Summary

Make JVM TI functions GetCurrentThreadCpuTime and GetThreadCpuTime optional for virtual threads.

Problem

The following two JVM TI timer functions are currently specified to return JVMTI_ERROR_UNSUPPORTED_OPERATION for virtual threads:

• GetCurrentThreadCpuTime
• GetThreadCpuTime

The support of these two functions must be specified as optional for virtual threads.

Solution

Each function spec should have the following description for JVMTI_ERROR_UNSUPPORTED_OPERATION error:

is a virtual thread and the implementation does not
support getting the thread CPU time of a virtual thread.

Specification

Here is the suggested JVM TI spec patch:

diff --git a/src/hotspot/share/prims/jvmti.xml b/src/hotspot/share/prims/jvmti.xml
index 4baaca503c0..5f68fc9a7a9 100644
--- a/src/hotspot/share/prims/jvmti.xml
+++ b/src/hotspot/share/prims/jvmti.xml
@@ -11058,7 +11058,8 @@ myInit() {
       </parameters>
       <errors>
         <error id="JVMTI_ERROR_UNSUPPORTED_OPERATION">
-          Current thread is a virtual thread.
+          The current thread is a virtual thread and the implementation does not support
+          getting the current thread CPU time when the current thread is a virtual thread.
         </error>
       </errors>
     </function>
@@ -11140,7 +11141,8 @@ myInit() {
       </parameters>
       <errors>
         <error id="JVMTI_ERROR_UNSUPPORTED_OPERATION">
-          <paramlink id="thread"/> is a virtual thread.
+          <paramlink id="thread"/> is a virtual thread and the implementation does not
+          support getting the thread CPU time of a virtual thread.
         </error>
       </errors>
     </function>