java thread pool 소개

스레드 풀

Public class GzipRunnable implements Runnable {

 

Private final File input;

 

Public GZipRunnable(File input) {

This.input = intpu;

}

 

@Override

Pulbic void run(){

 if (!input.getName().endsWith(".gz")) {

File output = new File(input.getParent(), input.getName() + ".gz");

If(!output.exists) {

Try (

InputStream in = new BufferedInputStream(new FileInputStream(input));

OutPutStream out = new BufferedOutputStream(

New GZIPOutputStream(new FileOutputStream(output)));

) {

Int b;

While ((b = in.read()) != -1) out.write(b);

Out.flush();

} catch (IOException ex){

}

}

}

 

위에 소스는 입력, 출력 스트림 모두 try 블록의 시작에서 선언되었고 try 블록 끝에서 자동으로 닫힌다. 또한 입력과 출력 모두에 사용된 버퍼링은 입출력이 많이 발생하는 부분에서 문제가 될 수 있다.

그래서 4개의 스레드 풀로 해당 스레드를 처리할 예정이다.

 

스레드풀을 이용한 스레드 처리 방식은 다음과 같다.

Public class GzipAllFiles {

Public final static int THREAD_COUNT = 4;

 

Public static void main(String args[]) {

 

ExecutorService pool = Executors.newFixedThreadPool(THREAD_COUNT);

 

For(String filename: args){

File f = new File(filename);

If (f.exist()) {

If (f.isDirectory()) {

File[] files = f.listFiles();

For (int I = 0; i< files.length; i++) {

If(!files[i].isDirectory()) {

Runnable task = new GZipRunnable(file[i]);

Pool.submit(task);

}

}

} else {

Runnable task = new GZipRunnable(f);

Pool.sublit(task);

}

}

}

Pool.shutdown();

}

}

Shutdown()은 진행중인 작업을 멈추는 것이 아닌 단순히 추가적으로 입력할 스레드가 없다는 의미이다.

즉시 멈추기 위해서는 shutdownNow() 메소드를 호출 할 수 있다.