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

Question

I get AttachNotSupportedException while running jmockit tests on linux (ubuntu 64bit). Java version is 1.7.0_51. This JDK is from Oracle. Tests are run using ant(that probably is not relevant)

See the stack trace.

[junit] [junit] java.lang.RuntimeException: com.sun.tools.attach.AttachNotSupportedException: Unable to open socket file: target process not responding or HotSpot VM not loaded [junit] at mockit.internal.startup.JDK6AgentLoader.getVirtualMachineImplementationFromEmbeddedOnes(JDK6AgentLoader.java:89) [junit] at mockit.internal.startup.JDK6AgentLoader.loadAgent(JDK6AgentLoader.java:54) [junit] at mockit.internal.startup.AgentInitialization.initializeAccordingToJDKVersion(AgentInitialization.java:21) [junit] at mockit.internal.startup.Startup.initializeIfNeeded(Startup.java:136) [junit] at mockit.internal.startup.Startup.initializeIfPossible(Startup.java:169) [junit] at junit.framework.TestResult.<clinit>(TestResult.java:15) [junit] at org.apache.tools.ant.taskdefs.optional.junit.JUnitTestRunner.run(JUnitTestRunner.java:356) [junit] at org.apache.tools.ant.taskdefs.optional.junit.JUnitTestRunner.launch(JUnitTestRunner.java:1165) [junit] at org.apache.tools.ant.taskdefs.optional.junit.JUnitTestRunner.main(JUnitTestRunner.java:1016) [junit] Caused by: com.sun.tools.attach.AttachNotSupportedException: Unable to open socket file: target process not responding or HotSpot VM not loaded [junit] at sun.tools.attach.LinuxVirtualMachine.<init>(LinuxVirtualMachine.java:106) [junit] at mockit.internal.startup.JDK6AgentLoader.getVirtualMachineImplementationFromEmbeddedOnes(JDK6AgentLoader.java:79) [junit] ... 8 more [junit] Exception in thread "main" java.lang.ExceptionInInitializerError [junit] at org.apache.tools.ant.taskdefs.optional.junit.JUnitTestRunner.run(JUnitTestRunner.java:356) [junit] at org.apache.tools.ant.taskdefs.optional.junit.JUnitTestRunner.launch(JUnitTestRunner.java:1165) [junit] at org.apache.tools.ant.taskdefs.optional.junit.JUnitTestRunner.main(JUnitTestRunner.java:1016) [junit] Caused by: java.lang.RuntimeException: com.sun.tools.attach.AttachNotSupportedException: Unable to open socket file: target process not responding or HotSpot VM not loaded [junit] at mockit.internal.startup.JDK6AgentLoader.getVirtualMachineImplementationFromEmbeddedOnes(JDK6AgentLoader.java:89) [junit] at mockit.internal.startup.JDK6AgentLoader.loadAgent(JDK6AgentLoader.java:54) [junit] at mockit.internal.startup.AgentInitialization.initializeAccordingToJDKVersion(AgentInitialization.java:21) [junit] at mockit.internal.startup.Startup.initializeIfNeeded(Startup.java:136) [junit] at mockit.internal.startup.Startup.initializeIfPossible(Startup.java:169) [junit] at junit.framework.TestResult.<clinit>(TestResult.java:15) [junit] ... 3 more [junit] Caused by: com.sun.tools.attach.AttachNotSupportedException: Unable to open socket file: target process not responding or HotSpot VM not loaded [junit] at sun.tools.attach.LinuxVirtualMachine.<init>(LinuxVirtualMachine.java:106) [junit] at mockit.internal.startup.JDK6AgentLoader.getVirtualMachineImplementationFromEmbeddedOnes(JDK6AgentLoader.java:79) [junit] ... 8 more [junit] Running chs.caf.cap

It appears to be related to AttachNotSupportedException while running jMockit tests on IBM JRE. This however is on IBM jre.

