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  • threading in Python taking up too much CPU

    - by KevinShaffer
    I wrote a chat program and have a GUI running using Tkinter, and to go and check when new messages have arrived, I create a new thread so Tkinter keeps doing its thing without locking up while the new thread goes and grabs what I need and updates the Tkinter window. This however becomes a huge CPU hog, and my guess is that it has to do somehow with the fact that the Thread is started and never really released when the function is done. Here's the relevant code (it's ugly and not optimized at the moment, but it gets the job done, and itself does not use too much processing power, as when I run it not threaded, it doesn't take up much CPU but it locks up Tkinter) Note: This is inside of a class, hence the extra tab. def interim(self): threading.Thread(target=self.readLog).start() self.after(5000,self.interim) def readLog(self): print 'reading' try: length = len(str(self.readNumber)) f = open('chatlog'+str(myport),'r') temp = f.readline().replace('\n','') while (temp[:length] != str(self.readNumber)) or temp[0] == '<': temp = f.readline().replace('\n','') while temp: if temp[0] != '<': self.updateChat(temp[length:]) self.readNumber +=1 else: self.updateChat(temp) temp = f.readline().replace('\n','') f.close() Is there a way to better manage the threading so I don't consume 100% of the CPU very quickly?

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  • Threading in client-server socket program - proxy sever

    - by crazyTechie
    I am trying to write a program that acts as a proxy server. Proxy server basically listens to a given port (7575) and sends the request to the server. As of now, I did not implement caching the response. The code looks like ServerSocket socket = new ServerSocket(7575); Socket clientSocket = socket.accept(); clientRequestHandler(clientSocket); I changed the above code as below: //calling the same clientRequestHandler method from inside another method. Socket clientSocket = socket.accept(); Thread serverThread = new Thread(new ConnectionHandler(client)); serverThread.start(); class ConnectionHandler implements Runnable { Socket clientSocket = null; ConnectionHandler(Socket client){ this.clientSocket = client; } @Override public void run () { try { PrxyServer.clientRequestHandler(clientSocket); } catch (Exception ex) { ex.printStackTrace(); } } } Using the code, I am able to open a webpage like google. However, if I open another web page even I completely receive the first response, I get connection reset by peer expection. 1. How can I handle this issue Can i use threading to handle different requests. Can someone give a reference where I look for example code that implements threading. Thanks. Thanks.

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  • How can one use multi threading in php applications

    - by Steve Obbayi
    Is there a realistic way of implementing a multi-threaded model in php whether truly or just simulating it. Some time back it was suggested that you can force the operating system to load another instance of the php executable and handle other simultaneous processes. The problem with this is that when the php code finished executing the php instance remains in memory because there is no way to kill it from within php. so if you are simulating several threads you can imagine whats going to happen. So am still looking for a way multi-threading can be done or simulated effectively from within php. Any ideas?

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  • Java threads for the beginner

    - by Boba
    I've been trying to explain Java threading to a colleague who has never been exposed to multi-threaded applications, but apparently I'm not a very good teacher. Can anyone recommend a good online or offline resource that can explain threading in a simple, step-by-step manner? I know it's a complex topic, but surely there exists an article, book, or other explanation that can result in an "Aha! I get it, finally!" moment.

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  • using a Singleton to pass credentials in a multi-tenant application a code smell?

