--- a/src/os/bsd/vm/os_bsd.cpp	Sat Aug 20 11:56:24 2016 -0700
+++ b/src/os/bsd/vm/os_bsd.cpp	Thu Apr 13 17:18:04 2017 -0400
@@ -163,6 +163,7 @@
 #endif
 pthread_t os::Bsd::_main_thread;
 int os::Bsd::_page_size = -1;
+pthread_condattr_t os::Bsd::_condattr[1];
 #ifndef _ALLBSD_SOURCE
 bool os::Bsd::_is_floating_stack = false;
 bool os::Bsd::_is_NPTL = false;
@@ -1633,7 +1634,10 @@
       ::clock_gettime(CLOCK_MONOTONIC, &tp)  == 0) {
     // yes, monotonic clock is supported
     _clock_gettime = ::clock_gettime;
-  }
+    return;
+  }
+  warning("No monotonic clock was available - timed services may " \
+          "be adversely affected if the time-of-day clock changes");
 }
 #else
 void os::Bsd::clock_init() {
@@ -1719,7 +1723,7 @@
 jlong os::javaTimeNanos() {
   if (Bsd::supports_monotonic_clock()) {
     struct timespec tp;
-    int status = Bsd::clock_gettime(CLOCK_MONOTONIC, &tp);
+    int status = ::clock_gettime(CLOCK_MONOTONIC, &tp);
     assert(status == 0, "gettime error");
     jlong result = jlong(tp.tv_sec) * (1000 * 1000 * 1000) + jlong(tp.tv_nsec);
     return result;
@@ -4768,6 +4772,25 @@
   Bsd::clock_init();
   initial_time_count = os::elapsed_counter();
 
+  // pthread_condattr initialization for monotonic clock
+  int status;
+  pthread_condattr_t* _condattr = os::Bsd::condAttr();
+  if ((status = pthread_condattr_init(_condattr)) != 0) {
+    fatal(err_msg("pthread_condattr_init: %s", strerror(status)));
+  }
+  // Only set the clock if CLOCK_MONOTONIC is available
+  if (Bsd::supports_monotonic_clock()) {
+    if ((status = pthread_condattr_setclock(_condattr, CLOCK_MONOTONIC)) != 0) {
+      if (status == EINVAL) {
+        warning("Unable to use monotonic clock with relative timed-waits" \
+                " - changes to the time-of-day clock may have adverse affects");
+      } else {
+        fatal(err_msg("pthread_condattr_setclock: %s", strerror(status)));
+      }
+    }
+  }
+  // else it defaults to CLOCK_REALTIME
+
 #ifdef __APPLE__
   // XXXDARWIN
   // Work around the unaligned VM callbacks in hotspot's
@@ -5688,21 +5711,36 @@
 
 static struct timespec* compute_abstime(struct timespec* abstime, jlong millis) {
   if (millis < 0)  millis = 0;
-  struct timeval now;
-  int status = gettimeofday(&now, NULL);
-  assert(status == 0, "gettimeofday");
+
   jlong seconds = millis / 1000;
   millis %= 1000;
   if (seconds > 50000000) { // see man cond_timedwait(3T)
     seconds = 50000000;
   }
-  abstime->tv_sec = now.tv_sec  + seconds;
-  long       usec = now.tv_usec + millis * 1000;
-  if (usec >= 1000000) {
-    abstime->tv_sec += 1;
-    usec -= 1000000;
-  }
-  abstime->tv_nsec = usec * 1000;
+
+  if (os::Bsd::supports_monotonic_clock()) {
+    struct timespec now;
+    int status = ::clock_gettime(CLOCK_MONOTONIC, &now);
+    assert_status(status == 0, status, "clock_gettime");
+    abstime->tv_sec = now.tv_sec  + seconds;
+    long nanos = now.tv_nsec + millis * NANOSECS_PER_MILLISEC;
+    if (nanos >= NANOSECS_PER_SEC) {
+      abstime->tv_sec += 1;
+      nanos -= NANOSECS_PER_SEC;
+    }
+    abstime->tv_nsec = nanos;
+  } else {
+    struct timeval now;
+    int status = gettimeofday(&now, NULL);
+    assert(status == 0, "gettimeofday");
+    abstime->tv_sec = now.tv_sec  + seconds;
+    long usec = now.tv_usec + millis * 1000;
+    if (usec >= 1000000) {
+      abstime->tv_sec += 1;
+      usec -= 1000000;
+    }
+    abstime->tv_nsec = usec * 1000;
+  }
   return abstime;
 }
 
