Uploading large binary files using multipart/form-data can be very inefficient because LF character may occur too frequently, resulting in the read_line_to_outer_boundary looping too many times.

*** cgi.py.Py24	Thu Dec  7 18:46:13 2006
--- cgi.py	Thu Dec  7 16:38:04 2006
***************
*** 707,713 ****
          last = next + "--"
          delim = ""
          while 1:
!             line = self.fp.readline()
              if not line:
                  self.done = -1
                  break
--- 703,709 ----
          last = next + "--"
          delim = ""
          while 1:
!             line = self.fp_readline()
              if not line:
                  self.done = -1
                  break
***************
*** 729,734 ****
--- 730,753 ----
                  delim = ""
              self.__write(odelim + line)
  
+     def fp_readline(self):
+ 
+         tell   = self.fp.tell()
+         buffer = self.fp.read(1 << 17)
+         parts  = buffer.split("\n")
+         retlst = []
+         for part in parts:
+             if part.startswith("--"):
+                 if retlst:
+                     retval = "\n".join(retlst) + "\n"
+                 else:
+                     retval = part + "\n"
+                 self.fp.seek(tell + len(retval))
+                 return retval
+             else:
+                 retlst.append(part)
+         return buffer
+ 
      def skip_lines(self):
          """Internal: skip lines until outer boundary if defined."""
          if not self.outerboundary or self.done:


The patch reads the file in larger increments. For my test file of 138 Mb, it reduced parsing time from 168 seconds to 19 seconds.

#------------ test script --------------------
import cgi
import cgi
import os
import profile
import stat

def run():
    filename = 'body.txt'
    size = os.stat(filename)[stat.ST_SIZE]
    fp = open(filename,'rb')
    environ = {}
    environ["CONTENT_TYPE"]   = open('content_type.txt','rb').read()
    environ["REQUEST_METHOD"] = "POST"
    environ["CONTENT_LENGTH"] = str(size)

    fieldstorage = cgi.FieldStorage(fp, None, environ=environ)
    return fieldstorage

import hotshot, hotshot.stats
import time
if 1:
    t1 = time.time()
    prof = hotshot.Profile("bug1718.prof")
    # hotshot profiler will crash with the 
    # patch applied on windows xp
    #prof_results = prof.runcall(run)
    prof_results  = run()
    prof.close()
    t2 = time.time()
    print t2-t1
    if 0:
      for key in prof_results.keys():
        if len(prof_results[key].value)> 100:
            print key, prof_results[key].value[:80] + "..."
        else:
            print key, prof_results[key]

content_type.txt
----------------------------
multipart/form-data; boundary=----------ThIs_Is_tHe_bouNdaRY_$

Chui Tey does this issue still apply?  If yes, could you please provide a patch according to the guidelines here.
python.org/dev/patches

No reply to msg110090.

I don't think it was appropriate to close this issue.

It needs tests to demonstrate the issue in 3.x, and an updated patch.

It would be great if someone could port this patch to Python 3.4 and verify its effectiveness.