    - by Hans Gruber
    Currently working on a multi-tenant application that employs Shared DB/Shared Schema approach. IOW, we enforce tenant data segregation by defining a TenantID column on all tables. By convention, all SQL reads/writes must include a Where TenantID = '?' clause. Not an ideal solution, but hindsight is 20/20. Anyway, since virtually every page/workflow in our app must display tenant specific data, I made the (poor) decision at the project's outset to employ a Singleton to encapsulate the current user credentials (i.e. TenantID and UserID). My thinking at the time was that I didn't want to add a TenantID parameter to each and every method signature in my Data layer. Here's what the basic pseudo-code looks like: public class UserIdentity { public UserIdentity(int tenantID, int userID) { TenantID = tenantID; UserID = userID; } public int TenantID { get; private set; } public int UserID { get; private set; } } public class AuthenticationModule : IHttpModule { public void Init(HttpApplication context) { context.AuthenticateRequest += new EventHandler(context_AuthenticateRequest); } private void context_AuthenticateRequest(object sender, EventArgs e) { var userIdentity = _authenticationService.AuthenticateUser(sender); if (userIdentity == null) { //authentication failed, so redirect to login page, etc } else { //put the userIdentity into the HttpContext object so that //its only valid for the lifetime of a single request HttpContext.Current.Items["UserIdentity"] = userIdentity; } } } public static class CurrentUser { public static UserIdentity Instance { get { return HttpContext.Current.Items["UserIdentity"]; } } } public class WidgetRepository: IWidgetRepository{ public IEnumerable<Widget> ListWidgets(){ var tenantId = CurrentUser.Instance.TenantID; //call sproc with tenantId parameter } } As you can see, there are several code smells here. This is a singleton, so it's already not unit test friendly. On top of that you have a very tight-coupling between CurrentUser and the HttpContext object. By extension, this also means that I have a reference to System.Web in my Data layer (shudder). I want to pay down some technical debt this sprint by getting rid of this singleton for the reasons mentioned above. I have a few thoughts on what an better implementation might be, but if anyone has any guidance or lessons learned they could share, I would be much obliged.

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  • Threading.Timer vs. Forms.Timer

    - by Jekke
    The short form of this question: When, if ever, is it appropriate to use the Forms.Timer in a multithreaded WinForms application? More specifically, I am architecting an application that uses multiple System.Threading.Timers to launch processes asynchronously, check queues containing the results of those asynchronous processes, and update the statistics to be shown by the application's main form. In an application like that, is it appropriate to use a Forms.Timer to actually check the application statistics and draw them to the main form or would that just throw a wrench into the application's smooth running?

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  • Actor model to replace the threading model?

    - by prosseek
    I read a chapter in a book (Seven languages in Seven Weeks by Bruce A. Tate) about Matz (Inventor of Ruby) saying that 'I would remove the thread and add actors, or some other more advanced concurrency features'. Why and how an actor model can be an advanced concurrency model that replaces the threading? What other models are the 'advanced concurrency model'?

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  • Can't install chef, gem version conflict with net-ssh net-ssh-multi net-ssh-gateway

    - by Mojo
    Using rvm, and an empty gemset, I get this: $ gem install chef --no-ri --no-rdoc ERROR: While executing gem ... (Gem::DependencyError) Unable to resolve dependencies: chef requires net-ssh (~> 2.2.2); net-ssh-multi requires net-ssh (>= 2.6.5); net-ssh-gateway requires net-ssh (>= 2.6.5) I've tried resolving it by installing earlier versions of net-ssh-gateway and net-ssh-multi, but net-ssh-multi version 1.1 confounds me by installing 1.1.2.

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  • Threading cost - minimum execution time when threads would add speed

    - by Lukas
    I am working on a C# application that works with an array. It walks through it (meaning that at one time only a narrow part of the array is used). I am considering adding threads in it to make it perform faster (it runs on a dualcore computer). The problem is that I do not know if it would actually help, because threads cost something and this cost could easily be more than the parallel gain... So how do I determine if threading would help?

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  • WCF threading - non-responsive UI

    - by Sphynx
    Hi everyone. I'm trying to configure some WCF stuff. Currently, I have a server which allows remote users to download files, and client. In the server, I use a ServiceHost class. I assume it should be running on a separate thread, however, the server UI (WinForms) becomes locked when someone downloads a file. Is there a way to manage the WCF threading model? Thank you!

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  • using qsub (sge) with multi-threaded applications

    - by dan12345
    i wanted to submit a multi-threaded job to the cluster network i'm working with - but the man page about qsub is not clear how this is done - By default i guess it just sends it as a normal job regardless of the multi-threading - but this might cause problems, i.e. sending many multi-threaded jobs to the same computer, slowing things down. Does anyone know how to accomplish this? thanks. The batch server system is sge.

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  • will php/apache ever support multi threading?

