Performing tasks in parallel with different priorities in Java

Used by the IterableObjectHelper to iterate collections or arrays in parallel, the BackgroundExecutor component is able to run different functional interfaces in parallel by setting the priority of the thread they will be assigned to. There is also the option to wait for them start or finish. To use this component we must add to our pom.xml the following dependency:

<dependency>
    <groupId>org.burningwave</groupId>
    <artifactId>core</artifactId>
    <version>12.64.3</version>
</dependency>

… And to use Burningwave Core as a Java module, add the following to your module-info.java:

requires org.burningwave.core;

For obtaining threads this component uses the ThreadSupplier that can be customized in the burningwave.static.properties file through the following properties:

thread-supplier.default-daemon-flag-value=true
thread-supplier.default-thread-priority=5
thread-supplier.max-detached-thread-count=${thread-supplier.max-poolable-thread-count}
thread-supplier.max-detached-thread-count.elapsed-time-threshold-from-last-increase-for-gradual-decreasing-to-initial-value=30000
thread-supplier.max-detached-thread-count.increasing-step=autodetect
thread-supplier.max-poolable-thread-count=autodetect
thread-supplier.poolable-thread-request-timeout=6000

The ThreadSupplier provides a fixed number of reusable threads indicated by the thread-supplier.max-poolable-thread-count property and, if these threads have already been assigned, new non-reusable threads will be created whose quantity maximum is indicated by the thread-supplier.max-detached-thread-count property. Once this limit is reached if the request for a new thread exceeds the waiting time indicated by the thread-supplier.poolable-thread-request-timeout property, the ThreadSupplier will proceed to increase the limit indicated by the ‘thread-supplier.max-detached-thread-count’ property for the quantity indicated by the thread-supplier.max-detached-thread-count.increasing-step property. Resetting the ‘thread-supplier.max-detached-thread-count’ property to its initial value, will occur gradually only when there have been no more waits on thread requests for an amount of time indicated by the thread-supplier.max-detached-thread-count.elapsed-time-threshold-from-last-increase-for-gradual-decreasing-to-initial-value property.

import static org.burningwave.core.assembler.StaticComponentContainer.BackgroundExecutor;

import org.burningwave.core.ManagedLogger;
import org.burningwave.core.concurrent.QueuedTasksExecutor.ProducerTask;
import org.burningwave.core.concurrent.QueuedTasksExecutor.Task;


public class TaskLauncher implements ManagedLogger {
    
    public void launch() {
        ProducerTask<Long> taskOne = BackgroundExecutor.createProducerTask(task -> {
            Long startTime = System.currentTimeMillis();
            logInfo("task one started");
            synchronized (this) {                
                wait(5000);
            }
            Task internalTask = BackgroundExecutor.createTask(tsk -> {
                logInfo("internal task started");    
                synchronized (this) {                
                    wait(5000);
                }
                logInfo("internal task finished");    
            }, Thread.MAX_PRIORITY).submit();
            internalTask.waitForFinish();
            logInfo("task one finished");
            return startTime;
        }, Thread.MAX_PRIORITY);
        taskOne.submit();
        Task taskTwo = BackgroundExecutor.createTask(task -> {
            logInfo("task two started and wait for task one finishing");
            taskOne.waitForFinish();
            logInfo("task two finished");    
        }, Thread.NORM_PRIORITY);
        taskTwo.submit();
        ProducerTask<Long> taskThree = BackgroundExecutor.createProducerTask(task -> {
            logInfo("task three started and wait for task two finishing");
            taskTwo.waitForFinish();
            logInfo("task two finished");
            return System.currentTimeMillis();
        }, Thread.MIN_PRIORITY);
        taskThree.submit();
        taskThree.waitForFinish();
        logInfo("Elapsed time: {}ms", taskThree.join() - taskOne.join());
    }
    
    public static void main(String[] args) {
        new TaskLauncher().launch();
    }
    
}