How to find list of java agents attached with a running JVM?

java

Solution

(This question is similar to Can a JVM retrieve a list of agents that have been loaded into it via the attach api?). For the sake of completeness, I will add this answer to both questions.)

Checking agents that have been added via command-line:

If you are interested in agents that were added to using the command line interface, you can check them by using the `RuntimeMXBean`.

This bean offers the method `getInputArguments`, which returns a list of all VM arguments. You can iterate over the list and check it for the arguments `agentpath`, `agentlib` and `javaagent`, similar to the following code snippet:

    RuntimeMXBean runtimeMXBean = ManagementFactory.getRuntimeMXBean();
    List<String> jvmArgs = runtimeMXBean.getInputArguments();
    System.out.println("JVM arguments:");
    for (String arg : jvmArgs) {
        if (arg.startsWith("-agentpath") || arg.startsWith("-agentlib") || arg.startsWith("-javaagent")) {
            System.out.print("***** ");
        }

        System.out.print(arg);

        if (arg.startsWith("-agentpath") || arg.startsWith("-agentlib") || arg.startsWith("-javaagent")) {
            System.out.println(" *****");
        } else {
            System.out.println();
        }
    }

Checking agents that have been added using the Attach API:

If you are interested in the agents that have been added to an application at run time using the Attach API, you can use the `DiagnosticCommandMBean`. This bean offers a diagnostic command called `vmDynlib`, a parameterless method that returns a `String` that list all dynamically loaded libraries.

Here is a snippet that prints all dynamic libraries loaded by the application's VM:

ObjectName diagnosticsCommandName = new ObjectName("com.sun.management:type=DiagnosticCommand");
String operationName = "vmDynlibs";
String result = (String) ManagementFactory.getPlatformMBeanServer().invoke(diagnosticsCommandName, operationName, null, null);
System.out.println(result);

This results in an output similar to this one:

Dynamic libraries:
0x00007ff7b8600000 - 0x00007ff7b8637000     C:\Program Files\Java\jdk1.8.0_181\bin\java.exe
0x00007ffdfeb00000 - 0x00007ffdfecf0000     C:\WINDOWS\SYSTEM32\ntdll.dll
0x00007ffdfe300000 - 0x00007ffdfe3b2000     C:\WINDOWS\System32\KERNEL32.DLL
0x00007ffdfbb30000 - 0x00007ffdfbdd3000     C:\WINDOWS\System32\KERNELBASE.dll
0x00007ffdfe950000 - 0x00007ffdfe9f3000     C:\WINDOWS\System32\ADVAPI32.dll
...

You can then check this text if it contains a certain `.so` or `.dll` file.

The same inspection can be performed non-programatically.

For this, you can use the `jconsole` tool.

Connect to a VM, switch to the tab `MBeans`, select `com.sun.management`, select `DiagnosticCommand`, select `Operations`, select `vmDynlibs`, and invoke it.

In the image, you can see one of my test agents attached to the application. The agent was attached using the `Attach API`, thus this agent would not be visible by checking the application's command line arguments (i.e., no `-agentpath=...` would be seen on the arguments) but is only visible as dynamically loaded library.

Problem

Original source