Mailman 3 March 2010 - Twisted

Re: [Twisted-Python] [sqlalchemy] Re: SQLAlchemy, Twisted, and sAsync
by Matthew Williams 26 Mar '10

26 Mar '10

Thank you, Simon, for clarifying this and pointing out that part of the SQLAlchemy docs... somehow I missed that part :-). On Mar 26, 2010, at 7:30 AM, King Simon-NFHD78 wrote: > I think that point should be clarified, so that people don't later > come > across this post and just accept it without understanding. > > I imagine that SQLALchemy is used in a lot of threaded applications. > For > example, it is the recommended ORM in web frameworks such as Pylons > and > TurboGears, which work fine in threaded environments. However, > typically > in these libraries a web request is handled by a single thread, and > all > the SQLAlchemy operations occur within the scope of that request. As > long as you don't share a Session instance between the threads, you > won't have any problems. SQLAlchemy provides a ScopedSession class > which > helps in these situations, as you can call the constructor many > times on > a single thread and always get the session instance back for that > thread. Sessions themselves aren't thread-safe. > > When an instance is loaded from the database, it is linked to the > session that loaded it. This means that when you have lazy-loading > properties on that instance (such as related classes, or deferred > column > properties), they will be automatically loaded when they are accessed, > in the same session. > > This will cause a problem if you load an instance in thread A, hand > the > object off to thread B, and then thread B accesses one of these > lazy-loading properties. The load will occur in thread A's session, > which might be in the middle of doing something else. > > The solution to this is either to eager-load all the attributes you > think you are going to need before handing the instance off to another > thread (difficult), or (probably better) to detach (expunge) the > instance from thread A's session. Thread B should then merge the > object > into its own session (using the load=False flag so that it doesn't > needlessly requery the database). > > The Session docs at http://www.sqlalchemy.org/docs/session.html > explain > the lifecycle of loaded instances. > > I haven't actually done any of this - I've only ever used SA from TG > and > command-line scripts, but I think the principles are about right. I > hope > that helps, > > Simon

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[Twisted-Python] SQLAlchemy, Twisted, and sAsync
by Matthew Williams 26 Mar '10

26 Mar '10

I have recently started a project using Twisted with a MySQL backend. From previous posts to this and other lists, it seems that ORMs and threads don't get along too well... and, as far as I can tell, there's no way to get away from threads if you don't want longish queries to block your entire application. At this point, I am using SQLAlchemy's SQL builder functionality (but not ORM layer) and using sAsync to manage the threading. Does anyone have experience with this technique and, if so, with what results? It took me quite some time to piece together everything I could find related to sAsync (which seems to be a dead but functional project), so I threw up a quick Trac page for it at http://sasync.org. Thanks in advance for any feedback! Matthew

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Re: [Twisted-Python] Twisted-Python Digest, Vol 72, Issue 35
by sara bai 24 Mar '10

