 35.9% 610.0MB/s 549.6MB/s -9.9% txt2
txt3 426754 42.9% 42.9% 683.8MB/s 614.4MB/s -10.2% txt3
txt4 481861 31.7% 31.7% 565.4MB/s 505.5MB/s -10.6% txt4
bin 513216 81.8% 81.8% 1.5GB/s 1.2GB/s -20.4% bin
sum 38240 48.1% 48.1% 838.1MB/s 771.6MB/s -7.9% sum
man 4227 40.6% 40.6% 856.9MB/s 847.2MB/s -1.1% man
pb 118588 76.8% 76.8% 1.7GB/s 1.5GB/s -12.9% pb
gaviota 184320 61.7% 61.7% 769.1MB/s 693.4MB/s -9.9% gaviota
JNI Java JNI Java
Input Size Compress Compress Throughput Throughput Change
---------------------------------------------------------------------
html 102400 76.4% 76.4% 300.3MB/s 287.1MB/s -4.4% html
urls 702087 49.1% 49.1% 182.7MB/s 177.0MB/s -3.2% urls
jpg 126958 0.1% 0.1% 2.6GB/s 2.6GB/s +1.1% jpg (not compressible)
pdf 94330 17.9% 17.9% 695.3MB/s 680.0MB/s -2.2% pdf
html4 409600 76.4% 76.4% 296.4MB/s 282.1MB/s -4.8% html4
cp 24603 51.9% 51.9% 177.0MB/s 172.5MB/s -2.5% cp
c 11150 57.6% 57.6% 221.7MB/s 218.3MB/s -1.5% c
lsp 3721 51.6% 51.6% 217.3MB/s 216.3MB/s -0.5% lsp
xls 1029744 58.7% 58.7% 213.3MB/s 209.9MB/s -1.6% xls
txt1 152089 40.2% 40.2% 129.4MB/s 126.3MB/s -2.4% txt1
txt2 125179 35.9% 35.9% 121.7MB/s 118.8MB/s -2.4% txt2
txt3 426754 42.9% 42.9% 135.2MB/s 132.8MB/s -1.8% txt3
txt4 481861 31.7% 31.7% 115.2MB/s 113.0MB/s -1.9% txt4
bin 513216 81.8% 81.8% 371.2MB/s 350.7MB/s -5.5% bin
sum 38240 48.1% 48.1% 164.2MB/s 160.0MB/s -2.6% sum
man 4227 40.6% 40.6% 184.8MB/s 185.3MB/s +0.3% man
pb 118588 76.8% 76.8% 344.1MB/s 326.3MB/s -5.2% pb
gaviota 184320 61.7% 61.7% 188.0MB/s 185.2MB/s -1.5% gaviota
There is no defined stream format for Snappy, but there is an effort to create a common format with the Google Snappy project.
The stream format used in this library has a couple of unique features not found in the other Snappy stream formats. Like the other formats, the user input is broken into blocks and each block is compressed. If the compressed block is smaller that the user input, the compressed block is written, otherwise the uncompressed original is written. This dramatically improves the speed of uncompressible input such as JPG images. Additionally, a checksum of the user input data for each block is written to the stream. This safety check assures that the stream has not been corrupted in transit or by a bad Snappy implementation. Finally, like gzip, compressed Snappy files can be concatenated together without issue, since the input stream will ignore a Snappy stream header in the middle of a stream. This makes combining files in Hadoop and S3 trivial.
The the SnappyOutputStream javadocs contain formal definition of the stream format.
The streaming mode performance can not be directly compared to other compression algorithms since most formats do not contain a checksum. The basic streaming code is significantly faster that the Snappy JNI library due to the completely unoptimized stream implementation in Snappy JNI, but once the check sum is enabled the performance drops off by about 20%.
