8247310: Shenandoah: pacer should not affect interrupt status

Reviewed-by: zgu

Author: shipilev

src/hotspot/share/gc/shenandoah/shenandoahPacer.cpp

@@ -28,6 +28,7 @@
 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
 #include "gc/shenandoah/shenandoahPacer.hpp"
 #include "runtime/atomic.hpp"
+#include "runtime/mutexLocker.hpp"
 
 /*
  * In normal concurrent cycle, we have to pace the application to let GC finish.
@@ -239,7 +240,7 @@ void ShenandoahPacer::pace_for_alloc(size_t words) {
   }
 
   // Threads that are attaching should not block at all: they are not
-  // fully initialized yet. Calling sleep() on them would be awkward.
+  // fully initialized yet. Blocking them would be awkward.
   // This is probably the path that allocates the thread oop itself.
   // Forcefully claim without waiting.
   if (JavaThread::current()->is_attaching_via_jni()) {
@@ -264,7 +265,7 @@ void ShenandoahPacer::pace_for_alloc(size_t words) {
     }
     cur = MAX2<size_t>(1, cur);
 
-    JavaThread::current()->sleep(cur);
+    wait(cur);
 
     double end = os::elapsedTime();
     total = (size_t)((end - start) * 1000);
@@ -289,6 +290,19 @@ void ShenandoahPacer::pace_for_alloc(size_t words) {
   }
 }
 
+void ShenandoahPacer::wait(long time_ms) {
+  // Perform timed wait. It works like like sleep(), except without modifying
+  // the thread interruptible status. MonitorLocker also checks for safepoints.
+  assert(time_ms > 0, "Should not call this with zero argument, as it would stall until notify");
+  MonitorLocker locker(_wait_monitor);
+  _wait_monitor->wait(time_ms);
+}
+
+void ShenandoahPacer::notify_waiters() {
+  MonitorLocker locker(_wait_monitor);
+  _wait_monitor->notify_all();
+}
+
 void ShenandoahPacer::print_on(outputStream* out) const {
   out->print_cr("ALLOCATION PACING:");
   out->cr();

src/hotspot/share/gc/shenandoah/shenandoahPacer.hpp

@@ -45,6 +45,7 @@ class ShenandoahPacer : public CHeapObj<mtGC> {
   ShenandoahHeap* _heap;
   BinaryMagnitudeSeq _delays;
   TruncatedSeq* _progress_history;
+  Monitor* _wait_monitor;
 
   // Set once per phase
   volatile intptr_t _epoch;
@@ -64,6 +65,7 @@ class ShenandoahPacer : public CHeapObj<mtGC> {
   ShenandoahPacer(ShenandoahHeap* heap) :
           _heap(heap),
           _progress_history(new TruncatedSeq(5)),
+          _wait_monitor(new Monitor(Mutex::leaf, "_wait_monitor", true, Monitor::_safepoint_check_always)),
           _epoch(0),
           _tax_rate(1),
           _budget(0),
@@ -98,6 +100,9 @@ class ShenandoahPacer : public CHeapObj<mtGC> {
   void restart_with(size_t non_taxable_bytes, double tax_rate);
 
   size_t update_and_get_progress_history();
+
+  void wait(long time_ms);
+  void notify_waiters();
 };
 
 #endif // SHARE_GC_SHENANDOAH_SHENANDOAHPACER_HPP