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  • Blocking error in celery

    - by dmitry
    I have no idea what's this. Python 2.7 + django-1.5.1 + httpd + rabbitmq + django-celery==3.0.17 Tasks are not executed because of some error. Below is celery's log. Maybe someone has faced it before. [2013-06-24 17:10:03,792: CRITICAL/MainProcess] Can't decode message body: AttributeError("'JoinInfo' object has no attribute '__dict__'",) (type:u'application/x-python-serialize' encoding:u'binary' raw:'\'\\x80\\x02}q\\x01(U\\x07expiresq\\x02NU\\x03utcq\\x03\\x88U\\x04argsq\\x04cdjango.contrib.auth.models\\nUser\\nq\\x05)\\x81q\\x06}q\\x07(U\\x08usernameq\\x08X\\x19\\x00\\x00\\[email protected]\\nfirst_nameq\\tX\\x05\\x00\\x00\\x00BibbyU\\tlast_nameq\\nX\\x08\\x00\\x00\\x00OffshoreU\\r_client_cacheq\\x0bccopy_reg\\n_reconstructor\\nq\\x0ccbongoregistration.models\\nClient\\nq\\rc__builtin__\\nobject\\nq\\x0eN\\x87Rq\\x0f}q\\x10(h\\nX\\x08\\x00\\x00\\x00OffshoreU\\x1bpurchase_confirmation_emailq\\x11X\\x1f\\x00\\x00\\[email protected]\\x1dpurchase_confirmation_email_1q\\x12X!\\x00\\x00\\[email protected]\\x06_stateq\\x13cdjango.db.models.base\\nModelState\\nq\\x14)\\x81q\\x15}q\\x16(U\\x06addingq\\x17\\x89U\\x02dbq\\x18U\\x07defaultq\\x19ubU\\x0buser_ptr_idq\\x1aJ\\xb4\\xa2\\x03\\x00U\\x08is_staffq\\x1b\\x89U\\x08postcodeq\\x1cX\\x08\\x00\\x00\\x00AB11 5BSU\\x0cdegree_limitq\\x1dK\\x06U\\x07messageq\\x1eX\\xd1E\\x00\\x00<table id="container" style="margin: 0px; padding: 0px; width: 100%; background-color: #ffffff;" cellspacing="0" cellpadding="0"... (22911b)'') Traceback (most recent call last): File "/opt/www/MyProject-main/eggs/kombu-2.5.10-py2.7.egg/kombu/messaging.py", line 556, in _receive_callback decoded = None if on_m else message.decode() File "/opt/www/MyProject-main/eggs/kombu-2.5.10-py2.7.egg/kombu/transport/base.py", line 147, in decode self.content_encoding, accept=self.accept) File "/opt/www/MyProject-main/eggs/kombu-2.5.10-py2.7.egg/kombu/serialization.py", line 187, in decode return decode(data) File "/opt/www/MyProject-main/eggs/kombu-2.5.10-py2.7.egg/kombu/serialization.py", line 74, in pickle_loads return load(BytesIO(s)) AttributeError: 'JoinInfo' object has no attribute '__dict__'

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  • Twitter Bootstrap Navbar blocking svg viewBox

    - by user1167650
    I have a navbar fixed to the bottom and I have page that has a title and a giant svg (created by d3.js). I would like the svg to take up the entire screen (whatever is left over), but it always seems to have some part appear behind the bottom nav bar. I've tried: 1) using viewBox to auto-resize, setting the parent div and the svg to be block elements 2) adding padding-bottom to the body element But the svg still appears behind the navbar on wide screen monitors.

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  • application blocking

    - by pradeep
    I have a application which runs over browser ...php application... i need to lock this application to only few machines and laptops that we allow to access. IP locking cannot be done as laptops can be on wifi from outside... Any Idea on how to do this?

