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为什么我的PipedOutputStream会死锁?

blocked-threads outputstream inputstream android java

Nathan Schwermann · 技术社区 · 14 年前

我正在尝试用PipedInputStream和PipedOutputStream实现一个线程循环缓冲区,但每次到达时它都会锁定mHead.写入在解码器中运行。我认为使用独立线程时不会出现死锁。

    private class DecoderTask implements Runnable{

    @Override
    public void run() {
        while(!mStop){
            try {
                    Log.d(TAG,"trying to write");
        mHead.write(decode( 0, 1000));
            mHead.flush();
            Log.d(TAG,"Decoded");
            } catch (DecoderException e) {
                Log.e(TAG,e.toString());
            } catch (IOException e) {
                Log.e(TAG,e.toString());
            }
        }
    }

}
private class WriteTask implements Runnable{

    @Override
    public void run() {
        while(!mStop){
            try {
                                 Log.d(TAG,"trying to read");
                 int read = mTail.read(mByteSlave, 0, mByteSlave.length);
                 mAudioTrack.flush();
                                 mAudioTrack.write(mByteSlave,0,read);
                                 Log.d(TAG,"read");                 
            } catch (IOException e) {
                Log.e(TAG,e.toString());
            }
        }
    }

}


//in some function
mTail = new PipedInputStream();
mHead = new PipedOutputStream(mTail);
mByteSlave = new byte[BUF];
mT1 = new Thread(new DecoderTask(), "Reader");
mT2 = new Thread(new WriteTask(), "Writer");
mT1.start();
mT2.start();
return;

http://pastie.org/1179792

logcat打印输出:

3 回复 | 直到 14 年前

Thomas Mueller 14 年前

程序没有阻塞,只是速度很慢,效率很低。它使用100%的CPU。问题是 if (mTail.available() >= mByteSlave.length) -在大多数情况下,这将返回false,因此在这个线程中会有一个繁忙的循环。如果你能摆脱这个,就去做吧。那么这个问题就解决了。如果你做不到,事情会变得更复杂。。。

还有一个问题: PipedInputStream.read 返回一个整数。您需要使用:

int len = mTail.read(mByteSlave, 0, mByteSlave.length);
mAudioTrack.write(mByteSlave, 0, len);

import java.io.*;
public class Test2 {
    PipedOutputStream mHead;
    PipedInputStream mTail;
    byte[] mByteSlave = new byte[1024];
    boolean mStop;
    public static void main(String... ar) throws Exception {
        new Test2().run();
    }
    void run() throws Exception {
        mTail = new PipedInputStream();
        mHead = new PipedOutputStream(mTail);
        Thread mT1 = new Thread(new DecoderTask(), "Reader");
        Thread mT2 = new Thread(new WriteTask(), "Writer");
        mT1.start();
        mT2.start();
    }
    class DecoderTask implements Runnable {
        public void run() {
            while (!mStop) {
                try {
                    mHead.write(new byte[3000]);
                    mHead.flush();
                    System.out.println("decoded 3000");
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
    class WriteTask implements Runnable {
        public void run() {
            while (!mStop) {
                try {
                    int len = mTail.read(mByteSlave, 0, mByteSlave.length);
                    if (len < 0) break; // EOF
                    // mAudioTrack.write(mByteSlave, 0, len);
                    // mAudioTrack.flush();
                    System.out.println("written " + len);
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

DraÅ¡ko KokiÄ chemalarrea 11 年前

我也遇到过同样的问题,并通过重写默认值来解决它 PIPE_SIZE 在 PipedInputStream(int) 建造师。方法 PipedOutputStream.write(byte[], int, int) 块,直到所有字节都写入输出流。这可能是默认管道大小的问题。

毕竟,大小确实很重要;-)

user207421 14 年前