8365026: G1: Initialization should start a "full" new collection set

Reviewed-by: ayang, kbarrett

Author: Thomas Schatzl

src/hotspot/share/gc/g1/g1CollectedHeap.cpp

@@ -1487,6 +1487,8 @@ jint G1CollectedHeap::initialize() {
 
   _collection_set.initialize(max_num_regions());
 
+  start_new_collection_set();
+
   allocation_failure_injector()->reset();
 
   CPUTimeCounters::create_counter(CPUTimeGroups::CPUTimeType::gc_parallel_workers);

src/hotspot/share/gc/g1/g1ConcurrentMark.cpp

@@ -1962,7 +1962,8 @@ class VerifyNoCSetOops {
 };
 
 void G1ConcurrentMark::verify_no_collection_set_oops() {
-  assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint");
+  assert(SafepointSynchronize::is_at_safepoint() || !is_init_completed(),
+         "should be at a safepoint or initializing");
   if (!_g1h->collector_state()->mark_or_rebuild_in_progress()) {
     return;
   }

src/hotspot/share/gc/g1/g1Policy.cpp

@@ -97,10 +97,6 @@ void G1Policy::init(G1CollectedHeap* g1h, G1CollectionSet* collection_set) {
   _free_regions_at_end_of_collection = _g1h->num_free_regions();
 
   update_young_length_bounds();
-
-  // We immediately start allocating regions placing them in the collection set.
-  // Initialize the collection set info.
-  _collection_set->start_incremental_building();
 }
 
 void G1Policy::record_young_gc_pause_start() {