@@ -5794,7 +5832,7 @@
     status = os::Bsd::safe_cond_timedwait(_cond, _mutex, &abst);
     if (status != 0 && WorkAroundNPTLTimedWaitHang) {
       pthread_cond_destroy (_cond);
-      pthread_cond_init (_cond, NULL) ;
+      pthread_cond_init (_cond, os::Bsd::condAttr()) ;
     }
     assert_status(status == 0 || status == EINTR ||
                   status == ETIMEDOUT,
@@ -5895,32 +5933,50 @@
 
 static void unpackTime(struct timespec* absTime, bool isAbsolute, jlong time) {
   assert (time > 0, "convertTime");
-
-  struct timeval now;
-  int status = gettimeofday(&now, NULL);
-  assert(status == 0, "gettimeofday");
-
-  time_t max_secs = now.tv_sec + MAX_SECS;
-
-  if (isAbsolute) {
-    jlong secs = time / 1000;
-    if (secs > max_secs) {
-      absTime->tv_sec = max_secs;
+  time_t max_secs = 0;
+
+  if (!os::Bsd::supports_monotonic_clock() || isAbsolute) {
+    struct timeval now;
+    int status = gettimeofday(&now, NULL);
+    assert(status == 0, "gettimeofday");
+
+    max_secs = now.tv_sec + MAX_SECS;
+
+    if (isAbsolute) {
+      jlong secs = time / 1000;
+      if (secs > max_secs) {
+        absTime->tv_sec = max_secs;
+      } else {
+        absTime->tv_sec = secs;
+      }
+      absTime->tv_nsec = (time % 1000) * NANOSECS_PER_MILLISEC;
+    } else {
+      jlong secs = time / NANOSECS_PER_SEC;
+      if (secs >= MAX_SECS) {
+        absTime->tv_sec = max_secs;
+        absTime->tv_nsec = 0;
+      } else {
+        absTime->tv_sec = now.tv_sec + secs;
+        absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_usec*1000;
+        if (absTime->tv_nsec >= NANOSECS_PER_SEC) {
+          absTime->tv_nsec -= NANOSECS_PER_SEC;
+          ++absTime->tv_sec; // note: this must be <= max_secs
+        }
+      }
     }
-    else {
-      absTime->tv_sec = secs;
-    }
-    absTime->tv_nsec = (time % 1000) * NANOSECS_PER_MILLISEC;
-  }
-  else {
+  } else {
+    // must be relative using monotonic clock
+    struct timespec now;
+    int status = ::clock_gettime(CLOCK_MONOTONIC, &now);
+    assert_status(status == 0, status, "clock_gettime");
+    max_secs = now.tv_sec + MAX_SECS;
     jlong secs = time / NANOSECS_PER_SEC;
     if (secs >= MAX_SECS) {
       absTime->tv_sec = max_secs;
       absTime->tv_nsec = 0;
-    }
-    else {
+    } else {
       absTime->tv_sec = now.tv_sec + secs;
-      absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_usec*1000;
+      absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_nsec;
       if (absTime->tv_nsec >= NANOSECS_PER_SEC) {
         absTime->tv_nsec -= NANOSECS_PER_SEC;
         ++absTime->tv_sec; // note: this must be <= max_secs
@@ -6000,15 +6056,19 @@
   jt->set_suspend_equivalent();
   // cleared by handle_special_suspend_equivalent_condition() or java_suspend_self()
 
