in my python program to upload a file to the internet, im using a GTK progress bar to show the upload progress. But the problems that im facing is that the progress bar does not show any activity until the upload is complete, and then it abruptly indicates upload complete. im using pycurl to make the http requests...my question is -
do i need to have a multi-threaded application to upload the file and simultaneously update the gui? or is there some other mistake that im making?
Thanks in advance!
I'm going to quote the PyGTK FAQ:
You have created a progress bar inside a window, then you start running a loop that does some work:
while work_left:
...do something...
progressbar.set_fraction(...)
You will notice that the window doesn't even show up, or if it does the progress bar stays frozen until the end of the task. The explanation is simple: gtk is event driven, and you are stealing control away from the gtk main loop, thus preventing it from processing normal GUI update events.
The simplest solution consists on temporarily giving control back to gtk every time the progress is changed:
while work_left:
...do something...
progressbar.set_fraction(...)
while gtk.events_pending():
gtk.main_iteration()
Notice that with this solution, the user cannot quit the application (gtk.main_quit would not work because of new loop [gtk.main_iteration()]) until your heavy_work is done.
Another solution consists on using gtk idle functions, which are called by the gtk main loop whenever it has nothing to do. Therefore, gtk is in control, and the idle function has to do a bit of work. It should return True if there's more work to be done, otherwise False.
The best solution (it has no drawbacks) was pointed out by James Henstridge. It is taking advantage of python's generators as idle functions, to make python automatically preserve the state for us. It goes like this:
def my_task(data):
...some work...
while heavy_work_needed:
...do heavy work here...
progress_label.set_text(data) # here we update parts of UI
# there's more work, return True
yield True
# no more work, return False
yield False
def on_start_my_task_button_click(data):
task = my_task(data)
gobject.idle_add(task.next)
The 'while' above is just an example. The only rules are that it should yield True after doing a bit of work and there's more work to do, and it must yield False when the task is done.
More than likely the issue is that in your progress callback, which is where I presume you're updating the progress bar, you're not making a call to manually update the display i.e. run through the GUI's event loop. This is just speculation though, if you can provide more code, it might be easier to narrow it down further.
The reason you need to manually update the display is because your main thread is also performing the upload, which is where it's blocking.
In python 2.x integer operands result in integer division. Try this:
#Callback function invoked when download/upload has progress
def progress(download_t, download_d, upload_t, upload_d):
print 'in fileupload progress'
mainwin.mainw.prog_bar.set_fraction(float(upload_d) / upload_t)
Yes, you probably need concurrency, and yes threads are one approach, but if you do use threads, please use an method like this one: http://unpythonic.blogspot.com/2007/08/using-threads-in-pygtk.html which will abstract away the pain, and allow you to focus on the important aspects.
(I have not repeated everything in that blog post through laziness, hence community wiki).
One option, if you are not married to pycurl, is to use GObject's IO watchers.
http://pygtk.org/pygtk2reference/gobject-functions.html#function-gobject--io-add-watch
Using this you can interleave the file upload with the normal PyGTK event loop, and even do the set_progress call in your IO watch callback. If you are offloading all the work for uploading onto pycurl this is not really feasible, but if you're just uploading a file over HTTP, io_add_watch will make using a socket for this much less painful as well.
Related
I am building an user interface using Python, Gtk3 and Glade. I want to change several things on the UI at the same time (i.e start an animation and display a new text) which leads to the application freezing.
I have read that Gtk wasn't thread safe so I didn't used the Thread module.
Instead, I used Glib.idle_add and Gdk.threads_add_idle functions. I am tryig to update a treeview, display some text and show an animated logo at the same time. The application works but it freezes a few seconds and then everything appears at the same time. I try to set different priorities to the threads but it does'nt seem to fix it.
Gtk.threads_add_idle(Glib.PRIORITY_DEFAULT, label.set_text, "text_to_set")
Gtk.threads_add_igle(GLib.PRIORITY_DEFAULT, function_to_display_logo)
I expect the different texts and the treeview and the logo to be displayed without any freeze. Does anyone know how I can fix that ?
Please have a look here at a script example in https://github.com/f4iteightiz/UWR_scoreboard : a GTK window is updated all 0,2s for example (countdowns of several timers appearing in labels; I think anything else could be updated) and it stay reactiv the whole time. No freezing noticeable.
I found out what my error was. I was using the GLib.idle_add function too many times even in some cases where I had no use for it.
For example in the main code I had :
Glib.idle_add(my_function,buffer)
but my_function looked like this :
def myfuntion(buffer):
GLib.idle_add(buffer.set_text,"text")
I deleted the GLib.idle_add call in the main code and now it works perfectly.
I have a GUI program built using Tkinter in python 2.7.10.
It works flawlessly, for it's root cause anyways.
Unfortunately, it briefly goes into windows dreaded "Not Responding" state when being interacted with.
Here's the layout in short:
Launch script launches Main script.
Main script reads settings file and boots GUI script.
GUI script starts GUI.
User enters a term to search for in a series of files.
GUI script goes into a side script to process files and retrieve results.
Side script inherits certain aspects of GUI script.
Side script attempts to update user while working using the inherited elements; the GUI has none of it.
GUI goes non-responsive briefly before returning to the GUI script and displaying the results.
Here's how I need it to go in short:
Launch script launches Main script.
Main script reads settings file and boots GUI script.
GUI script starts GUI.
User enters a term to search for in a series of files.
GUI script goes into a side script to process files and retrieve results.
Side script inherits certain aspects of GUI script.
Side script updates the user with a progress bar and imagery while working, using the GUI elements.
GUI returns to the GUI script and displays the results.
I have the progress bar built, but the imagery is not yet, but if the progress bar will not work, I will not waste my time on the imagery.