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  • Sending bulk notification emails without blocking

    - by FreshCode
    For my client's custom-built CRM, I want users (technicians) to be notified of changes to marked cases via email. This warrants a simple subscription mapping table between users and cases and automated emails to be sent every time a change is made to a case from within the logging method. How do I send 10-100 emails to subscribed users without bogging down my logging method? My SMTP server is on a peer on my LAN, so sends should be quick, but ideally this should be handled by an external queuing process. I can have a cron job send any outstanding emails every 10 minutes, but for this specific client cases are quite time-sensitive and instant notification (as instant as email can be) would be great. How can I send bulk notification emails from within ASP.NET MVC without bogging down my logging method?

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  • non blocking client server chat application in java using nio

    - by Amith
    I built a simple chat application using nio channels. I am very much new to networking as well as threads. This application is for communicating with server (Server / Client chat application). My problem is that multiple clients are not supported by the server. How do I solve this problem? What's the bug in my code? public class Clientcore extends Thread { SelectionKey selkey=null; Selector sckt_manager=null; public void coreClient() { System.out.println("please enter the text"); BufferedReader stdin=new BufferedReader(new InputStreamReader(System.in)); SocketChannel sc = null; try { sc = SocketChannel.open(); sc.configureBlocking(false); sc.connect(new InetSocketAddress(8888)); int i=0; while (!sc.finishConnect()) { } for(int ii=0;ii>-22;ii++) { System.out.println("Enter the text"); String HELLO_REQUEST =stdin.readLine().toString(); if(HELLO_REQUEST.equalsIgnoreCase("end")) { break; } System.out.println("Sending a request to HelloServer"); ByteBuffer buffer = ByteBuffer.wrap(HELLO_REQUEST.getBytes()); sc.write(buffer); } } catch (IOException e) { e.printStackTrace(); } finally { if (sc != null) { try { sc.close(); } catch (Exception e) { e.printStackTrace(); } } } } public void run() { try { coreClient(); } catch(Exception ej) { ej.printStackTrace(); }}} public class ServerCore extends Thread { SelectionKey selkey=null; Selector sckt_manager=null; public void run() { try { coreServer(); } catch(Exception ej) { ej.printStackTrace(); } } private void coreServer() { try { ServerSocketChannel ssc = ServerSocketChannel.open(); try { ssc.socket().bind(new InetSocketAddress(8888)); while (true) { sckt_manager=SelectorProvider.provider().openSelector(); ssc.configureBlocking(false); SocketChannel sc = ssc.accept(); register_server(ssc,SelectionKey.OP_ACCEPT); if (sc == null) { } else { System.out.println("Received an incoming connection from " + sc.socket().getRemoteSocketAddress()); printRequest(sc); System.err.println("testing 1"); String HELLO_REPLY = "Sample Display"; ByteBuffer buffer = ByteBuffer.wrap(HELLO_REPLY.getBytes()); System.err.println("testing 2"); sc.write(buffer); System.err.println("testing 3"); sc.close(); }}} catch (IOException e) { e.printStackTrace(); } finally { if (ssc != null) { try { ssc.close(); } catch (IOException e) { e.printStackTrace(); } } } } catch(Exception E) { System.out.println("Ex in servCORE "+E); } } private static void printRequest(SocketChannel sc) throws IOException { ReadableByteChannel rbc = Channels.newChannel(sc.socket().getInputStream()); WritableByteChannel wbc = Channels.newChannel(System.out); ByteBuffer b = ByteBuffer.allocate(1024); // read 1024 bytes while (rbc.read(b) != -1) { b.flip(); while (b.hasRemaining()) { wbc.write(b); System.out.println(); } b.clear(); } } public void register_server(ServerSocketChannel ssc,int selectionkey_ops)throws Exception { ssc.register(sckt_manager,selectionkey_ops); }} public class HelloClient { public void coreClientChat() { Clientcore t=new Clientcore(); new Thread(t).start(); } public static void main(String[] args)throws Exception { HelloClient cl= new HelloClient(); cl.coreClientChat(); }} public class HelloServer { public void coreServerChat() { ServerCore t=new ServerCore(); new Thread(t).start(); } public static void main(String[] args) { HelloServer st= new HelloServer(); st.coreServerChat(); }}

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  • ui header is blocking a div

