Java の上限スレッド数

環境依存かもしれないけれど，適当にコードを書いて実験してみた．

ThreadTest.java

public class ThreadTest {
    public static void main(String[] args) {
        int count = 0;

        try {
            while ( true ) {
                new NeverEndingThread().start();
                count++;
            }
        } catch ( OutOfMemoryError e ) {
            e.printStackTrace();
            System.err.println("number of threads = " + count);
            System.exit(1);
        }
    }
}

class NeverEndingThread extends Thread {
    public void run() {
        try {
            while( true ) {
                sleep(1000);
            }
        } catch ( Exception e ) {
            e.printStackTrace();
            System.exit(1);
        }
    }
}

Fedora Core 3 (kernel 2.6.9-1.667smp)
Pentium 4 3.4F GHz (Hyper-Threading on)
Mem 2GB + Swap 2GB
Java 1.4.2_08-b03

$ java ThreadTest
java.lang.OutOfMemoryError: unable to create new native thread
        at java.lang.Thread.start(Native Method)
        at ThreadTest.main(ThreadTest.java:7)
number of threads = 7619

※何回かの試行で変動するが，大体 7600 強．

Windows XP SP2
Pentium M 1.1GHz
実メモリ 760MB + 仮想メモリ 1137MB
Java 1.5.0_04

C:\>java ThreadTest
java.lang.OutOfMemoryError: unable to create new native thread
        at java.lang.Thread.start0(Native Method)
        at java.lang.Thread.start(Unknown Source)
        at ThreadTest.main(ThreadTest.java:7)
number of threads = 7117