如何以线程安全的方式清理ConcurrentHashMap

Question

我有一个ConcurrentHashMap oricginalCahce，其中mulptile线程从代码的许多地方并发写入。 我必须定期刷新地图，所以我在下面创建Map的临时副本并清理origianl Map

void flushcopyOfOriginalCache(String queueName) {
        Map<Integer, Date> copyOfOriginalCache = null;
        Object lock = getLastscheduledTimeUpdateLock(queueName);
        //this lock is not aquired at the time of writing as the writing in taking place in many places of the code
        synchronized (lock) {
        //rechecking for whether expired or not
            if (isOrigCacheExpired(queueName)) {
                log.info("origCache Expired for queue {}", queueName);
                if (orignalCache.containsKey(queueName)) {
                    copyOfOriginalCache = new ConcurrentHashMap<>(
                            orignalCache.get(queueName));
                    //How safe is below clean ??? as parallel writes might be going on orignalCache!
                    orignalCache.get(queueName).clear();
                }

            }
        }

        if (copyOfOriginalCache == null || copyOfOriginalCache.isEmpty()) {
            return;
        }
        //Below is expenssive DB operations on with data in copyOfOriginalCache  

        }

如何确保这个干净的方法不应该删除正在编写的条目。请指导。