cms GC_Thread CMSParInitialMarkTask

CMSParInitialMarkTask

task的主体逻辑

void CMSParInitialMarkTask::work(uint worker_id) {
  elapsedTimer _timer;
  ResourceMark rm;
  HandleMark   hm;
  // ---------- scan from roots --------------
  _timer.start();
  CMSHeap* heap = CMSHeap::heap();
  ParMarkRefsIntoClosure par_mri_cl(_collector->_span, &(_collector->_markBitMap));

  // ---------- young gen roots --------------
  {
    work_on_young_gen_roots(&par_mri_cl);
    _timer.stop();
  }

  // ---------- remaining roots --------------
  _timer.reset();
  _timer.start();
  CLDToOopClosure cld_closure(&par_mri_cl, true);
  heap->cms_process_roots(_strong_roots_scope,
                          false,     // yg was scanned above
                          GenCollectedHeap::ScanningOption(_collector->CMSCollector::roots_scanning_options()),
                          _collector->should_unload_classes(),
                          &par_mri_cl,
                          &cld_closure,
                          &_par_state_string);
  _timer.stop();
}