Re: asynchronous comunication, wxPython and threads.
On Tue, 21 Jun 2005 11:07:35 -0400, Peter Hansen wrote: Please clarify: what does this mean? Sending a socket is not a usual way to describe TCP communications. Do you mean your program _opens_ a socket (like a phone connection) and _sends_ some data, then waits for data to be received from the other end? Or are you (as it almost sounds) opening and closing sockets repeatedly for each part of the conversation? Sorry for the lack of clarity. I opened the socket once (i don't know if itit is important to open inside or outside the comunication thread). And them send packages and wait for data. I think you are using the term socket where you should be using packet. A socket is the virtual connection created by TCP. A packet is either a single blob of data sent by the TCP code in the operating system, or perhaps a single chunk of your own data. Thanks for the vocabulary correction. If you are using a single TCP socket to send multiple packets, and you are talking about those packets being sent out of order, it's very unlikely and there must be another explanation. TCP _is_ reliable, and you will not get data out of order unless you do something to screw things up, for example by creating a race condition by doing multithreaded code incorrectly. I think this is the case (see the post of Toby). I didn't try it out but I think the problem is that i *do* comunication in both threads. Some people advise that, but there's really nothing *wrong* with doing this in a second thread, and in fact I do similar things all the time with no ill effects. While async frameworks _can_ make this easier, they could also make it harder (at least for a while) as you adjust your brain to the new approach. Furthermore, at least in the case of wxPython and Twisted (on Windows) there can be problems integrating the two loops. I don't believe the latest Twisted claims to have fully solved the problems involved yet, so you might still be required to have a second thread for the TCP stuff. Yes, i have read that there is problems yet. I use a non-blocking socket and select() calls in my thread, and communicate with the GUI thread using appropriate Queue objects and calls to PostEvent() (or CallAfter()) on the wx side of things. It's pretty straightforward, so if you post a small piece of your application which reproduces the problem it shouldn't be hard for someone here to help you fix it. Thanks. First i would check if the problem is what Toby says. No more so than using threads, unless your problem is caused by the threads themselves (as I suggested above) in which case it might be easier to just fix the problem. -Peter Thank you very much Zunbeltz -- http://mail.python.org/mailman/listinfo/python-list
Re: asynchronous comunication, wxPython and threads.
On Wed, 22 Jun 2005 09:28:31 -0400, Peter Hansen wrote: Almost certainly it is. It would be simplest to set up a worker thread once, when the GUI thread begins, and simply send requests to it via a Queue. It can create the socket, connect to the server, communicate, close it down, and go back to waiting all in one place (so to speak... of course this would be several methods all called from a top-level loop in that thread). No chance of mis-steps. I corrected the problem. A bit of the comunication was done in the GUI thread. Thanks again for your help. Zunbeltz -- http://mail.python.org/mailman/listinfo/python-list
asynchronous comunication, wxPython and threads.
Hi, I have the following problem. I'm developing a GUI program (wxPython). This program has to comunicate (TCP) whit other program that controls a laboratory machine to do a measurement. I have a dialog box, wiht two buttoms Start measurement and Stop. Start executes a function that do the measurement in the following way. 1) My program send a socket. 2) The other program recives it an send confirmation. 3) My program waits for the confirmation and send the next when confirmation received. This comunication is done in a new thread not to frezee the GUI. The problem is that when Stop is done (it kills the thread) some confirmation sockets are mixed (are not receibed in the correct order although i use tcp). I have been told not to do comunication in a new thread; instead, I should use asyncronus comunication. My question: What module should i use, asyncore, asynchat, twisted,(anohter) How can i implement this asynchronous comunication and the ability to stop this long run funciton (the measurement can take hours or days, so i need a way to stop it)? Can asynchronous comunication garantee that the confirmation socket will arrive in the correct order (one after each sended socket)? Thanks for your help Zunbeltz Izaola -- http://mail.python.org/mailman/listinfo/python-list
Re: asynchronous comunication, wxPython and threads.