    - by Tumharyyaaden
    i have built jQuery drop-down menu which is having problems floating over the UI header. Flash and everything else is fine, menu has no problem floating over anything except UI headers, i have tried messing with z-index in css files but it seems that jQuery script is over writing all of my css. the JS files are minified so i can not edit them. I think a JS solution is necessary but i do not know how to solve this with JS. URL: http://patel.mine.nu/live%20site/metanoia/

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  • Doing some downloading without blocking you app

    - by Code
    Hi guys, I'm working on my first app that's doing a few different web connections at once. My first screen is my Menu. And at the bottom of viewDidLoad of MenuViewController i call a method that gets and parses a .xml file that is located on my webserver. Also at the bottom of viewDidLoad i do FootballScores = [[FootBallScores alloc] init]; and FootballScores makes a connection to a html page which it loads into a string and then parses out data. Now since both of these are getting called at the bottom of viewDidLoad of the class thats is responsible for the main menu(first screen in the app) it means the app is kinda slow to load. What is the right way to do the above? Should i remove the 2 pieces of code from my viewDidLoad and replace with maybe dataGetterOne = [NSTimer scheduledTimerWithTimeInterval:1.000 target:self selector:@selector(xmlParser) userInfo:nil repeats:NO]; dataGetterTwo = [NSTimer scheduledTimerWithTimeInterval:2.000 target:self selector:@selector(htmlParser) userInfo:nil repeats:NO]; This would mean that the methods get called later on and the viewDidLoad gets to finish before the i try get the data from the web servers. Making 2 connections to we bservers a second apart to quick? Can the iphone handle having 2 connections open at once? I'm really unsure of anything bad/dangerous I am doing in regards to connections. Many Thanks -Code

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  • Asynchronous Controller is blocking requests in ASP.NET MVC through jQuery

    - by Jason
    I have just started using the AsyncController in my project to take care of some long-running reports. Seemed ideal at the time since I could kick off the report and then perform a few other actions while waiting for it to come back and populate elements on the screen. My controller looks a bit like this. I tried to use a thread to perform the long task which I'd hoped would free up the controller to take more requests: public class ReportsController : AsyncController { public void LongRunningActionAsync() { AsyncManager.OutstandingOperations.Increment(); var newThread = new Thread(LongTask); newThread.Start(); } private void LongTask() { // Do something that takes a really long time //....... AsyncManager.OutstandingOperations.Decrement(); } public ActionResult LongRunningActionCompleted(string message) { // Set some data up on the view or something... return View(); } public JsonResult AnotherControllerAction() { // Do a quick task... return Json("..."); } } But what I am finding is that when I call LongRunningAction using the jQuery ajax request, any further requests I make after that back up behind it and are not processed until LongRunningAction completes. For example, call LongRunningAction which takes 10 seconds and then call AnotherControllerAction which is less than a second. AnotherControllerAction simply waits until LongRunningAction completes before returning a result. I've also checked the jQuery code, but this still happens if I specifically set "async: true": $.ajax({ async: true, type: "POST", url: "/Reports.aspx/LongRunningAction", dataType: "html", success: function(data, textStatus, XMLHttpRequest) { // ... }, error: function(XMLHttpRequest, textStatus, errorThrown) { // ... } }); At the moment I just have to assume that I'm using it incorrectly, but I'm hoping one of you guys can clear my mental block!

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  • Trying to read keyboard input without blocking (Windows, C++)

    - by Adam E
    I'm trying to write a Windows console application (in C++ compiled using g++) that will execute a series of instructions in a loop until finished OR until ctrl-z (or some other keystroke) is pressed. The code I'm currently using to catch it isn't working (otherwise I wouldn't be asking, right?): if(kbhit() && getc(stdin) == 26) //The code to execute when ctrl-z is pressed If I press a key, it is echoed and the application waits until I press Enter to continue on at all. With the value 26, it doesn't execute the intended code. If I use something like 65 for the value to catch, it will reroute execution if I press A then Enter afterward. Is there a way to passively check for input, throwing it out if it's not what I'm looking for or properly reacting when it is what I'm looking for? ..and without having to press Enter afterward?

