ThreadMetricsTest.java

/**
 * Copyright 2017 Pivotal Software, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.springframework.metrics.instrument.binder;

import org.junit.jupiter.api.Test;
import org.springframework.metrics.instrument.MeterRegistry;
import org.springframework.metrics.instrument.simple.SimpleMeterRegistry;

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

import static org.springframework.metrics.instrument.Assertions.assertGaugeValue;

class ThreadMetricsTest {
    @Test
    void threadMetrics() {
        MeterRegistry registry = new SimpleMeterRegistry()
                .bind(new ThreadMetrics());

        assertGaugeValue(registry, "threads_live", v -> v > 0);
        assertGaugeValue(registry, "threads_daemon", v -> v > 0);

        AtomicInteger peak = new AtomicInteger(0);
        assertGaugeValue(registry, "threads_peak", v -> {
            peak.set(v.intValue());
            return v > 0;
        });

        // should bump the peak by one
        Executors.newSingleThreadExecutor().submit(() -> {
            // do nothing
        });

        assertGaugeValue(registry, "threads_peak", v -> v >= peak.get());
    }
}