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Re: all webserver threads blocking on db.open()

by Claudiu Saftoiu :: Rate this Message:

On Mon, May 7, 2012 at 12:13 PM, Hanno Schlichting <hanno@...> wrote:

I think you might get better help on one of the Pyramid support channels.

Your problems all seem to be related to configuring a web server in
production mode, rather than database issues.

Thanks, I'll check out the Repoze.BFG IRC channel as well.

From what I can tell you are dealing with hung requests. I'd look at
either the paster configuration options for anything related to
timeouts, thread pools, handling of incomplete requests and so on. Or
use a more production quality web server like Apache (mod_wsgi), Nginx
(gevent/gunicon) which likely has better default configuration values
for these things.

The problem from my previous email was indeed hung requests. However, the

stack trace for those looked different:

Thread 140605868680960:

File "/usr/lib/python2.6/threading.py", line 504, in __bootstrap

self.__bootstrap_inner()

File "/usr/lib/python2.6/threading.py", line 532, in __bootstrap_inner

self.run()

File "/usr/lib/python2.6/threading.py", line 484, in run

self.__target(*self.__args, **self.__kwargs)

File "/home/tsa/env/lib/python2.6/site-packages/paste/httpserver.py", line 878, in worker_thread_callback

runnable()

File "/home/tsa/env/lib/python2.6/site-packages/paste/httpserver.py", line 1052, in <lambda>

lambda: self.process_request_in_thread(request, client_address))

File "/home/tsa/env/lib/python2.6/site-packages/paste/httpserver.py", line 1068, in process_request_in_thread

self.finish_request(request, client_address)

File "/usr/lib/python2.6/SocketServer.py", line 322, in finish_request

self.RequestHandlerClass(request, client_address, self)

File "/usr/lib/python2.6/SocketServer.py", line 617, in __init__

self.handle()

File "/home/tsa/env/lib/python2.6/site-packages/paste/httpserver.py", line 442, in handle

BaseHTTPRequestHandler.handle(self)

File "/usr/lib/python2.6/BaseHTTPServer.py", line 329, in handle

self.handle_one_request()

File "/home/tsa/env/lib/python2.6/site-packages/paste/httpserver.py", line 437, in handle_one_request

self.wsgi_execute()

File "/home/tsa/env/lib/python2.6/site-packages/paste/httpserver.py", line 287, in wsgi_execute

self.wsgi_start_response)

File "/home/tsa/env/lib/python2.6/site-packages/repoze/zodbconn/connector.py", line 21, in __call__

result = self.next_app(environ, start_response)

File "/home/tsa/env/lib/python2.6/site-packages/repoze/zodbconn/cachecleanup.py", line 25, in __call__

return self.next_app(environ, start_response)

File "/home/tsa/env/lib/python2.6/site-packages/repoze/retry/__init__.py", line 65, in __call__

chunk = original_wsgi_input.read(rest)

File "/home/tsa/env/lib/python2.6/site-packages/paste/httpserver.py", line 474, in read

data = self.file.read(length)

File "/usr/lib/python2.6/socket.py", line 377, in read

data = self._sock.recv(left)

Note the line it blocks on is "self._sock.recv(left)", well after the response started.

In the trace I just provided, the block was on opening the DB connection *at the start of the request*:

...

File "/home/tsa/env/lib/python2.6/site-packages/paste/httpserver.py", line 287, in wsgi_execute

self.wsgi_start_response)

File "/home/tsa/env/lib/python2.6/site-packages/repoze/zodbconn/connector.py", line 18, in __call__

conn = self.db.open()

File "/home/tsa/env/lib/python2.6/site-packages/ZODB/DB.py", line 729, in open

self._a()

File "/usr/lib/python2.6/threading.py", line 123, in acquire

rc = self.__block.acquire(blocking)

Why would the database start blocking on opening a new database connection? The

issue does indeed seem to be with ZODB.

Thanks,

- Claudiu

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