Acess memory in task manager using java

Question

I would like to consult memory used at the instant by MySQL, MongoDB and Neo4j using java. I've searched for it, but didn't found anything relevant. My OS is Windows and i am using Eclipse. Thanks

Answer 1

I just came up with a java code template to run a windows command, you need to run tasklist command to have all the process table with all information including memory used by each process.

Here is the code:

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;

public class TaskMemory {

    public static void main(String[] args) {
        Process process = null;
        if (System.getProperty("os.name").toLowerCase().indexOf("windows") >= 0) {
            String command = "cmd.exe /c tasklist";
            try {
                process = Runtime.getRuntime().exec(command);
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        if (process != null) {
            InputStream good = process.getInputStream();
            BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(good));
            StringBuffer sb = new StringBuffer();
            String str;

            try {
                for(int i = 0; i < 3; i++){
                    if((str = bufferedReader.readLine()) != null){
                        sb.append(str).append("\n");
                    }
                }
                while ((str = bufferedReader.readLine()) != null) {
                    if(str.matches("(.*)mysqld.exe(.*)|(.*)mongod.exe(.*)|(.*)neo4j.exe(.*)")){
                        sb.append(str).append("\n");
                    }
                }
                if (sb.toString().trim().isEmpty()) {
                    InputStream error = process.getErrorStream();
                    bufferedReader = new BufferedReader(new InputStreamReader(error));

                    while ((str = bufferedReader.readLine()) != null) {
                        sb.append(str).append("\n");
                    }
                }
                System.out.println(sb.toString());
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

    }

}

I just edit my solution so that it can grab just mysql, mongodb and neo4j process.

Answer 2

There is nothing that I know of in the API of the JDK that can query processes of the host operating system. Hence the only option that I can think of is to use class ProcessBuilder to execute a host OS command.

Since you state that your OS is Windows, the following PowerShell command will output the process name and memory usage of your selected processes.

Get-Process | Where-Object {$_.ProcessName -in 'MySQL','MongoDB','Neo4j'} | Select-Object -Property 'ProcessName','WorkingSet' | Format-Table -HideTableHeaders

Note that I am not sure about the process names because I don't use any of MySQL, MongoDB or Neo4j. I assume that you do know the correct process names so remember to correct them in the above command before you run it.

The below code uses ProcessBuilder to run the above [PowerShell] command and redirects the command output to System.out

import java.io.IOException;
import java.lang.ProcessBuilder;

public class PrcBldT2 {

    public static void main(String[] args) {
        ProcessBuilder pb = new ProcessBuilder("C:\\Windows\\System32\\WindowsPowerShell\\v1.0\\powershell.exe",
                "Get-Process | Where-Object {$_.ProcessName -in 'eclipse','oracle'} | Select-Object -Property 'ProcessName','WorkingSet' | Format-Table -HideTableHeaders");

        pb.redirectError(ProcessBuilder.Redirect.INHERIT);
        pb.redirectOutput(ProcessBuilder.Redirect.INHERIT);
        try {
            Process p = pb.start();
            int result = p.waitFor();
            System.out.println("Exit status = " + result);
        }
        catch (IOException | InterruptedException x) {
            x.printStackTrace();
        }
    }
}