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  • wxpython - Running threads sequentially without blocking GUI

    - by ryantmer
    I've got a GUI script with all my wxPython code in it, and a separate testSequences module that has a bunch of tasks that I run based on input from the GUI. The tasks take a long time to complete (from 20 seconds to 3 minutes), so I want to thread them, otherwise the GUI locks up while they're running. I also need them to run one after another, since they all use the same hardware. (My rationale behind threading is simply to prevent the GUI from locking up.) I'd like to have a "Running" message (with varying number of periods after it, i.e. "Running", "Running.", "Running..", etc.) so the user knows that progress is occurring, even though it isn't visible. I'd like this script to run the test sequences in separate threads, but sequentially, so that the second thread won't be created and run until the first is complete. Since this is kind of the opposite of the purpose of threads, I can't really find any information on how to do this... Any help would be greatly appreciated. Thanks in advance! gui.py import testSequences from threading import Thread #wxPython code for setting everything up here... for j in range(5): testThread = Thread(target=testSequences.test1) testThread.start() while testThread.isAlive(): #wait until the previous thread is complete time.sleep(0.5) i = (i+1) % 4 self.status.SetStatusText("Running"+'.'*i) testSequences.py import time def test1(): for i in range(10): print i time.sleep(1) (Obviously this isn't the actual test code, but the idea is the same.)

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  • Handling file upload in a non-blocking manner

    - by Kaliyug Antagonist
    The background thread is here Just to make objective clear - the user will upload a large file and must be redirected immediately to another page for proceeding different operations. But the file being large, will take time to be read from the controller's InputStream. So I unwillingly decided to fork a new Thread to handle this I/O. The code is as follows : The controller servlet /** * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse * response) */ protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // TODO Auto-generated method stub System.out.println("In Controller.doPost(...)"); TempModel tempModel = new TempModel(); tempModel.uploadSegYFile(request, response); System.out.println("Forwarding to Accepted.jsp"); /*try { Thread.sleep(1000 * 60); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); }*/ request.getRequestDispatcher("/jsp/Accepted.jsp").forward(request, response); } The model class package com.model; import java.io.IOException; import java.util.concurrent.ExecutionException; import java.util.concurrent.Future; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import com.utils.ProcessUtils; public class TempModel { public void uploadSegYFile(HttpServletRequest request, HttpServletResponse response) { // TODO Auto-generated method stub System.out.println("In TempModel.uploadSegYFile(...)"); /* * Trigger the upload/processing code in a thread, return immediately * and notify when the thread completes */ try { FileUploaderRunnable fileUploadRunnable = new FileUploaderRunnable( request.getInputStream()); /* * Future<FileUploaderRunnable> future = ProcessUtils.submitTask( * fileUploadRunnable, fileUploadRunnable); * * FileUploaderRunnable processed = future.get(); * * System.out.println("Is file uploaded : " + * processed.isFileUploaded()); */ Thread uploadThread = new Thread(fileUploadRunnable); uploadThread.start(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } /* * catch (InterruptedException e) { // TODO Auto-generated catch block * e.printStackTrace(); } catch (ExecutionException e) { // TODO * Auto-generated catch block e.printStackTrace(); } */ System.out.println("Returning from TempModel.uploadSegYFile(...)"); } } The Runnable package com.model; import java.io.File; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.nio.ByteBuffer; import java.nio.channels.Channels; import java.nio.channels.ReadableByteChannel; public class FileUploaderRunnable implements Runnable { private boolean isFileUploaded = false; private InputStream inputStream = null; public FileUploaderRunnable(InputStream inputStream) { // TODO Auto-generated constructor stub this.inputStream = inputStream; } public void run() { // TODO Auto-generated method stub /* Read from InputStream. If success, set isFileUploaded = true */ System.out.println("Starting upload in a thread"); File outputFile = new File("D:/06c01_output.seg");/* * This will be changed * later */ FileOutputStream fos; ReadableByteChannel readable = Channels.newChannel(inputStream); ByteBuffer buffer = ByteBuffer.allocate(1000000); try { fos = new FileOutputStream(outputFile); while (readable.read(buffer) != -1) { fos.write(buffer.array()); buffer.clear(); } fos.flush(); fos.close(); readable.close(); } catch (FileNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } System.out.println("File upload thread completed"); } public boolean isFileUploaded() { return isFileUploaded; } } My queries/doubts : Spawning threads manually from the Servlet makes sense to me logically but scares me coding wise - the container isn't aware of these threads after all(I think so!) The current code is giving an Exception which is quite obvious - the stream is inaccessible as the doPost(...) method returns before the run() method completes : In Controller.doPost(...) In TempModel.uploadSegYFile(...) Returning from TempModel.uploadSegYFile(...) Forwarding to Accepted.jsp Starting upload in a thread Exception in thread "Thread-4" java.lang.NullPointerException at org.apache.coyote.http11.InternalInputBuffer.fill(InternalInputBuffer.java:512) at org.apache.coyote.http11.InternalInputBuffer.fill(InternalInputBuffer.java:497) at org.apache.coyote.http11.InternalInputBuffer$InputStreamInputBuffer.doRead(InternalInputBuffer.java:559) at org.apache.coyote.http11.AbstractInputBuffer.doRead(AbstractInputBuffer.java:324) at org.apache.coyote.Request.doRead(Request.java:422) at org.apache.catalina.connector.InputBuffer.realReadBytes(InputBuffer.java:287) at org.apache.tomcat.util.buf.ByteChunk.substract(ByteChunk.java:407) at org.apache.catalina.connector.InputBuffer.read(InputBuffer.java:310) at org.apache.catalina.connector.CoyoteInputStream.read(CoyoteInputStream.java:202) at java.nio.channels.Channels$ReadableByteChannelImpl.read(Unknown Source) at com.model.FileUploaderRunnable.run(FileUploaderRunnable.java:39) at java.lang.Thread.run(Unknown Source) Keeping in mind the point 1., does the use of Executor framework help me in anyway ? package com.utils; import java.util.concurrent.Future; import java.util.concurrent.ScheduledThreadPoolExecutor; public final class ProcessUtils { /* Ensure that no more than 2 uploads,processing req. are allowed */ private static final ScheduledThreadPoolExecutor threadPoolExec = new ScheduledThreadPoolExecutor( 2); public static <T> Future<T> submitTask(Runnable task, T result) { return threadPoolExec.submit(task, result); } } So how should I ensure that the user doesn't block and the stream remains accessible so that the (uploaded)file can be read from it?

