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