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#! /usr/bin/python
"""
Test by Karen Tracey for threading problem reported in
http://www.mail-archive.com/matplotlib-devel@lists.sourceforge.net/msg04819.html
and solved by JDH in git commit 175e3ec5bed9144.
"""
from __future__ import print_function
import os
import threading
import traceback
import numpy as np
from matplotlib.backends.backend_agg import FigureCanvasAgg as FigureCanvas
from matplotlib.figure import Figure
thread_count = 8
max_iterations = 50
exception_raised = False
def png_thread(tn):
png_fname = 'out%d.png' % tn
vals = 100 + 15 * np.random.randn(10000)
i = 0
excp = None
global exception_raised
while not exception_raised and i < max_iterations:
i += 1
png_f = open(png_fname, 'wb')
try:
fig = Figure()
ax = fig.add_subplot(111)
ax.hist(vals, 50)
FigureCanvas(fig).print_png(png_f)
except Exception as excp:
pass
png_f.close()
if excp:
print('png_thread %d failed on iteration %d:' % (tn, i))
print(traceback.format_exc(excp))
exception_raised = True
else:
print('png_thread %d completed iteration %d.' % (tn, i))
os.unlink(png_fname)
def main(tc):
threads = []
for i in range(tc):
threads.append(threading.Thread(target=png_thread, args=(i + 1,)))
for t in threads:
t.start()
for t in threads:
t.join()
if not exception_raised:
msg = 'Success! %d threads completed %d iterations with no exceptions raised.'
else:
msg = 'Failed! Exception raised before %d threads completed %d iterations.'
print(msg % (tc, max_iterations))
if __name__ == "__main__":
main(thread_count)
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