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  • How to prevent GUI blocking?

    - by Kovu
    Hi, I have a timer that ticks every 3 seconds. If the timer found something a messagebox will show. Then the timer should wait 30 seconds, before he show again the messagebox (the user of course must have time to react). How can I handle this? I tried a Thread.Sleep(30000), but the GUI blocks of course. My other Idea is a second timer that will be activated after the first ticks and reactivate the first timer in the tick-method. So: t1 tick - msg box - after click - t2 enable (30 sec tick) - t2 tick, enable t1 But I think thats not a good idea, is there a better way?

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  • How can I interrupt a ServerSocket accept() method?

    - by lukeo05
    Hi, In my main thread I have a while(listening) loop which calls accept() on my ServerSocket object, then starts a new client thread and adds it to a Collection when a new client is accepted. I also have an Admin thread which I want to use to issue commands, like 'exit', which will cause all the client threads to be shut down, shut itself down, and shut down the main thread, by turning listening to false. However, the accept() call in the while(listening) loop blocks, and there doesn't seem to be any way to interrupt it, so the while condition cannot be checked again and the program cannot exit! Is there a better way to do this? Or some way to interrupt the blocking method? Thanks!

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  • Two BlockingQueue in the same endless loop?

    - by DrDol
    I have a thread, that processes incomming messages (endless loop). For this, I use a BlockingQueue (Java), which works as quite nice. Now, I want to add a second processor in the same Class oder method. The problem now is, that in the endless loop i have this part newIncomming = this.incommingProcessing.take(); This part blocks if the Queue is empty. I'm looking for a solution to process to queues in the same class. The second queue can only processed, it some data is coming in for the first Queue. Is there a way to handle tow blocking queues in the same endless loop?

