I don't know, Mike, perhaps a good question to ask the mailing list?
On Monday, October 16, 2017 at 10:52:25 AM UTC+10, Mike Bayer wrote: > > oh, a "pre fork" problem, does that mean TCP connections to mysql are > being copied from the main process to forked child processes? I > didn't know uwsgi was that kind of server. That would have because > multiple processes sending data on the same filehandle and would also > cause this problem, though I'd think it would be more severe in its > symptoms. > > > On Sun, Oct 15, 2017 at 7:55 PM, <jens.t...@gmail.com <javascript:>> > wrote: > > After asking at the uWSGI mailing list (see this thread) the suggested > > solution was to enable the lazy-apps flags. That seems to have worked... > > > > > > On Friday, September 29, 2017 at 10:46:47 AM UTC+10, jens.t...@gmail.com > > wrote: > >> > >> Again, thank you Mike! > >> > >> I never see these issues happening locally, which is where I use > gunicorn > >> as the server. Your theory might explain that. The trace comes from our > beta > >> server online, which runs nginx/uwsgi. I'll poke around the > configuration, > >> maybe that'll show something. > >> > >> Eventually though (in the next one-two months) I would like to move to > >> gunicorn as the sole server, because handling API requests is the only > thing > >> it needs to do. > >> > >> Cheers, > >> Jens > >> > >> > >> On Friday, September 29, 2017 at 9:55:30 AM UTC+10, Mike Bayer wrote: > >>> > >>> On Thu, Sep 28, 2017 at 7:17 PM, <jens.t...@gmail.com> wrote: > >>> > Thank you, Mike! > >>> > > >>> > I would have never extracted your interpretation from the trace! (I > >>> > don’t > >>> > know the code…) > >>> > > >>> > The two questions that arise now, though, are > >>> > > >>> > - Why would connections drop out of the pool, is this a > configuration > >>> > problem that I should worry about? > >>> > >>> something was already wrong with the connection when the pool got it > >>> back, so it had to be discarded. as far as what was wrong, it had to > >>> do with the request itself, and it was very possibly the web request's > >>> client dropped the connection, e.g. user hit the stop button. Not > >>> sure what uswgi does but it might have called a thread.exit() / > >>> SystemExit that interrupted PyMySQL's work on the socket. This is > >>> something we definitely see in the eventlet world at least. > >>> > >>> > - The request still failed with a 502 although, as you said, it’s a > >>> > harmless exception. What is the proper way of handling these > >>> > situations? > >>> > >>> if uwsgi is killing off threads when a connection is cut, it might > >>> want to be more graceful about that and at least log that the thread > >>> was killed in the middle. If this is in fact what's going on. I > >>> stick with apache/mod_wsgi for reasons like these. > >>> > >>> > >>> > > >>> > Still learning new things here, and I’m curious about your > suggestions > >>> > :-) > >>> > Jens > >>> > > >>> > > >>> > On Friday, September 29, 2017 at 6:59:48 AM UTC+10, Mike Bayer > wrote: > >>> >> > >>> >> On Thu, Sep 28, 2017 at 2:48 PM, <jens.t...@gmail.com> wrote: > >>> >> > Hello, > >>> >> > > >>> >> > I’m using SQLAlchemy (1.1.13) and SQLAlchemy-Utils (0.32.14) in > the > >>> >> > context > >>> >> > of a Pyramid (1.9.1) web-browser, PyMySQL (0.7.11) as a driver, > and > >>> >> > mysql > >>> >> > 5.6.3. I followed the Pyramid/Alchemy Cookiecutter > implementation. > >>> >> > > >>> >> > On seemingly random requests (although all seem to be OPTIONS) I > see > >>> >> > the > >>> >> > following exception in the server logs (see also this PyMySQL > >>> >> > issue): > >>> >> > > >>> >> > 2017-09-28 18:13:17,765 ERROR > >>> >> > [sqlalchemy.pool.QueuePool][b'uWSGIWorker1Core0'] Exception > during > >>> >> > reset > >>> >> > or > >>> >> > similar > >>> >> > Traceback (most recent call last): > >>> >> > File > >>> >> > > >>> >> > > "/var/www/…/lib64/python3.6/site-packages/sqlalchemy/engine/base.py", > >>> >> > line 1182, in _execute_context > >>> >> > context) > >>> >> > File > >>> >> > > >>> >> > > "/var/www/…/lib64/python3.6/site-packages/sqlalchemy/engine/default.py", > >>> >> > line 470, in do_execute > >>> >> > cursor.execute(statement, parameters) > >>> >> > File > >>> >> > "/var/www/…/lib64/python3.6/site-packages/pymysql/cursors.py", > >>> >> > line > >>> >> > 166, in execute > >>> >> > result = self._query(query) > >>> >> > File > >>> >> > "/var/www/…/lib64/python3.6/site-packages/pymysql/cursors.py", > >>> >> > line > >>> >> > 322, in _query > >>> >> > conn.query(q) > >>> >> > File > >>> >> > > "/var/www/…/lib64/python3.6/site-packages/pymysql/connections.py", > >>> >> > line 856, in query > >>> >> > self._affected_rows = > >>> >> > self._read_query_result(unbuffered=unbuffered) > >>> >> > File > >>> >> > > "/var/www/…/lib64/python3.6/site-packages/pymysql/connections.py", > >>> >> > line 1057, in _read_query_result > >>> >> > result.read() > >>> >> > File > >>> >> > > "/var/www/…/lib64/python3.6/site-packages/pymysql/connections.py", > >>> >> > line 1340, in read > >>> >> > first_packet = self.connection._read_packet() > >>> >> > File > >>> >> > > "/var/www/…/lib64/python3.6/site-packages/pymysql/connections.py", > >>> >> > line 1001, in _read_packet > >>> >> > % (packet_number, self._next_seq_id)) > >>> >> > pymysql.err.InternalError: Packet sequence number wrong - got 102 > >>> >> > expected 8 > >>> >> > > >>> >> > > >>> >> > I see this error in different variations for the packet sequence. > >>> >> > Any > >>> >> > hint > >>> >> > or tip to explain this issue is appreciated! > >>> >> > >>> >> the log seems to indicate the connection pool has gotten the > >>> >> connection back and is attempting to emit a rollback() upon it. > These > >>> >> can fail if the connection has already had some varieties of error > >>> >> occur upon it, most often when the work on the connection was > >>> >> interrupted, such as when receiving a greenlet or thread exit. > It's > >>> >> likely when a WSGI request is interrupted, the cleanup logic here > >>> >> fails because the connection has been thrown into an invalid state. > >>> >> The connection is invalidated (e.g. discarded) in this case and is > >>> >> harmless. > >>> >> > >>> >> > >>> >> > > >>> >> > Thank you! > >>> >> > Jens > >>> >> > > >>> >> > -- > >>> >> > SQLAlchemy - > >>> >> > The Python SQL Toolkit and Object Relational Mapper > >>> >> > > >>> >> > http://www.sqlalchemy.org/ > >>> >> > > >>> >> > To post example code, please provide an MCVE: Minimal, Complete, > and > >>> >> > Verifiable Example. 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