在这里你可以看到我的优先级ThreadPoolExecator-它工作得很好,但问题是,如果实现了数量的的话,它不会创建新线程。
import java.util.Comparator;
import java.util.concurrent.Callable;
import java.util.concurrent.Future;
import java.util.concurrent.FutureTask;
import java.util.concurrent.PriorityBlockingQueue;
import java.util.concurrent.RejectedExecutionHandler;
import java.util.concurrent.RunnableFuture;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
/**
* Created by ngrigoriev on 4/24/14.
*/
public class PriorityExecutor extends ThreadPoolExecutor {
public PriorityExecutor(int corePoolSize, int maxPoolSize, int quequSize) {
super(corePoolSize, maxPoolSize, 60L, TimeUnit.SECONDS, new PriorityBlockingQueue<>(quequSize, new PriorityTaskComparator()));
}
public PriorityExecutor(int corePoolSize, int maxPoolSize, long time, TimeUnit unit, int quequSize) {
super(corePoolSize, maxPoolSize, time, unit, new PriorityBlockingQueue<>(quequSize, new PriorityTaskComparator()));
}
public PriorityExecutor() {
super(0, Integer.MAX_VALUE, 60L, TimeUnit.SECONDS, new PriorityBlockingQueue<>(11, new PriorityTaskComparator()));
}
public PriorityExecutor(final ThreadFactory threadFactory, int quequSize) {
super(0, Integer.MAX_VALUE, 60L, TimeUnit.SECONDS, new PriorityBlockingQueue<>(quequSize, new PriorityTaskComparator()), threadFactory);
}
public PriorityExecutor(final RejectedExecutionHandler handler, int quequSize) {
super(0, Integer.MAX_VALUE, 60L, TimeUnit.SECONDS, new PriorityBlockingQueue<>(quequSize, new PriorityTaskComparator()), handler);
}
public PriorityExecutor(final ThreadFactory threadFactory, final RejectedExecutionHandler handler, int quequSize) {
super(0, Integer.MAX_VALUE, 60L, TimeUnit.SECONDS, new PriorityBlockingQueue<>(quequSize, new PriorityTaskComparator()), threadFactory,
handler);
}
@Override
public Future<?> submit(final Runnable task) {
if (task == null)
throw new NullPointerException();
final RunnableFuture<Object> ftask = newTaskFor(task, null);
execute(ftask);
return ftask;
}
@Override
public <T> Future<T> submit(Callable<T> task) {
if (task == null)
throw new NullPointerException();
final RunnableFuture<T> ftask = newTaskFor(task);
execute(ftask);
return ftask;
}
@Override
public <T> Future<T> submit(Runnable task, T result) {
if (task == null)
throw new NullPointerException();
final RunnableFuture<T> ftask = newTaskFor(task, result);
execute(ftask);
return ftask;
}
@Override
protected <T> RunnableFuture<T> newTaskFor(final Callable<T> callable) {
if (callable instanceof Important)
return new PriorityTask<>(((Important) callable).getPriority(), callable);
else
return new PriorityTask<>(0, callable);
}
@Override
protected <T> RunnableFuture<T> newTaskFor(final Runnable runnable, final T value) {
if (runnable instanceof Important)
return new PriorityTask<>(((Important) runnable).getPriority(), runnable, value);
else
return new PriorityTask<>(0, runnable, value);
}
public interface Important {
int getPriority();
}
private static final class PriorityTask<T> extends FutureTask<T> implements Comparable<PriorityTask<T>> {
private final int priority;
public PriorityTask(final int priority, final Callable<T> tCallable) {
super(tCallable);
this.priority = priority;
}
public PriorityTask(final int priority, final Runnable runnable, final T result) {
super(runnable, result);
this.priority = priority;
}
@Override
public int compareTo(final PriorityTask<T> o) {
final long diff = o.priority - priority;
return 0 == diff ? 0 : 0 > diff ? -1 : 1;
}
}
private static class PriorityTaskComparator implements Comparator<Runnable> {
@Override
public int compare(final Runnable left, final Runnable right) {
return ((PriorityTask) left).compareTo((PriorityTask) right);
}
}
}
在调试过程中,我发现在第1368行的方法执行
中,我们给出了一个创建非核心工作人员的条件,但这个条件永远不会成立,这个方法(workerCountOf(recheck)
)如果没有调试字节码就无法调试
if (isRunning(c) && workQueue.offer(command)) {
int recheck = ctl.get();
if (! isRunning(recheck) && remove(command))
reject(command);
1368 **else if (workerCountOf(recheck) == 0)**
addWorker(null, false);
}
这其实是个答案
池仅在队列无法接受任务时创建非核心线程。队列始终接受任务,因此不会创建更多线程。
谢谢,但是我可以更改线程池策略以通过某些条件添加新的非核心线程吗-例如通过核心线程状态等待
您将需要提供一个自定义的BlockingQueue和RejecttedExecutionHandler实现来包装您的优先级队列。此自定义队列将需要对ThreadPoolExecator的引用,并根据ThreadPoolExecator的当前活动计数选择是否接受“提供”的Runnable实例。它还必须是ThreadPoolExecator的拒绝执行处理程序,以便如果同时提供多个对象,导致超过最大大小,则仍会将作业添加到优先级队列中。
另一种方法( /much/更简单)是简单地将“核心”大小设置为您希望允许的最大数量,并允许核心线程超时。