Script blocked while Vizard-window resizes

[willpower2727]

Hi I was hoping someone here might help me understand this issue I'm having:

I'm running a multi-thread python script where one of the threads gets motion data from a camera system and another thread takes that information and updates the objects in the main worldviz window.

Sometimes, there is a short 500 millisecond block of the script execution and thus a 500 ms delay in updating the main window. Without spewing out a ton of details, I'll just say this 500 ms gap in the flow of data is unacceptable. I need to avoid similar delays.

The only known cause I have determined so far is that moving/re-sizing (by mouse drag) the main window onto a second monitor can cause it. I have come to understand that this might be Windows7 changing "modes" and blocking the python script until the window is finished moving/re-sizing. I have gotten around this issue by setting up a vizcore.cfg file that initializes the window the way I need it, thus avoiding the re-sizing problem.

However, I feel certain that there will be other events that can cause this type of block to happen. Can anyone help me understand how worldviz handles update commands? For example, if I call vizobject.setPosition(), is there some kind of response that my python script is waiting to receive from worldviz?

Any help or insight will be helpful and appreciated. Thanks!

P.S. I'm using Vizard 4, windows 7

[Jeff]

If Vizard's main update loop gets blocked then it's possible to see the script freeze. If you're still having an issue with this it's best to post Vizard code (http://forum.worldviz.com/faq.php?faq=vb3_reading_posting#faq_faq_vizard_cod e) that shows the problem.

[willpower2727]

Ok here is a slightly simplified version of my code, however I doubt anyone else will be able to run it due to the lack of having all the dependencies.


import socket
import sys
import io
import re
from xml.etree import ElementTree
import viz
import threading
import Queue
import time
import json
import vizact

viz.go()

#initialize objects
global scalorxx
scalorxx = 0.6667
global targetL
targetL = 1
global targetR
targetR = 1
global targettol
targettol = 0.05
global boxL
boxL = viz.addChild('target.obj',color=(0.063,0.102,0.898 ),scale=[0.1,(targettol+0.04)*0.75,0.0125])
boxL.setPosition([-0.2,targetL*scalorxx,0])
global boxR
boxR = viz.addChild('target.obj',color=(0.063,0.102,0.898 ),scale=[0.1,(targettol+0.04)*0.75,0.0125])
boxR.setPosition([0.2,targetR*scalorxx,0])
global cursorR
cursorR = viz.add('box3.obj', color=viz.RED, scale=[0.1,0.1,0.0125], cache=viz.CACHE_NONE)
cursorR.setPosition([0.2,0,0.05])
global cursorL
cursorL = viz.add('box3.obj', color=viz.GREEN, scale=[0.1,0.1,0.0125], cache=viz.CACHE_NONE)
cursorL.setPosition([-0.2,0,0.05])
global HistBallR
HistBallR = viz.add('footprint2.obj', color=viz.YELLOW, scale=[0.03,0.03,0.1], cache=viz.CACHE_NONE)
HistBallR.setPosition([0.2,targetR*scalorxx,0])
HistBallR.setEuler(0,0,0)
HistBallR.alpha(0.8)
global HistBallL
HistBallL = viz.add('footprint2.obj', color=viz.YELLOW, scale=[0.03,0.03,0.1], cache=viz.CACHE_NONE)
HistBallL.setPosition([-0.2,targetL*scalorxx,0])
HistBallR.setEuler(180,0,0)
HistBallL.alpha(0.8)

viz.MainView.setPosition(0, 0.5, -1.5)
viz.MainView.setEuler(0,0,0)

global histzR
global histzL
histzR = 0
histzL = 0

global rstridetime
global lstridetime
rstridetime = 0
lstridetime = 0

#global RHS
#global LHS
#RHS = 0
#LHS = 0
global FNold
FNold = 0

#definition for the first thread
def UpdateViz(root,q,savestring,q3):
timeold = time.time()
RHS = 0
LHS = 0

while not endflag.isSet():
global targetR
global targettol
global histzR
global histzL
global rstridetime
global lstridetime
# print(Queue.Queue.qsize(q))
root = q.get()#look for the next frame data in the thread queue
q.task_done()
# print(Queue.Queue.qsize(q))
timediff = time.time()-timeold

lp1 = root.find(".//Forceplate_0/Subframe_9/F_z")#Left Treadmill
rp1 = root.find(".//Forceplate_1/Subframe_9/F_z")#Right Treadmill

temp = rp1.attrib.values()
Rz = float(temp[0])#cast forceplate data as float
temp3 = lp1.attrib.values()
Lz = float(temp3[0])
cursorR.setScale(0.1,rstridetime*scalorxx,0.01250)
cursorL.setScale(-0.1,lstridetime*scalorxx,0.01250)
#check for gait events
if (Rz < -30) & (histzR >= -30):#HS condition
HistBallR.setPosition([0.2, rstridetime*scalorxx, 0])
RHS = 1
if (abs(rstridetime-targetR) <= targettol):
boxR.color( viz.WHITE )
else:
boxR.color( viz.BLUE )
rstridetime = 0
else:
rstridetime = rstridetime+timediff
RHS = 0

