Java Thread Affinity support for ExecutorService

Overview

The Java Thread Affinity version 1.4.1 library has support for the concurrency library through an AffinityThreadFactory.

This follows my previous article on HyperThreading support in the library which give mroe detail on what it does and how it works.

Example

In the AffinityThreadFactoryMain example,

private static final ExecutorService ES = Executors.newFixedThreadPool(4,
        new AffinityThreadFactory("bg", SAME_CORE, DIFFERENT_SOCKET, ANY));

public static void main(String... args) throws InterruptedException {
    for (int i = 0; i < 12; i++)
        ES.submit(new Callable() {
            @Override
            public Void call() throws InterruptedException {
                Thread.sleep(100);
                return null;
            }
        });
    Thread.sleep(200);
    System.out.println("\nThe assignment of CPUs is\n" + AffinityLock.dumpLocks());
    ES.shutdown();
    ES.awaitTermination(1, TimeUnit.SECONDS);
}

by changing the ThreadFactory, you can decide how threads in the factory should be laid out. The default behaviour is to allocate from highest CPU id to lowest, however by changing the AffinityStrategy you can make it try to minimise the number of cores it uses.

Assigning cpu 7 to Thread[bg,5,main]
Assigning cpu 6 to Thread[bg-2,5,main]
Assigning cpu 3 to Thread[bg-3,5,main]
Assigning cpu 2 to Thread[bg-4,5,main]

The assignment of CPUs is
0: General use CPU
1: General use CPU
2: Thread[bg-4,5,main] alive=true
3: Thread[bg-3,5,main] alive=true
4: General use CPU
5: General use CPU
6: Thread[bg-2,5,main] alive=true
7: Thread[bg,5,main] alive=true

Releasing cpu 7 from Thread[bg,5,main]
Releasing cpu 6 from Thread[bg-2,5,main]
Releasing cpu 3 from Thread[bg-3,5,main]
Releasing cpu 2 from Thread[bg-4,5,main]

In this case, the second thread is allocated to the SAME_CORE as the first, the third cannot get one on the same core so it tries to get on on a DIFFERENT_SOCKET, but there is only one so it takes ANY available core which can be reserved.

Related topics

Java Thread Affinity support for hyper threading.
Java Thread Affinity supports groups of threads.
Thread Affinity library for Java supports JNA
Thread Affinity library for Java.