[B! Java][unsafe][serialize] yassのブックマーク

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Javaとunsafeとserializeに関するyassのブックマーク (5)

Only the Good Die Young (or Move Off-heap?) | Blog of Christian Felde
yass 2014/08/31
"keep only a few private fields, 2 ints + 2 longs + 2 object references (Unsafe and a hash function), for the duration of the instance. The rest are short lived or managed off-heap. / BOHMap must do more work than the standard HashMap, since it needs to copy data between on-heap and off-heap memory"

java

gc

offheap

unsafe

hashtable

binary

java8

serialize
リンク
デシリアライズ速度の比較 ByteBuffer vs DirectBuffer vs Unsafe vs C - Blog by Sadayuki Furuhashi
OpenJDK や Hotspot VM には sun.misc.Unsafe という内部APIがあり*1、これを使うと ByteBuffer.getInt や ByteBuffer.getLong よりも高速にバイト列から整数値をデコードできるという。これを駆使することで、Cで実装された拡張ライブラリに匹敵する速度を出せるらしい。それが本当なら、データ圧縮やハッシュ関数、シリアライザ/デシリアライザなどの実装を高速化できる。例えば、lz4 や xxhash のJava実装が Unsafe API を使用している*2：jpountz/lz4-java Prestoも、中間データのシリアライズ/デシリアライズにはすべて Unsafe API を使っている*3。そこで、実際にベンチマークしてみた。ベンチマーク内容 10MBのランダムなバイト列を生成する先頭から1バイト読み出すその1バ
yass 2014/03/12
"sun.misc.Unsafe という内部APIがあり、ByteBuffer.getInt や ByteBuffer.getLong よりも高速にバイト列から整数値をデコードできるという。これを駆使することで、Cで実装された拡張ライブラリに匹敵する速度を出せるらしい"

unsafe

java

serialize

ByteBuffer

offheap
リンク
Speed Up with Fast Java and File Serialization - DZone
Since the first version of Java, day-by-day many developers have been trying to achieve at least as good of performance as in C/C++. JVM vendors are doing their best by implementing some new JIT algorithms, but there is still a lot to do, especially in how we use Java. For example, there is a lot to win in objects<->file serialization - notably in writing/reading objects that can readily fit in th
yass 2013/05/04
" Unsafe serialization is greater than 23 times faster than standard use of java.io.Serializable / Use of RandomAccessFile can speed up standard buffered serialization by almost 4 times/ Kryo-dynamic serialization is about 35% slower than the hand-implemented direct buffer"

java

serialize

kryo

unsafe

offheap
リンク
Java Serialization Performance: Methods, Performance, and Security
yass 2013/05/04
" If you have primitive array fields – always use bulk methods to process them. ByteBuffer bulk methods performance is close to those of Unsafe (but ByteBuffer are always a little slower). "

java

serialize

unsafe

offheap

primitive

array
リンク
Native C/C++ Like Performance For Java Object Serialisation
Do you ever wish you could turn a Java object into a stream of bytes as fast as it can be done in a native language like C++? If you use standard Java Serialization you could be disappointed with the performance. Java Serialization was designed for a very different purpose than serialising objects as quickly and compactly as possible. Why do we need fast and compact serialisation? Many of our s
yass 2013/05/03
" To write and read back a single relatively small object on my fast 2.4 GHz Sandy Bridge laptop can take ~10,000ns using Java Serialization, whereas when using Unsafe this can come down to well less than 100ns even accounting for the test code itself. "

java

memory

offheap

gc

ByteBuffer

unsafe

serialize
リンク
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