Sample impossible, not-being-used-but-shows-the-point code;
GUI;
import Tkinter, PIL, SideScript1
Tkinter()
ShowText()
ShowStuff()
input = GetInput()
ShowProgressBar()
SideScript1.processfilesbasedoninput(input, progressbarcontrolvar)
DisplayResults()
SideScript1
def proccessfilesbasedoninput(input, pbcv):
DoStuff()
pbcv.gofurther(5)
DoMoreStuff()
pbcv.goevenfurther(10)
a1sauce = RandomMathsStuffs()
for all the data in every file in that one directory:
ReadData()
pbcv.goabitfurther(a1sauce)
if data is what I want:
break
pbcv.step(-100)
return data
I guess my question is, How would I get the GUI to update those elements instead of going unconscious?
We are talking 100 000 files and 1.5 seconds its done in.
UPDATE: This question has been marked as a duplicate of another. Is it? Yep. but that's both because I was ((and still am)) unsure of how to search for this kind of question, and that the three solutions there; multithreading, multiprocessing, and smaller tasks. Unfortunately, the program was built to run on a single thread and process, and without a complete rewrite, getting the intended GUI response would cause a massive slowdown, if it worked at all.
I do see the issue, being TKinter is a blocking module. Unfortunately, I am fresh out of ideas on how I would un-block it without causing mass errors, and or a total rewrite.
The linked duplicate question held an answer. A bad one - but an answer none the less.
update_idletasks.
I tried that, and, it Worked! Well. Sort of.
It worked at first, then the same result came about. The GUI temporarily froze.
Then an idea popped in my head. Why not try update instead?
I did so, and it worked as I needed it to, however, it had a massive performance hit - nearly identical to update_idletasks.
To tackle this new problem, I added a bit more math to cause updates to happen, in my case, every 300 files, instead of every single file-balancing the performance hit and users not instantly deleting my program, because yes, it takes a toll on your resources. No, I did not initially heed that advice. Shoot first, ask questions later, right?
How did I use it? Glad I asked! Here's an example;
#GUI Code
DoStuff()
SideScript1.proccessdata(arg, kwarg, debate)
DoMoreStuff()
#File Management Code
DoStuff()
filenumber = 0
maxfilenumber = 0
for every file I need to search:
SearchFile()
filenumber +=1
if filenumber == maxfilenumber:
tkinter.update() #in my case, it was tkinst, or "TkInter Instance", since it was inherited from the GUI attributes.
filenumber = 0
if data is what I want:
break
return data
I'm not sure about all the backend and hard facts, but update() seemed a lot more user friendly and quicker than update_idletasks(), and a lot less prone to errors and slowdowns as well.
My shenanigans are now back in order, running in 60 ((30? 120? 250 million??)) frames a seconds, smoothly and efficiently - and Tk doesn't have a sit-down strike every time I ask it for info anymore!
Thanks #Rawing for the attempt to help!
I am writing an app in kivy which does cpu-heavy calculations at launch. I want the app to display what it's doing at the moment along with the progress, however, since the main loop is not reached yet, it just displays empty white screen until it finishes working. Can I force kivy to update the interface?
Basically I'm looking for kivy's equivalent of Tkinter's root.update()
I could create a workaround by defining a series of functions with each calling the next one through Clock.schedule_once(nextFunction, 1), but that would be very sloppy.
Thanks in advance.
Leaving aside the question of whether you should be using threading or something instead (which possibly you should), the answer is just that you should move your cpu calculations to somewhere else. Display something simple initially (i.e. returning a simple widget from your build method), then do the calculations after that, such as by clock scheduling them.
Your calculations will still block the gui in this case. You can work around this by doing them in a thread or by manually breaking them up into small pieces that can be sequentially scheduled.
It might be possible to update the gui by manually calling something like Clock.tick(), but I'm not sure if this will work right, and even if so it won't be able to display graphics before they have been initialised.
I'd like to know how to have a program wait for another program to finish a task. I'm not sure what I'd look for for that...
Also, I'm using a mac.
I'd like to use Python or perhaps even applescript (I could just osascript python if the solution if for applescript anyway)
Basically this program "MPEGstreamclip" converts videos, and it opens what appears to be 2 new windows while it's converting. One window is a conversion progress bar, and the other window is a preview of the conversion. (Not sure if these actually count as windows)
(Also, MPEGstreamclip does not have an applescript dictionary, so as far as I know, it can't listen for certain window names existence)
But basically I want my program to listen for when MPEGstreamclip is done, and then run its tasks.
If it helps, when the conversion is done, the mpegstreamclip icon in the dock bounces once. I'm not sure what that means but I'd think you could use that to trigger something couldn't you?
Thanks!
I realized GUI applescript was the answer in this scenario. With it I could tell the PROCESS to get every window, and that worked. However, I'm leaving this up because I'd like to know other ways. I'm sure this GUI workaround won't work for everything.
If the MPEGstreamclip actually ends when it is done, you could wrap the whole thing up in a python script using various techniques already discussed in another post. Just be sure to wait for the external process to end before continuing with your other steps.
How can I get a Progressbar to "pulse" while another function is run?
There is an example of how to do this here.
Push that another function into a separate thread. As long as your main thread runs any code, GUI is frozen. This is not a problem for short code pieces, but obviously a problem in your case.
Also read what PyGTK FAQ has to say about using threads in PyGTK program.
If your function runs in many iterations that don't take too long by themselves, then you don't necessarily need to mess around with separate threads. You can also cause the GUI to update itself during your long calculation:
def long_function(some_args):
while task_is_not_finished():
do_some_stuff_that_doesnt_take_too_long()
progress_bar.pulse()
while gtk.events_pending():
gtk.main_iteration()