--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/runtime/serviceThread.cpp	Wed Feb 02 14:38:01 2011 -0500
@@ -0,0 +1,122 @@
+/*
+ * Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "runtime/interfaceSupport.hpp"
+#include "runtime/javaCalls.hpp"
+#include "runtime/serviceThread.hpp"
+#include "runtime/mutexLocker.hpp"
+#include "prims/jvmtiImpl.hpp"
+
+ServiceThread* ServiceThread::_instance = NULL;
+
+void ServiceThread::initialize() {
+  EXCEPTION_MARK;
+
+  instanceKlassHandle klass (THREAD,  SystemDictionary::Thread_klass());
+  instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
+
+  const char* name = JDK_Version::is_gte_jdk17x_version() ?
+      "Service Thread" : "Low Memory Detector";
+
+  Handle string = java_lang_String::create_from_str(name, CHECK);
+
+  // Initialize thread_oop to put it into the system threadGroup
+  Handle thread_group (THREAD, Universe::system_thread_group());
+  JavaValue result(T_VOID);
+  JavaCalls::call_special(&result, thread_oop,
+                          klass,
+                          vmSymbols::object_initializer_name(),
+                          vmSymbols::threadgroup_string_void_signature(),
+                          thread_group,
+                          string,
+                          CHECK);
+
+  {
+    MutexLocker mu(Threads_lock);
+    ServiceThread* thread =  new ServiceThread(&service_thread_entry);
+
+    // At this point it may be possible that no osthread was created for the
+    // JavaThread due to lack of memory. We would have to throw an exception
+    // in that case. However, since this must work and we do not allow
+    // exceptions anyway, check and abort if this fails.
+    if (thread == NULL || thread->osthread() == NULL) {
+      vm_exit_during_initialization("java.lang.OutOfMemoryError",
+                                    "unable to create new native thread");
+    }
+
+    java_lang_Thread::set_thread(thread_oop(), thread);
+    java_lang_Thread::set_priority(thread_oop(), NearMaxPriority);
+    java_lang_Thread::set_daemon(thread_oop());
+    thread->set_threadObj(thread_oop());
+
+    Threads::add(thread);
+    Thread::start(thread);
+
+    _instance = thread;
+  }
+}
+
+void ServiceThread::service_thread_entry(JavaThread* jt, TRAPS) {
+  while (true) {
+    bool sensors_changed = false;
+    bool has_jvmti_events = false;
+    JvmtiDeferredEvent jvmti_event;
+    {
+      // Need state transition ThreadBlockInVM so that this thread
+      // will be handled by safepoint correctly when this thread is
+      // notified at a safepoint.
+
+      // This ThreadBlockInVM object is not also considered to be
+      // suspend-equivalent because ServiceThread is not visible to
+      // external suspension.
+
+      ThreadBlockInVM tbivm(jt);
+
+      MutexLockerEx ml(Service_lock, Mutex::_no_safepoint_check_flag);
+      while (!(sensors_changed = LowMemoryDetector::has_pending_requests()) &&
+             !(has_jvmti_events = JvmtiDeferredEventQueue::has_events())) {
+        // wait until one of the sensors has pending requests, or there is a
+        // pending JVMTI event to post
+        Service_lock->wait(Mutex::_no_safepoint_check_flag);
+      }
+
+      if (has_jvmti_events) {
+        jvmti_event = JvmtiDeferredEventQueue::dequeue();
+      }
+    }
+
+    if (has_jvmti_events) {
+      jvmti_event.post();
+    }
+
+    if (sensors_changed) {
+      LowMemoryDetector::process_sensor_changes(jt);
+    }
+  }
+}
+
+bool ServiceThread::is_service_thread(Thread* thread) {
+  return thread == _instance;
+}