24 Mar '10

hi all, i run into this problem “ ”The debugged program raised the exception unhandled Error "[('PEM routines', 'PEM_read_bio', 'no start line'), ('SSL routines', 'SSL_CTX_use_PrivateKey_file', 'PEM lib')]" File: /usr/lib/python2.5/site-packages/Twisted-10.0.0-py2.5-linux-i686.egg/twisted/internet/ssl.py, Line: 99" ( usr/lib/python25/site-packages/Twisted-10.0.0-py2.5-linux-i686.egg/twisted/internet/ssl.py line 99 ) def cacheContext(self): if self._context is None: ctx = self._contextFactory(self.sslmethod) # Disallow SSLv2! It's insecure! SSLv3 has been around since # 1996. It's time to move on. ctx.set_options(SSL.OP_NO_SSLv2) ctx.use_certificate_file(self.certificateFileName) ctx.use_privatekey_file(self.privateKeyFileName) # Line: 99 self._context = ctx here is the way i create privkey file : $ openssl genrsa > privkey.pem then $ openssl req -new -x509 -key privkey.pem -out cacert.pem -days 1000 i have checked the cacert.pem file it do has 'strt line ' －－BEGIN CERTIFICATE－－－－ part of my code : class syslogOptions(usage.Options): optParameters = [['cert', 'c', '/home/ssltest/cacert.pem','SSL Server certificate'], ['ip', 'i', None, 'IP Address to listen on']] def postOptions(self): if (not self.opts['cert']) or (not os.path.isfile(self.opts['cert'])): raise usage.UsageError, "%s: is not a file" % self.opts['cert'] . . . syslogSSL = syslogFactory() syslogSSL.protocol = outputTCP ctx = ssl.DefaultOpenSSLContextFactory(config.opts['cert'], config.opts['cert']) .. .. . reactor.listenSSL(708, syslogSSL , ctx, interface=config.opts['ip']) reactor.run() any ideas ? ... 2010/3/25 <twisted-python-request(a)twistedmatrix.com> > Send Twisted-Python mailing list submissions to > twisted-python(a)twistedmatrix.com > > To subscribe or unsubscribe via the World Wide Web, visit > http://twistedmatrix.com/cgi-bin/mailman/listinfo/twisted-python > or, via email, send a message with subject or body 'help' to > twisted-python-request(a)twistedmatrix.com > > You can reach the person managing the list at > twisted-python-owner(a)twistedmatrix.com > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of Twisted-Python digest..." > > > Today's Topics: > > 1. Re: Nothing Succeeds Like Success (Stories) (David) > 2. Logout from a perspective broker server (Ramiro Alba Queipo) > 3. Re: stdio.StandardIO blocks? (Glyph Lefkowitz) > 4. Re: Logout from a perspective broker server (Glyph Lefkowitz) > 5. Re: Logout from a perspective broker server (Ramiro Alba Queipo) > 6. NetstringReceiver (Albert Brandl) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Tue, 23 Mar 2010 10:48:41 -0600 > From: David <dvkeeney(a)gmail.com> > Subject: Re: [Twisted-Python] Nothing Succeeds Like Success (Stories) > To: Twisted general discussion <twisted-python(a)twistedmatrix.com> > Message-ID: > <6e04113a1003230948j41fd0e5bn53ceda6970b36e43(a)mail.gmail.com> > Content-Type: text/plain; charset=ISO-8859-1 > > On Mon, Mar 22, 2010 at 8:39 PM, Glyph Lefkowitz > <glyph(a)twistedmatrix.com> wrote: > > > If you're a happy Twisted user who has used Twisted to do something cool, > *please* send in a blurb for the success stories page! ?This could translate > into more money and more development for Twisted, thus making it even more > awesome. ?This goes double if you're a sponsor: please let us know why you > sponsored and how happy you were that you did :). > > > Rdbhost > > Rdbhost uses Twisted for a streaming web-server. The streaming server > allows users to stream large SQL 'dump' files to and from the database > host using a web browser. > > http://www.rdbhost.com > > -- > dkeeney(a)rdbhost.com > Rdbhost -> SQL databases as a webservice [www.rdbhost.com] > > > > ------------------------------ > > Message: 2 > Date: Tue, 23 Mar 2010 19:30:36 +0100 > From: Ramiro Alba Queipo <raq(a)cttc.upc.edu> > Subject: [Twisted-Python] Logout from a perspective broker server > To: Twisted general discussion <twisted-python(a)twistedmatrix.com> > Message-ID: <1269369036.6222.11.camel@mundo> > Content-Type: text/plain; charset=ISO-8859-1 > > Hi all, > > I wonder, if I client using pygtk, can logout from the server without > calling reactor.stop(), as you would kill the GUI. I tried to delete the > perspective got from the server but it does not work... > > Thanks in advance > Regards > > -- > Ramiro Alba > > Centre Tecnol?gic de Tranfer?ncia de Calor > http://www.cttc.upc.edu > > > Escola T?cnica Superior d'Enginyeries > Industrial i Aeron?utica de Terrassa > Colom 11, E-08222, Terrassa, Barcelona, Spain > Tel: (+34) 93 739 86 46 > > > -- > Aquest missatge ha estat analitzat per MailScanner > a la cerca de virus i d'altres continguts perillosos, > i es considera que est? net. > > > > > ------------------------------ > > Message: 3 > Date: Wed, 24 Mar 2010 05:22:39 -0400 > From: Glyph Lefkowitz <glyph(a)twistedmatrix.com> > Subject: Re: [Twisted-Python] stdio.StandardIO blocks? > To: Twisted general discussion <twisted-python(a)twistedmatrix.com> > Message-ID: <6EB44FA1-3F26-433F-A2B3-3FE4AC3A5BD0(a)twistedmatrix.com> > Content-Type: text/plain; charset="us-ascii" > > > On Mar 23, 2010, at 10:00 AM, Willy Lai wrote: > > > What I want, is writing stuff in the console, without interrupting the > > ping mechanism. > > (The pings and pongs in my case should continue to be sent while typing > > stuff in the console) > > Without a *complete* program example, we can't really tell you what might > be blocking. It may be a lot of things, from some very simple problems to > some very complex ones. Please see <http://sscce.org/> for details on > what types of examples would be useful. > > Based on your simple description, this really should work. If it didn't, > 'twistd' wouldn't be able to log to stdout and run a server at the same time > (and it definitely can, I do that every day, at least ten times). > > Thanks, > > -glyph > >

