Snappy in Java

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https://github.com/dain/snappy

Snappy in Java

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.

Performance

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.

Block Compress

                        JNI      Java         JNI        JavaInput        Size  Compress  Compress  Throughput  Throughput  Change---------------------------------------------------------------------html       102400     76.4%     76.4%   294.9MB/s   384.8MB/s  +30.5%  htmlurls       702087     49.1%     49.1%   178.7MB/s   226.5MB/s  +26.8%  urlsjpg        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%  pdfhtml4      409600     76.4%     76.4%   289.2MB/s   377.3MB/s  +30.5%  html4cp          24603     51.9%     51.9%   166.4MB/s   233.7MB/s  +40.5%  cpc           11150     57.6%     57.6%   177.1MB/s   295.4MB/s  +66.8%  clsp          3721     51.6%     51.6%   245.5MB/s   278.0MB/s  +13.2%  lspxls       1029744     58.7%     58.7%   263.0MB/s   292.5MB/s  +11.2%  xlstxt1       152089     40.2%     40.2%   116.8MB/s   163.1MB/s  +39.7%  txt1txt2       125179     35.9%     35.9%   112.5MB/s   153.4MB/s  +36.3%  txt2txt3       426754     42.9%     42.9%   123.3MB/s   169.8MB/s  +37.6%  txt3txt4       481861     31.7%     31.7%   107.8MB/s   146.2MB/s  +35.6%  txt4bin        513216     81.8%     81.8%   413.1MB/s   497.8MB/s  +20.5%  binsum         38240     48.1%     48.1%   162.4MB/s   213.9MB/s  +31.7%  summan          4227     40.6%     40.6%   194.6MB/s   241.7MB/s  +24.2%  manpb         118588     76.8%     76.8%   363.7MB/s   450.3MB/s  +23.8%  pbgaviota    184320     61.7%     61.7%   166.7MB/s   253.7MB/s  +52.2%  gaviota

Block Uncompress

                        JNI      Java         JNI        JavaInput        Size  Compress  Compress  Throughput  Throughput  Change---------------------------------------------------------------------html       102400     76.4%     76.4%     1.5GB/s     1.3GB/s  -12.2%  htmlurls       702087     49.1%     49.1%   969.2MB/s   827.5MB/s  -14.6%  urlsjpg        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%  pdfhtml4      409600     76.4%     76.4%     1.5GB/s     1.2GB/s  -16.8%  html4cp          24603     51.9%     51.9%   965.2MB/s   956.0MB/s   -1.0%  cpc           11150     57.6%     57.6%   989.1MB/s   924.9MB/s   -6.5%  clsp          3721     51.6%     51.6%   991.6MB/s   964.8MB/s   -2.7%  lspxls       1029744     58.7%     58.7%   798.4MB/s   747.3MB/s   -6.4%  xlstxt1       152089     40.2%     40.2%   643.8MB/s   580.8MB/s   -9.8%  txt1txt2       125179     35.9%     35.9%   610.0MB/s   549.6MB/s   -9.9%  txt2txt3       426754     42.9%     42.9%   683.8MB/s   614.4MB/s  -10.2%  txt3txt4       481861     31.7%     31.7%   565.4MB/s   505.5MB/s  -10.6%  txt4bin        513216     81.8%     81.8%     1.5GB/s     1.2GB/s  -20.4%  binsum         38240     48.1%     48.1%   838.1MB/s   771.6MB/s   -7.9%  summan          4227     40.6%     40.6%   856.9MB/s   847.2MB/s   -1.1%  manpb         118588     76.8%     76.8%     1.7GB/s     1.5GB/s  -12.9%  pbgaviota    184320     61.7%     61.7%   769.1MB/s   693.4MB/s   -9.9%  gaviota

Block Round Trip

                        JNI      Java         JNI        JavaInput        Size  Compress  Compress  Throughput  Throughput  Change---------------------------------------------------------------------html       102400     76.4%     76.4%   300.3MB/s   287.1MB/s   -4.4%  htmlurls       702087     49.1%     49.1%   182.7MB/s   177.0MB/s   -3.2%  urlsjpg        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%  pdfhtml4      409600     76.4%     76.4%   296.4MB/s   282.1MB/s   -4.8%  html4cp          24603     51.9%     51.9%   177.0MB/s   172.5MB/s   -2.5%  cpc           11150     57.6%     57.6%   221.7MB/s   218.3MB/s   -1.5%  clsp          3721     51.6%     51.6%   217.3MB/s   216.3MB/s   -0.5%  lspxls       1029744     58.7%     58.7%   213.3MB/s   209.9MB/s   -1.6%  xlstxt1       152089     40.2%     40.2%   129.4MB/s   126.3MB/s   -2.4%  txt1txt2       125179     35.9%     35.9%   121.7MB/s   118.8MB/s   -2.4%  txt2txt3       426754     42.9%     42.9%   135.2MB/s   132.8MB/s   -1.8%  txt3txt4       481861     31.7%     31.7%   115.2MB/s   113.0MB/s   -1.9%  txt4bin        513216     81.8%     81.8%   371.2MB/s   350.7MB/s   -5.5%  binsum         38240     48.1%     48.1%   164.2MB/s   160.0MB/s   -2.6%  summan          4227     40.6%     40.6%   184.8MB/s   185.3MB/s   +0.3%  manpb         118588     76.8%     76.8%   344.1MB/s   326.3MB/s   -5.2%  pbgaviota    184320     61.7%     61.7%   188.0MB/s   185.2MB/s   -1.5%  gaviota

Stream Format

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.