    - by fayer
    i mainly focus on the web, i think i will never create desktop applications. so i think it's better for me to focus on typical web languages like php. i know an advantage java has over php is multi threading though. will php ever support this feature in the future? thanks

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  • Dynamically loading modules in Python (+ threading question)

    - by morpheous
    I am writing a Python package which reads the list of modules (along with ancillary data) from a configuration file. I then want to iterate through each of the dynamically loaded modules and invoke a do_work() function in it which will spawn a new thread, so that the code runs in a separate thread. At the moment, I am importing the list of all known modules at the beginning of my main script - this is a nasty hack I feel, and is not very flexible, as well as being a maintenance pain. This is the function that spawns the threads. I will like to modify it to dynamically load the module when it is encountered. The key in the dictionary is the name of the module containing the code: def do_work(work_info): for (worker, dataset) in work_info.items(): #import the module defined by variable worker here... t = threading.Thread(target=worker.do_work, args=[dataset]) # I'll NOT dameonize since spawned children need to clean up on shutdown # Since the threads will be holding resources #t.daemon = True t.start() Question 1 When I call the function in my script (as written above), I get the following error: AttributeError: 'str' object has no attribute 'do_work' Which makes sense, since the dictionary key is a string (name of the module to be imported). When I add the statement: import worker before spawning the thread, I get the error: ImportError: No module named worker This is strange, since the variable name rather than the value it holds are being used - when I print the variable, I get the value (as I expect) whats going on? Question 2 As I mentioned in the comments section, I realize that the do_work() function written in the spawned children needs to cleanup after itself. My understanding is to write a clean_up function that is called when do_work() has completed successfully, or an unhandled exception is caught - is there anything more I need to do to ensure resources don't leak or leave the OS in an unstable state? Question 3 If I comment out the t.daemon flag statement, will the code stil run ASYNCHRONOUSLY?. The work carried out by the spawned children are pretty intensive, and I don't want to have to be waiting for one child to finish before spawning another child. BTW, I am aware that threading in Python is in reality, a kind of time sharing/slicing - thats ok Lastly is there a better (more Pythonic) way of doing what I'm trying to do?

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  • "Multi-threading" w/ NSTimers in an iPhone app

    - by MrDatabase
    Say I have two NSTimers in my iPhone app: timer1 and timer2. timer1 calls function1 30 times per second and timer2 calls function2 30 times per second. Assume these two functions are reading and updating the same integer variables. Are there any "multi-threading" issues here? If not how does iPhone OS handle the execution of the two functions (in general)?

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  • wxPython, Threads, and PostEvent between modules

    - by Sam Starling
    I'm relatively new to wxPython (but not Python itself), so forgive me if I've missed something here. I'm writing a GUI application, which at a very basic level consists of "Start" and "Stop" buttons that start and stop a thread. This thread is an infinite loop, which only ends when the thread is stopped. The loop generates messages, which at the moment are just output using print. The GUI class and the infinite loop (using threading.Thread as a subclass) are held in separate files. What is the best way to get the thread to push an update to something like a TextCtrl in the GUI? I've been playing around with PostEvent and Queue, but without much luck. Here's some bare bones code, with portions removed to keep it concise: main_frame.py import wx from loop import Loop class MainFrame(wx.Frame): def __init__(self, parent, title): # Initialise and show GUI # Add two buttons, btnStart and btnStop # Bind the two buttons to the following two methods self.threads = [] def onStart(self): x = Loop() x.start() self.threads.append(x) def onStop(self): for t in self.threads: t.stop() loop.py class Loop(threading.Thread): def __init__(self): self._stop = threading.Event() def run(self): while not self._stop.isSet(): print datetime.date.today() def stop(self): self._stop.set() I did, at one point, have it working by having the classes in the same file by using wx.lib.newevent.NewEvent() along these lines. If anyone could point me in the right direction, that'd be much appreciated.

