Why is do_GET much faster than do_POST - http

Question

Python's BaseHTTPRequestHandler has an issue with forms sent through post!
I have seen other people asking the same question (Why GET method is faster than POST?), but the time difference in my case is too much (1 second)
Python server:
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()
Get request with python server is very fast
time curl -i http://0.0.0.0:8082\?one\=1
prints
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
and on the server side:
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
Instantaneous!
Post request when sending form to python server is very slow
time curl http://0.0.0.0:8082 -F one=1
prints
--------------------------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
and on the server side:
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
Specifically, self.rfile.read(length) is taking 1 second for very little form data
Post request when sending data (not form) to python server is very fast
time curl -i http://0.0.0.0:8082 -d one=1
prints
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
and on the server side:
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 server:
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)
Post request when sending form to node.js server is very fast
time curl -i http://0.0.0.0:8082 -F one=1
prints:
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

I think this is the answer to your problem: libcurl delays for 1 second before uploading data, command-line curl does not
libcurl is sending the Expect 100-Continue header, and waiting 1 second for a response before sending the form data (in the case of the -F command).
In the case of -d, it does not send the 100-Continue header, for whatever reason.