http - 为什么 do_GET 比 do_POST 快得多

Question

Python 的 BaseHTTPRequestHandler 对于通过邮寄发送的表单有问题!

我看到其他人问同样的问题(Why GET method is faster than POST?)，但我的时间差太大(1 秒)

Python 服务器:

from BaseHTTPServer import BaseHTTPRequestHandler, HTTPServer
import datetime


def get_ms_since_start(start=False):
    global start_ms
    cur_time = datetime.datetime.now()
    # I made sure to stay within hour boundaries while making requests
    ms = cur_time.minute*60000 + cur_time.second*1000 + int(cur_time.microsecond/1000)
    if start:
        start_ms = ms
        return 0
    else:
        return ms - start_ms

class MyServer(BaseHTTPRequestHandler, object):
    def do_GET(self):
        print "Start get method at %d ms" % get_ms_since_start(True)
        field_data = self.path
        self.send_response(200)
        self.end_headers()
        self.wfile.write(str(field_data))
        print "Sent response at %d ms" % get_ms_since_start()
        return

    def do_POST(self):
        print "Start post method at %d ms" % get_ms_since_start(True)
        length = int(self.headers.getheader('content-length'))
        print "Length to read is %d at %d ms" % (length, get_ms_since_start())
        field_data = self.rfile.read(length)
        print "Reading rfile completed at %d ms" % get_ms_since_start()
        self.send_response(200)
        self.end_headers()
        self.wfile.write(str(field_data))
        print "Sent response at %d ms" % get_ms_since_start()
        return


if __name__ == '__main__':
    server = HTTPServer(('0.0.0.0', 8082), MyServer)
    print 'Starting server, use <Ctrl-C> to stop'
    server.serve_forever()

用python服务器获取请求非常快

time curl -i http://0.0.0.0:8082\?one\=1

打印

HTTP/1.0 200 OK
Server: BaseHTTP/0.3 Python/2.7.6
Date: Sun, 18 Sep 2016 07:13:47 GMT

/?one=1curl http://0.0.0.0:8082\?one\=1  0.00s user 0.00s system 45% cpu 0.012 total

在服务器端:

Start get method at 0 ms
127.0.0.1 - - [18/Sep/2016 00:26:30] "GET /?one=1 HTTP/1.1" 200 -
Sent response at 0 ms

瞬间!

向 python 服务器发送表单时的 Post 请求非常慢

time curl http://0.0.0.0:8082 -F one=1

打印

--------------------------2b10061ae9d79733
Content-Disposition: form-data; name="one"

1
--------------------------2b10061ae9d79733--
curl http://0.0.0.0:8082 -F one=1  0.00s user 0.00s system 0% cpu 1.015 total

在服务器端:

Start post method at 0 ms
Length to read is 139 at 0 ms
Reading rfile completed at 1002 ms
127.0.0.1 - - [18/Sep/2016 00:27:16] "POST / HTTP/1.1" 200 -
Sent response at 1002 ms

具体来说，self.rfile.read(length) 对于非常少的表单数据需要 1 秒

向 python 服务器发送数据(不是表单)时的 Post 请求非常快

time curl -i http://0.0.0.0:8082 -d one=1

打印

HTTP/1.0 200 OK
Server: BaseHTTP/0.3 Python/2.7.6
Date: Sun, 18 Sep 2016 09:09:25 GMT

one=1curl -i http://0.0.0.0:8082 -d one=1  0.00s user 0.00s system 32% cpu 0.022 total

在服务器端:

Start post method at 0
Length to read is 5 at 0
Reading rfile completed at 0
127.0.0.1 - - [18/Sep/2016 02:10:18] "POST / HTTP/1.1" 200 -
Sent response at 0

node.js 服务器:

var http = require('http');
var qs = require('querystring');

http.createServer(function(req, res) {
    if (req.method == 'POST') {
        whole = ''
        req.on('data', function(chunk) {
            whole += chunk.toString()
        })

        req.on('end', function() {
            console.log(whole)
            res.writeHead(200, 'OK', {'Content-Type': 'text/html'})
            res.end('Data received.')
        })
    }
}).listen(8082)

将表单发送到 node.js 服务器时的 Post 请求非常快

time curl -i http://0.0.0.0:8082 -F one=1

打印:

HTTP/1.1 100 Continue

HTTP/1.1 200 OK
Content-Type: text/html
Date: Sun, 18 Sep 2016 10:31:38 GMT
Connection: keep-alive
Transfer-Encoding: chunked

Data received.curl -i http://0.0.0.0:8082 -F one=1  0.00s user 0.00s system 42% cpu 0.013 total

Answer 1

我认为这是您问题的答案:libcurl delays for 1 second before uploading data, command-line curl does not

libcurl 正在发送 Expect 100-Continue header ，并在发送表单数据之前等待 1 秒的响应(在 -F 命令的情况下)。

在 -d 的情况下，无论出于何种原因，它都不会发送 100-Continue header 。