MBean access to the PID

Summary

Introduced new API java.lang.management.RuntimeMXBean.getPid to get process ID of running Java virtual machine.

Problem

The platform MBean does not provide any API to get the process ID of a running JVM. Some JMX tools rely on the hotspot implementation of RuntimeMXBean::getName which returns < pid >@< hostname >.

Solution

Introduced new API java.lang.management.RuntimeMXBean.getPid, so that JMX tools can directly get process ID instead of relying on the implementation detail, RuntimeMXBean#getName().split("@")[0].

Specification

  --- old/src/java.management/share/classes/java/lang/management/RuntimeMXBean.java 2017-11-02 15:03:57.177210581 +0530
+++ new/src/java.management/share/classes/java/lang/management/RuntimeMXBean.java   2017-11-02 15:03:56.993210581 +0530
@@ -25,6 +25,9 @@

 package java.lang.management;

+import java.security.AccessController;
+import java.security.PrivilegedAction;
+
 /**
  * The management interface for the runtime system of
  * the Java virtual machine.
@@ -61,6 +64,22 @@
  */
 public interface RuntimeMXBean extends PlatformManagedObject {
     /**
+     * Returns the {@linkplain ProcessHandle#pid process ID} representing
+     * the running Java virtual machine.
+     *
+     * @implSpec The default implementation returns {@link ProcessHandle#pid process ID}
+     * of the {@linkplain ProcessHandle#current current process}.
+     *
+     * @return the process ID representing the running Java virtual machine.
+     *
+     * @since 10
+     */
+    public default long getPid() {
+        return AccessController.doPrivileged((PrivilegedAction<Long>)
+                () -> ProcessHandle.current().pid());
+    }
+
+    /**
      * Returns the name representing the running Java virtual machine.
      * The returned name string can be any arbitrary string and
      * a Java virtual machine implementation can choose