[英]Python readline on a pipe that has been opened as non-blocking
I have a Linux fifo that has been opened in non-blocking mode. 我有一个以非阻塞模式打开的Linux fifo。 As expected, when I call read on the file object, it returns immediately.
正如预期的那样,当我调用文件对象上的read时,它会立即返回。 I use select to make sure there is no busy waiting, but that my program is still notified when there is any data available.
我使用select来确保没有忙碌的等待,但是当有任何数据可用时我的程序仍会收到通知。 Out of curiosity, I tried the readline function and was surprised to find that readline blocks until a newline character is found.
出于好奇,我尝试了readline函数,并惊讶地发现readline阻塞直到找到换行符。 I examined the processor usage via top and it seems like readline does not busy wait.
我通过top检查了处理器的使用情况,看起来readline并不忙等待。 Since my application is performance sensitive, I am wondering if there are any performance implications when using readline on a non-blocking socket.
由于我的应用程序对性能敏感,我想知道在非阻塞套接字上使用readline时是否存在性能影响。
The core part of Python's readline is in fileobject.c:get_line and is Python的readline的核心部分是在fileobject.c:get_line和
FILE_BEGIN_ALLOW_THREADS(f)
FLOCKFILE(fp);
while ((c = GETC(fp)) != EOF &&
(*buf++ = c) != '\n' &&
buf != end)
;
FUNLOCKFILE(fp);
FILE_END_ALLOW_THREADS(f)
where 哪里
#ifdef HAVE_GETC_UNLOCKED
#define GETC(f) getc_unlocked(f)
#define FLOCKFILE(f) flockfile(f)
#define FUNLOCKFILE(f) funlockfile(f)
#else
#define GETC(f) getc(f)
#define FLOCKFILE(f)
#define FUNLOCKFILE(f)
#endif
There's nothing special going on. 没什么特别的。 Are you sure your observations are what you think they are?
你确定你的观察结果是你认为的吗?
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