450   virtual void print_on(outputStream* st) const = 0;
 451   // The default behavior is to call print_on() on tty.
 452   virtual void print() const;
 453 
 454   // Print more detailed heap information on the given
 455   // outputStream. The default behavior is to call print_on(). It is
 456   // up to each subclass to override it and add any additional output
 457   // it needs.
 458   virtual void print_extended_on(outputStream* st) const {
 459     print_on(st);
 460   }
 461 
 462   virtual void print_on_error(outputStream* st) const;
 463 
 464   // Used to print information about locations in the hs_err file.
 465   virtual bool print_location(outputStream* st, void* addr) const = 0;
 466 
 467   // Iterator for all GC threads (other than VM thread)
 468   virtual void gc_threads_do(ThreadClosure* tc) const = 0;
 469 
 470   // Run given task. Possibly in parallel if the GC supports it.
 471   virtual void run_task(AbstractGangTask* task) = 0;


 472 
 473   // Print any relevant tracing info that flags imply.
 474   // Default implementation does nothing.
 475   virtual void print_tracing_info() const = 0;
 476 
 477   void print_heap_before_gc();
 478   void print_heap_after_gc();
 479 
 480   // Registering and unregistering an nmethod (compiled code) with the heap.
 481   virtual void register_nmethod(nmethod* nm) = 0;
 482   virtual void unregister_nmethod(nmethod* nm) = 0;
 483   // Callback for when nmethod is about to be deleted.
 484   virtual void flush_nmethod(nmethod* nm) = 0;
 485   virtual void verify_nmethod(nmethod* nm) = 0;
 486 
 487   void trace_heap_before_gc(const GCTracer* gc_tracer);
 488   void trace_heap_after_gc(const GCTracer* gc_tracer);
 489 
 490   // Heap verification
 491   virtual void verify(VerifyOption option) = 0;

 450   virtual void print_on(outputStream* st) const = 0;
 451   // The default behavior is to call print_on() on tty.
 452   virtual void print() const;
 453 
 454   // Print more detailed heap information on the given
 455   // outputStream. The default behavior is to call print_on(). It is
 456   // up to each subclass to override it and add any additional output
 457   // it needs.
 458   virtual void print_extended_on(outputStream* st) const {
 459     print_on(st);
 460   }
 461 
 462   virtual void print_on_error(outputStream* st) const;
 463 
 464   // Used to print information about locations in the hs_err file.
 465   virtual bool print_location(outputStream* st, void* addr) const = 0;
 466 
 467   // Iterator for all GC threads (other than VM thread)
 468   virtual void gc_threads_do(ThreadClosure* tc) const = 0;
 469 
 470   // Runs the given task with (up to) the requested number of workers.
 471   // Some GCs don't support parallel worker threads and will run the
 472   // task in one thread, with worker id 0.
 473   void run_task_at_safepoint(AbstractGangTask* task, uint num_workers);
 474 
 475   // Print any relevant tracing info that flags imply.
 476   // Default implementation does nothing.
 477   virtual void print_tracing_info() const = 0;
 478 
 479   void print_heap_before_gc();
 480   void print_heap_after_gc();
 481 
 482   // Registering and unregistering an nmethod (compiled code) with the heap.
 483   virtual void register_nmethod(nmethod* nm) = 0;
 484   virtual void unregister_nmethod(nmethod* nm) = 0;
 485   // Callback for when nmethod is about to be deleted.
 486   virtual void flush_nmethod(nmethod* nm) = 0;
 487   virtual void verify_nmethod(nmethod* nm) = 0;
 488 
 489   void trace_heap_before_gc(const GCTracer* gc_tracer);
 490   void trace_heap_after_gc(const GCTracer* gc_tracer);
 491 
 492   // Heap verification
 493   virtual void verify(VerifyOption option) = 0;