if (Lz < -30) & (histzL >= -30):
HistBallL.setPosition([-0.2, lstridetime*scalorxx, 0])
LHS = 1
if (abs(lstridetime-targetL) <= targettol):
boxL.color( viz.WHITE )
else:
boxL.color( viz.BLUE )
lstridetime = 0
else:
lstridetime = lstridetime+timediff
LHS = 0

timeold = time.time()
histzR = Rz
histzL = Lz

#send some data to be saved
fn = root.find(".//FrameNumber")#Left Treadmill
fnn = fn.attrib.values()
# print(fnn[0])

savestring = [int(fnn[0]),Rz,Lz,RHS,LHS]
# print(sys.getsizeof(savestring))
q3.put(savestring)
# print(q3.qsize())
q3.join()
print("data has all been gotten")

#definition of tcp thread
def runclient(root,q):

#illegal characters to remove from string later before going to xml
RE_XML_ILLEGAL = u'([\u0000-\u0008\u000b-\u000c\u000e-\u001f\ufffe-\uffff])' + \
u'|' + \
u'([%s-%s][^%s-%s])|([^%s-%s][%s-%s])|([%s-%s]$)|(^[%s-%s])' % \
(unichr(0xd800),unichr(0xdbff),unichr(0xdc00),unic hr(0xdfff),
unichr(0xd800),unichr(0xdbff),unichr(0xdc00),unich r(0xdfff),
unichr(0xd800),unichr(0xdbff),unichr(0xdc00),unich r(0xdfff))
HOST = 'localhost'#IP address of CPP server
PORT = 50008
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
print 'Socket created'
print 'Socket now connecting'
s.connect((HOST,PORT))
s.send('1')#send initial request for data

while not endflag.isSet():
global FNold
data = s.recv(50)#receive the initial message
data3 = data[:3]#get first 3 letters
if (data3 == "New"):
nextsizestring = data[3:]#get the integer after "New"
nextsizestring2 = nextsizestring.rstrip('\0')#format
nextsize = int(nextsizestring2,10)#cast as type int
# print("Next Packet is size: ")
# print(nextsize)
s.send('b')#tell cpp server we are ready for the packet
databuf = ''#initialize a buffer
while (sys.getsizeof(databuf) < nextsize+21):
data = s.recv(nextsize)#data buffer as a python string
databuf = databuf + data#collect data into buffer until size is matched
# print(sys.getsizeof(databuf))
root = ElementTree.ElementTree(ElementTree.fromstring(dat abuf))#create the element tree
q.put(root)#place the etree into the threading queue
fn = root.find(".//FrameNumber")#Left Treadmill
fnn = fn.attrib.values()
FN = int(fnn[0])
if (FN - FNold >= 20) & (FNold != 0):
print("gap larger than 20 has occured")

FNold = FN
elif (data3 != "New"):
print("WARNING! TCP SYNCH HAS FAILED")
break
if not data: break
s.send('b')

s.close()
q.join()

#thread that saves data (no problems here)
def savedata(savestring,q3):

#initialize the file
mst = time.time()
mst2 = int(round(mst))
mststring = str(mst2)+'StrideTime.txt'
print("Data file created named:")
print(mststring)
file = open(mststring,'w+')
json.dump(['FrameNumber','Rfz','Lfz','RHS','LHS'],file)
file.close()

file = open(mststring,'a')#reopen for appending only
print('file is open for appending')
while not endflag.isSet():
# print(q3.empty())
savestring = q3.get()#look in the queue for data to write
print(savestring)
q3.task_done()
if savestring is None:
continue
else:
json.dump(savestring, file)
print("savedata stop flag raised, finishing...")
while 1:
try:
savestring = q3.get(False,2)
except:
savestring = 'g'
# print(savestring)
if savestring == 'g':
break
print("data finished write to file")
else:
json.dump(savestring, file)
print("data still writing to file")

print("savedata finished writing")
file.close()

#event callback when user presses 'q'
endflag = threading.Event()
def raisestop(sign):
print("stop flag raised")
endflag.set()
t1.join()
t2.join()
t4.join()
viz.quit()

root = ''#empty string
savestring = ''
q = Queue.Queue()#initialize the queue
q3 = Queue.Queue()#intialize another queue for saving data
#create threads for client
t1 = threading.Thread(target=runclient,args=(root,q))
t2 = threading.Thread(target=UpdateViz,args=(root,q,sav estring,q3))
t4 = threading.Thread(target=savedata,args=(savestring, q3))

t1.daemon = True
t2.daemon = True
t4.daemon = True
#start the threads
t1.start()
t2.start()
t4.start()

print("\n")
print("press 'q' to stop")
print("\n")

vizact.onkeydown('q',raisestop,'t')

[Jeff]

You might try using Vizard's director function (http://docs.worldviz.com/vizard/#Director_basics.htm) to read the motion data instead of creating your own thread. It's designed for cases such as this where you need to perform some IO operation without halting rendering of the scene.