Stream Performance

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%.

Stream Compress (no checksums)

                        JNI      Java         JNI        JavaInput        Size  Compress  Compress  Throughput  Throughput  Change---------------------------------------------------------------------html       102400     76.4%     76.4%   275.8MB/s   373.5MB/s  +35.4%  htmlurls       702087     49.1%     49.1%   176.5MB/s   225.2MB/s  +27.6%  urlsjpg        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%  pdfhtml4      409600     76.4%     76.4%   281.0MB/s   369.9MB/s  +31.7%  html4cp          24603     51.8%     51.8%   151.7MB/s   214.3MB/s  +41.3%  cpc           11150     57.4%     57.5%   149.1MB/s   243.3MB/s  +63.1%  clsp          3721     51.1%     51.2%   141.3MB/s   181.1MB/s  +28.2%  lspxls       1029744     58.6%     58.6%   253.9MB/s   290.5MB/s  +14.4%  xlstxt1       152089     40.2%     40.2%   114.8MB/s   159.4MB/s  +38.8%  txt1txt2       125179     35.9%     35.9%   110.0MB/s   150.4MB/s  +36.7%  txt2txt3       426754     42.9%     42.9%   121.0MB/s   167.9MB/s  +38.8%  txt3txt4       481861     31.6%     31.6%   105.1MB/s   143.2MB/s  +36.2%  txt4bin        513216     81.8%     81.8%   387.7MB/s   484.5MB/s  +25.0%  binsum         38240     48.1%     48.1%   153.0MB/s   203.1MB/s  +32.8%  summan          4227     40.2%     40.3%   125.9MB/s   171.9MB/s  +36.5%  manpb         118588     76.8%     76.8%   342.2MB/s   431.4MB/s  +26.1%  pbgaviota    184320     61.7%     61.7%   161.1MB/s   246.1MB/s  +52.7%  gaviota

Stream Uncompress (no checksums)

                        JNI      Java         JNI        JavaInput        Size  Compress  Compress  Throughput  Throughput  Change---------------------------------------------------------------------html       102400     76.4%     76.4%     1.2GB/s     1.2GB/s   +0.4%  htmlurls       702087     49.1%     49.1%   853.9MB/s   786.6MB/s   -7.9%  urlsjpg        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%  pdfhtml4      409600     76.4%     76.4%     1.2GB/s     1.1GB/s   -8.4%  html4cp          24603     51.8%     51.8%   785.2MB/s   905.6MB/s  +15.3%  cpc           11150     57.4%     57.5%   778.9MB/s   889.7MB/s  +14.2%  clsp          3721     51.1%     51.2%   739.0MB/s   905.5MB/s  +22.5%  lspxls       1029744     58.6%     58.6%   730.3MB/s   718.8MB/s   -1.6%  xlstxt1       152089     40.2%     40.2%   582.4MB/s   559.0MB/s   -4.0%  txt1txt2       125179     35.9%     35.9%   540.7MB/s   526.4MB/s   -2.6%  txt2txt3       426754     42.9%     42.9%   620.5MB/s   583.9MB/s   -5.9%  txt3txt4       481861     31.6%     31.6%   519.4MB/s   487.0MB/s   -6.2%  txt4bin        513216     81.8%     81.8%     1.2GB/s     1.1GB/s  -11.6%  binsum         38240     48.1%     48.1%   693.4MB/s   742.4MB/s   +7.1%  summan          4227     40.2%     40.3%   637.3MB/s   784.3MB/s  +23.1%  manpb         118588     76.8%     76.8%     1.4GB/s     1.4GB/s   +0.4%  pbgaviota    184320     61.7%     61.7%   688.5MB/s   668.2MB/s   -3.0%  gaviota

Stream RoundTrip (no checksums)

                        JNI      Java         JNI        JavaInput        Size  Compress  Compress  Throughput  Throughput  Change---------------------------------------------------------------------html       102400     76.4%     76.4%   223.8MB/s   272.5MB/s  +21.8%  htmlurls       702087     49.1%     49.1%   142.8MB/s   174.1MB/s  +22.0%  urlsjpg        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%  pdfhtml4      409600     76.4%     76.4%   226.2MB/s   275.5MB/s  +21.8%  html4cp          24603     51.8%     51.8%   125.3MB/s   160.3MB/s  +27.9%  cpc           11150     57.4%     57.5%   125.1MB/s   183.2MB/s  +46.5%  clsp          3721     51.1%     51.2%   130.6MB/s   149.5MB/s  +14.5%  lspxls       1029744     58.6%     58.6%   188.2MB/s   206.1MB/s   +9.5%  xlstxt1       152089     40.2%     40.2%    95.3MB/s   123.3MB/s  +29.4%  txt1txt2       125179     35.9%     35.9%    91.4MB/s   116.8MB/s  +27.9%  txt2txt3       426754     42.9%     42.9%   101.3MB/s   130.3MB/s  +28.6%  txt3txt4       481861     31.6%     31.6%    87.9MB/s   111.1MB/s  +26.3%  txt4bin        513216     81.8%     81.8%   294.7MB/s   337.9MB/s  +14.7%  binsum         38240     48.1%     48.1%   122.9MB/s   152.9MB/s  +24.3%  summan          4227     40.2%     40.3%   113.0MB/s   139.1MB/s  +23.1%  manpb         118588     76.8%     76.8%   269.5MB/s   313.8MB/s  +16.4%  pbgaviota    184320     61.7%     61.7%   131.1MB/s   180.3MB/s  +37.6%  gaviota

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