Thread Test on HotSpot 1.4 and JRockit 7.0

This section provides a tutorial example to see how many running threads can be supported on HotSpot 1.4.0_02 Client/Server and JRockit 7.0 JVMs.

An old version program was used in 2002 to perform a similar test on JRockit 7.0, HotSpot 1.4.0_02 Client and Server JVMs in 2002:

 * Copyright (c) All Rights Reserved.
import java.util.*;
import java.text.*;
class CrashThread extends Thread {
   public static void main(String[] a) {
      Thread t;
      int m = 16;
      Date now;
      DateFormat df = DateFormat.getTimeInstance();
      for (int n=1; n<=m; n++) {
         now = new Date();
         t = new CrashThread();
         System.out.println(df.format(now) + " Launched thread "+n);
   public void run() {
      while (true);

Output on JRockit 7.0:

10:28:21 AM Launched thread 1
10:28:22 AM Launched thread 16

Output on HotSpot Client 1.4.0_02:

10:30:06 AM Launched thread 1
10:30:09 AM Launched thread 16

Output on HotSpot Server 1.4.0_02:

10:31:56 AM Launched thread 1
10:31:58 AM Launched thread 16

As you can see, all 3 JVMs had no problems launching 16 threads, and kept them running. Note that all threads are user threads by default. They continue to run even after the calling threads has been terminated.

When I increase the number of threads to 32, the executions were getting interesting:

I guess the problem was in the operating system (Windows 2000). It failed to treat the running JVM process as one single process even it had 32 threads running inside. The operating system should be able to put the JVM process in wait mode when its CPU time share is used up, and process my mouse clicks before returning back to the JVM process. Could someone verify this on a UNIX system?

Table of Contents

 About This Book

 JVM (Java Virtual Machine) Specification

 Java HotSpot VM - JVM by Oracle/Sun

 java.lang.Runtime Class - The JVM Instance

 java.lang.System Class - The Operating System

 ClassLoader Class - Class Loaders

 Class Class - Class Reflections

 JVM Runtime Data Areas

 JVM Stack, Frame and Stack Overflow

Thread Testing Program and Result - Thread Testing Program

 Thread Test on HotSpot JVM 10

 Thread Test on HotSpot 1.7

 Thread Test on JRockit 28.7

Thread Test on HotSpot 1.4 and JRockit 7.0

 Thread Test on HotSpot 1.6

 CPU Impact of Multi-Thread Applications

 I/O Impact of Multi-Thread Applications

 CDS (Class Data Sharing)

 Micro Benchmark Runner and JVM Options

 Micro Benchmark Tests on "int" Operations

 Micro Benchmark Tests on "long" Operations

 Micro Benchmark Tests in JIT Compilation Mode

 Micro Benchmark Tests on "float" and "double" Operations

 OpenJ9 by Eclipse Foundation

 JRockit JVM 28.2.7 by Oracle Corporation

 Archived Tutorials


 Full Version in PDF/EPUB