Java Executors: how can I set task priority?

Answer 1

Currently the only concrete implementations of the Executor interface are the ThreadPoolExecutor and the ScheduledThreadpoolExecutor

Instead of using the utility / factory class Executors, you should create an instance using a constructor.

You can pass a BlockingQueue to the constructors of the ThreadPoolExecutor.

One of the implementations of the BlockingQueue, the PriorityBlockingQueue lets you pass a Comparator to a constructor, that way enabling you to decide the order of execution.

Answer 2

davyM has a good answer but I thought I'd also mention that the following method exists in Java:

Thread.setPriority(int newPriority)

This sets the internal Java thread scheduling priority for the thread. A thread can use Thread.currentThread() to set its own priority, or you can set the priority of a thread externally. According to the code, the default priority is 5, the minimum is 1, and the maximum is 10. A thread inherits the priority of the thread that created it.

This priority is only relevant for CPU intensive threads only -- in situations where you have a number of threads that are performing calculations and you want one to get larger time-slices from the scheduler. Obviously if a thread is blocking on IO, the priority is going help marginally. Also, I suspect that how this behaves on a multi-processor box is very OS dependent.

Here's a page that seems useful although they don't seem to take into account thread starvation: http://www.janeg.ca/scjp/threads/scheduling.html