unix 管道多个编写器

Question

如果有多个线程将固定长度的数据(比如 4 字节地址)写入单个管道，并且该管道只有一个读取器，是否可以保证读取器按顺序获取字节？换句话说，是 write()到管道原子？

Answer 1

http://pubs.opengroup.org/onlinepubs/009695399/functions/write.html

Atomic/non-atomic: A write is atomic if the whole amount written in one operation is not interleaved with data from any other process. This is useful when there are multiple writers sending data to a single reader. Applications need to know how large a write request can be expected to be performed atomically. This maximum is called {PIPE_BUF}. This volume of IEEE Std 1003.1-2001 does not say whether write requests for more than {PIPE_BUF} bytes are atomic, but requires that writes of {PIPE_BUF} or fewer bytes shall be atomic.