Summary

Modify the statements in GetCurrentThreadCpuTime and GetThreadCpuTime that prohibit calling on virtual threads, so that virtual threads are allowed.

Problem

JDK-8302615 modified GetCurrentThreadCpuTime and GetThreadCpuTime so that calling them on virtual threads changed from being not supported to being optional. However, both functions still contain a sentence that declares their use with virtual threads is prohibited. These sentence need to be updated to avoid a conflict in the spec.

Solution

Two sentences in the JVM TI spec need adjustment. In the functions GetCurrentThreadCpuTime and GetThreadCpuTime, the fragment:

The current thread may not be a virtual thread. Otherwise, the error code ...

is replaced with:

An implementation is not required to support this function when the current thread is a virtual thread, in which case ...

Specification

The specification diff is:

diff --git a/src/hotspot/share/prims/jvmti.xml b/src/hotspot/share/prims/jvmti.xml
index 5f68fc9a7a9..b0c045f9322 100644
--- a/src/hotspot/share/prims/jvmti.xml
+++ b/src/hotspot/share/prims/jvmti.xml
@@ -11022,7 +11022,8 @@ myInit() {
             the current thread (see
             <functionlink id="GetCurrentThreadCpuTimerInfo"/> vs
             <functionlink id="GetThreadCpuTimerInfo"/>).
-            The current thread may not be a virtual thread. Otherwise, the error code
+            An implementation is not required to support this function
+            when the current thread is a virtual thread, in which case 
             <errorlink id="JVMTI_ERROR_UNSUPPORTED_OPERATION"></errorlink> will be returned.
             On many platforms this call will be equivalent to:
 <example>
@@ -11125,7 +11126,8 @@ myInit() {
           <jthread null="current" impl="noconvert"/>
             <description>
               The thread to query.
-              The <code>thread</code> may not be a virtual thread. Otherwise, the error code
+              An implementation is not required to support this function
+              when the given thread is a virtual thread, in which case
                <errorlink id="JVMTI_ERROR_UNSUPPORTED_OPERATION"></errorlink> will be returned.
              </description>
         </param>