outgoingMessage.writableHighWaterMark

• <number>

如果分配了底层套接字的 highWaterMark。 否则，writable.write() 开始时的默认缓冲级别返回 false（16384）。

• <number>

The highWaterMark of the underlying socket if assigned. Otherwise, the default buffer level when writable.write() starts returning false (16384).