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  • python thread prob after build

    - by Apache
    hi expert, i'm having task to scan wifi at specific interval and send it to the server, i've it in python and its works fine when i run manually, then build it to package and when run there is no progress at all, i already ask this question before at http://stackoverflow.com/questions/2735410/python-scritp-problem-once-build-and-package-it, then, i re-modify my code as below, then i found that thread is not functioning once i build, #!/usr/bin/env python import subprocess,threading,... configFile = open('/opt/Jemapoh_Wifi/config.txt', 'r') url = configFile.readline().strip() intervalTime = configFile.readline().strip() status = configFile.readline().strip() print "url "+url print "intervalTime "+intervalTime print "Status "+status.strip() def getMacAddress(): proc = subprocess.Popen('ifconfig -a wlan0 | grep HWaddr | sed \'/^.*HWaddr */!d; s///;q\'', shell=True, stdout=subprocess.PIPE, ) macAddress = proc.communicate()[0].strip() return macAddress def getTimestamp(): from time import strftime timeStamp = strftime("%Y-%m-%d %H:%M:%S") return timeStamp def scanWifi(): try: print "Scanning..." proc = subprocess.Popen('iwlist scan 2>/dev/null', shell=True, stdout=subprocess.PIPE, ) stdout_str = proc.communicate()[0] stdout_list=stdout_str.split('\n') essid=[] rssi=[] preQuality=[] for line in stdout_list: line=line.strip() match=re.search('ESSID:"(\S+)"',line) if match: essid.append(match.group(1)) match=re.search('Quality=(\S+)',line) if match: preQuality.append(match.group(1)) for qualityConversion in preQuality: qualityConversion = qualityConversion.split()[0].split('/') temp = str(int(round(float(qualityConversion[0]) / float(qualityConversion[1]) * 100))).rjust(2) rssi.append(temp) dataToPost = '{"userId":"' + getMacAddress() + '","timestamp":"' + getTimestamp() + '","wifi":[' for no in range(len(essid)): dataToPost += '{"ssid":"' + essid[no] + '","rssi":"' + rssi[no] + '"}' if no+1 == len(essid): pass else: dataToPost += ',' dataToPost += ']}' query_args = {"data":dataToPost} request = urllib2.Request(url) request.add_data(urllib.urlencode(query_args)) request.add_header('Content-Type', 'application/x-www-form-urlencoded') print "Waiting for server response..." print urllib2.urlopen(request).read() print "Data Sent @ " + getTimestamp() print "------------------------------------------------------" t = threading.Timer(int(intervalTime), scanWifi).start() except Exception, e: print e t = threading.Timer(int(intervalTime), scanWifi) t.start() once build, its not reaching the thread, do can anyone help, why the thread is not working after build thanks

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  • Python 4 step setup with progressBars

