jonatan-ivanov

import java.time.Duration;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.*;
import java.util.concurrent.atomic.AtomicInteger;

public class ForkJoinPoolDemo {
    private static final int SUBMISSIONS = 10;
    private static final int FORKS = 24;
    private static final int PARALLELISM = 5;

jonatan-ivanov

// from Jon Schneider
public class GaugeUpdateTrick {
    public static void main(String[] args) {
        AtomicLong lastCalculatedTime = new AtomicLong(0);
        AtomicLong gaugeValue = new AtomicLong(0);
        Gauge.builder("expensive", () -> {
            long curr = System.nanoTime();
            return gaugeValue.updateAndGet(old ->
                    lastCalculatedTime.updateAndGet(ts -> curr - ts > 10_000 ? curr : ts) == curr ? 0L /* new */ : old);
        });

jonatan-ivanov

package org.example;

import java.lang.management.ManagementFactory;
import java.lang.management.OperatingSystemMXBean;
import java.time.Instant;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.ForkJoinPool;

jonatan-ivanov

adoptopenjdk:11-jre-hotspot
java.runtime.name: OpenJDK Runtime Environment
java.runtime.version: 11.0.11+9
java.vendor: AdoptOpenJDK
java.version: 11.0.11
java.vm.name: OpenJDK 64-Bit Server VM
java.vm.vendor: AdoptOpenJDK
java.vm.version: 11.0.11+9

jonatan-ivanov

Complicated API

• As a user, it is somewhat complex and quite puzzling using the API
• There are a lot of components
• The components are doing different things as I would expect based on their names
• I think it would worth a review and refactor to make it more usable.

Examples

• GlobalMetricsProvider
  • Based on its name, it should provide Metrics instances
• In fact, it provides two things neither of them are Metrics

jonatan-ivanov

{
    "status": "UP",
    "components": {
        "discoveryComposite": {
            "status": "UP",
            "components": {
                "discoveryClient": {
                    "status": "UP",
                    "details": {
                        "services": [

jonatan-ivanov

4.0.0 org.springframework.boot spring-boot-starter-parent 2.4.2-SNAPSHOT

jonatan-ivanov

Andrei Pangin - Memory Footprint of a Java Process

• pmap
• Native Memory Tracking
• Memory areas
  • GC memory consumption
  • Class Loader memory consumption
  • Compiler (JIT)
  • (Threads](https://vimeo.com/364039638#t=23m05s)
  • Symbols
• Internal/Other

jonatan-ivanov

Responsible Microservices (Nate Schutta)

• Thinking Architecturally (book)
• Building Evolutionary Architectures (book)
• Should that be a Microservice? Keep These Six Factors in Mind (article)
• Distributed big balls of mud (article)
• Modular monoliths by Simon Brown (talk)
• git heatmap: git log --pretty=format: --name-only | sort | uniq -c | sort -rg | head -10
• Getting Empirical about Refactoring (article)
• Turbulence (tool)
• CodeScene (tool)

jonatan-ivanov

@Configuration
@EnableScheduling
@EnableBatchProcessing
public class BatchConfiguration {
  @Bean
  @StepScope
  public ResourceReader reader(
      @Value("...") String url,
      @Value("...") int pageSize,
      @Value("#{jobParameters['ResourceReader.index']}") int index) {