线程管道的一个实验

我一直在想，如果在线程管道中，输入的速度比输出的速度快很多的话会出现什么情况，或者反过来又是怎样
写了个实验程序，发现不管是哪种情况，最后都将快的变慢。当输入快时，会抑制输入线程；输出快时，会抑制输出线程

package com.threadlesson01.study;

import java.io.DataOutputStream;
import java.io.IOException;
import java.io.PipedOutputStream;

public class SendDataThread extends Thread ...{
    private DataOutputStream dos = null ;
    
    /** *//**
     * @param dos
     */
    public SendDataThread(PipedOutputStream pos) ...{
        this.dos = new DataOutputStream(pos);
    }

    @Override
    public void run() ...{
        int index = 0 ;
        while(true)...{
            try ...{
                index ++ ;
                sleep(1000);
                double rand = Math.random();
                dos.writeDouble(rand);
                System.out.println("This is in the " + index + " Send Thread: " + rand);
            } catch (InterruptedException e) ...{
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (IOException e) ...{
                // TODO Auto-generated catch block
                e.printStackTrace();
            }            
        }
    }
    
}

package com.threadlesson01.study;


import java.io.*;

public class RecieveDataThread extends Thread ...{
    private DataInputStream dis = null ;

    /** *//**
     * @param dis
     */
    public RecieveDataThread(PipedInputStream pis) ...{
        this.dis = new DataInputStream(pis);
    }

    @Override
    public void run() ...{
        // TODO Auto-generated method stub
        int index = 0 ;
        while(true)...{
            try ...{
                index++;
                sleep(100);
                System.out.println("The " + index + " Read from PipedInputStream: " + dis.readDouble());
            } catch (InterruptedException e) ...{
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (IOException e) ...{
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    }
}

package com.threadlesson01.study;

import java.io.IOException;
import java.io.PipedInputStream;
import java.io.PipedOutputStream;

public class TestMain ...{
    public static void main(String arg[])...{

        try ...{
            PipedOutputStream pos = new PipedOutputStream();            
            PipedInputStream pis = new PipedInputStream(pos);
            SendDataThread sdt = new SendDataThread(pos);
            RecieveDataThread rdt = new RecieveDataThread(pis);
            sdt.start();
            rdt.start();
        } catch (IOException e) ...{
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}

当输出比输入快时，Result:
This is in the 1 Send Thread: 0.16151098740750125
The 1 Read from PipedInputStream: 0.16151098740750125
This is in the 2 Send Thread: 0.7120194002253469
The 2 Read from PipedInputStream: 0.7120194002253469
This is in the 3 Send Thread: 0.8528097261914339
The 3 Read from PipedInputStream: 0.8528097261914339
This is in the 4 Send Thread: 0.9109161534568372
The 4 Read from PipedInputStream: 0.9109161534568372
This is in the 5 Send Thread: 0.7768039908168954
The 5 Read from PipedInputStream: 0.7768039908168954
This is in the 6 Send Thread: 0.8719109921893281
The 6 Read from PipedInputStream: 0.8719109921893281
This is in the 7 Send Thread: 0.7247112439236129
The 7 Read from PipedInputStream: 0.7247112439236129
This is in the 8 Send Thread: 0.22120976865470565
The 8 Read from PipedInputStream: 0.22120976865470565
当输入比输出快时，Result:
……
The 13 Read from PipedInputStream: 0.2315708377615764
This is in the 129 Send Thread: 0.23167266261217678
This is in the 130 Send Thread: 0.5757523398415085
This is in the 131 Send Thread: 0.9662210303251764
This is in the 132 Send Thread: 0.9538605084985049
This is in the 133 Send Thread: 0.8889780948652806
This is in the 134 Send Thread: 0.7419512492943433
This is in the 135 Send Thread: 0.3622398890338431
This is in the 136 Send Thread: 0.253115630971971
This is in the 137 Send Thread: 0.4309240925796164
This is in the 138 Send Thread: 0.6814706087861843
The 14 Read from PipedInputStream: 0.7872902847515667
This is in the 139 Send Thread: 0.15388195849710673
This is in the 140 Send Thread: 0.43686862090227363
This is in the 141 Send Thread: 0.4155404423497907
This is in the 142 Send Thread: 0.2789332111567
The 15 Read from PipedInputStream: 0.5652592690681899
This is in the 143 Send Thread: 0.41013128238855456
The 16 Read from PipedInputStream: 0.6409729371490666
This is in the 144 Send Thread: 0.11322627532609841
The 17 Read from PipedInputStream: 0.6281227248523248
This is in the 145 Send Thread: 0.6754434599524916
The 18 Read from PipedInputStream: 0.2433345275064387
This is in the 146 Send Thread: 0.9870542183973696
The 19 Read from PipedInputStream: 0.1706111109960894
This is in the 147 Send Thread: 0.6330426569615286
The 20 Read from PipedInputStream: 0.9658561550134379
对于线程管道，里面应该存在一个缓冲器，在java source中可以找到
private static final int DEFAULT_PIPE_SIZE = 1024;
buffer = new byte[pipeSize];
PipedInputStream.java

    private void awaitSpace() throws IOException ...{
    while (in == out) ...{
        checkStateForReceive();

        /**//* full: kick any waiting readers */
        notifyAll();
        try ...{
            wait(1000);
        } catch (InterruptedException ex) ...{
        throw new java.io.InterruptedIOException();
        }
    }
    }

当PipedInputStream的存储慢了以后，会等候1s