djspiewak

Quick Tips for Fast Code on the JVM

I was talking to a coworker recently about general techniques that almost always form the core of any effort to write very fast, down-to-the-metal hot path code on the JVM, and they pointed out that there really isn't a particularly good place to go for this information. It occurred to me that, really, I had more or less picked up all of it by word of mouth and experience, and there just aren't any good reference sources on the topic. So… here's my word of mouth.

This is by no means a comprehensive gist. It's also important to understand that the techniques that I outline in here are not 100% absolute either. Performance on the JVM is an incredibly complicated subject, and while there are rules that almost always hold true, the "almost" remains very salient. Also, for many or even most applications, there will be other techniques that I'm not mentioning which will have a greater impact. JMH, Java Flight Recorder, and a good profiler are your very best friend! Mea

danielepolencic

3 Virtual Machines Kubernetes cluster

Dependencies

You should install VirtualBox and Vagrant before you start.

Creating the cluster

You should create a Vagrantfile in an empty directory with the following content:

belgoros

package hello;

import hello.dto.PostDto;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.batch.core.Job;
import org.springframework.batch.core.Step;
import org.springframework.batch.core.configuration.annotation.EnableBatchProcessing;
import org.springframework.batch.core.configuration.annotation.JobBuilderFactory;
import org.springframework.batch.core.configuration.annotation.StepBuilderFactory;

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) {