public void forcePurge() {
    pendingCancels.getAndSet(0);
    timer.timerPurge();
  }
ExpirationScheduler uses a single instance of java.util.Timer (and therefore a single thread) per
VM to schedule and execute region and entry expiration tasks.
geode-core/src/main/java/org/apache/geode/internal/cache/ExpirationScheduler.java