VisualVM monitoring like jconsole

VisualVM is a powerful tool for monitoring and troubleshooting Java applications. It provides detailed information about the running Java applications, such as memory consumption, CPU usage, thread activity, and more. Here is a guide on how to use VisualVM for monitoring your Java applications.

Step 1: Install VisualVM

VisualVM comes bundled with the JDK (Java Development Kit) in JDK 8 and earlier versions. For JDK 9 and later, you need to download and install it separately.

1. Download VisualVM:
• Visit the VisualVM website and download the appropriate version for your operating system.
2. Install VisualVM:
• Follow the installation instructions specific to your operating system.

Step 2: Start VisualVM

1. Locate VisualVM:
• For JDK 8 and earlier: jdk/bin/jvisualvm
• For downloaded version: Run the visualvm executable from the installation directory.
2. Start VisualVM:
• On Windows: Double-click the visualvm.exe file.
• On macOS/Linux: Open a terminal and run the visualvm command.

Step 3: Configure VisualVM

1. Add JMX Connection (if needed):
• If your application runs on a remote machine or requires JMX (Java Management Extensions) to connect, add a JMX connection.
• Go to File > Add JMX Connection and provide the necessary connection details.

Step 4: Monitor a Java Application

1. Open VisualVM:
• Once VisualVM is open, you will see a list of local Java applications running on your machine under the "Local" node.
2. Select an Application:
• Click on the application you want to monitor. VisualVM will open several tabs with different monitoring tools.

Step 5: Use Monitoring Tools

VisualVM provides several built-in tools for monitoring:

1. Overview:
• Provides a high-level summary of the application's performance, including heap size, thread count, and CPU usage.
2. Monitor:
• Shows real-time graphs of heap and non-heap memory usage, classes loaded/unloaded, and CPU usage.
• For remote monitoring:

JVM Arguments that needs to be added in eclipse or ant file or command prompt for remote monitoring: -Dcom.sun.management.jmxremote.port=7878 -Dcom.sun.management.jmxremote.ssl=false -Dcom.sun.management.jmxremote.authenticate=false"

 

3. Threads:
• Displays a list of active threads and their states. You can take thread dumps to analyze thread activity.
4. Sampler:
• Allows you to sample CPU and memory usage. This helps in identifying performance bottlenecks.
5. Profiler:
• Provides detailed profiling information about CPU and memory usage. You can start and stop profiling sessions to gather data.
6. Heap Dump:
• Allows you to take a heap dump to analyze memory usage. This is useful for identifying memory leaks.

Example: Monitoring a Sample Application

Here’s a step-by-step example of how to monitor a sample Java application using VisualVM:

1. Start a Sample Application:
• Create a simple Java application and run it.

java

package com.jconsole.example;     public class ThreadProcess implements Runnable{    @Override    public void run() {     int count=0;     while(true){      System.out.println("Count method test by JConsole"+count++);   }  } }     B>   package com.jconsole.example;     public class ThreadProcessDemo {      public static void main(String[] args) {      ThreadProcess tProcess=new ThreadProcess();      Thread t=new Thread(tProcess);      t.start();      System.out.println("Main Thread is running");  } }

 

Compile and run the application:

Sh

javac ThreadProcessDemo.java ThreadProcess.java   ThreadProcessDemo.java

 

2. Open VisualVM:
• Start VisualVM and locate your running ThreadProcessDemo under the "Local" node.
3. Monitor the Application:
• Click on ThreadProcessDemo. VisualVM will open various tabs for monitoring.
4. Analyze Data:
• Use the Monitor tab to observe real-time memory and CPU usage.
• Use the Threads tab to view active threads and take thread dumps.
• Use the Sampler and Profiler tabs to identify performance bottlenecks.

VisualVM monitoring

 

 

Tips for Effective Monitoring

• Regular Monitoring: Regularly monitor your applications, especially during load tests and production runs, to identify and resolve performance issues early.
• Profiling: Use the profiler to get detailed insights into CPU and memory usage. Be aware that profiling can impact application performance.
• Thread Dumps: Take thread dumps when you encounter issues like deadlocks or high CPU usage. Analyze the thread dumps to identify the root cause.
• Heap Dumps: Use heap dumps to identify memory leaks and understand memory usage patterns. Analyze heap dumps with tools like VisualVM or Eclipse MAT (Memory Analyzer Tool).

Conclusion

VisualVM is a versatile and powerful tool for monitoring and troubleshooting Java applications. By following the steps above, you can effectively use VisualVM to gain insights into your application's performance and identify potential issues. Regular monitoring with VisualVM can help you maintain optimal performance and stability for your Java applications.