CODEWITHSUNDEEP
javalinuxsocketsjvmagent
Joe
Joe

Reputation: 1342

Java - AttachNotSupportedException: Unable to open socket file: HotSpot VM not loaded

When attempting to attach an agent jar file onto another process running in java, I have came across the exception:

com.sun.tools.attach.AttachNotSupportedException: Unable to open socket file: target process not responding or HotSpot VM not loaded

I was running linux, with java Oracle JDK 8_101, however after answering this question I've realized the O.S does not matter for the cause of this problem.

Edit: Answer:

If you encounter this problem, the reason it occured for me is because I was launching a program from a different JVM, other than the default JVM specified for the system.

i.e)

Program A (The launcher), is running on JVM-1 (JDK_8_1 for example, or JDK_8_1/jdk/jre).

Program A (The launcher), creates a process with java -jar programB.jar

Program B (The target), is running on the system's default JVM, JVM-2 (JDK_8_2 for example, or JDK_8_2/jre).

Program A (The launcher) CANNOT attatch to Program B (The target), because the JVM Program A (The launcher) is running on, does not match the JVM of which Program B (The target) is running on, thus throwing the com.sun.tools.attach.AttachNotSupportedException:

Upvotes: 3

Views: 11391

Answers (2)

Sergej Isbrecht
Sergej Isbrecht

Reputation: 4002

Problem: different user executing jcmd

It might happen, that the user calling jcmd is different, than the user running the proccess.

Example:

  • user invoking jcmd as root
  • user running JVM as fancyUser

Solution:

On Linux try to run jcmd with the same user, as the process is running.

When you have such a scenario, you will get given error.

Problem: AppArmor

When AppArmor is enabled for running JVM instance, which restricts sys-calls, it might be the case, that opening a socket-connection is restricted.

Solution:

Change AppArmor-Profile for process

Upvotes: 5

apangin
apangin

Reputation: 98334

Common reasons for this problem:

  • Attach socket /tmp/.java_pid1234 has been removed (e.g. by a scheduled job that periodically cleans up /tmp).
  • Target JVM is started with -XX:+DisableAttachMechanism option.
  • Garbage Collection or other long VM operation (e.g. Heap Dump) is in progress.
  • JVM cannot reach safepoint within attach timeout. This happens rarely, and the problem is typically intermittent.

Upvotes: 10

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