On Tuesday, February 3, 2015 at 3:17:37 PM UTC+1, Amirouche Boubekki wrote:
> What you want is to prevent the socket to wait indefinetly for data (based on
> strace output) which is done with socket.setblocking/settimeout [1].
> asynchronous (asyncio) is something else, and you would still need to handle
> blocking I think.
I have installed Faulthandler, a beautiful tool written by Victor "Haypo"
Stinner, and thanks to it I could determine precisely where the program hangs.
It is in ssl.py::SSLSocket::read
def read(self, len=1024):
"""Read up to LEN bytes and return them.
Return zero-length string on EOF."""
try:
> return self._sslobj.read(len) >*< python hangs on this line
except SSLError, x:
if x.args[0] == SSL_ERROR_EOF and self.suppress_ragged_eofs:
return ''
else:
raise
>From the traceback given by faulthandler it seems to me that the problem isn't
>from my webserver trying to receive connections from clients, but from my
>server (acting as a client) trying a request on a distant server (https URL ->
>use of ssl.py). Here's the traceback :
1 Current thread 0x00007fb9cb41f700 (most recent call first):
2 File "/usr/lib/python2.7/ssl.py", line 160 in read
3 File "/usr/lib/python2.7/ssl.py", line 241 in recv
4 File "/usr/lib/python2.7/socket.py", line 447 in readline
5 File "/usr/lib/python2.7/httplib.py", line 365 in _read_status
6 File "/usr/lib/python2.7/httplib.py", line 407 in begin
7 File "/usr/lib/python2.7/httplib.py", line 1034 in getresponse
8 File
"/usr/local/lib/python2.7/dist-packages/requests/packages/urllib3/connectionpool.py",
line 353 in _make_request
9 File
"/usr/local/lib/python2.7/dist-packages/requests/packages/urllib3/connectionpool.py",
line 518 in urlopen
10 File "/usr/local/lib/python2.7/dist-packages/requests/adapters.py",
line 370 in send
11 File "/usr/local/lib/python2.7/dist-packages/requests/sessions.py",
line 573 in send
12 File "/usr/local/lib/python2.7/dist-packages/requests/sessions.py",
line 461 in request
13 File "/usr/local/lib/python2.7/dist-packages/requests/sessions.py",
line 473 in get
14 File "/usr/local/lib/python2.7/dist-packages/infomaniak/infomaniak.py",
line 29 in getFlux
15 File "/usr/local/lib/python2.7/dist-packages/infomaniak/server.py",
line 52 in do_GET
16 File "/usr/lib/python2.7/BaseHTTPServer.py", line 328 in
handle_one_request
17 File "/usr/lib/python2.7/BaseHTTPServer.py", line 340 in handle
18 File "/usr/lib/python2.7/SocketServer.py", line 649 in __init__
19 File "/usr/lib/python2.7/SocketServer.py", line 334 in finish_request
20 File "/usr/lib/python2.7/SocketServer.py", line 321 in process_request
21 File "/usr/lib/python2.7/SocketServer.py", line 295 in
_handle_request_noblock
22 File "/usr/lib/python2.7/SocketServer.py", line 238 in serve_forever
23 File "/usr/local/lib/python2.7/dist-packages/infomaniak/server.py",
line 71 in <module>
24 File "/usr/bin/infomaniak", line 2 in <module>
25
If you look at line 13, it shows that the server is actually doing a get to an
external URL via the requests library, which is itself relying on urllib3,
which in turn is using httplib.py
Below is the code of the last three functions to have been called, in
chronoligical order :
In socket.py::_fileobject::readline
[...]
while True:
try:
data = self._sock.recv(self._rbufsize) #<------------
except error, e:
if e.args[0] == EINTR:
continue
raise
if not data:
break
nl = data.find('\n')
if nl >= 0:
nl += 1
buf.write(data[:nl])
self._rbuf.write(data[nl:])
del data
break
buf.write(data)
return buf.getvalue()
[...]
In ssl.py::SSLSocket::recv
def recv(self, buflen=1024, flags=0):
if self._sslobj:
if flags != 0:
raise ValueError(
"non-zero flags not allowed in calls to recv() on %s" %
self.__class__)
return self.read(buflen) #<-------
else:
return self._sock.recv(buflen, flags)
In ssl.py::SSLSocket::read
def read(self, len=1024):
"""Read up to LEN bytes and return them.
Return zero-length string on EOF."""
try:
return self._sslobj.read(len) # >*< python hangs on this line
except SSLError, x:
if x.args[0] == SSL_ERROR_EOF and self.suppress_ragged_eofs:
return ''
else:
raise
I can't go any further because the _sslobj is create via the _ssl.so library,
it is very likely C code.
Do you have any idea about how I can investigate this any further ?
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