    - by Samuel Taylor
    I'm having a problem with the code below. When I run it the progress bar will pulse for around 10 secs as meant to and then move on to downloading and will show the progress but when finished it will not move on to the next step it just locks up. import sys import time import pygtk import gtk import gobject import threading import urllib import urlparse class WorkerThread(threading.Thread): def __init__ (self, function, parent, arg = None): threading.Thread.__init__(self) self.function = function self.parent = parent self.arg = arg self.parent.still_working = True def run(self): # when does "run" get executed? self.parent.still_working = True if self.arg == None: self.function() else: self.function(self.arg) self.parent.still_working = False def stop(self): self = None class MainWindow: def __init__(self): gtk.gdk.threads_init() self.wTree = gtk.Builder() self.wTree.add_from_file("gui.glade") self.mainWindows() def mainWindows(self): self.mainWindow = self.wTree.get_object("frmMain") dic = { "on_btnNext_clicked" : self.mainWindowNext, } self.wTree.connect_signals(dic) self.mainWindow.show() self.installerStep = 0 # 0 = none, 1 = preinstall, 2 = download, 3 = install info, 4 = install #gtk.main() self.mainWindowNext() def pulse(self): self.wTree.get_object("progress").pulse() if self.still_working == False: self.mainWindowNext() return self.still_working def preinstallStep(self): self.wTree.get_object("progress").set_fraction(0) self.wTree.get_object("btnNext").set_sensitive(0) self.wTree.get_object("notebook1").set_current_page(0) self.installerStep = 1 WT = WorkerThread(self.heavyWork, self) #Would do a heavy function here like setup some thing WT.start() gobject.timeout_add(75, self.pulse) def downloadStep(self): self.wTree.get_object("progress").set_fraction(0) self.wTree.get_object("btnNext").set_sensitive(0) self.wTree.get_object("notebook1").set_current_page(0) self.installerStep = 2 urllib.urlretrieve('http://mozilla.mirrors.evolva.ro//firefox/releases/3.6.3/win32/en-US/Firefox%20Setup%203.6.3.exe', '/tmp/firefox.exe', self.updateHook) self.mainWindowNext() def updateHook(self, blocks, blockSize, totalSize): percentage = float ( blocks * blockSize ) / totalSize if percentage > 1: percentage = 1 self.wTree.get_object("progress").set_fraction(percentage) while gtk.events_pending(): gtk.main_iteration() def installInfoStep(self): self.wTree.get_object("btnNext").set_sensitive(1) self.wTree.get_object("notebook1").set_current_page(1) self.installerStep = 3 def installStep(self): self.wTree.get_object("progress").set_fraction(0) self.wTree.get_object("btnNext").set_sensitive(0) self.wTree.get_object("notebook1").set_current_page(0) self.installerStep = 4 WT = WorkerThread(self.heavyWork, self) #Would do a heavy function here like setup some thing WT.start() gobject.timeout_add(75, self.pulse) def mainWindowNext(self, widget = None): if self.installerStep == 0: self.preinstallStep() elif self.installerStep == 1: self.downloadStep() elif self.installerStep == 2: self.installInfoStep() elif self.installerStep == 3: self.installStep() elif self.installerStep == 4: sys.exit(0) def heavyWork(self): time.sleep(10) if __name__ == '__main__': MainWindow() gtk.main()

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  • Python 4 steps setup with progressBars

    - by Samuel Taylor
    I'm having a problem with the code below. When I run it the progress bar will pulse for around 10 secs as meant to and then move on to downloading and will show the progress but when finished it will not move on to the next step it just locks up. import sys import time import pygtk import gtk import gobject import threading import urllib import urlparse class WorkerThread(threading.Thread): def __init__ (self, function, parent, arg = None): threading.Thread.__init__(self) self.function = function self.parent = parent self.arg = arg self.parent.still_working = True def run(self): # when does "run" get executed? self.parent.still_working = True if self.arg == None: self.function() else: self.function(self.arg) self.parent.still_working = False def stop(self): self = None class MainWindow: def __init__(self): gtk.gdk.threads_init() self.wTree = gtk.Builder() self.wTree.add_from_file("gui.glade") self.mainWindows() def mainWindows(self): self.mainWindow = self.wTree.get_object("frmMain") dic = { "on_btnNext_clicked" : self.mainWindowNext, } self.wTree.connect_signals(dic) self.mainWindow.show() self.installerStep = 0 # 0 = none, 1 = preinstall, 2 = download, 3 = install info, 4 = install #gtk.main() self.mainWindowNext() def pulse(self): self.wTree.get_object("progress").pulse() if self.still_working == False: self.mainWindowNext() return self.still_working def preinstallStep(self): self.wTree.get_object("progress").set_fraction(0) self.wTree.get_object("btnNext").set_sensitive(0) self.wTree.get_object("notebook1").set_current_page(0) self.installerStep = 1 WT = WorkerThread(self.heavyWork, self) #Would do a heavy function here like setup some thing WT.start() gobject.timeout_add(75, self.pulse) def downloadStep(self): self.wTree.get_object("progress").set_fraction(0) self.wTree.get_object("btnNext").set_sensitive(0) self.wTree.get_object("notebook1").set_current_page(0) self.installerStep = 2 urllib.urlretrieve('http://mozilla.mirrors.evolva.ro//firefox/releases/3.6.3/win32/en-US/Firefox%20Setup%203.6.3.exe', '/tmp/firefox.exe', self.updateHook) self.mainWindowNext() def updateHook(self, blocks, blockSize, totalSize): percentage = float ( blocks * blockSize ) / totalSize if percentage > 1: percentage = 1 self.wTree.get_object("progress").set_fraction(percentage) while gtk.events_pending(): gtk.main_iteration() def installInfoStep(self): self.wTree.get_object("btnNext").set_sensitive(1) self.wTree.get_object("notebook1").set_current_page(1) self.installerStep = 3 def installStep(self): self.wTree.get_object("progress").set_fraction(0) self.wTree.get_object("btnNext").set_sensitive(0) self.wTree.get_object("notebook1").set_current_page(0) self.installerStep = 4 WT = WorkerThread(self.heavyWork, self) #Would do a heavy function here like setup some thing WT.start() gobject.timeout_add(75, self.pulse) def mainWindowNext(self, widget = None): if self.installerStep == 0: self.preinstallStep() elif self.installerStep == 1: self.downloadStep() elif self.installerStep == 2: self.installInfoStep() elif self.installerStep == 3: self.installStep() elif self.installerStep == 4: sys.exit(0) def heavyWork(self): time.sleep(10) if __name__ == '__main__': MainWindow() gtk.main() I have a feeling that its something to do with: while gtk.events_pending(): gtk.main_iteration() Is there a better way of doing this?

