1778       register_gc_start(cause);
1779       // Reset the expansion cause, now that we are about to begin
1780       // a new cycle.
1781       clear_expansion_cause();
1782 
1783       // Clear the MetaspaceGC flag since a concurrent collection
1784       // is starting but also clear it after the collection.
1785       MetaspaceGC::set_should_concurrent_collect(false);
1786     }
1787     // Decide if we want to enable class unloading as part of the
1788     // ensuing concurrent GC cycle.
1789     update_should_unload_classes();
1790     _full_gc_requested = false;           // acks all outstanding full gc requests
1791     _full_gc_cause = GCCause::_no_gc;
1792     // Signal that we are about to start a collection
1793     gch->increment_total_full_collections();  // ... starting a collection cycle
1794     _collection_count_start = gch->total_full_collections();
1795   }
1796 
1797   // Used for PrintGC
1798   size_t prev_used;
1799   if (PrintGC && Verbose) {
1800     prev_used = _cmsGen->used();
1801   }
1802 
1803   // The change of the collection state is normally done at this level;
1804   // the exceptions are phases that are executed while the world is
1805   // stopped.  For those phases the change of state is done while the
1806   // world is stopped.  For baton passing purposes this allows the
1807   // background collector to finish the phase and change state atomically.
1808   // The foreground collector cannot wait on a phase that is done
1809   // while the world is stopped because the foreground collector already
1810   // has the world stopped and would deadlock.
1811   while (_collectorState != Idling) {
1812     if (TraceCMSState) {
1813       gclog_or_tty->print_cr("Thread " INTPTR_FORMAT " in CMS state %d",
1814         p2i(Thread::current()), _collectorState);
1815     }
1816     // The foreground collector
1817     //   holds the Heap_lock throughout its collection.
1818     //   holds the CMS token (but not the lock)

1778       register_gc_start(cause);
1779       // Reset the expansion cause, now that we are about to begin
1780       // a new cycle.
1781       clear_expansion_cause();
1782 
1783       // Clear the MetaspaceGC flag since a concurrent collection
1784       // is starting but also clear it after the collection.
1785       MetaspaceGC::set_should_concurrent_collect(false);
1786     }
1787     // Decide if we want to enable class unloading as part of the
1788     // ensuing concurrent GC cycle.
1789     update_should_unload_classes();
1790     _full_gc_requested = false;           // acks all outstanding full gc requests
1791     _full_gc_cause = GCCause::_no_gc;
1792     // Signal that we are about to start a collection
1793     gch->increment_total_full_collections();  // ... starting a collection cycle
1794     _collection_count_start = gch->total_full_collections();
1795   }
1796 
1797   // Used for PrintGC
1798   size_t prev_used = 0;
1799   if (PrintGC && Verbose) {
1800     prev_used = _cmsGen->used();
1801   }
1802 
1803   // The change of the collection state is normally done at this level;
1804   // the exceptions are phases that are executed while the world is
1805   // stopped.  For those phases the change of state is done while the
1806   // world is stopped.  For baton passing purposes this allows the
1807   // background collector to finish the phase and change state atomically.
1808   // The foreground collector cannot wait on a phase that is done
1809   // while the world is stopped because the foreground collector already
1810   // has the world stopped and would deadlock.
1811   while (_collectorState != Idling) {
1812     if (TraceCMSState) {
1813       gclog_or_tty->print_cr("Thread " INTPTR_FORMAT " in CMS state %d",
1814         p2i(Thread::current()), _collectorState);
1815     }
1816     // The foreground collector
1817     //   holds the Heap_lock throughout its collection.
1818     //   holds the CMS token (but not the lock)