请问：关于ACE_Message_Queue::low_water_mark()的理解

lovelypp

:)ACE文档是这么写的：
By default, the high_water_mark equals the low_water_mark, which means that suppliers will be able to enqueue new messages as soon as a consumer removes any message from the queue. Making the low_water_mark smaller than the high_water_mark forces consumers to drain more messages from the queue before suppliers can enqueue new messages, which can minimize the "silly window syndrome."

请问如何理解？