Glassfish - JEE6 - 使用拦截器测量性能 [英] Glassfish - JEE6 - Use of Interceptor to measure performance

问题描述

为了测量方法的执行时间，我已经看到了使用

  public class PerformanceInterceptor {
 @ AroundInvoke 
 Object measureTime（InvocationContext ctx）抛出异常{
 long beforeTime = System.currentTimeMillis（）; 
 Object obj = null; 
尝试{
 obj = ctx.proceed（）; 
 return obj; 
} 
 finally {
 time = System.currentTimeMillis（） -  beforeTime; 
 //记录时间
} 
} 
  

然后把

  @Interceptors（PerformanceInterceptor.class）
  

之前，无论你想测量的任何方法。

无论如何，我试过这个，它似乎工作正常。

我还添加了一个

  public static long countCalls = 0; 
  

添加到PerformanceInterceptor类和a

  countCalls ++; 
  

加入到measureTime（）中，这似乎也可以正常工作。

随着我的newby帽子，我会问，如果我使用countCalls是好的即
Glassfish / JEE6是o.k.与我一起使用Java类中的静态变量
作为拦截器......特别是关于线程安全性。我知道
通常你应该用Java来同步类变量的设置，但是我b $ b不知道JEE6 / Glassfish的情况。有什么想法？在这种情况下，容器没有提供任何额外的线程安全性。每个bean实例都有自己的拦截器实例。因此，多线程可以同时访问静态countCalls。

这就是为什么你必须像往常一样保护读写。其他可能性是使用 AtomicLong ：

  private static final AtomicLong callCount = new AtomicLong（）; 
 
 private long getCallCount（）{
 return callCount.get（）; 
} 
 
 private void increaseCountCall（）{
 callCount.getAndIncrement（）; 
} 
  

正如预期的那样，只要所有实例都是在同一个JVM中，需要集群共享存储。

For measuring execution time of methods, I've seen suggestions to use

public class PerformanceInterceptor {
   @AroundInvoke
   Object measureTime(InvocationContext ctx) throws Exception {
   long beforeTime = System.currentTimeMillis();
   Object obj = null;
   try {
      obj = ctx.proceed();
      return obj;
   }
   finally {
      time = System.currentTimeMillis() - beforeTime;
      // Log time
   }
}

Then put

@Interceptors(PerformanceInterceptor.class) 

before whatever method you want measured.

Anyway I tried this and it seems to work fine.

I also added a

public static long countCalls = 0;

to the PerformanceInterceptor class and a

countCalls++; 

to the measureTime() which also seems to work o.k.

With my newby hat on, I will ask if my use of the countCalls is o.k. i.e that Glassfish/JEE6 is o.k. with me using static variables in a Java class that is used as an Interceptor.... in particular with regard to thread safety. I know that normally you are supposed to synchronize setting of class variables in Java, but I don't know what the case is with JEE6/Glassfish. Any thoughts ?

解决方案

There is not any additional thread safety provided by container in this case. Each bean instance does have its own instance of interceptor. As a consequence multiple thread can access static countCalls same time.

That's why you have to guard both reads and writes to it as usual. Other possibility is to use AtomicLong:

private static final AtomicLong callCount = new AtomicLong();

private long getCallCount() {
   return callCount.get();
}

private void increaseCountCall() {
   callCount.getAndIncrement();
}

As expected, these solutions will work only as long as all of the instances are in same JVM, for cluster shared storage is needed.

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