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  • How does one SELECT block another?

    - by Krip
    I'm looking at output of SP_WhoIsActive on SQL Server 2005, and it's telling me one session is blocking another - fine. However they both are running a SELECT. How does one SELECT block another? Shouldn't they both be acquiring shared locks (which are compatible with one another)? Some more details: Neither session has an open transaction count - so they are stand-alone. The queries join a view with a table. They are complex queries which join lots of tables and results in 10,000 or so reads. Any insight much appreciated.

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  • C++: static function member shared between threads, can block all?

    - by mhambra
    Hi all, I have a class, which has static function defined to work with C-style extern C { static void callback(foo bar) { } }. // static is defined in header. Three objects (each in separate pthread) are instantiated from this class, each of them has own loop (in class constructor), which can receive the callback. The pointer to function is passed as: x = init_function(h, queue_id, &callback, NULL); while(1) { loop_function(x); } So each thread has the same pointer to &callback. Callback function can block for minutes. Each thread object, excluding the one which got the blocking callback, can call callback again. If the callback function exists only once, then any thread attempting to callback will also block. This would give me an undesired bug, circa is interesting to ask: can anything in C++ become acting this way? Maybe, due to extern { } or some pointer usage?

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  • A Question about using jython when run a receving socket in python

    - by abusemind
    Hi, I have not a lot of knowledge of python and network programming. Currently I am trying to implement a simple application which can receive a text message sent by the user, fetch some information from the google search api, and return the results via text message to the user. This application will continue to listening to the users messages and reply immediately. How I get the text short message sent by the user? It's a program named fetion from the mobile supplier in China. The client side fetion, just like a instant communication tool, can send/receive messages to/from other people who are using mobile to receive/send SMS. I am using a open source python program that simulates the fetion program. So basically I can use this python program to communate with others who using cell phone via SMS. My core program is based on java, so I need to take this python program into java environment. I am using jython, and now I am available to send messages to users by some lines of java codes. But the real question is the process of receving from users via SMS. In python code, a new thread is created to continuously listen to the user. It should be OK in Python, but when I run the similar process in Jython, the following exception occurs: Exception in thread Thread:Traceback (most recent call last): File "D:\jython2.5.1\Lib\threading.py", line 178, in _Thread__bootstrap self.run() File "<iostream>", line 1389, in run File "<iostream>", line 1207, in receive File "<iostream>", line 1207, in receive File "<iostream>", line 150, in recv File "D:\jython2.5.1\Lib\select.py", line 223, in native_select pobj.register(fd, POLLIN) File "D:\jython2.5.1\Lib\select.py", line 104, in register raise _map_exception(jlx) error: (20000, 'socket must be in non-blocking mode') The line 150 in the python code is as follows: def recv(self,timeout=False): if self.login_type == "HTTP": time.sleep(10) return self.get_offline_msg() pass else: if timeout: infd,outfd,errfd = select([self.__sock,],[],[],timeout)//<---line 150 here else: infd,outfd,errfd = select([self.__sock,],[],[]) if len(infd) != 0: ret = self.__tcp_recv() num = len(ret) d_print(('num',),locals()) if num == 0: return ret if num == 1: return ret[0] for r in ret: self.queue.put(r) d_print(('r',),locals()) if not self.queue.empty(): return self.queue.get() else: return "TimeOut" Because of I am not very familiar with python, especially the socket part, and also new in Jython use, I really need your help or only advice or explanation. Thank you very much!

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  • Twisted: why is it that passing a deferred callback to a deferred thread makes the thread blocking a

