Can't establish more than about 1024 HTTP connections - linux

Question

I'm curious what limit I'm raised? I have the next code:
import httplib, resource, socket, traceback
print("NOFILE: %s" % str(resource.getrlimit(resource.RLIMIT_NOFILE)))
socket.setdefaulttimeout(100000)
conns = []
for _ in xrange(10000000):
con = httplib.HTTPConnection('ya.ru') # or 93.158.134.3
try:
con.connect()
conns.append(con)
except:
print("Total connections: %s\n" % len(conns))
print(traceback.format_exc())
break
input("Press any key to exit...")
When HTTPConnection uses a host name, I get the next output:
NOFILE: (2560, 9223372036854775807)
Total connections: 1019
Traceback (most recent call last):
File "test.py", line 13, in <module>
con.connect()
File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/httplib.py", line 772, in connect
self.timeout, self.source_address)
File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/socket.py", line 571, in create_connection
raise err
error: [Errno 65] No route to host
And when I use the direct IP address:
NOFILE: (2560, 9223372036854775807)
Total connections: 1021
Traceback (most recent call last):
File "test.py", line 13, in <module>
con.connect()
File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/httplib.py", line 772, in connect
self.timeout, self.source_address)
File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/socket.py", line 571, in create_connection
raise err
error: [Errno 36] Operation now in progress
It looks like pretty the same point of failure because 1019, 1021 and 1024 are very close values. I think 1024 is a some limit within my OS.
uname -a
Darwin hackmachine 13.3.0 Darwin Kernel Version 13.3.0: Tue Jun 3 21:27:35 PDT 2014; root:xnu-2422.110.17~1/RELEASE_X86_64 x86_64
ulimit -a
core file size (blocks, -c) 0
data seg size (kbytes, -d) unlimited
file size (blocks, -f) unlimited
max locked memory (kbytes, -l) unlimited
max memory size (kbytes, -m) unlimited
open files (-n) 2560
pipe size (512 bytes, -p) 1
stack size (kbytes, -s) 8192
cpu time (seconds, -t) unlimited
max user processes (-u) 709
virtual memory (kbytes, -v) unlimited
So, my questions are:
What's the limitation I encountered?
What are explanations for the error
messages? They don't look very self-explaining.
UPD: Tried the same thing on Debian 7. ulimit -n <limit> works as expected and I can establish as much connections as is set by ulimit. So, it looks like an OS X specific problem.