JMX - Tutorials

  1. 1. Introduction
  2. 2. Why need this?
  3. 3. Components
    1. 3.1 MBean
  4. 4. Example
  5. 5. Operations and attributes
  6. Reference

1. Introduction

  • JMX - Java Management extensions
    • export standard metrics and custom metrics using MBeans to a monitoring system
    • understand how your application is performing
      • memory
      • cpu
      • threads
      • API calls in a REST endpoint

2. Why need this?

  • Large scale java applications
    • gather performance information
      • number of users connected
  • could provide a monitoring interface
  • any class that exports data to JMX is called a Managed Bean(MBean). These MBeans publish their metrics to a MBean Server provided by the Java platform.

3. Components

3.1 MBean

  • Objects with methods that return information and export the information via the MBeanServer
  • Mainly have 4 types
    • Standard MBean
      • create an interface with getter
    • Dynamic MBean
      • implements getters and setters to retrieve or modify the metric that can be auto discovered by implementing the javax.management.DynamicMBean interface
    • Model MBean
      • Generic, dynamic in runtime to instrument the resources
    • Open MBean
      • Using a predefined set of java classes

4. Example

// Create an interface that the MBeanServer will retrieve information 
public interface SystemStatusMBean {
   Integer getNumberOfSecondsRunning();
   String getProgramName();
   Long getNumberOfUnixSecondsRunning();
   Boolean getSwitchStatus();
}

Actual Implementation

    public class SystemStatus implements SystemStatusMBean {
   private Integer numberOfSecondsRunning;
   private String programName;
   private Long numberOfUnixSecondsRunning;
   private Boolean switchStatus;
   private Thread backgroundThread;

   public SystemStatus(String programName) {
       // First we initialize all the metrics
       this.backgroundThread = new Thread();
       this.programName = programName;
       this.numberOfSecondsRunning = 0;
       this.numberOfUnixSecondsRunning = System.currentTimeMillis() / 1000L;
       this.switchStatus = false;

       // We will use a background thread to update the metrics
       this.backgroundThread = new Thread(() -> {
           try {
               while (true) {
                   // Every second we update the metrics
                   numberOfSecondsRunning += 1;
                   numberOfUnixSecondsRunning += 1;
                   switchStatus = !switchStatus;
                   Thread.sleep(1000L);
               }
           } catch (Exception e) {
               e.printStackTrace();
           }
       });
       this.backgroundThread.setName("backgroundThread");
       this.backgroundThread.start();
   }

5. Operations and attributes

Class properties exported through MBeans are called attributes, and methods exported through MBeans are called operations.

  • TotalCompilationTime
    • Total time spent doing in JIT compilation
  • Garbage Collector - CollectionCount
    • Number of garbage collection events fired since the JVM launch
  • Garbage Collector - CollectionTime
  • FreePyhsicalMemorySize
  • CommitedVirtualMemorySize
    • The amount of memory that is guaranteed to be available for use by JVM
  • ProcessCpuTime
    • Time CPU has spent running the process
  • PeakThreadCount
    • maximum number of threads being executed at the same time since the JVM was started or the peak was reset
  • ThreadCount
    • the number of threads running at the current moment

Reference

  1. https://sysdig.com/blog/jmx-monitoring-custom-metrics/

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文章标题:JMX - Tutorials

文章字数:377

本文作者:Leilei Chen

发布时间:2020-02-08, 21:15:44

最后更新:2020-02-08, 21:16:07

原始链接:https://www.llchen60.com/JMX-Tutorials/

版权声明: "署名-非商用-相同方式共享 4.0" 转载请保留原文链接及作者。

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