Hello Egor,

By default, SA checks for the exact match of the version between the debugger 
and the debuggee.  If you want SA to ignore the version, you need to provide 
the "-Dsun.jvm.hotspot.runtime.VM.disableVersionCheck" option to the java 
launcher from the command line.  This is the case even if you are not using the 
debug server.  However since 'jstack' and similar tools don’t  take the "-D" 
option of java, you can invoke it as follows:

java   -cp <jdk>/lib/sa-jdi.jar   
-Dsun.jvm.hotspot.runtime.VM.disableVersionCheck   sun.jvm.hotspot.tools.JStack 
  localhost

If you invoke the SA tools with this option, you will get a warning that the 
version check has been disabled.

Example:
$ <jdk>/bin/java -cp <jdk>/lib/sa-jdi.jar 
-Dsun.jvm.hotspot.runtime.VM.disableVersionCheck sun.jvm.hotspot.tools.JStack 
localhost
Attaching to remote server localhost, please wait...
WARNING: You have disabled SA and VM version check. You may be using 
incompatible version of SA and you may see unexpected results.
Debugger attached successfully.
Server compiler detected.
JVM version is 25.121-b13
Deadlock Detection:

No deadlocks found.

Thread t@ 2804: (state = BLOCKED)


Thread t@ 2803: (state = BLOCKED)
 - java.lang.Object.wait(long) @bci=0 (Interpreted frame)
 - java.lang.ref.ReferenceQueue.remove(long) @bci=59, line=143 (Interpreted 
frame)
 - java.lang.ref.ReferenceQueue.remove() @bci=2, line=164 (Interpreted frame)
 - java.lang.ref.Finalizer$FinalizerThread.run() @bci=36, line=209 (Interpreted 
frame)


Thread t@ 2802: (state = BLOCKED)
 - java.lang.Object.wait(long) @bci=0 (Interpreted frame)
 - java.lang.Object.wait() @bci=2, line=502 (Interpreted frame)
 - java.lang.ref.Reference.tryHandlePending(boolean) @bci=54, line=191 
(Interpreted frame)
 - java.lang.ref.Reference$ReferenceHandler.run() @bci=1, line=153 (Interpreted 
frame)


Thread t@ 2798: (state = BLOCKED)
 - java.lang.Thread.sleep(long) @bci=0 (Interpreted frame)
 - HelloWorld.main(java.lang.String[]) @bci=72, line=15 (Interpreted frame)


Hope this helps.

Thanks,
Sharath


-----Original Message-----
From: Egor Ushakov [mailto:egor.usha...@jetbrains.com] 
Sent: Monday, August 20, 2018 3:42 PM
To: serviceability-dev@openjdk.java.net serviceability-dev@openjdk.java.net
Subject: SA Debug attach to another jvm version possible?

Hi all,

documentation for SA Debug Server Attaching Connector here: 
https://docs.oracle.com/javase/8/docs/technotes/guides/jpda/conninv.html#Connectors
states that the SADebugServer has to run on the same vm version as the debugee 
process, but "the debugger does not have to be the same bit size and version."
However any attempts to connect from another version fail with 
sun.jvm.hotspot.runtime.VMVersionMismatchException.

Please help, what do I do wrong (locally for simplicity):
- start the debugee process with jdk1.8.0_162  - get the PID
- start "jdk1.8.0_162\bin>jsadebugd.exe PID" - all starts well
- trying to attach jstack, jdb or whatever from another version:
jdk1.8.0_152\bin>jstack localhost
Attaching to remote server localhost, please wait...
Error attaching to remote server: 
sun.jvm.hotspot.runtime.VMVersionMismatchException: Supported versions are 
25.152-b16. Target VM is 25.162-b12
sun.jvm.hotspot.debugger.DebuggerException: 
sun.jvm.hotspot.runtime.VMVersionMismatchException: Supported versions are 
25.152-b16. Target VM is 25.162-b12

jdk1.8.0_152\bin>jdb -connect
"sun.jvm.hotspot.jdi.SADebugServerAttachingConnector:debugServerName=localhost"
java.io.IOException
         at
sun.jvm.hotspot.jdi.SADebugServerAttachingConnector.attach(SADebugServerAttachingConnector.java:106)
         at
com.sun.tools.example.debug.tty.VMConnection.attachTarget(VMConnection.java:519)
         at
com.sun.tools.example.debug.tty.VMConnection.open(VMConnection.java:328)
         at com.sun.tools.example.debug.tty.Env.init(Env.java:63)
         at com.sun.tools.example.debug.tty.TTY.main(TTY.java:1082)
Caused by: java.lang.reflect.InvocationTargetException
         at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
         at
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
         at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
         at java.lang.reflect.Method.invoke(Method.java:498)
         at
sun.jvm.hotspot.jdi.SADebugServerAttachingConnector.createVirtualMachine(SADebugServerAttachingConnector.java:72)
         at
sun.jvm.hotspot.jdi.SADebugServerAttachingConnector.attach(SADebugServerAttachingConnector.java:91)
         ... 4 more
Caused by: sun.jvm.hotspot.debugger.DebuggerException: 
sun.jvm.hotspot.runtime.VMVersionMismatchException: Supported versions are 
25.152-b16. Target VM is 25.162-b12
         at sun.jvm.hotspot.HotSpotAgent.setupVM(HotSpotAgent.java:435)
         at sun.jvm.hotspot.HotSpotAgent.go(HotSpotAgent.java:305)
         at sun.jvm.hotspot.HotSpotAgent.attach(HotSpotAgent.java:183)
         at
sun.jvm.hotspot.jdi.VirtualMachineImpl.createVirtualMachineForServer(VirtualMachineImpl.java:241)
         ... 10 more
Caused by: sun.jvm.hotspot.runtime.VMVersionMismatchException: Supported 
versions are 25.152-b16. Target VM is 25.162-b12
         at sun.jvm.hotspot.runtime.VM.checkVMVersion(VM.java:227)
         at sun.jvm.hotspot.runtime.VM.<init>(VM.java:294)
         at sun.jvm.hotspot.runtime.VM.initialize(VM.java:370)
         at sun.jvm.hotspot.HotSpotAgent.setupVM(HotSpotAgent.java:431)
         ... 13 more

Thanks!

--
Egor Ushakov
Software Developer
JetBrains
http://www.jetbrains.com
The Drive to Develop

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