聊聊TaskExecutorMetricsAutoConfiguration

/**
 * {@link EnableAutoConfiguration Auto-configuration} for metrics on all available
 * {@link ThreadPoolTaskExecutor task executors} and {@link ThreadPoolTaskScheduler task
 * schedulers}.
 *
 * @author Stephane Nicoll
 * @author Scott Frederick
 * @since 2.6.0
 */
@AutoConfiguration(after = { MetricsAutoConfiguration.class, SimpleMetricsExportAutoConfiguration.class,
		TaskExecutionAutoConfiguration.class, TaskSchedulingAutoConfiguration.class })
@ConditionalOnClass(ExecutorServiceMetrics.class)
@ConditionalOnBean({ Executor.class, MeterRegistry.class })
public class TaskExecutorMetricsAutoConfiguration {

	@Autowired
	public void bindTaskExecutorsToRegistry(Map<String, Executor> executors, MeterRegistry registry) {
		executors.forEach((beanName, executor) -> {
			if (executor instanceof ThreadPoolTaskExecutor) {
				monitor(registry, safeGetThreadPoolExecutor((ThreadPoolTaskExecutor) executor), beanName);
			}
			else if (executor instanceof ThreadPoolTaskScheduler) {
				monitor(registry, safeGetThreadPoolExecutor((ThreadPoolTaskScheduler) executor), beanName);
			}
		});
	}

	private void monitor(MeterRegistry registry, ThreadPoolExecutor threadPoolExecutor, String name) {
		if (threadPoolExecutor != null) {
			new ExecutorServiceMetrics(threadPoolExecutor, name, Collections.emptyList()).bindTo(registry);
		}
	}

	private ThreadPoolExecutor safeGetThreadPoolExecutor(ThreadPoolTaskExecutor taskExecutor) {
		try {
			return taskExecutor.getThreadPoolExecutor();
		}
		catch (IllegalStateException ex) {
			return null;
		}
	}

	private ThreadPoolExecutor safeGetThreadPoolExecutor(ThreadPoolTaskScheduler taskScheduler) {
		try {
			return taskScheduler.getScheduledThreadPoolExecutor();
		}
		catch (IllegalStateException ex) {
			return null;
		}
	}

}

@NonNullApi
@NonNullFields
public class ExecutorServiceMetrics implements MeterBinder {

    private static boolean allowIllegalReflectiveAccess = true;

    private static final InternalLogger log = InternalLoggerFactory.getInstance(ExecutorServiceMetrics.class);

    private static final String DEFAULT_EXECUTOR_METRIC_PREFIX = "";

    @Nullable
    private final ExecutorService executorService;

    private final Iterable<Tag> tags;

    private final String metricPrefix;

    public ExecutorServiceMetrics(@Nullable ExecutorService executorService, String executorServiceName,
            Iterable<Tag> tags) {
        this(executorService, executorServiceName, DEFAULT_EXECUTOR_METRIC_PREFIX, tags);
    }

    /**
     * Create an {@code ExecutorServiceMetrics} instance.
     * @param executorService executor service
     * @param executorServiceName executor service name which will be used as
     * {@literal name} tag
     * @param metricPrefix metrics prefix which will be used to prefix metric name
     * @param tags additional tags
     * @since 1.5.0
     */
    public ExecutorServiceMetrics(@Nullable ExecutorService executorService, String executorServiceName,
            String metricPrefix, Iterable<Tag> tags) {
        this.executorService = executorService;
        this.tags = Tags.concat(tags, "name", executorServiceName);
        this.metricPrefix = sanitizePrefix(metricPrefix);
    }


    @Override
    public void bindTo(MeterRegistry registry) {
        if (executorService == null) {
            return;
        }

