8336254: Virtual thread implementation + test updates

Reviewed-by: sspitsyn, kevinw

Author: Alan Bateman

make/test/JtregNativeHotspot.gmk

@@ -871,6 +871,7 @@ ifeq ($(call isTargetOs, windows), true)
   BUILD_HOTSPOT_JTREG_EXECUTABLES_CFLAGS_exeFPRegs := -MT
   BUILD_HOTSPOT_JTREG_EXCLUDE += exesigtest.c libterminatedThread.c libTestJNI.c libCompleteExit.c libMonitorWithDeadObjectTest.c libTestPsig.c exeGetCreatedJavaVMs.c
   BUILD_HOTSPOT_JTREG_LIBRARIES_JDK_LIBS_libnativeStack := java.base:libjvm
+  BUILD_HOTSPOT_JTREG_LIBRARIES_JDK_LIBS_libVThreadEventTest := java.base:libjvm
 else
   BUILD_HOTSPOT_JTREG_LIBRARIES_LIBS_libbootclssearch_agent += -lpthread
   BUILD_HOTSPOT_JTREG_LIBRARIES_LIBS_libsystemclssearch_agent += -lpthread
@@ -1509,6 +1510,7 @@ else
   BUILD_HOTSPOT_JTREG_LIBRARIES_LIBS_libCompleteExit += -lpthread
   BUILD_HOTSPOT_JTREG_LIBRARIES_LIBS_libMonitorWithDeadObjectTest += -lpthread
   BUILD_HOTSPOT_JTREG_LIBRARIES_LIBS_libnativeStack += -lpthread
+  BUILD_HOTSPOT_JTREG_LIBRARIES_JDK_LIBS_libVThreadEventTest := java.base:libjvm
   BUILD_HOTSPOT_JTREG_EXECUTABLES_LIBS_exeGetCreatedJavaVMs := -lpthread
   BUILD_HOTSPOT_JTREG_EXECUTABLES_JDK_LIBS_exeGetCreatedJavaVMs := java.base:libjvm
 

src/java.base/share/classes/java/lang/System.java

@@ -65,7 +65,6 @@
 import java.util.ResourceBundle;
 import java.util.Set;
 import java.util.WeakHashMap;
-import java.util.concurrent.Callable;
 import java.util.function.Supplier;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.stream.Stream;
@@ -2264,6 +2263,7 @@ private static class Out extends FileOutputStream {
             super(fd);
         }
 
+        @Override
         public void write(int b) throws IOException {
             boolean attempted = Blocker.begin();
             try {
@@ -2677,14 +2677,6 @@ public Thread currentCarrierThread() {
                 return Thread.currentCarrierThread();
             }
 
-            public <V> V executeOnCarrierThread(Callable<V> task) throws Exception {
-                if (Thread.currentThread() instanceof VirtualThread vthread) {
-                    return vthread.executeOnCarrierThread(task);
-                } else {
-                    return task.call();
-                }
-            }
-
             public <T> T getCarrierThreadLocal(CarrierThreadLocal<T> local) {
                 return ((ThreadLocal<T>)local).getCarrierThreadLocal();
             }