    - by surtyaarthoughts
    I unsuccessfully tried using txredis (the non blocking twisted api for redis) for a persisting message queue I'm trying to set up with a scrapy project I am working on. I found that although the client was not blocking, it became much slower than it could have been because what should have been one event in the reactor loop was split up into thousands of steps. So instead, I tried making use of redis-py (the regular blocking twisted api) and wrapping the call in a deferred thread. It works great, however I want to perform an inner deferred when I make a call to redis as I would like to set up connection pooling in attempts to speed things up further. Below is my interpretation of some sample code taken from the twisted docs for a deferred thread to illustrate my use case: #!/usr/bin/env python from twisted.internet import reactor,threads from twisted.internet.task import LoopingCall import time def main_loop(): print 'doing stuff in main loop.. do not block me!' def aBlockingRedisCall(): print 'doing lookup... this may take a while' time.sleep(10) return 'results from redis' def result(res): print res def main(): lc = LoopingCall(main_loop) lc.start(2) d = threads.deferToThread(aBlockingRedisCall) d.addCallback(result) reactor.run() if __name__=='__main__': main() And here is my alteration for connection pooling that makes the code in the deferred thread blocking : #!/usr/bin/env python from twisted.internet import reactor,defer from twisted.internet.task import LoopingCall import time def main_loop(): print 'doing stuff in main loop.. do not block me!' def aBlockingRedisCall(x): if x<5: #all connections are busy, try later print '%s is less than 5, get a redis client later' % x x+=1 d = defer.Deferred() d.addCallback(aBlockingRedisCall) reactor.callLater(1.0,d.callback,x) return d else: print 'got a redis client; doing lookup.. this may take a while' time.sleep(10) # this is now blocking.. any ideas? d = defer.Deferred() d.addCallback(gotFinalResult) d.callback(x) return d def gotFinalResult(x): return 'final result is %s' % x def result(res): print res def aBlockingMethod(): print 'going to sleep...' time.sleep(10) print 'woke up' def main(): lc = LoopingCall(main_loop) lc.start(2) d = defer.Deferred() d.addCallback(aBlockingRedisCall) d.addCallback(result) reactor.callInThread(d.callback, 1) reactor.run() if __name__=='__main__': main() So my question is, does anyone know why my alteration causes the deferred thread to be blocking and/or can anyone suggest a better solution?

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  • Is there an use case for non-blocking receive when I have threads?

    - by Gabriel Šcerbák
    I know non-blocking receive is not used as much in message passing, but still some intuition tells me, it is needed. Take for example GUI event driven applications, you need some way to wait for a message in a non-blocking way, so your program can execute some computations. One of the ways to solve this is to have a special thread with message queue. Is there some use case, where you would really need non-blocking receive even if you have threads?

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  • Is there a way to ‘join’ (block) in POSIX threads, without exiting the joinee?

    - by elliottcable
    I’m buried in multithreading / parallelism documents, trying to figure out how to implement a threading implementation in a programming language I’ve been designing. I’m trying to map a mental model to the pthreads.h library, but I’m having trouble with one thing: I need my interpreter instances to continue to exist after they complete interpretation of a routine (the language’s closure/function data type), because I want to later assign other routines to them for interpretation, thus saving me the thread and interpreter setup/teardown time. This would be fine, except that pthread_join(3) requires that I call pthread_exit(3) to ‘unblock’ the original thread. How can I block the original thread (when it needs the result of executing the routine), and then unblock it when interpretation of the child routine is complete?

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  • Mysql SELECT FOR UPDATE - strange issue

    - by Michal Fronczyk
    Hi, I have a strange issue (at least for me :)) with the MySQL's locking facility. I have a table: Create Table: CREATE TABLE test ( id int(11) NOT NULL AUTO_INCREMENT, PRIMARY KEY (id) ) ENGINE=InnoDB AUTO_INCREMENT=13 DEFAULT CHARSET=latin1 With this data: +----+ | id | +----+ | 3 | | 4 | | 5 | | 6 | | 7 | | 8 | | 10 | | 11 | | 12 | +----+ Now I have 2 clients with these commands executed at the beginning: set autocommit=0; set session transaction isolation level serializable; begin; Now the most interesting part. The first client executes this query: (makes an intent to insert a row with id equal to 9) SELECT * from test where id = 9 FOR UPDATE; Empty set (0.00 sec) Then the second client does the same: SELECT * from test where id = 9 FOR UPDATE; Empty set (0.00 sec) My question is: Why the second client does not block ? An exclusive gap lock should have been set by the first query because FOR UPDATE have been used and the second client should block. If I am wrong, could somebody tell me how to do it correctly ? The MySql version I use is: 5.1.37-1ubuntu5.1 Thanks, Michal

