I need to perform some tasks (most often call several external URLs with request parameters and read data) at the same time in the Java servlet and send a response to the user within a few seconds. I am trying to use ExecutorService to achieve the same. I need four FutureTasks created in each user request in the doGet method. Each task takes about 5-10 seconds, and the total response time for the user is about 15 seconds.
Can you suggest which of the following options is best used when using ExecutorService in a Java servlet?
1) (Creating newFixedThreadPool for each request and closing it as soon as possible)
public class MyTestServlet extends HttpServlet
{
ExecutorService myThreadPool = null;
public void init()
{
super.init();
}
protected void doGet(HttpServletRequest request,HttpServletResponse response)
{
myThreadPool = Executors.newFixedThreadPool(4);
taskOne = myThreadPool.submit();
taskTwo = myThreadPool.submit();
taskThree = myThreadPool.submit();
taskFour = myThreadPool.submit();
...
...
taskOne.get();
taskTwo.get();
taskThree.get();
taskFour.get();
...
myThreadPool.shutdown();
}
public void destroy()
{
super.destroy();
}
}
2) ( newFixedThreadPool )
public class MyTestServlet extends HttpServlet
{
ExecutorService myThreadPool = null;
public void init()
{
super.init();
myThreadPool = Executors.newFixedThreadPool(20);
}
protected void doGet(HttpServletRequest request,HttpServletResponse response)
{
taskOne = myThreadPool.submit();
taskTwo = myThreadPool.submit();
taskThree = myThreadPool.submit();
taskFour = myThreadPool.submit();
...
...
taskOne.get();
taskTwo.get();
taskThree.get();
taskFour.get();
...
}
public void destroy()
{
super.destroy();
myThreadPool.shutdown();
}
}
3) ( newCachedThreadPool )
public class MyTestServlet extends HttpServlet
{
ExecutorService myThreadPool = null;
public void init()
{
super.init();
myThreadPool = Executors.newCachedThreadPool();
}
protected void doGet(HttpServletRequest request,HttpServletResponse response)
{
taskOne = myThreadPool.submit();
taskTwo = myThreadPool.submit();
taskThree = myThreadPool.submit();
taskFour = myThreadPool.submit();
...
...
taskOne.get();
taskTwo.get();
taskThree.get();
taskFour.get();
...
}
public void destroy()
{
super.destroy();
myThreadPool.shutdown();
}
}