package multithreading.thread_pool;

public class Api {

    void makeRequest() throws InterruptedException {
        Thread.sleep(3000); // simulate io blocking
    }
}

package multithreading.thread_pool;

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;

public class MyThreadPool {

    private final BlockingQueue<Runnable> tasks;
    private volatile boolean isStopped = false;
    private final List<Thread> threadsInPoll;

    public MyThreadPool(int countOfThreads, int countOfTasks) {
        tasks = new ArrayBlockingQueue<>(countOfTasks);
        threadsInPoll = new ArrayList<>(countOfThreads);
        for (int i = 0; i < countOfThreads; i++) {
            Thread thread = new Thread(() -> {
                while(true) {
                    try {
                        getTask().run();
                    } catch (InterruptedException e) {
                        System.out.println("Interruption... tasks left " + tasks.size());
                        break;
                    }
                }
            }, "Thread " + i);
            threadsInPoll.add(thread);
        }

        threadsInPoll.forEach(Thread::start);
    }

    public void execute(Runnable runnable) throws InterruptedException {
        if (!isStopped) {
            tasks.put(runnable);
        }
    }

    public void stop() {
        synchronized (this) {
            if (isStopped) return;
            isStopped = true;
            threadsInPoll.forEach(Thread::interrupt);
        }
    }

    private Runnable getTask() throws InterruptedException {
        if (!isStopped) {
            return tasks.take();
        }
        throw new InterruptedException();
    }
}

Client:
package multithreading.thread_pool;

public class Client {

    private static Api api;

    public static void main(String[] args) throws InterruptedException {
        int countOfThreads = 5;
        int countOfTasks = countOfThreads * 3;

        MyThreadPool threadPool = new MyThreadPool(countOfThreads, countOfTasks);

        api = new Api();

        for (int i = 0; i < 15; i++) {
            int finalI = i;
            threadPool.execute(() -> {
                System.out.println("Thread " + Thread.currentThread().getName() + " makes network request number " + finalI);
                makeRequest();
                System.out.println("Thread " + Thread.currentThread().getName() + " fetched response for the network request number " + finalI);
            });
        }

        Thread.sleep(3500);
        threadPool.stop();
    }

    private static void makeRequest() {
        try {
            api.makeRequest();
        } catch (InterruptedException e) {
            System.out.println("Interruption while making a request has occurred");
        }
    }
}