src/hotspot/share/gc/g1/g1RootProcessor.cpp

rev 56301 : imported patch 8159984-slow

@@ -69,26 +69,20 @@
 
 G1RootProcessor::G1RootProcessor(G1CollectedHeap* g1h, uint n_workers) :
     _g1h(g1h),
     _process_strong_tasks(G1RP_PS_NumElements),
     _srs(n_workers),
-    _lock(Mutex::leaf, "G1 Root Scanning barrier lock", false, Monitor::_safepoint_check_never),
+    _lock(Mutex::leaf, "G1 Root Scan barrier lock", false, Monitor::_safepoint_check_never),
     _n_workers_discovered_strong_classes(0) {}
 
 void G1RootProcessor::evacuate_roots(G1ParScanThreadState* pss, uint worker_i) {
   G1GCPhaseTimes* phase_times = _g1h->phase_times();
 
   G1EvacPhaseTimesTracker timer(phase_times, pss, G1GCPhaseTimes::ExtRootScan, worker_i);
 
   G1EvacuationRootClosures* closures = pss->closures();
-  process_java_roots(closures, phase_times, worker_i);
-
-  // This is the point where this worker thread will not find more strong CLDs/nmethods.
-  // Report this so G1 can synchronize the strong and weak CLDs/nmethods processing.
-  if (closures->trace_metadata()) {
-    worker_has_discovered_all_strong_classes();
-  }
+  process_java_roots(closures, phase_times, worker_i, closures->trace_metadata() /* notify_claimed_roots_done */);
 
   process_vm_roots(closures, phase_times, worker_i);
 
   {
     // Now the CM ref_processor roots.

@@ -101,27 +95,15 @@
       _g1h->ref_processor_cm()->weak_oops_do(closures->strong_oops());
     }
   }
 
   if (closures->trace_metadata()) {
-    {
-      G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::WaitForStrongCLD, worker_i);
-      // Barrier to make sure all workers passed
-      // the strong CLD and strong nmethods phases.
+    G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::WaitForStrongRoots, worker_i);
+    // Wait here to make sure all workers passed the strong nmethods phase.
       wait_until_all_strong_classes_discovered();
     }
 
-    // Now take the complement of the strong CLDs.
-    G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::WeakCLDRoots, worker_i);
-    assert(closures->second_pass_weak_clds() != NULL, "Should be non-null if we are tracing metadata.");
-    ClassLoaderDataGraph::roots_cld_do(NULL, closures->second_pass_weak_clds());
-  } else {
-    phase_times->record_time_secs(G1GCPhaseTimes::WaitForStrongCLD, worker_i, 0.0);
-    phase_times->record_time_secs(G1GCPhaseTimes::WeakCLDRoots, worker_i, 0.0);
-    assert(closures->second_pass_weak_clds() == NULL, "Should be null if not tracing metadata.");
-  }
-
   _process_strong_tasks.all_tasks_completed(n_workers());
 }
 
 // Adaptor to pass the closures to the strong roots in the VM.
 class StrongRootsClosures : public G1RootClosures {

@@ -187,28 +169,37 @@
   _process_strong_tasks.all_tasks_completed(n_workers());
 }
 
 void G1RootProcessor::process_java_roots(G1RootClosures* closures,
                                          G1GCPhaseTimes* phase_times,
-                                         uint worker_i) {
-  // Iterating over the CLDG and the Threads are done early to allow us to
-  // first process the strong CLDs and nmethods and then, after a barrier,
-  // let the thread process the weak CLDs and nmethods.
-  {
-    G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::CLDGRoots, worker_i);
-    if (_process_strong_tasks.try_claim_task(G1RP_PS_ClassLoaderDataGraph_oops_do)) {
-      ClassLoaderDataGraph::roots_cld_do(closures->strong_clds(), closures->weak_clds());
-    }
-  }
-
+                                         uint worker_i,
+                                         bool notify_claimed_roots_done) {
+  // Iterating over the the threads is done early to allow us to make sure that
+  // the "strong" nmethods are processed first using the strong closure. After a barrier,
+  // let the thread process the weak nmethods.
+  // The problem is that nmethods are claimed to avoid duplicate iteration. This is
+  // a way to make sure that for these nmethods we always apply the strong closure.
   {
     G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::ThreadRoots, worker_i);
     bool is_par = n_workers() > 1;
     Threads::possibly_parallel_oops_do(is_par,
                                        closures->strong_oops(),
                                        closures->strong_codeblobs());
   }
+
+  // This is the point where this worker thread will not find more strong nmethods.
+  // Report this so G1 can synchronize the strong and weak CLDs/nmethods processing.
+  if (notify_claimed_roots_done) {
+    worker_has_discovered_all_strong_classes();
+  }
+
+  {
+    G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::CLDGRoots, worker_i);
+    if (_process_strong_tasks.try_claim_task(G1RP_PS_ClassLoaderDataGraph_oops_do)) {
+      ClassLoaderDataGraph::roots_cld_do(closures->strong_clds(), closures->weak_clds());
+    }
+  }
 }
 
 void G1RootProcessor::process_vm_roots(G1RootClosures* closures,
                                        G1GCPhaseTimes* phase_times,
                                        uint worker_i) {