There is a great answer: stackoverflow.com/questions/26140182/… — gavenkoa
– gavenkoa, Commented Dec 21, 2020 at 20:41
In my case it was due to launching jcmd with a different user from the one owning the running process. One of the cases described into stackoverflow.com/a/35963059/1996150 — Mariano Paniga
– Mariano Paniga, Commented Feb 8, 2023 at 13:36

message · Accepted Answer · 2023-02-19 18:47:06Z

60

I had the same issue while I was trying to dump threads using jcmd. I was getting same error message even though I was running jcmd under the root user.

You need to run jcmd <pid> Thread.print under the same user as java process has, otherwise your connections will be dropped. Java doesn't care if you are root or not.

So basically:

sudo -u <java_process_user> jcmd <pid> Thread.print

edited Feb 19, 2023 at 18:47

answered Jul 24, 2018 at 21:11

message

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3 Comments

egelev Over a year ago

Thank you. This was exactly what I was looking for. However, with Thread.dump I get the following error java.lang.IllegalArgumentException: Unknown diagnostic command. I had to use Thread.print.

Brent Writes Code Over a year ago

+100 THANK YOU VERY MUCH

SUMIT Over a year ago

still facing the issue on java 8 (1.8.0_192).

Jayan · Accepted Answer · 2014-08-22 03:16:01Z

Work around for now.

Adding '-XX:+StartAttachListener' to jvm argument fixed the issue.

A similar issue is discussed here at https://code.google.com/p/jmockit/issues/detail?id=136 and http://mail.openjdk.java.net/pipermail/macosx-port-dev/2013-October/006098.html (which talks about a possible regression in jdk7 build)

Apparently, it's a bug in the Attach API implementation in this version of the Oracle JRE for Linux. It's likely already fixed in 1.7.0_60 and above.
This was actually still an issue for me in 1.8.0_131 on Linux

Erik Finnman · Accepted Answer · 2018-03-07 07:27:56Z

Like @bbarker, I got the same error but on JDK 1.8.0_161 using the Linux subsystem in Windows 10 ("Bash on Ubuntu on Windows"). Configuring the Surefire plugin with the JVM argument mentioned above fixed the issue for me as well:

 <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-surefire-plugin</artifactId> <version>2.21.0</version> <configuration> <argLine>-XX:+StartAttachListener</argLine> </configuration> </plugin>

Running the tests from a "normal" Windows command prompt works without the above, though.

Bằng Rikimaru · Accepted Answer · 2025-06-23 09:31:12Z

In my case, I have tomcat9 running as a system service (managedby systemd). Then, I need to do like below:

the issue is due to

/etc/systemd/system/multi-user.target.wants/tomcat9.service

has PrivateTmp=yes

hence, the pid file is created in private folder in /tmp like this

/tmp/systemd-private-7f6b4999adf04e82a776c41b6c6fa0c4-tomcat9.service-1ZW0Hg/tmp/.java_pid3856662

and no java tool can access to it.

So the easiest option is to set PrivateTmp=no then it will create pid in /tmp, e.g.

ls -la /tmp | grep '.java_pid' srw------- 1 tomcat tomcat 0 Jun 23 11:15 .java_pid3857180

then can extract heap dump from:

sudo -u tomcat jcmd 3857180 GC.heap_dump /tmp/heapdump.hprof 3857180: Dumping heap to /tmp/heapdump.hprof ... Heap dump file created [39099431 bytes in 0.300 secs]

Manas · Accepted Answer · 2020-06-22 16:54:26Z

I also got a similar problem when tried to check for Thread Deadlock. You can also use the command jcmd <PID> Thread.print to print the thread dump on the console and check if the program has a deadlock. You can check my answer with steps on Deadlock detection in Java

elhose · Accepted Answer · 2021-04-22 08:57:34Z

I got similar issue, in my case, changing JDK vendor from OPENJ9 to OPENJDK resolved the issue.

g o l d · Accepted Answer · 2024-05-07 14:25:52Z

0

The -F option fixed this for me. jcmd -F Thread.print

Can use this as well: jmap -dump:live,format=b,file=heapdump.hprof -F

answered May 7, 2024 at 14:25

g o l d

1

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