net.algart.arrays.DefaultThreadPoolFactory Maven / Gradle / Ivy
Show all versions of algart Show documentation
/*
* The MIT License (MIT)
*
* Copyright (c) 2007-2024 Daniel Alievsky, AlgART Laboratory (http://algart.net)
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
package net.algart.arrays;
import java.util.Objects;
import java.util.concurrent.*;
import java.util.concurrent.atomic.AtomicInteger;
/**
* A simple implementation of {@link ThreadPoolFactory} interface.
* It uses a thread pool, created by Executors.newFixedThreadPool method,
* and uses {@link Arrays.SystemSettings#cpuCount()} method to determine
* the desired number of parallel tasks, if you did not specify another number in
* numberOfTasks argument of the {@link #DefaultThreadPoolFactory constructor}
* or {@link #getDefaultThreadPoolFactory(int)} method.
* See details below in comments to the methods and fields.
*
*
This class is immutable and thread-safe:
* there are no ways to modify settings of the created instance.
*
* @author Daniel Alievsky
*/
public class DefaultThreadPoolFactory extends AbstractThreadPoolFactory implements ThreadPoolFactory {
private static final long MIN_MULTITHREADING_LENGTH = InternalUtils.getLongProperty(
"net.algart.arrays.minMultithreadingLength", 16);
private static final int GLOBAL_THREAD_POOLS_PER_CPU = Math.min(128, Math.max(1, InternalUtils.getIntProperty(
"net.algart.arrays.globalThreadPoolsPerCPU", 2)));
private static final int GLOBAL_THREAD_POOL_SIZE = Math.min(8192, InternalUtils.getIntProperty(
"net.algart.arrays.globalThreadPoolSize",
1 + GLOBAL_THREAD_POOLS_PER_CPU * InternalUtils.availableProcessors()));
private static final int GLOBAL_THREAD_POOL_KEEP_ALIVE_TIME = Math.max(0, InternalUtils.getIntProperty(
"net.algart.arrays.globalThreadPoolKeepAliveTime", 30000)); // 30 sec keep-alive for core threads
/**
* Returns the global thread pool, returned by {@link #getThreadPool(Array, ThreadFactory)} method
* in factories, created by {@link #getDefaultThreadPoolFactory()}
* and {@link #getDefaultThreadPoolFactory(int)} methods.
*
* More precisely, if there is the system property "net.algart.arrays.globalThreadPoolSize",
* containing a positive integer value N, this method returns a global thread pool,
* created by Executors.newFixedThreadPool(N,...(someOurFactory)) (or analogous) operator
* while the first call of this method and saved in an internal static field.
* If this property contains an integer greater than 8192, this value is truncated to 8192.
* If this property contains 0 or a negative value, this method returns {@code null}
* (in this case, no global thread pool will be created).
* If there is no such property, or if it contains not a number,
* or if some exception occurred while calling Integer.getInteger,
* this method returns the default value, which is equal (in the current implementation) to
* {@link Arrays.SystemSettings#availableProcessors()}*MULT+1,
* where MULT is an integer value, stored in "net.algart.arrays.globalThreadPoolsPerCPU"
* system property, or default multiplier 2 if there is no such property or it contains not a number.
* Default value MULT=2 provides a suitable choice for most multiprocessor configurations.
* The value of these system properties are loaded and checked only once
* while initializing {@link DefaultThreadPoolFactory} class.
*
*
Note: the default value {@link Arrays.SystemSettings#availableProcessors()}*MULT+1
* can be changed in future implementations. It is only guaranteed that this value is chosen
* not less than {@link Arrays.SystemSettings#availableProcessors()}.
*
*
Note: the threads, created in the global thread pool (if it exists), are daemons.
* So, the application can be terminated by the usual way, even
* if the global thread pool contains some working threads.
*
* @return the global thread pool, usually returned by this factory, if it exists, or {@code null} in another case.
*/
public static ThreadPoolExecutor globalThreadPool() {
return ConstantHolder.GLOBAL_THREAD_POOL;
}
private final int numberOfTasks;
private final ThreadPoolExecutor persistentThreadPool;
/**
* Returns an instance of this class with the default (simplest) behavior.
* Namely, it is equivalent to {@link #getDefaultThreadPoolFactory(int)
* getDefaultThreadPoolFactory(0)}. This method is the typical way for getting instances of this class.
*
*
Note: this method works very quickly (it just returns a global internal constant).
*
* @return an instance of this class with the default behavior.
*/
public static DefaultThreadPoolFactory getDefaultThreadPoolFactory() {
return ConstantHolder.DEFAULT;
}
/**
* Returns an instance of this class with the specified recommended number of tasks.
*
*
If numberOfTasks argument is positive,
* it will be always returned by {@link #recommendedNumberOfTasks()} and
* {@link #recommendedNumberOfTasks(Array)} methods.
* If it is zero, that method will use the common algorithm, based on the system property:
* see comments to {@link #recommendedNumberOfTasks()}.
*
*
This method is equivalent to new {@link #DefaultThreadPoolFactory(int, ThreadPoolExecutor)
* DefaultThreadPoolFactory}(numberOfTasks, {@link #globalThreadPool()}).
