357   DEBUG_ONLY(Thread* my_thread = Thread::current();)
 358 
 359   assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
 360   assert(my_thread->is_VM_thread() ||
 361          my_thread->is_ConcurrentGC_thread(),
 362          "incorrect thread type capability");
 363   assert(Heap_lock->is_locked(),
 364          "the requesting thread should have the Heap_lock");
 365   guarantee(!is_gc_active(), "collection is not reentrant");
 366   assert(max_level < n_gens(), "sanity check");
 367 
 368   if (GC_locker::check_active_before_gc()) {
 369     return; // GC is disabled (e.g. JNI GetXXXCritical operation)
 370   }
 371 
 372   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
 373                           collector_policy()->should_clear_all_soft_refs();
 374 
 375   ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
 376 
 377   const size_t metadata_prev_used = MetaspaceAux::allocated_used_bytes();
 378 
 379   print_heap_before_gc();
 380 
 381   {
 382     FlagSetting fl(_is_gc_active, true);
 383 
 384     bool complete = full && (max_level == (n_gens()-1));
 385     const char* gc_cause_prefix = complete ? "Full GC" : "GC";
 386     gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
 387     TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
 388     GCTraceTime t(GCCauseString(gc_cause_prefix, gc_cause()), PrintGCDetails, false, NULL);
 389 
 390     gc_prologue(complete);
 391     increment_total_collections(complete);
 392 
 393     size_t gch_prev_used = used();
 394 
 395     int starting_level = 0;
 396     if (full) {
 397       // Search for the oldest generation which will collect all younger

 357   DEBUG_ONLY(Thread* my_thread = Thread::current();)
 358 
 359   assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
 360   assert(my_thread->is_VM_thread() ||
 361          my_thread->is_ConcurrentGC_thread(),
 362          "incorrect thread type capability");
 363   assert(Heap_lock->is_locked(),
 364          "the requesting thread should have the Heap_lock");
 365   guarantee(!is_gc_active(), "collection is not reentrant");
 366   assert(max_level < n_gens(), "sanity check");
 367 
 368   if (GC_locker::check_active_before_gc()) {
 369     return; // GC is disabled (e.g. JNI GetXXXCritical operation)
 370   }
 371 
 372   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
 373                           collector_policy()->should_clear_all_soft_refs();
 374 
 375   ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
 376 
 377   const size_t metadata_prev_used = MetaspaceAux::used_bytes();
 378 
 379   print_heap_before_gc();
 380 
 381   {
 382     FlagSetting fl(_is_gc_active, true);
 383 
 384     bool complete = full && (max_level == (n_gens()-1));
 385     const char* gc_cause_prefix = complete ? "Full GC" : "GC";
 386     gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
 387     TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
 388     GCTraceTime t(GCCauseString(gc_cause_prefix, gc_cause()), PrintGCDetails, false, NULL);
 389 
 390     gc_prologue(complete);
 391     increment_total_collections(complete);
 392 
 393     size_t gch_prev_used = used();
 394 
 395     int starting_level = 0;
 396     if (full) {
 397       // Search for the oldest generation which will collect all younger