8075210: Refactor strong root processing in order to allow G1 to evolve separately from GenCollectedHeap

Create a G1RootProcessor and move SharedHeap root processing to GenCollectedHeap Reviewed-by: brutisso, tschatzl, ehelin
2025-09-20 11:04:34 +02:00 · 2014-12-01 15:24:56 +01:00 · 2014-12-01 15:24:56 +01:00 · f5292016ee
commit f5292016ee
parent 68b1e61637
15 changed files with 645 additions and 596 deletions
--- a/hotspot/src/share/vm/gc_implementation/g1/g1RootProcessor.hpp
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1RootProcessor.hpp
@ -0,0 +1,116 @@
+/*
+ * Copyright (c) 2015, 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.
+ *
+ */
+
+#ifndef SHARE_VM_GC_IMPLEMENTATION_G1_ROOTPROCESSOR_HPP
+#define SHARE_VM_GC_IMPLEMENTATION_G1_ROOTPROCESSOR_HPP
+
+#include "memory/allocation.hpp"
+#include "memory/sharedHeap.hpp"
+#include "runtime/mutex.hpp"
+
+class CLDClosure;
+class CodeBlobClosure;
+class G1CollectedHeap;
+class G1ParPushHeapRSClosure;
+class Monitor;
+class OopClosure;
+class SubTasksDone;
+
+// Scoped object to assist in applying oop, CLD and code blob closures to
+// root locations. Handles claiming of different root scanning tasks
+// and takes care of global state for root scanning via a StrongRootsScope.
+// In the parallel case there is a shared G1RootProcessor object where all
+// worker thread call the process_roots methods.
+class G1RootProcessor : public StackObj {
+  G1CollectedHeap* _g1h;
+  SubTasksDone* _process_strong_tasks;
+  SharedHeap::StrongRootsScope _srs;
+
+  // Used to implement the Thread work barrier.
+  Monitor _lock;
+  volatile jint _n_workers_discovered_strong_classes;
+
+  enum G1H_process_roots_tasks {
+    G1RP_PS_Universe_oops_do,
+    G1RP_PS_JNIHandles_oops_do,
+    G1RP_PS_ObjectSynchronizer_oops_do,
+    G1RP_PS_FlatProfiler_oops_do,
+    G1RP_PS_Management_oops_do,
+    G1RP_PS_SystemDictionary_oops_do,
+    G1RP_PS_ClassLoaderDataGraph_oops_do,
+    G1RP_PS_jvmti_oops_do,
+    G1RP_PS_CodeCache_oops_do,
+    G1RP_PS_filter_satb_buffers,
+    G1RP_PS_refProcessor_oops_do,
+    // Leave this one last.
+    G1RP_PS_NumElements
+  };
+
+  void worker_has_discovered_all_strong_classes();
+  void wait_until_all_strong_classes_discovered();
+
+  void process_java_roots(OopClosure* scan_non_heap_roots,
+                          CLDClosure* thread_stack_clds,
+                          CLDClosure* scan_strong_clds,
+                          CLDClosure* scan_weak_clds,
+                          CodeBlobClosure* scan_strong_code);
+
+  void process_vm_roots(OopClosure* scan_non_heap_roots,
+                        OopClosure* scan_non_heap_weak_roots);
+
+public:
+  G1RootProcessor(G1CollectedHeap* g1h);
+
+  // Apply closures to the strongly and weakly reachable roots in the system
+  // in a single pass.
+  // Record and report timing measurements for sub phases using the worker_i
+  void evacuate_roots(OopClosure* scan_non_heap_roots,
+                      OopClosure* scan_non_heap_weak_roots,
+                      CLDClosure* scan_strong_clds,
+                      CLDClosure* scan_weak_clds,
+                      bool trace_metadata,
+                      uint worker_i);
+
+  // Apply oops, clds and blobs to all strongly reachable roots in the system
+  void process_strong_roots(OopClosure* oops,
+                            CLDClosure* clds,
+                            CodeBlobClosure* blobs);
+
+  // Apply oops, clds and blobs to strongly and weakly reachable roots in the system
+  void process_all_roots(OopClosure* oops,
+                         CLDClosure* clds,
+                         CodeBlobClosure* blobs);
+
+  // Apply scan_rs to all locations in the union of the remembered sets for all
+  // regions in the collection set
+  // (having done "set_region" to indicate the region in which the root resides),
+  void scan_remembered_sets(G1ParPushHeapRSClosure* scan_rs,
+                            OopClosure* scan_non_heap_weak_roots,
+                            uint worker_i);
+
+  // Inform the root processor about the number of worker threads
+  void set_num_workers(int active_workers);
+};
+
+#endif // SHARE_VM_GC_IMPLEMENTATION_G1_ROOTPROCESSOR_HPP