On Tue, 21 Jun 2005 15:30:41 +0100, Toby Dickenson wrote: On Tuesday 21 June 2005 14:22, Zunbeltz Izaola wrote: I guess you are accessing the socket from both your GUI thread and communications thread. Dont do that. An action in the GUI thread should signal the communictions thread, then the communictions thread talks to the socket. I see ..., Could be the problem that the socket is created in the GUI thread? the function that end the theraded function (abort()) set want_abort = True This make the Measurement() function to return. The Measurement() funtion is called by startmeasurement() which is the threaded funciton. After aborting i execute a function that FinalizeMeasuremnt() that does comunication to some adjustament in the machine. Maybe i have to move this portion to the threaded funtion. Using non-blocking sockets in the GUI thread may cause the opposite problem to the one that led you to use threads in the first place: a blocking operation in the GUI may freeze the communications. Maybe that isnt a problem for you. If it is, I suggest sticking to two threads. Yes, i think i have to stick to two threads. If you are talking to only one device, then using blocking sockets is a good approach. However Ive never written an application like this that didnt need to support a second (or third) machine sooner or later, and three communictions threads is starting to get ugly. A framework like Twisted will let you handle many machines in the one thread, but it still makes sense to keep a second one for the GUI. I didn't get this. What do you do when you have more tham one device; use thread or use Twisted? Did you use it whit wxPython. I think thereis some problems of compatibility. Thank you very much. Zunbeltz -- http://mail.python.org/mailman/listinfo/python-list
asyncore and GUI (wxPython)
Hi, I have the followin situation. 1) I've a machine controled by a computer programn that can comunicate with TCP/IP (server)to recive the request of other program to knwo what the machine should do. 2) The other program (client) has a GUI (with wxPython), recives data from the machine and should process it (draw and write to file). In the current situation the comunication is done in a thread. Every time data is collected it is pased to the main thread of the GUI, with a wxPostEvent. Every stream_socketk sended by the client has its correspondig answer from the server. (I log the comunication an every received socket is the anser of the sended one) The problem: when i stop the thread (i don't no why) the answer to the last socket don't correspond to the last sended (they mix). The possible correction? I have been told not to do network connection in other thread, instead i should use asyncore. I'll be sending sockets every 0.1 seconds or faster. Will be the main progam freeze in the asyncore loop, or it will refresh the windows and response to mouse/keyboard properly? How fast can i be sending sockets without distourbing the main program; or (it is very likeyly) i am totaly wrong and i should take another way? Thanks in advance Zunbeltz -- http://mail.python.org/mailman/listinfo/python-list
Re: avl tree
On Tue, 31 May 2005 22:40:19 +0200, Berthold Höllmann wrote: You can grab it from http://starship.python.net/~bhoel/avl-2.1.0.tar.gz Thanks i will play with it. But i have realize that what i need was exactly a binary tree. I haven't used tree yet and i don't know if i can use the avl instaead an ordinary binary tree. I have to construct a tree like this A B C A C A B B C A B B C A C but i think i can construct a avl using left/right. Am I correct? Thanks again, Zunbeltz Please report any problems to me. I'll do my best to solve them. Regards, Berthold -- http://mail.python.org/mailman/listinfo/python-list
Re: avl tree
On Mon, 30 May 2005 21:13:57 +0200, Berthold Höllmann wrote: I'm afraid you won't be happy with the code. It's very old and likely won't compile. We have an inhouse version of this module which compiles and run on Sparc solaris (32 Bit) and linux x86 with Python up to 2.4. I fixed some warnigs just today for compilation on Linux x86_64, it also seems to work on this platform now. Installation is setup.py based. I'm quite sure we once sent patches to Sam Rushing, but they never made it into his release. I'll try to publish our version the next days. Thanks. I will be looking forward to the release. regards, Zunbeltz Regards Berthold -- http://mail.python.org/mailman/listinfo/python-list