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  • Using the Queue class in Python 2.6

    - by voipme
    Let's assume I'm stuck using Python 2.6, and can't upgrade (even if that would help). I've written a program that uses the Queue class. My producer is a simple directory listing. My consumer threads pull a file from the queue, and do stuff with it. If the file has already been processed, I skip it. The processed list is generated before all of the threads are started, so it isn't empty. Here's some pseudo-code. import Queue, sys, threading processed = [] def consumer(): while True: file = dirlist.get(block=True) if file in processed: print "Ignoring %s" % file else: # do stuff here dirlist.task_done() dirlist = Queue.Queue() for f in os.listdir("/some/dir"): dirlist.put(f) max_threads = 8 for i in range(max_threads): thr = Thread(target=consumer) thr.start() dirlist.join() The strange behavior I'm getting is that if a thread encounters a file that's already been processed, the thread stalls out and waits until the entire program ends. I've done a little bit of testing, and the first 7 threads (assuming 8 is the max) stop, while the 8th thread keeps processing, one file at a time. But, by doing that, I'm losing the entire reason for threading the application. Am I doing something wrong, or is this the expected behavior of the Queue/threading classes in Python 2.6?

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  • Partially constructed object / Multi threading

    - by reto
    Heya! I'm using joda due to it's good reputation regarding multi threading. It goes great distances to make multi threaded date handling efficient, for example by making all Date/Time/DateTime objects immutable. But here's a situation where I'm not sure if Joda is really doing the right thing. It probably is correct, but I'd be very interested to see the explanation for it. When a toString() of a DateTime is being called Joda does the following: /* org.joda.time.base.AbstractInstant */ public String toString() { return ISODateTimeFormat.dateTime().print(this); } All formatters are thread safe, as they are as well ready-only. But what's about the formatter-factory: private static DateTimeFormatter dt; /* org.joda.time.format.ISODateTimeFormat */ public static DateTimeFormatter dateTime() { if (dt == null) { dt = new DateTimeFormatterBuilder() .append(date()) .append(tTime()) .toFormatter(); } return dt; } This is a common pattern in single threaded applications. I see the following dangers: Race condition during null check -- worst case: two objects get created. No Problem, as this is solely a helper object (unlike a normal singleton pattern situation), one gets saved in dt, the other is lost and will be garbage collected sooner or later. the static variable might point to a partially constructed object before the objec has been finished initialization (before calling me crazy, read about a similar situation in this Wikipedia article. So how does Joda ensure that not partially created formatter gets published in this static variable? Thanks for your explanations! Reto

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  • Core Parking in Ubuntu?

    - by Xxx Xxx
    Core parking is a new feature that introduced in Windows 7 to get better Battery performance . Depending on the resource use of the operating system it may park one or multiple cores of a multi-core cpu to reduce the computer’s power consumption and thermal emissions. Once operations require more processing power, the parked cores are activated again to assist in the tasks So my question is that is there any way i can do it on Ubuntu 12.04 " Core Parking " ?

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