*
*
Note: this method works very quickly (it just returns global internal constants) in cases
* numberOfTasks=0 and numberOfTasks=1.
*
* @param numberOfTasks the desired number of tasks.
* @return an instance of this class with the specified recommended number of tasks.
* @throws IllegalArgumentException if numberOfTasks is negative.
*/
public static DefaultThreadPoolFactory getDefaultThreadPoolFactory(int numberOfTasks) {
if (numberOfTasks == 0) {
return ConstantHolder.DEFAULT;
}
if (numberOfTasks == 1) {
return ConstantHolder.DEFAULT_SINGLE_THREAD;
}
return new DefaultThreadPoolFactory(numberOfTasks, ConstantHolder.GLOBAL_THREAD_POOL);
}
/**
* Creates new instance of this class with the specified recommended number of tasks
* and the specified thread pool.
*
*
If numberOfTasks argument is positive,
* it will be always returned by {@link #recommendedNumberOfTasks()} and
* {@link #recommendedNumberOfTasks(Array)} methods.
* If it is zero, that method will use the common algorithm, based on the system property:
* see comments to {@link #recommendedNumberOfTasks()}.
*
*
If persistentThreadPool is not {@code null},
* it will be always returned by {@link #getThreadPool(Array, ThreadFactory)} method and
* {@link #releaseThreadPool(ExecutorService)} method will do nothing.
* In this case, please note, that if the threads, created by this pool, are not daemons,
* then the application will probably not be exited until you will directly call shutdown()
* method for the passed persistentThreadPool.
*
*
If persistentThreadPool==null, {@link #getThreadPool(Array, ThreadFactory)} method
* will always create new thread pool and
* {@link #releaseThreadPool(ExecutorService)} method will shutdown the passed pool.
*
* @param numberOfTasks the desired number of tasks.
* @param persistentThreadPool the desired thread pool,
* or {@code null} if {@link #getThreadPool(Array, ThreadFactory)}
* should create new thread pool every time.
* @throws IllegalArgumentException if numberOfTasks is negative.
*/
public DefaultThreadPoolFactory(int numberOfTasks, ThreadPoolExecutor persistentThreadPool) {
if (numberOfTasks < 0) {
throw new IllegalArgumentException("Negative numberOfTasks=" + numberOfTasks);
}
this.numberOfTasks = numberOfTasks;
this.persistentThreadPool = persistentThreadPool;
}
/**
* If this instance was created by the {@link #DefaultThreadPoolFactory constructor}
* with numberOfTasks=0 argument
* (or via {@link #getDefaultThreadPoolFactory()} method), this implementation returns
* the result of {@link Arrays.SystemSettings#cpuCount()} method.
*
*
If this instance was created by the {@link #DefaultThreadPoolFactory constructor}
* with non-zero numberOfTasks argument
* (or via {@link #getDefaultThreadPoolFactory(int numberOfTask)} method
* with numberOfTasks>0 method),
* the given numberOfTasks argument is returned always
* regardless of any system properties.
*
*
If this instance uses persistent thread pool, that is if
* {@link #persistentThreadPool()}!=null (a typical situation),
* then the result of this method, calculated by the rules above,
* is also truncated by the limit
* Math.max(1, ((ThreadPoolExecutor){@link #persistentThreadPool()}).getCorePoolSize())
* — if the previously calculated result is greater then this limit, then this limit is returned instead.
* So, there is a guarantee, that this method never returns a value greater than
* the core number of threads in a thread pool, returned by
* {@link #getThreadPool(ThreadFactory)} and {@link #getThreadPool(Array, ThreadFactory)} methods.
* It is important if you are going to run threads which can depend on each other.
*
* @return the recommended number of parallel tasks to perform the processing.
* @see #recommendedNumberOfTasks(Array)
*/
public int recommendedNumberOfTasks() {
int nt = numberOfTasks != 0 ? numberOfTasks : Arrays.SystemSettings.cpuCount();
if (nt > 1 && persistentThreadPool != null) {
int corePoolSize = Math.max(1, persistentThreadPool.getCorePoolSize());
if (corePoolSize < nt) {
nt = corePoolSize;
}
}
return nt;
}
/**
* This method returns the same value as {@link #recommendedNumberOfTasks()}, excepting that
* when the passed array is very little, this method may return less value (usually 1).
*
*
However, if this instance was created by the {@link #DefaultThreadPoolFactory constructor}
* with non-zero numberOfTasks argument
* (or via {@link #getDefaultThreadPoolFactory(int numberOfTask)} method
* with numberOfTasks>0 method),
* then this method is strictly equivalent to {@link #recommendedNumberOfTasks()}.
*
* @param sourceArray some AlgART array that should be processed.
* @return the recommended number of parallel tasks to perform the processing.
* @throws NullPointerException if the argument is {@code null}.
