westhood westhood

今天看到一个帖子说 python 中 while 1: pass 要比 while True: pass 速度更快。

第一感觉是有点反直觉。 while 1: pass 貌似应等价于 while bool(1): pass ，怎么也要比 while True: pass 多一次转换的调用。

于是做了一个简单的实验，

In [1]: timeit while True: break
10000000 loops, best of 3: 109 ns per loop

	package puzzle;

	import java.util.ArrayList;
	import java.util.concurrent.locks.ReentrantLock;


	public abstract class Buffer<T> {
	private ArrayList<T> _items = null;
	private ArrayList<T> _prepare = null;

	import ssl
	import socket

	context = ssl.SSLContext(ssl.PROTOCOL_SSLv23)
	context.set_npn_protocols(["http/1.1", "spdy/3"])

	sock = socket.socket()
	ssl_sock = context.wrap_socket(sock)

	ssl_sock.connect(("www.google.com", 443))

	import subprocess

	p = subprocess.Popen(["redis-cli", "--pipe"],
	stdin=subprocess.PIPE)

	for x in xrange(0, 100):
	# write to redis-cli stdin in redis protocol
	p.stdin.write("set %s %s\r\n" % (x, x + 1)

	p.stdin.close()

	local ffi = require("ffi")

	ffi.cdef[[
	typedef unsigned char uuid_t[16];
	void uuid_generate(uuid_t out);
	void uuid_unparse(const uuid_t uu, char *out);
	]]

	local libuuid = ffi.os == "OSX" and ffi.C or ffi.load("uuid")

	import gevent.monkey

	import logging
	logger = logging.getLogger(__name__)

	logger.info("Gevent monkey patch is applied")
	gevent.monkey.patch_all()

	# RLock of sentry log handler may be created before applying gevent monkey
	# patch, which will lead to a deadlock. Replace it with a gevent RLock