        String className = executorService.getClass().getName();

        if (executorService instanceof ThreadPoolExecutor) {
            monitor(registry, (ThreadPoolExecutor) executorService);
        }
        else if (executorService instanceof ForkJoinPool) {
            monitor(registry, (ForkJoinPool) executorService);
        }
        else if (allowIllegalReflectiveAccess) {
            if (className.equals("java.util.concurrent.Executors$DelegatedScheduledExecutorService")) {
                monitor(registry, unwrapThreadPoolExecutor(executorService, executorService.getClass()));
            }
            else if (className.equals("java.util.concurrent.Executors$FinalizableDelegatedExecutorService")) {
                monitor(registry,
                        unwrapThreadPoolExecutor(executorService, executorService.getClass().getSuperclass()));
            }
            else {
                log.warn("Failed to bind as {} is unsupported.", className);
            }
        }
        else {
            log.warn("Failed to bind as {} is unsupported or reflective access is not allowed.", className);
        }
    }       

    // ...... 

}    

    private void monitor(MeterRegistry registry, @Nullable ThreadPoolExecutor tp) {
        if (tp == null) {
            return;
        }

        FunctionCounter.builder(metricPrefix + "executor.completed", tp, ThreadPoolExecutor::getCompletedTaskCount)
            .tags(tags)
            .description("The approximate total number of tasks that have completed execution")
            .baseUnit(BaseUnits.TASKS)
            .register(registry);

        Gauge.builder(metricPrefix + "executor.active", tp, ThreadPoolExecutor::getActiveCount)
            .tags(tags)
            .description("The approximate number of threads that are actively executing tasks")
            .baseUnit(BaseUnits.THREADS)
            .register(registry);

        Gauge.builder(metricPrefix + "executor.queued", tp, tpRef -> tpRef.getQueue().size())
            .tags(tags)
            .description("The approximate number of tasks that are queued for execution")
            .baseUnit(BaseUnits.TASKS)
            .register(registry);

        Gauge.builder(metricPrefix + "executor.queue.remaining", tp, tpRef -> tpRef.getQueue().remainingCapacity())
            .tags(tags)
            .description("The number of additional elements that this queue can ideally accept without blocking")
            .baseUnit(BaseUnits.TASKS)
            .register(registry);

        Gauge.builder(metricPrefix + "executor.pool.size", tp, ThreadPoolExecutor::getPoolSize)
            .tags(tags)
            .description("The current number of threads in the pool")
            .baseUnit(BaseUnits.THREADS)
            .register(registry);

        Gauge.builder(metricPrefix + "executor.pool.core", tp, ThreadPoolExecutor::getCorePoolSize)
            .tags(tags)
            .description("The core number of threads for the pool")
            .baseUnit(BaseUnits.THREADS)
            .register(registry);

        Gauge.builder(metricPrefix + "executor.pool.max", tp, ThreadPoolExecutor::getMaximumPoolSize)
            .tags(tags)
            .description("The maximum allowed number of threads in the pool")
            .baseUnit(BaseUnits.THREADS)
            .register(registry);
    }

    private void monitor(MeterRegistry registry, ForkJoinPool fj) {
        FunctionCounter.builder(metricPrefix + "executor.steals", fj, ForkJoinPool::getStealCount)
            .tags(tags)
            .description("Estimate of the total number of tasks stolen from "
                    + "one thread's work queue by another. The reported value "
                    + "underestimates the actual total number of steals when the pool " + "is not quiescent")
            .register(registry);

        Gauge.builder(metricPrefix + "executor.queued", fj, ForkJoinPool::getQueuedTaskCount)
            .tags(tags)
            .description("An estimate of the total number of tasks currently held in queues by worker threads")
            .register(registry);

        Gauge.builder(metricPrefix + "executor.active", fj, ForkJoinPool::getActiveThreadCount)
            .tags(tags)
            .description("An estimate of the number of threads that are currently stealing or executing tasks")
            .register(registry);

        Gauge.builder(metricPrefix + "executor.running", fj, ForkJoinPool::getRunningThreadCount)
            .tags(tags)
            .description(
                    "An estimate of the number of worker threads that are not blocked waiting to join tasks or for other managed synchronization threads")
            .register(registry);
    }