*/
public int recommendedNumberOfTasks(Array sourceArray) {
Objects.requireNonNull(sourceArray, "Null sourceArray argument");
if (numberOfTasks != 0) {
return recommendedNumberOfTasks();
}
long len = sourceArray.length();
if (len < MIN_MULTITHREADING_LENGTH) {
return 1;
} else {
return (int) Math.min(len, recommendedNumberOfTasks());
// no sense to create more threads than the number of elements
}
}
public ThreadPoolFactory singleThreadVersion() {
if (this.numberOfTasks == 1) {
return this;
}
return new DefaultThreadPoolFactory(1, persistentThreadPool);
}
/**
* This implementation returns the {@link #persistentThreadPool() persistent thread pool},
* if it exists, or creates new thread pool by the following call:
* Executors.newFixedThreadPool({@link #recommendedNumberOfTasks()},
* threadFactory==null ? Executors.defaultThreadFactory() : threadFactory).
*
* @param threadFactory if not {@code null} and there is no
* {@link #persistentThreadPool() persistent thread pool},
* specifies the desired thread factory for using by new thread pool.
* @return the thread pool for parallel processing the array.
* @throws NullPointerException if sourceArray argument is {@code null}.
* @see #getThreadPool(Array, ThreadFactory)
*/
public ExecutorService getThreadPool(ThreadFactory threadFactory) {
return persistentThreadPool != null ? persistentThreadPool :
Executors.newFixedThreadPool(recommendedNumberOfTasks(),
threadFactory == null ? Executors.defaultThreadFactory() : threadFactory);
}
/**
* This implementation returns the {@link #persistentThreadPool() persistent thread pool},
* if it exists, or creates new thread pool by the following call:
* Executors.newFixedThreadPool({@link #recommendedNumberOfTasks(Array)
* recommendedNumberOfTasks}(sourceArray),
* threadFactory==null ? Executors.defaultThreadFactory() : threadFactory).
*
* @param sourceArray some AlgART array that should be processed.
* @param threadFactory if not {@code null} and there is no
* {@link #persistentThreadPool() persistent thread pool},
* specifies the desired thread factory for using by new thread pool.
* @return the thread pool for parallel processing the array.
* @throws NullPointerException if sourceArray argument is {@code null}.
*/
public ExecutorService getThreadPool(Array sourceArray, ThreadFactory threadFactory) {
Objects.requireNonNull(sourceArray, "Null sourceArray argument");
return persistentThreadPool != null ? persistentThreadPool :
Executors.newFixedThreadPool(recommendedNumberOfTasks(sourceArray),
threadFactory == null ? Executors.defaultThreadFactory() : threadFactory);
}
/**
* This implementation calls pool.shutdown(), if there is no persistent thread pool
* ({@link #persistentThreadPool()} returns {@code null}), or does nothing in another case.
*
* @param pool the thread pool created by the previous {@link #getThreadPool(Array, ThreadFactory)} call.
* @throws NullPointerException if poll argument is {@code null}
* and there is no persistent thread pool.
*/
public void releaseThreadPool(ExecutorService pool) {
if (persistentThreadPool == null) {
pool.shutdown();
}
}
/**
* Returns the persistent thread pool,
* returned by all calls of {@link #getThreadPool(Array, ThreadFactory)} method,
* if it exists, or {@code null} in another case.
* (In the second case, every call of {@link #getThreadPool(Array, ThreadFactory)} method
* creates new thread pool.)
*
*
More precisely, if this instance was created
* by the {@link #DefaultThreadPoolFactory(int, ThreadPoolExecutor) constructor},
* this method returns its 2nd argument.
* If this instance was created
* by {@link #getDefaultThreadPoolFactory()}
* or {@link #getDefaultThreadPoolFactory(int)},
* this method returns the result of {@link #globalThreadPool()}.
*
* @return the persistent thread pool and {@code null} if it exists, or {@code null} in another case.
*/
public final ExecutorService persistentThreadPool() {
return persistentThreadPool;
}
private static class ConstantHolder {
private static final ThreadPoolExecutor GLOBAL_THREAD_POOL = GLOBAL_THREAD_POOL_SIZE <= 0 ? null :
new ThreadPoolExecutor(GLOBAL_THREAD_POOL_SIZE, GLOBAL_THREAD_POOL_SIZE,
GLOBAL_THREAD_POOL_KEEP_ALIVE_TIME, TimeUnit.MILLISECONDS,
new LinkedBlockingQueue<>(),
new ThreadFactory() {
private final AtomicInteger threadNumber = new AtomicInteger(1);
public Thread newThread(Runnable r) {
Thread t = new Thread(r, "AlgART-arrays-thread-" + threadNumber.getAndIncrement());
t.setDaemon(true);
return t;
}
}
);
static {
if (GLOBAL_THREAD_POOL != null && GLOBAL_THREAD_POOL_KEEP_ALIVE_TIME > 0) {
GLOBAL_THREAD_POOL.allowCoreThreadTimeOut(true);
}
}
private static final DefaultThreadPoolFactory DEFAULT =
new DefaultThreadPoolFactory(0, GLOBAL_THREAD_POOL);
private static final DefaultThreadPoolFactory DEFAULT_SINGLE_THREAD =
new DefaultThreadPoolFactory(1, GLOBAL_THREAD_POOL);
}
}