Question

How do you add all the values that return by all the threads from threadpools?
I have created a threadpool with 1000 of threads and run the task 1000 times. However, when I try to print out the result it gives a whole bunch of values that return by all the threads, it looks like...
Thread-1 xxxx
Thread-2 xxxx
Thread-3 xxxx
Thread-4 xxxx
.
.
.
.
.

Is there a possible way to get a single value back instead of whole bunch of value? Taking the average value of all the threads are fine as well.

This question is based on Java only. Thank you!!

Answer 1

I believe what you are looking for is "atomic Object" to hold values from all the Threads in a single variable.

In Java for concurrent execution we have java.util.concurrent.atomic package

a reference to the same can be find here

https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/atomic/package-summary.html

Example: you have 1000 threads and each thread is doing "task" 1000 times. You want to keep a counter of how many times task was executed in total.

Solution : Each time the task is executed by any thread we will increment atomicInteger variable.

/*****Sample Code********/

AtomicInteger counter = new AtomicInteger(0); //Declaring the atomic integer variable

counter.incrementAndGet() //do this each time task is executed.

/*************Sample Code********/

Moreover you can create your atomic variable static so that it is shared between all the object of the class and there remains only a single instance of atomic variable.

In case you need more help on this, Comment :) Happy to help.