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org.apache.hadoop.fs.CosNFileSystem

Preconditions.checkArgument(uploadThreadPoolSize > 0,
                String.format("The uploadThreadPoolSize[%d] should be positive.", uploadThreadPoolSize));
        Preconditions.checkArgument(readAheadPoolSize > 0,
                String.format("The readAheadQueueSize[%d] should be positive.", readAheadPoolSize));
        // 核心线程数取用户配置的为准，最大线程数结合用户配置和IO密集型任务的最优线程数来看
        int ioCoreTaskSize = uploadThreadPoolSize + readAheadPoolSize;
        int ioMaxTaskSize = Math.max(uploadThreadPoolSize + readAheadPoolSize,
                Runtime.getRuntime().availableProcessors() * 2 + 1);
        if (this.getConf().get(CosNConfigKeys.IO_THREAD_POOL_MAX_SIZE_KEY) != null) {
            int ioThreadPoolMaxSize = this.getConf().getInt(
                    CosNConfigKeys.IO_THREAD_POOL_MAX_SIZE_KEY, CosNConfigKeys.DEFAULT_IO_THREAD_POOL_MAX_SIZE);
            Preconditions.checkArgument(ioThreadPoolMaxSize > 0,
                    String.format("The ioThreadPoolMaxSize[%d] should be positive.", ioThreadPoolMaxSize));
            // 如果设置了 IO 线程池的最大限制，则整个线程池需要被限制住
            ioCoreTaskSize = Math.min(ioCoreTaskSize, ioThreadPoolMaxSize);
            ioMaxTaskSize = ioThreadPoolMaxSize;
        }

int readAheadPoolSize = this.getConf().getInt(
                CosNConfigKeys.READ_AHEAD_QUEUE_SIZE,
                CosNConfigKeys.DEFAULT_READ_AHEAD_QUEUE_SIZE
        );

• java/org/apache/hadoop/fs/CosNFSInputStream.java

以下是顺序读，随机读的判断

private synchronized void reopen(long pos) throws IOException {
...
		boolean isRandomIO = true;
        if (pos == this.nextPos) {
            isRandomIO = false;
        } else {
            while (this.readBufferQueue.size() != 0) {
                if (this.readBufferQueue.element().getStart() != pos) {
                    this.readBufferQueue.poll();
                } else {
                    break;
                }
            }
        }
...
}

        this.maxReadPartNumber = conf.getInt(
                CosNConfigKeys.READ_AHEAD_QUEUE_SIZE,
                CosNConfigKeys.DEFAULT_READ_AHEAD_QUEUE_SIZE);
        this.socketErrMaxRetryTimes = conf.getInt(
                CosNConfigKeys.CLIENT_SOCKET_ERROR_MAX_RETRIES,
                CosNConfigKeys.DEFAULT_CLIENT_SOCKET_ERROR_MAX_RETRIES);

public static final String CLIENT_SOCKET_ERROR_MAX_RETRIES = "fs.cosn.socket.error.maxRetries";
    public static final int DEFAULT_CLIENT_SOCKET_ERROR_MAX_RETRIES = 5;

this.readBufferQueue =
                new ArrayDeque<ReadBuffer>(this.maxReadPartNumber);