java虚拟机能并发的启动多少个线程

 1 public class TestNativeOutOfMemoryError {
 2     public static void main(String[] args) {
 3 
 4         for (int i = 0;; i++) {
 5             System.out.println("i = " + i);
 6             new Thread(new HoldThread()).start();
 7         }
 8     }
 9 
10 }
11 
12 class HoldThread extends Thread {
13     CountDownLatch cdl = new CountDownLatch(1);
14 
15     public HoldThread() {
16         this.setDaemon(true);
17     }
18 
19     public void run() {
20         try {
21             cdl.await();
22         } catch (InterruptedException e) {
23         }
24     }
25 }

1 ......
2 i = 3935
3 Exception in thread "main" java.lang.OutOfMemoryError: unable to create new native thread
4     at java.lang.Thread.start0(Native Method)
5     at java.lang.Thread.start(Thread.java:714)
6     at com.study.thinking.in.java.concurrent.TestNativeOutOfMemoryError.main(TestNativeOutOfMemoryError.java:15)

1. 物理内存
使用64位OS能给虚拟机分配更大内存

2.JVMMemory
减少这项参数能增加并发的线程数，非倍数关系
-Xms1024m -Xmx1024m并不能比-Xms512m -Xmx512m多一倍的线程

3.ThreadStackSize
减少单个线程的栈大小，在有效范围内，是倍数关系