[PyQt] pyqt4 amd multiprocessing
Lic. José M. Rodriguez Bacallao
jmrbcu at gmail.com
Mon May 9 14:46:43 BST 2011
sound interesting but, how do you use QProcess, what I have read about
it is that this class is for executing external applications (yes,
processes), how to use QProcess in a pool. Could you tell me more
about HDF5, for example, how do you use it with python. My dataset
could be very big (or what I think is big), for example, a serie of
1500 dicom images so I think that HDF5 could be useful to me.
On Mon, May 9, 2011 at 9:24 AM, Belzile Marc-André <mabxsi at hotmail.com> wrote:
> As an alternative to python multiprocessing module, I'm using QProcess for
> loading and exporting files with my own pool manager. It's pretty darn fast
> and works well, my data sets are managed with HDF5 which takes care of
> handling huge data sets pretty easily. If you want to pass data back to the
> UI you can use QSharedMemory to give the GUI access to your data.
> Check out my project for a QProcess example.
> http://code.google.com/p/ice-cache-explorer/
>
> -mab
> "The world goin' one way, people another!" - Poot
>
>
>
>> Date: Mon, 9 May 2011 09:10:20 -0400
>> From: jmrbcu at gmail.com
>> To: sam.carcagno at gmail.com
>> CC: pyqt at riverbankcomputing.com
>> Subject: Re: [PyQt] pyqt4 amd multiprocessing
>>
>> I am very interested in the answer because I have plan to use
>> multiprocessing module to do my hard work (because of the python GIL),
>> my future design is something like Samuele say, a pool of process
>> ready to do some hard job (using multiprocessing) and the GUI with
>> pyqt4 and vtk, data pass back and forth between the gui and the worker
>> processes (data will be vtk datasets)
>>
>> On Mon, May 9, 2011 at 6:26 AM, Samuele Carcagno <sam.carcagno at gmail.com>
>> wrote:
>> > Hi,
>> >
>> > I would like to use the multiprocessing module to create a set of sounds
>> > (as numpy arrays) in parallel.
>> > The parameters of the sounds (duration, volume, etc..) are controlled by
>> > a pyqt4 GUI, and the sounds
>> > need to be passed back to the GUI for further processing and
>> > presentation. The sounds are generated
>> > in a separate module from the GUI. I'm attaching a minimal example with
>> > a file that creates the gui and
>> > a second file that contains the functions for generating the sounds.
>> >
>> > I've had mixed success so far, it seems to work on Kubuntu Natty -
>> > Python 2.7.1+ - Qt 4.7.2 - PyQt 4.8.3
>> > but sometimes it fails on Kubuntu Lucid - Python 2.6.5 - Qt 4.6.2 -
>> > PyQt 4.7.2 with the following error:
>> >
>> > Traceback (most recent call last):
>> > File "test_gui.py", line 20, in onClickButton1
>> > self.doTrial()
>> > File "test_gui.py", line 32, in doTrial
>> > x = complexTone(F0, lowHarm, highHarm, level, duration, ramp,
>> > channel, fs, maxLevel)
>> > File "/media/ntfsShared/mptest/simple_test/stim.py", line 45, in
>> > complexTone
>> > pool.join()
>> > File "/usr/lib/python2.6/multiprocessing/pool.py", line 342, in join
>> > p.join()
>> > File "/usr/lib/python2.6/multiprocessing/process.py", line 119, in join
>> > res = self._popen.wait(timeout)
>> > File "/usr/lib/python2.6/multiprocessing/forking.py", line 117, in wait
>> > return self.poll(0)
>> > File "/usr/lib/python2.6/multiprocessing/forking.py", line 106, in poll
>> > pid, sts = os.waitpid(self.pid, flag)
>> > OSError: [Errno 4] Interrupted system call
>> >
>> > Am I doing something fundamentally unsafe by using multiprocessing in
>> > this way with a pyqt4 GUI?
>> > What is the best approach to use multiprocessing together with pyqt4?
>> >
>> > Thanks for any suggestions!
>> >
>> > Sam
>> >
>> > ###---------GUI----------File 1
>> > from PyQt4 import QtGui
>> > from PyQt4 import QtCore
>> > import sys
>> > from stim import* #import module for stimulus generation
>> >
>> >
>> > class Example(QtGui.QWidget):
>> >
>> > def __init__(self):
>> > super(Example, self).__init__()
>> > self.setGeometry(300, 300, 250, 150)
>> > self.setWindowTitle('Multiprocessing Test')
>> >
>> > self.button1 = QtGui.QPushButton('Button 1', self)
>> > QtCore.QObject.connect(self.button1,
>> > QtCore.SIGNAL('clicked()'),
>> > self.onClickButton1)
>> >
>> > def onClickButton1(self):
>> > self.doTrial()
>> >
>> > def doTrial(self):
>> > F0 = 200
>> > lowHarm=1
>> > highHarm = 20
>> > level = 50
>> > duration = 180
>> > ramp = 10
>> > channel = "Both"
>> > fs = 44100
>> > maxLevel = 100.0
>> > x = complexTone(F0, lowHarm, highHarm, level, duration, ramp,
>> > channel, fs, maxLevel)
>> >
>> >
>> > if __name__ == '__main__':
>> > app = QtGui.QApplication(sys.argv)
>> > ex = Example()
>> > ex.show()
>> > app.exec_()
>> > #----------END OF FILE 1
>> >
>> >
>> > ###-SOUND GENERATION-- File stim.py
>> > from numpy import*
>> > import multiprocessing
>> >
>> > def pureTone(frequency, phase, level, duration, ramp, channel, fs,
>> > maxLevel):
>> >
>> > amp = 10**((level - maxLevel) / 20.)
