ThreadPoolExecutor pool = (ThreadPoolExecutor) Executors.newFixedThreadPool(15);
As it has been pointed out in the comments, you could achieve what you're asking by using only one ThreadPoolExecutor.
In fact, a ThreadPoolExecutor contains a pool of threads whose number is adjusted according to the CorePoolSize and MaximumPoolSize properties. The PoolSize property represents the current number of threads running or in idle within the ThreadPoolExecutor. While, the CorePoolSize and MaximumPoolSize represent the bounds for minimum and maximum thread creation.
In fact, if a new task is submitted and fewer threads than CorePoolSize are running, a new thread is created, even if there are other threads in idle.
If a new task is submitted and the number of threads is greater or equal than CorePoolSize but lower than MaximumPoolSize then a new thread is created only if the queue is full; otherwise the task is queued.
Finally, if a new task is submitted when the MaximumCoreSize has been reached and the queue is full, then the task is rejected and handled by the default or provided RejectedExecutionHandler object which will invoke the rejectedExecution method to handle the rejection.
In your case, to have at most 15 threads running at the same, you could just use the newFixedThreadPool method of the Executors class and pass 15 as the argument to have both CorePoolSize and MaximumPoolSize set to 15. Like so, you'll have at most 15 threads running at the same time within the same executor.
ThreadPoolExecutor pool = (ThreadPoolExecutor) Executors.newFixedThreadPool(15);
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正如评论中指出的那样，您只需使用一个
threadpoolexecutor就可以实现所要求的。实际上，
threadpoolexecutor包含一个线程池，该线程的数字是根据corepoolsize和maximumpoolsize属性调整的。poolsize属性代表当前正在运行的线程数或在threadpoolpoolexecutor中闲置。同时，corepoolSize和maximumpoolsize表示最小和最大线程创建的边界。实际上，如果提交了一个新任务，并且与
corepoolsize正在运行的线程更少，那么即使在空闲中还有其他线程也会创建新线程。如果提交了一个新任务，并且线程的数量大于
corepoolsize，但低于maximumpoolSize，则创建了一个新线程唯一b>如果队列已满；否则任务已排队。最后，如果已达到
最大值时提交新任务，并且队列已满，则该任务将由默认值或提供的receptreceptedexeciTion拒绝和处理。将调用拒绝的对象处理拒绝的方法。在您的情况下，最多可以在15个线程中运行同样，您只需使用
newFixedThreadPool执行人class的方法，然后将15传递给参数，以使corepoolsize和maximumpoolSize < /code>设置为15。就像这样，您最多可以在同一执行人内同时运行15个线程。As it has been pointed out in the comments, you could achieve what you're asking by using only one
ThreadPoolExecutor.In fact, a
ThreadPoolExecutorcontains a pool of threads whose number is adjusted according to theCorePoolSizeandMaximumPoolSizeproperties. ThePoolSizeproperty represents the current number of threads running or in idle within theThreadPoolExecutor. While, theCorePoolSizeandMaximumPoolSizerepresent the bounds for minimum and maximum thread creation.In fact, if a new task is submitted and fewer threads than
CorePoolSizeare running, a new thread is created, even if there are other threads in idle.If a new task is submitted and the number of threads is greater or equal than
CorePoolSizebut lower thanMaximumPoolSizethen a new thread is created only if the queue is full; otherwise the task is queued.Finally, if a new task is submitted when the
MaximumCoreSizehas been reached and the queue is full, then the task is rejected and handled by the default or providedRejectedExecutionHandlerobject which will invoke therejectedExecutionmethod to handle the rejection.https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/util/concurrent/ThreadPoolExecutor.html
In your case, to have at most 15 threads running at the same, you could just use the
newFixedThreadPoolmethod of theExecutorsclass and pass 15 as the argument to have bothCorePoolSizeandMaximumPoolSizeset to 15. Like so, you'll have at most 15 threads running at the same time within the same executor.