ThreadStackSize －Xss

時間 2019-12-07

標籤 threadstacksize xss 欄目 JavaScript 简体版

原文原文鏈接

/*
 * Copyright (c) 2011.  Peter Lawrey
 *
 * "THE BEER-WARE LICENSE" (Revision 128)
 * As long as you retain this notice you can do whatever you want with this stuff.
 * If we meet some day, and you think this stuff is worth it, you can buy me a beer in return
 * There is no warranty.
 */

package com.google.code.java.core.threads;

import java.util.ArrayList;
import java.util.List;

public class MaxThreadsMain {

  public static final int BATCH_SIZE = 4000;

  public static void main(String... args) throws InterruptedException {
    List<Thread> threads = new ArrayList<Thread>();
    try {
      for (int i = 0; i <= 100 * 1000; i += BATCH_SIZE) {
        long start = System.currentTimeMillis();
        addThread(threads, BATCH_SIZE);
        long end = System.currentTimeMillis();
        Thread.sleep(1000);
        long delay = end - start;
        System.out.printf("%,d threads: Time to create %,d threads was %.3f seconds %n", threads.size(), BATCH_SIZE, delay / 1e3);
      }
    } catch (Throwable e) {
      System.err.printf("After creating %,d threads, ", threads.size());
      e.printStackTrace();
    }

  }

  private static void addThread(List<Thread> threads, int num) {
    for (int i = 0; i < num; i++) {
      Thread t = new Thread(new Runnable() {
        @Override
        public void run() {
          try {
            while (!Thread.interrupted()) {
              Thread.sleep(1000);
            }
          } catch (InterruptedException ignored) {
            //
          }
        }
      });
      t.setDaemon(true);
      t.setPriority(Thread.MIN_PRIORITY);
      threads.add(t);
      t.start();
    }
  }
}

I have seen a number of tests where a JVM has 10K threads. However, what happens if you go beyond this?

My recommendation is to consider having more servers once your total reaches 10K. You can get a decent server for $2K and a powerful one for $10K. java

Creating threads gets slower

The time it takes to create a thread increases as you create more thread. For the 32-bit JVM, the stack size appears to limit the number of threads you can create. This may be due to the limited address space. In any case, the memory used by each thread's stack add up. If you have a stack of 128KB and you have 20K threads it will use 2.5 GB of virtual memory.

Bitness	Stack Size	Max threads
32-bit	64K	32,073
32-bit	128K	20,549
32-bit	256K	11,216
64-bit	64K	stack too small
64-bit	128K	32,072
64-bit	512K	32,072

Note: in the last case, the thread stacks total 16 GB of virtual memory.

Java 6 update 26 32-bit,-XX:ThreadStackSize=64

view source

print ?

01. 4,000 threads: Time to create 4,000 threads was 0.522 seconds

02. 8,000 threads: Time to create 4,000 threads was 1.281 seconds

03. 12,000 threads: Time to create 4,000 threads was 1.874 seconds

04. 16,000 threads: Time to create 4,000 threads was 2.725 seconds

05. 20,000 threads: Time to create 4,000 threads was 3.333 seconds

06. 24,000 threads: Time to create 4,000 threads was 4.151 seconds

07. 28,000 threads: Time to create 4,000 threads was 5.293 seconds

08. 32,000 threads: Time to create 4,000 threads was 6.636 seconds

09. After creating 32,073 threads, java.lang.OutOfMemoryError: unable to create new native thread

10. at java.lang.Thread.start0(Native Method)

11. at java.lang.Thread.start(Thread.java:640)

12. at com.google.code.java.core.threads.MaxThreadsMain.addThread(MaxThreadsMain.java:46)

13. at com.google.code.java.core.threads.MaxThreadsMain.main(MaxThreadsMain.java:16)

Java 6 update 26 32-bit,-XX:ThreadStackSize=128

view source

print ?

01. 4,000 threads: Time to create 4,000 threads was 0.525 seconds

02. 8,000 threads: Time to create 4,000 threads was 1.239 seconds

03. 12,000 threads: Time to create 4,000 threads was 1.902 seconds

04. 16,000 threads: Time to create 4,000 threads was 2.529 seconds

05. 20,000 threads: Time to create 4,000 threads was 3.165 seconds

06. After creating 20,549 threads, java.lang.OutOfMemoryError: unable to create new native thread

07. at java.lang.Thread.start0(Native Method)

08. at java.lang.Thread.start(Thread.java:640)

09. at com.google.code.java.core.threads.MaxThreadsMain.addThread(MaxThreadsMain.java:46)

10. at com.google.code.java.core.threads.MaxThreadsMain.main(MaxThreadsMain.java:16)

Java 6 update 26 32-bit,-XX:ThreadStackSize=128

view source

print ?

1. 4,000 threads: Time to create 4,000 threads was 0.526 seconds

2. 8,000 threads: Time to create 4,000 threads was 1.212 seconds

3. After creating 11,216 threads, 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:640)

6. at com.google.code.java.core.threads.MaxThreadsMain.addThread(MaxThreadsMain.java:46)

7. at com.google.code.java.core.threads.MaxThreadsMain.main(MaxThreadsMain.java:16)

Java 6 update 26 64-bit,-XX:ThreadStackSize=128

view source

print ?

01. 4,000 threads: Time to create 4,000 threads was 0.577 seconds

02. 8,000 threads: Time to create 4,000 threads was 1.292 seconds

03. 12,000 threads: Time to create 4,000 threads was 1.995 seconds

04. 16,000 threads: Time to create 4,000 threads was 2.653 seconds

05. 20,000 threads: Time to create 4,000 threads was 3.456 seconds

06. 24,000 threads: Time to create 4,000 threads was 4.663 seconds

07. 28,000 threads: Time to create 4,000 threads was 5.818 seconds

08. 32,000 threads: Time to create 4,000 threads was 6.792 seconds

09. After creating 32,072 threads, java.lang.OutOfMemoryError: unable to create new native thread

10. at java.lang.Thread.start0(Native Method)

11. at java.lang.Thread.start(Thread.java:640)

12. at com.google.code.java.core.threads.MaxThreadsMain.addThread(MaxThreadsMain.java:46)

13. at com.google.code.java.core.threads.MaxThreadsMain.main(MaxThreadsMain.java:16)

Java 6 update 26 64-bit,-XX:ThreadStackSize=512