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[Twisted-Python] Nothing Succeeds Like Success (Stories)
by Glyph Lefkowitz 24 Mar '10

24 Mar '10

Hello successful Twisted users, Several times over the last month I've been contacted by Twisted supporters who are looking to make the case to others within their organizations that Twisted is a worthwhile thing to sponsor. The most common question has been: "what are other people using this for?". Inevitably they'll end up at <http://twistedmatrix.com/trac/wiki/SuccessStories> - if we're lucky, they'll also see <http://twistedmatrix.com/trac/wiki/ProjectsUsingTwisted>, but that's only a slight improvement. These pages are pretty anemic and frankly don't present a good impression of what is really possible with Twisted. I note that several prominent users aren't represented at all. You know who you are! If you're a happy Twisted user who has used Twisted to do something cool, *please* send in a blurb for the success stories page! This could translate into more money and more development for Twisted, thus making it even more awesome. This goes double if you're a sponsor: please let us know why you sponsored and how happy you were that you did :). If you're looking to volunteer some time for Twisted, but don't have much time to volunteer, becoming to be the official curator of these pages would be a small commitment but it would be quite helpful. As I said, presenting a good public face for Twisted's maturity and broad applicability can translate directly into increased resources, so in the long term it would have a big impact. Finally, if you're _not_ happy, it's always great to get some constructive criticism. Best would be in the form of well-specified bugs filed at <http://twistedmatrix.com/trac/newticket>, of course ;). Thanks, -glyph

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[Twisted-Python] Logout from a perspective broker server
by Ramiro Alba Queipo 24 Mar '10

24 Mar '10

Hi all, I wonder, if I client using pygtk, can logout from the server without calling reactor.stop(), as you would kill the GUI. I tried to delete the perspective got from the server but it does not work... Thanks in advance Regards -- Ramiro Alba Centre Tecnològic de Tranferència de Calor http://www.cttc.upc.edu Escola Tècnica Superior d'Enginyeries Industrial i Aeronàutica de Terrassa Colom 11, E-08222, Terrassa, Barcelona, Spain Tel: (+34) 93 739 86 46 -- Aquest missatge ha estat analitzat per MailScanner a la cerca de virus i d'altres continguts perillosos, i es considera que està net.

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[Twisted-Python] stdio.StandardIO blocks?
by Willy Lai 24 Mar '10

24 Mar '10

Hi all I'm new to twisted and also have not a lot of Python experience. My problem boils down to following situation: I have a server and a client over TCP, once the client is connected to the server, the server periodically pings the client in order to check if it is still alive. The client sends a response/pong back to each ping. These messages are printed to stdout. The two consoles would then look like: [connected] ping pong ...2 seconds ... ping pong ...2 seconds ... ping pong ... Now the user should be able to write commands in the command line, which get's sent to the server, without interrupting the pings. But in my case, while writing on the console the output stops. The server will send a ping, but the client does not seem to receive the ping, since I don't get a pong on the server. What happens at the moment I type something in the command line? What I want, is writing stuff in the console, without interrupting the ping mechanism. (The pings and pongs in my case should continue to be sent while typing stuff in the console) That's how I use StandardIO: class CommandLine(protocol.Protocol): def __init__(self, protocol): self.protocol = protocol def dataReceived(self, data): print('INPUT: %s' % (data) class Client(protocol.DatagramProtocol): def __init__(self): # initialize command line connector commandLine = CommandLine(self) # connect member to command line output self.output = stdio.StandardIO(commandLine) Cheers

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[Twisted-Python] Error: filedescriptor out of range in select
by Don Schoeman 23 Mar '10

23 Mar '10

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[Twisted-Python] python-daemon PID file
by null null 22 Mar '10

22 Mar '10

Hi all, Im trying to get a daemon up and running but i cant get python-daemon to create a PID file. versions: Python 2.5.2 python-daemon-1.5.5 Debian Linux 2.6.26-2-686 <code> import daemon import lockfile daemon.DaemonContext(pidfile=lockfile.FileLock('/var/run/mydaemon.pid'),) daemon.__enter__() main() daemon.__exit__() </code> The above doesnt create a pid file, ive tried different permissions for the daemon and manualy making the pid file in the main() but no luck. In summary: I cant get a PID file created or populated with a PID by python-daemon. Anyone see something that im doing wrong? ive been sitting on this way too long. I looked at the python-daemon source and i cant see where the pid is inserted into the pid file, only where it __enter__'s the lockfile so is this functionality missing? Thanks!

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[Twisted-Python] sara bai wants to chat
by sara bai 21 Mar '10

21 Mar '10

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[Twisted-Python] Weekly Bug Summary
by exarkun＠twistedmatrix.com 20 Mar '10

20 Mar '10

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