Executors.newFixedThreadPool（）-此操作的成本是多少

Question

I have a requirement where i need to process some tasks for current live shows . This is a scheduled tasks and runs every minute.

At any given minute, there can be any number of live shows (though number cannot be that large, approx max 10 ). There are more than 20 functionalities needs to be done for all the live shows. or say 20 worker classes are there , all are doing there job .

Let say for first functionality, there are 5 shows, then after few minutes shows reduced to 2, then again after few minutes shows increase to 7 .

Currently i am doing something like this,

int totalShowsCount = getCurrentShowsCount();
ExecutorService executor = Executors.newFixedThreadPool(showIds.size());

The above statements gets executed every minute.

Problem Statement

1.) How much expensive the above operation be..??. Creating fixedThreadPool at every given minute.

2.) What can i do to optimize my solution, should i use a fixed thread pool, say (10), and maybe 3 or 5 or 6 or any number of threads getting utilized at any given minute.

Can i create a fixed thread pool at worker level, and maintain it and utilize that.

FYI, using Java8, if any better approach is available.

Answer 1

How much expensive the above operation be..??. Creating fixedThreadPool at every given minute.

Creating a thread pool is a relatively expensive operation which can take milli-seconds. You don't want to be doing this many times per second.

A second is an eternity for a computer, if you have a 36 core machine it can execute as much as 100 billion instructions in that amount of time. A minute is a very, very long time, and if you only do something once a minute you could even restart your JVM every minute and still get reasonable throughput.

What can i do to optimize my solution, should i use a fixed thread pool, say (10), and maybe 3 or 5 or 6 or any number of threads getting utilized at any given minute.

Possibly, it depends on what you are doing. Without most analysis you could say for sure. Note: If you are using parallelStream(), if not you should see if you can, you can use the built in ForkJoinPool.commonPool() and not need to create another pool. But again, this depends on what you are doing.