>> > duration = duration / 1000. #convert from ms to sec
>> > ramp = ramp / 1000.
>> >
>> > nSamples = int(round(duration * fs))
>> > nRamp = int(round(ramp * fs))
>> > nTot = nSamples + (nRamp * 2)
>> >
>> > timeAll = arange(0., nTot) / fs
>> > timeRamp = arange(0., nRamp)
>> >
>> > snd = zeros((nTot, 2))
>> >
>> > if channel == "Right":
>> > snd[0:nRamp, 1] = amp * ((1-cos(pi * timeRamp/nRamp))/2) *
>> > sin(2*pi*frequency * timeAll[0:nRamp] + phase)
>> > snd[nRamp:nRamp+nSamples, 1] = amp* sin(2*pi*frequency *
>> > timeAll[nRamp:nRamp+nSamples] + phase)
>> > snd[nRamp+nSamples:len(timeAll), 1] = amp * ((1+cos(pi *
>> > timeRamp/nRamp))/2) * sin(2*pi*frequency *
>> > timeAll[nRamp+nSamples:len(timeAll)] + phase)
>> > elif channel == "Left":
>> > snd[0:nRamp, 0] = amp * ((1-cos(pi * timeRamp/nRamp))/2) *
>> > sin(2*pi*frequency * timeAll[0:nRamp] + phase)
>> > snd[nRamp:nRamp+nSamples, 0] = amp* sin(2*pi*frequency *
>> > timeAll[nRamp:nRamp+nSamples] + phase)
>> > snd[nRamp+nSamples:len(timeAll), 0] = amp * ((1+cos(pi *
>> > timeRamp/nRamp))/2) * sin(2*pi*frequency *
>> > timeAll[nRamp+nSamples:len(timeAll)] + phase)
>> > elif channel == "Both":
>> > snd[0:nRamp, 0] = amp * ((1-cos(pi * timeRamp/nRamp))/2) *
>> > sin(2*pi*frequency * timeAll[0:nRamp] + phase)
>> > snd[nRamp:nRamp+nSamples, 0] = amp* sin(2*pi*frequency *
>> > timeAll[nRamp:nRamp+nSamples] + phase)
>> > snd[nRamp+nSamples:len(timeAll), 0] = amp * ((1+cos(pi *
>> > timeRamp/nRamp))/2) * sin(2*pi*frequency *
>> > timeAll[nRamp+nSamples:len(timeAll)] + phase)
>> > snd[:, 1] = snd[:, 0]
>> >
>> > return snd
>> >
>> >
>> > def complexTone(F0, lowHarm, highHarm, level, duration, ramp, channel,
>> > fs, maxLevel):
>> > pool = multiprocessing.Pool()
>> > tn = []
>> >
>> > for i in range(lowHarm, highHarm+1):
>> > res = pool.apply_async(pureTone, (F0*i, 0, level, duration, ramp,
>> > channel, fs, maxLevel,), callback=tn.append)
>> >
>> > pool.close()
>> > pool.join()
>> >
>> > for i in range(len(tn)):
>> > if i == 0:
>> > snd = tn[i]
>> > else:
>> > snd = snd + tn[i]
>> >
>> > return snd
>> >
>> > #----------END OF FILE 2
>> > _______________________________________________
>> > PyQt mailing list PyQt at riverbankcomputing.com
>> > http://www.riverbankcomputing.com/mailman/listinfo/pyqt
>> >
>>
>>
>>
>> --
>> Lic. José M. Rodriguez Bacallao
>> Centro de Biofisica Medica
>> -----------------------------------------------------------------
>> Todos somos muy ignorantes, lo que ocurre es que no todos ignoramos lo
>> mismo.
>>
>> Recuerda: El arca de Noe fue construida por aficionados, el titanic
>> por profesionales
>> -----------------------------------------------------------------
>> _______________________________________________
>> PyQt mailing list PyQt at riverbankcomputing.com
>> http://www.riverbankcomputing.com/mailman/listinfo/pyqt
>
--
Lic. José M. Rodriguez Bacallao
Centro de Biofisica Medica
-----------------------------------------------------------------
Todos somos muy ignorantes, lo que ocurre es que no todos ignoramos lo mismo.
Recuerda: El arca de Noe fue construida por aficionados, el titanic
por profesionales
-----------------------------------------------------------------
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