如何减少Java的抖动？

为了解决这个问题，我创建了一个开源的Java线程关联库

当我有许多线程紧密交互时，它可以减少延迟并提高吞吐量。对于单线程任务，它仍然可以减少相当多的抖动。

此程序查看调用之间的时间差，并报告超过 10x，000 ns 的呼叫。System.nanoTime()

public class TimeJumpingMain {
    static final long IGNORE_TIME = 1000 * 1000 * 1000; // the first second to allow warmup.
    static final int minJump = 10; // smallest jump of 10 us.
    static final int midJump = 100; // mid size jump of 100 us.
    static final int bigJump = 1000; // big jump of 1 ms.

    public static void main(String... args) {
        int[] intervalTimings = new int[1000];
        int[] jumpTimings = new int[1000];

        long start = System.nanoTime();
        long prev = start;
        long prevJump = start;
        int jumpCount = 0;
        int midJumpCount = 0;
        int bigJumpCount = 0;

        while (true) {
            long now = System.nanoTime();
            long jump = (now - prev) / 1000;
            if (jump > minJump && now - start > IGNORE_TIME) {
                long interval = (now - prevJump) / 1000;
                if (jumpCount < intervalTimings.length) {
                    intervalTimings[jumpCount] = (int) interval;
                    jumpTimings[jumpCount] = (int) jump;
                }
                if (jump >= midJump)
                    midJumpCount++;
                if (jump >= bigJump)
                    bigJumpCount++;
                prevJump = now;
                jumpCount++;
            }
            prev = now;
            if (now - start > 120L * 1000 * 1000 * 1000 + IGNORE_TIME)
                break;
        }
        System.out.println("interval us\tdelay us");
        for (int i = 0; i < jumpCount && i < intervalTimings.length; i++) {
            System.out.println(intervalTimings[i] + "\t" + jumpTimings[i]);
        }
        System.out.printf("Time jumped %,d / %,d / %,d times by at least %,d / %,d / %,d us in %.1f seconds %n",
                jumpCount, midJumpCount, bigJumpCount, minJump, midJump, bigJump, (System.nanoTime() - start - IGNORE_TIME) / 1e9);
    }
}

在我的机器上此报告

Time jumped 2,905 / 131 / 20 times by at least 10 / 100 / 1,000 us in 120.0 seconds   

我试图设置实时优先级，并尝试在启动该过程后锁定到单个内核，但这些都没有像我预期的那样有所帮助。chrttaskset

我配置了该框以将所有中断移动到cpu 0-3，并将cpu掩码用于所有进程，0xFF 0x0F。在前四个 CPU 中，大约 99% 处于空闲状态，最后四个 CPU 处于 100.0% 空闲状态。top

用作根目录chrt -r 99

Time jumped 673 / 378 / 44 times by at least 10 / 100 / 1,000 us in 120.0 seconds 

但是，单独使用时（我已确保cpu7是免费的）taskset -c 7

Time jumped 24 / 1 / 0 times by at least 10 / 100 / 1,000 us in 120.0 seconds 

用chrt - r 99 taskset -c 7

Time jumped 7 / 1 / 0 times by at least 10 / 100 / 1,000 us in 120.0 seconds  

似乎在进程启动后尝试使用任务集对我不起作用。

更广泛的问题是;

如何减少Java进程的抖动？有没有更多关于减少Linux抖动的技巧？

注意：在运行此过程期间不会发生 GC（使用 -verbosegc 进行检查）

代码编译似乎可能会导致每次在 100 - 102 毫秒后出现 3.62 毫秒的延迟。出于这个原因，我忽略了第一秒作为热身的所有内容。