+  assert(_cur_index == -1, "invariant");
   if (time == 0) {
-    status = pthread_cond_wait (_cond, _mutex) ;
+    _cur_index = REL_INDEX; // arbitrary choice when not timed
+    status = pthread_cond_wait (&_cond[_cur_index], _mutex) ;
   } else {
-    status = os::Bsd::safe_cond_timedwait (_cond, _mutex, &absTime) ;
+    _cur_index = isAbsolute ? ABS_INDEX : REL_INDEX;
+    status = os::Bsd::safe_cond_timedwait (&_cond[_cur_index], _mutex, &absTime) ;
     if (status != 0 && WorkAroundNPTLTimedWaitHang) {
-      pthread_cond_destroy (_cond) ;
-      pthread_cond_init    (_cond, NULL);
+      pthread_cond_destroy (&_cond[_cur_index]) ;
+      pthread_cond_init    (&_cond[_cur_index], isAbsolute ? NULL : os::Bsd::condAttr());
     }
   }
+  _cur_index = -1;
   assert_status(status == 0 || status == EINTR ||
                 status == ETIMEDOUT,
                 status, "cond_timedwait");
@@ -6037,17 +6097,26 @@
   s = _counter;
   _counter = 1;
   if (s < 1) {
-     if (WorkAroundNPTLTimedWaitHang) {
-        status = pthread_cond_signal (_cond) ;
-        assert (status == 0, "invariant") ;
+    // thread might be parked
+    if (_cur_index != -1) {
+      // thread is definitely parked
+      if (WorkAroundNPTLTimedWaitHang) {
+        status = pthread_cond_signal (&_cond[_cur_index]);
+        assert (status == 0, "invariant");
         status = pthread_mutex_unlock(_mutex);
-        assert (status == 0, "invariant") ;
-     } else {
+        assert (status == 0, "invariant");
+      } else {
+        // must capture correct index before unlocking
+        int index = _cur_index;
         status = pthread_mutex_unlock(_mutex);
-        assert (status == 0, "invariant") ;
-        status = pthread_cond_signal (_cond) ;
-        assert (status == 0, "invariant") ;
-     }
+        assert (status == 0, "invariant");
+        status = pthread_cond_signal (&_cond[index]);
+        assert (status == 0, "invariant");
+      }
+    } else {
+      pthread_mutex_unlock(_mutex);
+      assert (status == 0, "invariant") ;
+    }
   } else {
     pthread_mutex_unlock(_mutex);
     assert (status == 0, "invariant") ;

--- a/src/os/bsd/vm/os_bsd.hpp	Sat Aug 20 11:56:24 2016 -0700
+++ b/src/os/bsd/vm/os_bsd.hpp	Thu Apr 13 17:18:04 2017 -0400
@@ -228,6 +228,13 @@
   static jlong fast_thread_cpu_time(clockid_t clockid);
 #endif
 
+  // pthread_cond clock suppport
+  private:
+  static pthread_condattr_t _condattr[1];
+
+  public:
+  static pthread_condattr_t* condAttr() { return _condattr; }
+
   // Stack repair handling
 
   // none present
@@ -293,7 +300,7 @@
   public:
     PlatformEvent() {
       int status;
-      status = pthread_cond_init (_cond, NULL);
+      status = pthread_cond_init (_cond, os::Bsd::condAttr());
       assert_status(status == 0, status, "cond_init");
       status = pthread_mutex_init (_mutex, NULL);
       assert_status(status == 0, status, "mutex_init");
@@ -308,14 +315,19 @@
     void park () ;
     void unpark () ;
     int  TryPark () ;
-    int  park (jlong millis) ;
+    int  park (jlong millis) ; // relative timed-wait only
     void SetAssociation (Thread * a) { _Assoc = a ; }
 };
 
 class PlatformParker : public CHeapObj<mtInternal> {
   protected:
+    enum {
+        REL_INDEX = 0,
+        ABS_INDEX = 1
+    };
+    int _cur_index;  // which cond is in use: -1, 0, 1
     pthread_mutex_t _mutex [1] ;
-    pthread_cond_t  _cond  [1] ;
+    pthread_cond_t  _cond  [2] ; // one for relative times and one for abs.
 
   public:       // TODO-FIXME: make dtor private
     ~PlatformParker() { guarantee (0, "invariant") ; }
@@ -323,10 +335,13 @@
   public:
     PlatformParker() {
       int status;
-      status = pthread_cond_init (_cond, NULL);
-      assert_status(status == 0, status, "cond_init");
+      status = pthread_cond_init (&_cond[REL_INDEX], os::Bsd::condAttr());
+      assert_status(status == 0, status, "cond_init rel");
+      status = pthread_cond_init (&_cond[ABS_INDEX], NULL);
+      assert_status(status == 0, status, "cond_init abs");
       status = pthread_mutex_init (_mutex, NULL);
       assert_status(status == 0, status, "mutex_init");
+      _cur_index = -1; // mark as unused
     }
 };