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  • Mixing NIO with IO

    - by Steffen Heil
    Hi Usually you have a single bound tcp port and several connections on these. At least there are usually more connections as bound ports. My case is different: I want to bind a lot of ports and usually have no (or at least very few) connections. So I want to use NIO to accept the incoming connections. However, I need to pass the accepted connections to the existing jsch ssh library. That requires IO sockets instead of NIO sockets, it spawns one (or two) thread(s) per connection. But that's fine for me. Now, I thought that the following lines would deliver the very same result: Socket a = serverSocketChannel.accept().socket(); Socket b = serverSocketChannel.socket().accep(); SocketChannel channel = serverSocketChannel.accpet(); channel.configureBlocking( true ); Socket c = channel.socket(); Socket d = serverSocket.accept(); However the getInputStream() and getOutputStream() functions of the returned sockets seem to work different. Only if the socket was accepted using the last call, jsch can work with it. In the first three cases, it fails (and I am sorry: I don't know why). So is there a way to convert such a socket? Regards, Steffen

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  • Why does Python's math.factorial not play nice with threads?

    - by W1N9Zr0
    Why does math.factorial act so weird in a thread? Here is an example, it creates three threads: thread that just sleeps for a while thread that increments an int for a while thread that does math.factorial on a large number. It calls start on the threads, then join with a timeout The sleep and spin threads work as expected and return from start right away, and then sit in the join for the timeout. The factorial thread on the other hand does not return from start until it runs to the end! import sys from threading import Thread from time import sleep, time from math import factorial # Helper class that stores a start time to compare to class timed_thread(Thread): def __init__(self, time_start): Thread.__init__(self) self.time_start = time_start # Thread that just executes sleep() class sleep_thread(timed_thread): def run(self): sleep(15) print "st DONE:\t%f" % (time() - time_start) # Thread that increments a number for a while class spin_thread(timed_thread): def run(self): x = 1 while x < 120000000: x += 1 print "sp DONE:\t%f" % (time() - time_start) # Thread that calls math.factorial with a large number class factorial_thread(timed_thread): def run(self): factorial(50000) print "ft DONE:\t%f" % (time() - time_start) # the tests print print "sleep_thread test" time_start = time() st = sleep_thread(time_start) st.start() print "st.start:\t%f" % (time() - time_start) st.join(2) print "st.join:\t%f" % (time() - time_start) print "sleep alive:\t%r" % st.isAlive() print print "spin_thread test" time_start = time() sp = spin_thread(time_start) sp.start() print "sp.start:\t%f" % (time() - time_start) sp.join(2) print "sp.join:\t%f" % (time() - time_start) print "sp alive:\t%r" % sp.isAlive() print print "factorial_thread test" time_start = time() ft = factorial_thread(time_start) ft.start() print "ft.start:\t%f" % (time() - time_start) ft.join(2) print "ft.join:\t%f" % (time() - time_start) print "ft alive:\t%r" % ft.isAlive() And here is the output on Python 2.6.5 on CentOS x64: sleep_thread test st.start: 0.000675 st.join: 2.006963 sleep alive: True spin_thread test sp.start: 0.000595 sp.join: 2.010066 sp alive: True factorial_thread test ft DONE: 4.475453 ft.start: 4.475589 ft.join: 4.475615 ft alive: False st DONE: 10.994519 sp DONE: 12.054668 I've tried this on python 2.6.5 on CentOS x64, 2.7.2 on Windows x86 and the factorial thread does not return from start on either of them until the thread is done executing. I've also tried this with PyPy 1.8.0 on Windows x86, and there result is slightly different. The start does return immediately, but then the join doesn't time out! sleep_thread test st.start: 0.001000 st.join: 2.001000 sleep alive: True spin_thread test sp.start: 0.000000 sp DONE: 0.197000 sp.join: 0.236000 sp alive: False factorial_thread test ft.start: 0.032000 ft DONE: 9.011000 ft.join: 9.012000 ft alive: False st DONE: 12.763000

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