JNI Java JNI Java
Input Size Compress Compress Throughput Throughput Change
---------------------------------------------------------------------
html 102400 76.4% 76.4% 275.8MB/s 373.5MB/s +35.4% html
urls 702087 49.1% 49.1% 176.5MB/s 225.2MB/s +27.6% urls
jpg 126958 0.1% -0.0% 1.7GB/s 2.0GB/s +15.8% jpg (not compressible)
pdf 94330 17.8% 16.0% 557.2MB/s 793.2MB/s +42.4% pdf
html4 409600 76.4% 76.4% 281.0MB/s 369.9MB/s +31.7% html4
cp 24603 51.8% 51.8% 151.7MB/s 214.3MB/s +41.3% cp
c 11150 57.4% 57.5% 149.1MB/s 243.3MB/s +63.1% c
lsp 3721 51.1% 51.2% 141.3MB/s 181.1MB/s +28.2% lsp
xls 1029744 58.6% 58.6% 253.9MB/s 290.5MB/s +14.4% xls
txt1 152089 40.2% 40.2% 114.8MB/s 159.4MB/s +38.8% txt1
txt2 125179 35.9% 35.9% 110.0MB/s 150.4MB/s +36.7% txt2
txt3 426754 42.9% 42.9% 121.0MB/s 167.9MB/s +38.8% txt3
txt4 481861 31.6% 31.6% 105.1MB/s 143.2MB/s +36.2% txt4
bin 513216 81.8% 81.8% 387.7MB/s 484.5MB/s +25.0% bin
sum 38240 48.1% 48.1% 153.0MB/s 203.1MB/s +32.8% sum
man 4227 40.2% 40.3% 125.9MB/s 171.9MB/s +36.5% man
pb 118588 76.8% 76.8% 342.2MB/s 431.4MB/s +26.1% pb
gaviota 184320 61.7% 61.7% 161.1MB/s 246.1MB/s +52.7% gaviota
JNI Java JNI Java
Input Size Compress Compress Throughput Throughput Change
---------------------------------------------------------------------
html 102400 76.4% 76.4% 1.2GB/s 1.2GB/s +0.4% html
urls 702087 49.1% 49.1% 853.9MB/s 786.6MB/s -7.9% urls
jpg 126958 0.1% -0.0% 3.0GB/s 10.3GB/s +239.0% jpg (not compressible)
pdf 94330 17.8% 16.0% 2.0GB/s 3.4GB/s +71.5% pdf
html4 409600 76.4% 76.4% 1.2GB/s 1.1GB/s -8.4% html4
cp 24603 51.8% 51.8% 785.2MB/s 905.6MB/s +15.3% cp
c 11150 57.4% 57.5% 778.9MB/s 889.7MB/s +14.2% c
lsp 3721 51.1% 51.2% 739.0MB/s 905.5MB/s +22.5% lsp
xls 1029744 58.6% 58.6% 730.3MB/s 718.8MB/s -1.6% xls
txt1 152089 40.2% 40.2% 582.4MB/s 559.0MB/s -4.0% txt1
txt2 125179 35.9% 35.9% 540.7MB/s 526.4MB/s -2.6% txt2
txt3 426754 42.9% 42.9% 620.5MB/s 583.9MB/s -5.9% txt3
txt4 481861 31.6% 31.6% 519.4MB/s 487.0MB/s -6.2% txt4
bin 513216 81.8% 81.8% 1.2GB/s 1.1GB/s -11.6% bin
sum 38240 48.1% 48.1% 693.4MB/s 742.4MB/s +7.1% sum
man 4227 40.2% 40.3% 637.3MB/s 784.3MB/s +23.1% man
pb 118588 76.8% 76.8% 1.4GB/s 1.4GB/s +0.4% pb
gaviota 184320 61.7% 61.7% 688.5MB/s 668.2MB/s -3.0% gaviota
JNI Java JNI Java
Input Size Compress Compress Throughput Throughput Change
---------------------------------------------------------------------
html 102400 76.4% 76.4% 223.8MB/s 272.5MB/s +21.8% html
urls 702087 49.1% 49.1% 142.8MB/s 174.1MB/s +22.0% urls
jpg 126958 0.1% -0.0% 1.1GB/s 1.6GB/s +52.1% jpg (not compressible)
pdf 94330 17.8% 16.0% 421.9MB/s 610.1MB/s +44.6% pdf
html4 409600 76.4% 76.4% 226.2MB/s 275.5MB/s +21.8% html4
cp 24603 51.8% 51.8% 125.3MB/s 160.3MB/s +27.9% cp
c 11150 57.4% 57.5% 125.1MB/s 183.2MB/s +46.5% c
lsp 3721 51.1% 51.2% 130.6MB/s 149.5MB/s +14.5% lsp
xls 1029744 58.6% 58.6% 188.2MB/s 206.1MB/s +9.5% xls
txt1 152089 40.2% 40.2% 95.3MB/s 123.3MB/s +29.4% txt1
txt2 125179 35.9% 35.9% 91.4MB/s 116.8MB/s +27.9% txt2
txt3 426754 42.9% 42.9% 101.3MB/s 130.3MB/s +28.6% txt3
txt4 481861 31.6% 31.6% 87.9MB/s 111.1MB/s +26.3% txt4
bin 513216 81.8% 81.8% 294.7MB/s 337.9MB/s +14.7% bin
sum 38240 48.1% 48.1% 122.9MB/s 152.9MB/s +24.3% sum
man 4227 40.2% 40.3% 113.0MB/s 139.1MB/s +23.1% man
pb 118588 76.8% 76.8% 269.5MB/s 313.8MB/s +16.4% pb
gaviota 184320 61.7% 61.7% 131.1MB/s 180.3MB/s +37.6% gaviota
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