千分尺-普罗米修斯量规显示NaN [英] Micrometer - Prometheus Gauge displays NaN

问题描述

我正在尝试通过将Micrometer.io与Spring Boot 2.0.0.RELEASE结合使用来生成Prometheus指标.

I am trying to generate Prometheus metrics with using Micrometer.io with Spring Boot 2.0.0.RELEASE.

当我尝试将List的大小显示为Gauge时，它会一直显示NaN.在文档中说:

您有责任对要使用量规进行测量的状态对象保持严格的引用.

It is your responsibility to hold a strong reference to the state object that you are measuring with a Gauge.

我尝试了一些不同的方法，但无法解决问题.这是我的一些试用代码.

I have tried some different ways but I could not solve the problem. Here is my code with some trials.

import io.micrometer.core.instrument.*;
import io.swagger.backend.model.Product;
import io.swagger.backend.service.ProductService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

import java.util.List;
import java.util.concurrent.atomic.AtomicInteger;

@RestController
@RequestMapping("metrics")
public class ExampleController {

    private AtomicInteger atomicInteger = new AtomicInteger();

    private ProductService productService;
    private final Gauge productGauge;

    @Autowired
    public HelloController(ProductService productService,
                           MeterRegistry registry) {

        this.productService = productService;

        createGauge("product_gauge", productService.getProducts(), registry);
    }

    private void createGauge(String metricName, List<Product> products,
                                    MeterRegistry registry) {

        List<Product> products = productService.getProducts();

        // #1
        // this displays product_gauge as NaN
        AtomicInteger n = registry.gauge("product_gauge", new AtomicInteger(0));
        n.set(1);
        n.set(2);

        // #2
        // this also displays product_gauge as NaN
        Gauge
            .builder("product_gauge", products, List::size)
            .register(registry);

        // #3
        // this displays also NaN
        testListReference = Arrays.asList(1, 2);
        Gauge
            .builder("random_gauge", testListReference, List::size)
            .register(registry);

        // #4
        // this also displays NaN
        AtomicInteger currentHttpRequests = registry.gauge("current.http.requests", new AtomicInteger(0));
    }

    @GetMapping(path = "/product/decrement")
    public Counter decrementAndGetProductCounter() {
        // decrement the gague by one
    }
}

有没有人可以帮助解决这个问题?任何帮助将不胜感激.

Is there anyone who can help with this issue? Any help would be appreciated.

推荐答案

在所有情况下，您都必须拥有对观察到的实例的强引用.退出createGauge()方法时，所有为函数堆栈分配的引用都可以进行垃圾回收.

In all cases, you must hold a strong reference to the observed instance. When your createGauge() method is exited, all function stack allocated references are eligible for garbage collection.

对于#1，像这样传递您的atomicInteger字段:registry.gauge("my_ai", atomicInteger);.然后根据需要增加/减少.每当千分尺需要查询时，只要找到参考，就可以.

For #1, pass your atomicInteger field like this: registry.gauge("my_ai", atomicInteger);. Then increment/decrement as you wish. Whenever micrometer needs to query it, it will as long as it finds the reference.

对于#2，传递您的productService字段和一个lambda.基本上，每当查询量规时，它将使用提供的对象调用该lambda:registry.gauge("product_gauge", productService, productService -> productService.getProducts().size());

For #2, pass your productService field and a lambda. Basically whenever the gauge is queried, it will call that lambda with the provided object: registry.gauge("product_gauge", productService, productService -> productService.getProducts().size());

(不保证语法错误.)

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