QThread and pyqtgraph no performance improvement - python-2.7

Question

I am trying to do a multigraph window for plotting different data using pyqtgraph. I have a working version with no threads using timers for getting the data. I also tried a threaded version but it seems to have no performance boost when use htop for visually inspecting the CPU Usage.
I am new to GUIs and Threads so I followed this code that I saw in a youtube tutorial. It uses a QThread to get the CPU usage using psutil.cpu_percent in intervals of 0.1 seconds and then updates a progress bar.
import sys
from PyQt4 import QtCore
from PyQt4 import QtGui
import progress
import sysinfo
class MainUIClass(QtGui.QMainWindow, progress.Ui_MainWindow):
def __init__(self, parent = None):
super(MainUIClass, self).__init__(parent)
self.setupUi(self)
self.threadClass = ThreadClass()
self.threadClass.start()
self.connect(self.threadClass, QtCore.SIGNAL('CPU_VALUE'),
self.updateProgressBar)
def updateProgressBar(self, val):
self.progressBar.setValue(val)
class ThreadClass(QtCore.QThread):
def __init__(self, parent = None):
super(ThreadClass, self).__init__(parent)
def run(self):
while 1:
val = sysinfo.getCPU()
self.emit(QtCore.SIGNAL('CPU_VALUE'), val)
if __name__ == '__main__':
a = QtGui.QApplication(sys.argv)
app = MainUIClass()
app.show()
a.exec_()
I tried using cProfile for comparing performance but it throws lot of stuff that couldn't read, so I use the example of the progress bar to average the cpu usage after 10 seconds. Sorry if my measure performance method is so poor.
My two codes for benchmarking are
Threaded Version with a very consistent average CPU Usage of 64%:
import sys
from pyqtgraph.Qt import QtCore
from pyqtgraph.Qt import QtGui
import pyqtgraph as pg
import numpy as np
import time
class GraphWindow_Thread(pg.GraphicsWindow):
def __init__(self, rows, cols, titles):
super(GraphWindow_Thread, self).__init__()
# Code to draw the GUI
self.rows = rows
self.cols = cols
self.titles = titles
self.plots = [] # List of PlotItems
self.curves = [] # List of PlotDataItems in each PlotItem
for i in range(self.rows):
for j in range(self.cols):
p = self.addPlot()
self.plots.append(p)
if titles != [] or len(titles) == 1:
p.setLabel('left', self.titles[i+j+1])
p.setDownsampling(mode='peak')
p.setClipToView(True)
pp = p.plot(pen=(155, 255, 50))
pp1 = p.plot(pen=(55, 130, 255))
self.curves.append((pp, pp1))
self.nextRow()
# Thread to get the data and redraw plots
self.thread_graph = DataThread()
self.thread_graph.start()
self.connect(self.thread_graph, QtCore.SIGNAL('DATA_VALUE'),
self.update_plots)
def set_titles(self, titles):
for i, p in enumerate(self.plots):
p.setLabel('left', titles[i])
def update_plots(self, data, dataD):
for curve in self.curves:
curve[0].setData(data)
curve[1].setData(dataD)
class DataThread(QtCore.QThread):
def __init__(self, parent = None):
super(DataThread, self).__init__(parent)
def run(self):
while 1:
data = np.random.random((30,))
dataD = np.random.random((30,))
self.emit(QtCore.SIGNAL('DATA_VALUE'), data, dataD)
time.sleep(.1)
if __name__ == '__main__':
app = QtGui.QApplication(sys.argv)
gui = GraphWindow_Thread(2,3,[])
gui.show()
app.exec_()
No Thread Version with a very consistent average CPU Usage of 65%:
import sys
from pyqtgraph.Qt import QtCore
from pyqtgraph.Qt import QtGui
import pyqtgraph as pg
import numpy as np
import time
class GraphWindow(pg.GraphicsWindow):
def __init__(self, rows, cols, titles):
super(GraphWindow, self).__init__()
# Code to draw the GUI
self.rows = rows
self.cols = cols
self.titles = titles
self.plots = [] # List of PlotItems
self.curves = [] # List of PlotDataItems in each PlotItem
for i in range(self.rows):
for j in range(self.cols):
p = self.addPlot()
self.plots.append(p)
if titles != [] or len(titles) == 1:
p.setLabel('left', self.titles[i+j+1])
p.setDownsampling(mode='peak')
p.setClipToView(True)
pp = p.plot(pen=(155, 255, 50))
pp1 = p.plot(pen=(55, 130, 255))
self.curves.append((pp, pp1))
self.nextRow()
# Timer to redraw plots
timer = QtCore.QTimer(self)
self.connect(timer, QtCore.SIGNAL('timeout()'),self.update_plots)
timer.start(100)
def set_titles(self, titles):
for i, p in enumerate(self.plots):
p.setLabel('left', titles[i])
def update_plots(self):
np.random.seed()
data = np.random.random((30,))
dataD = np.random.random((30,))
for curve in self.curves:
curve[0].setData(data)
curve[1].setData(dataD)
if __name__ == '__main__':
app = QtGui.QApplication(sys.argv)
gui = GraphWindow(2,3,[])
gui.show()
app.exec_()
The full app is meant to be a window with multiple tabs, each one with a GraphWindow in which each graph uses a Thread for plotting different data.
What am I missing? Why my threaded version does not represent a performance improvement?