avl tree
Hi, I'm trying to install avl module from http://www.nightmare.com/squirl/python-ext/avl and i had the following instruction to install Building: Unix: First, cd $(AVL_LIB), then 'make libavl.a' Then copy AVLmodule.c into your Modules directory. add a few lines like this to your Python/Modules/Setup file. --- # avl module AVL_LIB=/usr/src/other-homes/rushing/python/avl avl AVLmodule.o -DDEBUG_AVL -I$(AVL_LIB) -L$(AVL_LIB) -lavl - I have build livavl.a, but i don't understan where is Python/Modules/Setup and where goes the AVLModule.c file goes. Could anyone help me, Thanks, Zunbeltz -- http://mail.python.org/mailman/listinfo/python-list
stop a thread safetely
Hi, I have a wxPython application that call makes a thread (with threading module). In some moment i've to stop the thread but i need to finish a funtion in the thread before it can stop. How can i achive this? Thanks in advance Zunbletz -- http://mail.python.org/mailman/listinfo/python-list
Re: stop a thread safetely
On Fri, 13 May 2005 09:10:13 -0400, Peter Hansen wrote: How did you intend to stop the thread in a manner which might be unsafe? (Hint, unless you're doing something unusual, you can't.) I have a threaded object (Mythread). It checks if want_thread variable is True to return. The problem is that this object execute a function that is a tcp comunication def Client(self,Request,Answer): totalsent = 0 while totalsent 608: sent = self.sock.send(Request.struct2string()[totalsent:]) if sent == 0: raise RuntimeError, socket broken totalsent = totalsent + sent if Request.Codigo != 37: self.WriteLog(Request,Request) data = self.sock.recv(608) Answer.string2struct(data) if int(Answer.Param[9]) != 37: self.WriteLog(Answer,Answer) The Client function send a Request (them write it in a log file), gets and answer and and write it. The problem is that when i stop the thread a get somethime the Request writed but not the answer, as if the funciton Client returns before it ends. Zunbeltz -Peter -- http://mail.python.org/mailman/listinfo/python-list
Re: save an opengl canvas (wxPython)
Mike C. Fletcher [EMAIL PROTECTED] writes: There's sample code in PyOpenGL and OpenGLContext for saving canvases to PNG or JPEG formats using PIL. Saving to Postscript requires considerably more work (if you're implying saving as triangles, lines and the like). There is a GPL library which lets you do this, and I have an old SWIG wrapper for it sitting around somewhere (I think, haven't touched it in years), but even then, it's fairly poor quality compared to capturing a bitmap image. Anyway, the function for reading a buffer is glReadPixels: http://pyopengl.sourceforge.net/documentation/manual/glReadPixels.3G.xml see the end of that man page for pointers to Python sample code. Good luck, Mike Hi Mike, Thanks for the answer. I'll check the code. For the moment png or jpeg is ok, but maybe in the future i'll like to save the image as postscript to use it with LaTeX font and so on. I've se the gl2ps library and the last version is 21 September 2004. Can you send me the SWIG file? I don't know much about swig and it would be easier to start with a file that has work in same older version. Thanks again Zunbeltz -- Zunbeltz Izaola Azkona| wmbizazz at lg dot ehu dotes Materia Kondentsatuaren Fisika Saila | Zientzia eta Teknologia Fakultatea| Phone: 34946015326 Euskal Herriko Unibertsitatea | PK 644| Fax: 34 944648500 48080 Bilbo (SPAIN) | -- http://mail.python.org/mailman/listinfo/python-list
save an opengl canvas (wxPython)
Hi, I've a drawing made in an OpenGL canvas. I want to save it to a file (preferibly PostScript format). Somebody knows how to do it? TIA Zunbeltz -- Zunbeltz Izaola Azkona| wmbizazz at lg dot ehu dotes Materia Kondentsatuaren Fisika Saila | Zientzia eta Teknologia Fakultatea| Phone: 34946015326 Euskal Herriko Unibertsitatea | PK 644| Fax: 34 944648500 48080 Bilbo (SPAIN) | -- http://mail.python.org/mailman/listinfo/python-list
