Tomcat 默认支持的处理请求的并发数量

这里参阅了网络上一段著名的对Servlet线程安全性进行测试的代码(http://zwchen.iteye.com/blog/91088)。运行之后，我们可以看一下这个例子的输出：

package p.test.servlet.threadSecurity;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet(asyncSupported = true, urlPatterns = { "/threadSafeTestServlet" })
public class ThreadSafeTestServlet extends HttpServlet {

private static final long serialVersionUID = -5360278358684235455L;
// 定义一个实例变量，并非一个线程安全的变量
private int counter = 0;

public void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
doPost(req, resp);
}

public void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
// 输出当前Servlet的信息以及当前线程的信息
System.out.println(this + ":" + Thread.currentThread()
+ " Startttttttttttttttttttttt");
// 循环，并增加实例变量counter的值
for (int i = 0; i < 5; i++) {
System.out.println(this + ":" + Thread.currentThread()
+ "Counter = " + counter);
try {
Thread.sleep(20000);
counter++;
} catch (InterruptedException exc) {
}
}

System.out.println(this + ":" + Thread.currentThread()
+ " Enddddddddddddddddddddddddd");

//		resp.getWriter().println(
//				this + ":" + Thread.currentThread()
//						+ " Enddddddddddddddddddddddddd");
//		resp.getWriter().println("Done");
//		resp.getWriter().flush();
//		resp.getWriter().close();

}
}

sample.SimpleServlet@11e1bbf:Thread[http-8081-Processor23,5,main]

Counter = 60

Counter = 61

Counter = 62

Counter = 65

Counter = 68

Counter = 71

Counter = 74

Counter = 77

Counter = 80

Counter = 83

sample.SimpleServlet@11e1bbf:Thread[http-8081-Processor22,5,main]

Counter = 61

Counter = 63

Counter = 66

Counter = 69

Counter = 72

Counter = 75

Counter = 78

Counter = 81

Counter = 84

Counter = 87

sample.SimpleServlet@11e1bbf:Thread[http-8081-Processor24,5,main]

Counter = 61

Counter = 64

Counter = 67

Counter = 70

Counter = 73

Counter = 76

Counter = 79

Counter = 82

Counter = 85

Counter = 88

Tomcat 3.0, 默认的状态下，没有大量请求时，并发数好像是 50，

更大量的请求到来时，默认的并发数好像可以自动增加到 300，

但在这里，像这样如果命名一个 类变量 counter，肯定不是线程安全的，