java多少个线程在执行,在Java中要运行多少个线程？

I had this brilliant idea to speed up the time needed for generating 36 files: use 36 threads!! Unfortunately if I start one connection (one j2ssh connection object) with 36 threads/sessions, everything lags way more than if I execute each thread at a time.

Now if I try to create 36 new connections (36 j2ssh connection objects) then each thread has a separate connection to server, either i get out of memory exception (somehow the program still runs, and successfully ends its work, slower than the time when I execute one thread after another).

So what to do? how to find the optimal thread number I should use?

because Thread.activeCount() is 3 before starting mine 36 threads?! i'm using Lenovo laptop Intel core i5.

解决方案

You could narrow it down to a more reasonable number of threads with an ExecutorService. You probably want to use something near the number of processor cores available, e.g:

int threads = Runtime.getRuntime().availableProcessors();

ExecutorService service = Executors.newFixedThreadPool(threads);

for (int i = 0; i < 36; i++) {

service.execute(new Runnable() {

public void run() {

// do what you need per file here

}

});

}

service.shutdown();