JSch コマンド出力を読み取るときにデッドロックを回避するにはどうすればよいですか?

<code class="java">ChannelExec channel = (ChannelExec)session.openChannel("exec");

channel.setCommand(...);

ByteArrayOutputStream outputBuffer = new ByteArrayOutputStream();
ByteArrayOutputStream errorBuffer = new ByteArrayOutputStream();

InputStream in = channel.getInputStream();
InputStream err = channel.getExtInputStream();

channel.connect();

while (!channel.isClosed()) {
    // Read stdout continuously
    while (in.available() > 0) {
        outputBuffer.write(in.read(tmp, 0, 1024));
    }

    // Read stderr continuously
    while (err.available() > 0) {
        errorBuffer.write(err.read(tmp, 0, 1024));
    }

    try {
        Thread.sleep(1000);
    } catch (Exception e) {}
}

System.out.println("output: " + outputBuffer.toString("UTF-8"));
System.out.println("error: " + errorBuffer.toString("UTF-8"));

channel.disconnect();</code>