Re: [分享] java nio performance tuning

看板java作者AI3767 (AIIA)時間11年前 (2013/10/06 17:04)推噓0(0推 0噓 0→)

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※ 引述《sbrhsieh (十年一夢)》之銘言：恕刪看完你的測試, 原來還有個block的讀取方式, 是我沒有考量到的前面我的測試中說的, 單純 read byte 是只讀取1個 byte 先說結論好了我增加了一次讀取一個區塊的測試, S2的讀取效率確實又大幅增進以一般不是太大的檔案來說, 比起S3的方式, 時間上差不多甚至, S3因為為了區塊讀取, 所增加code的部分還多花了點時間使得 S3 還比 S2 輕微慢了點為什麼這麼說呢, 因為, 當以較大的檔案做同樣的測試時, S3 就會比S2快一丁點確實, 沒有過大的幅度的差異, 只是差異已經可以確認觀察出來也的確, 沒有原以為的那樣大的增進, 以1.6G來說, 增進不到 20% 吧 S2以區塊讀取: 2.02 秒 S3以區塊讀取: 1.728 到這邊, 我不把code附上, 就顯得太沒誠意了 XD 不過, 修改了只留下針對 S2, S3 對一次一byte讀取,以及區塊讀取的部分 [GenNIOData.java] 生成測試檔用 import java.io.*; import java.util.Random; public class GenNIOData { private static final Random rand = new Random(); //COUNT*4*16 = 1671901184 COUNT*16 = 417975296 public static int COUNT = 26123456; public static int MULT = 16; public static void main(String[] args) throws Exception { //MULT = 1; outBin("ip_16.bin", MULT); //ip.bin ; ip_16.bin } /** Create 4 * COUNT bytes */ static void outBin(String fName, int mul) throws Exception { BufferedOutputStream bos = new BufferedOutputStream( new FileOutputStream(fName)); DataOutputStream dos = new DataOutputStream(bos); int total = COUNT * mul; for(int i=total; i>0; i--) { int ip = rand.nextInt(255); for(int p=0; p<3; p++) ip = ip<<8 | rand.nextInt(255); dos.writeInt(ip); } dos.close(); } } [NIOTest.java] 執行測試用 import java.io.*; import java.nio.*; import java.nio.channels.*; import java.nio.file.*; public class NIOTest { static int[] ipArr = new int[GenNIOData.COUNT]; // size of MULT==1 static StringBuilder msg = new StringBuilder(); static int bufferSize = ipArr.length; //ipArr.length ; 64*1024 static int testVer = 1; public static void main(String[] args) throws Exception { int testCount = 1; String fName = "ip_16.bin"; // ip.bin ; ip_16.bin for(int i=testCount; i>0; i--) { testS2(fName); testS3(fName); } System.out.println(msg.toString()); } static void outMsg(String m) { msg.append(m+"\n"); } static int toIpArr(byte[] bArr, int len) { int count = 0; for(int i=0; i<len; ) { int ip = bArr[i++]&0xFF; ip = ip<<8 | bArr[i++]&0xFF; ip = ip<<8 | bArr[i++]&0xFF; ip = ip<<8 | bArr[i++]&0xFF; ipArr[count++] = ip; } return count; } static void testS2(String fName) throws Exception { outMsg("Strategt 2 -->"); long startTime = System.currentTimeMillis(); FileInputStream fis = new FileInputStream(new File(fName)); BufferedInputStream bis = new BufferedInputStream(fis, bufferSize); DataInputStream dis = new DataInputStream(bis); int offset = 0; int counter = 0; byte[] bArr = new byte[bufferSize<<2]; //outMsg("bArr size: "+bArr.length); //outMsg("ipArr size: "+ipArr.length); try { while(true) { //ipArr[counter++] = dis.readInt(); //original version only for MULT==1 //dis.readByte(); //read byte version //offset++; int len = dis.read(bArr, 0, bArr.length); //read block version //counter += toIpArr(bArr, len); if( len<0 ) break; //offset += len; } } catch(EOFException e){ } finally { long endTime = System.currentTimeMillis(); outMsg("offset:"+offset+" count"+counter+" took: "+ (endTime-startTime)/1000.0F); dis.close(); } } static void testS3(String fName) throws IOException { outMsg("Strategt 3 -->"); long startTime = System.currentTimeMillis(); FileInputStream fis = new FileInputStream(new File(fName)); FileChannel channel = fis.getChannel(); ByteBuffer bb = ByteBuffer.allocateDirect(ipArr.length<<2); bb.clear(); byte[] bArr = new byte[bufferSize<<2]; //outMsg("channel size: "+channel.size()/4); //outMsg("bArr size: "+bArr.length); //outMsg("ipArr size: "+ipArr.length); long len = 0; int offset = 0; int counter = 0; while((len=channel.read(bb))!=-1) { bb.flip(); //int numData = (int)(len>>2); //original verion only for MULT==1 //IntBuffer ib = bb.asIntBuffer(); //ib.get(ipArr, offset, numData); //counter += numData; //for(; len>0; len--) { //read byte version // bb.get(); // offset++; //} int remain = (int)len; //read block version while(remain>0) { int needLen = remain>bArr.length? bArr.length: remain; bb.get(bArr, 0, needLen); //counter += toIpArr(bArr, needLen); remain -= needLen; //offset += needLen; } bb.clear(); } long endTime = System.currentTimeMillis(); outMsg("offset:"+offset+" count"+counter+" took: "+ (endTime-startTime)/1000.0F); } } -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 114.45.188.160 ※ 編輯: AI3767 來自: 114.45.188.160 (10/06 17:09)