bool  OSContainer::_is_initialized   = false;
bool  OSContainer::_is_containerized = false;
CgroupSubsystem* cgroup_subsystem;

// more code

int OSContainer::active_processor_count() {
  assert(cgroup_subsystem != NULL, "cgroup subsystem not available");
  return cgroup_subsystem->active_processor_count();
}

/* active_processor_count
 *
 * Calculate an appropriate number of active processors for the
 * VM to use based on these three inputs.
 *
 * cpu affinity
 * cgroup cpu quota & cpu period
 * cgroup cpu shares
 *
 * Algorithm:
 *
 * Determine the number of available CPUs from sched_getaffinity
 *
 * If user specified a quota (quota != -1), calculate the number of
 * required CPUs by dividing quota by period.
 *
 * If shares are in effect (shares != -1), calculate the number
 * of CPUs required for the shares by dividing the share value
 * by PER_CPU_SHARES.
 *
 * All results of division are rounded up to the next whole number.
 *
 * If neither shares or quotas have been specified, return the
 * number of active processors in the system.
 *
 * If both shares and quotas have been specified, the results are
 * based on the flag PreferContainerQuotaForCPUCount.  If true,
 * return the quota value.  If false return the smallest value
 * between shares or quotas.
 *
 * If shares and/or quotas have been specified, the resulting number
 * returned will never exceed the number of active processors.
 *
 * return:
 *    number of CPUs
 */
int CgroupSubsystem::active_processor_count() {
  int quota_count = 0, share_count = 0;
  int cpu_count, limit_count;
  int result;

  // We use a cache with a timeout to avoid performing expensive
  // computations in the event this function is called frequently.
  // [See 8227006].
  CachingCgroupController* contrl = cpu_controller();
  CachedMetric* cpu_limit = contrl->metrics_cache();
  if (!cpu_limit->should_check_metric()) {
    int val = (int)cpu_limit->value();
    log_trace(os, container)("CgroupSubsystem::active_processor_count (cached): %d", val);
    return val;
  }

  cpu_count = limit_count = os::Linux::active_processor_count();
  int quota  = cpu_quota();
  int period = cpu_period();
  int share  = cpu_shares();

  if (quota > -1 && period > 0) {
    quota_count = ceilf((float)quota / (float)period);
    log_trace(os, container)("CPU Quota count based on quota/period: %d", quota_count);
  }
  if (share > -1) {
    share_count = ceilf((float)share / (float)PER_CPU_SHARES);
    log_trace(os, container)("CPU Share count based on shares: %d", share_count);
  }

  // If both shares and quotas are setup results depend
  // on flag PreferContainerQuotaForCPUCount.
  // If true, limit CPU count to quota
  // If false, use minimum of shares and quotas
  if (quota_count !=0 && share_count != 0) {
    if (PreferContainerQuotaForCPUCount) {
      limit_count = quota_count;
    } else {
      limit_count = MIN2(quota_count, share_count);
    }
  } else if (quota_count != 0) {
    limit_count = quota_count;
  } else if (share_count != 0) {
    limit_count = share_count;
  }

  result = MIN2(cpu_count, limit_count);
  log_trace(os, container)("OSContainer::active_processor_count: %d", result);

  // Update cached metric to avoid re-reading container settings too often
  cpu_limit->set_value(result, OSCONTAINER_CACHE_TIMEOUT);

  return result;
}