# pvpython and multiprocess

**URL:** https://discourse.paraview.org/t/pvpython-and-multiprocess/10771
**Category:** ParaView Support
**Tags:** python
**Created:** [November 16, 2022, 5:04pm UTC](https://discourse.paraview.org/t/pvpython-and-multiprocess/10771 "2022-11-16T17:04:48Z")
**Posts on this page:** 5
**Page:** 1

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### Author: ![Stefano\_Godi](https://discourse.paraview.org/user_avatar/discourse.paraview.org/stefano_godi/32/10292_2.png) [@Stefano\_Godi](https://discourse.paraview.org/u/Stefano_Godi)
#### Post date: [November 16, 2022, 5:04pm UTC](https://discourse.paraview.org/t/pvpython-and-multiprocess/10771/1 "2022-11-16T17:04:49Z")

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Hi, I’m trying to use the ProcessThreadPool class of python but I get the following error: Some resources might leak . I’m trying to understand if it’s because I run my python script under pvpython or not.

What am I doing?

I have a grid of points from which I want to extract the streamTracer filter. Essentially I give to the python script the list of the points and he moves the filter around the script saving each time a data file. Since I have more that 5.000 points (I could have easily \>30k points), it turns that I need to save a lot of files and it keeps \>2 minutes. I was thinking on a multi process solution (multi thread doesn’t improve performance), but I cannot get rid of the following error:

```auto
pvpython export_streamlines.py receivers.geojson 0.5 3
/Applications/ParaView-5.11.0-RC2.app/Contents/Libraries/lib/python3.9/multiprocessing/resource_tracker.py:96: UserWarning: resource_tracker: process died unexpectedly, relaunching. Some resources might leak.
  warnings.warn('resource_tracker: process died unexpectedly, '

```

Here my code:

```auto
from paraview.simple import *
import os
import json
import time
from concurrent.futures import ProcessPoolExecutor as pool

def extract_and_save(feature,streamTracer1):
	x = feature['geometry']['coordinates'][0]
	y = feature['geometry']['coordinates'][1]
	z = feature['geometry']['coordinates'][2]
	ID = feature['properties']['PK']
	Center = [x,y,z]
	streamTracer1.SeedType.Center = Center
	SaveData('../streamlines/'+str(ID)+'.txt', proxy=streamTracer1, ChooseArraysToWrite=1,
    PointDataArrays=['IntegrationTime', 'U [m/s]'],
    CellDataArrays=['ReasonForTermination', 'SeedIds'],
    FieldDataArrays=['CasePath'])

start_time = time.time()

if len(sys.argv)<4:
    print("Inputs: <geojson path> , <Radius> , <numberOfPoints> ")
    sys.exit(1)

with open(sys.argv[1], 'r') as json_file:
    data = json.load(json_file)

# get the time-keeper
timeKeeper1 = GetTimeKeeper()

# load state
LoadState('../streamlines.pvsm')

# find source
streamTracer1 = FindSource('StreamTracer1')

# set active source
SetActiveSource(streamTracer1)

#Inputs
streamTracer1.SeedType.Radius = float(sys.argv[2])
streamTracer1.SeedType.NumberOfPoints = int(sys.argv[3])

# save data
if not os.path.exists("../streamlines"):
	    os.makedirs("../streamlines")

#for feature in data['features']:
	 #extract_and_save(feature,streamTracer1)
with pool(max_workers=1) as exe:
	_ = exe.submit(extract_and_save, data['features'])

print('[Finished in: %s seconds]' % (time.time() - start_time))

```

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<div class="post-metadata">

### Author: ![Stefano\_Godi](https://discourse.paraview.org/user_avatar/discourse.paraview.org/stefano_godi/32/10292_2.png) [@Stefano\_Godi](https://discourse.paraview.org/u/Stefano_Godi)
#### Post date: [November 21, 2022, 10:00pm UTC](https://discourse.paraview.org/t/pvpython-and-multiprocess/10771/2 "2022-11-21T22:00:11Z")

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is there anybody here?

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### Author: ![mwestphal](https://discourse.paraview.org/user_avatar/discourse.paraview.org/mwestphal/32/17_2.png) [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [November 22, 2022, 8:07am UTC](https://discourse.paraview.org/t/pvpython-and-multiprocess/10771/3 "2022-11-22T08:07:40Z")

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> [@Stefano\_Godi](#):
>
> ```auto
> /Applications/ParaView-5.11.0-RC2.app/Contents/Libraries/lib/python3.9/multiprocessing/resource_tracker.py:96: UserWarning: resource_tracker: process died unexpectedly, relaunching. Some resources might leak.
> warnings.warn('resource_tracker: process died unexpectedly, '
> 
> ```

This looks not related to ParaView at all, did you try your scripts without using ParaView ?

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<div class="post-metadata">

### Author: ![Stefano\_Godi](https://discourse.paraview.org/user_avatar/discourse.paraview.org/stefano_godi/32/10292_2.png) [@Stefano\_Godi](https://discourse.paraview.org/u/Stefano_Godi)
#### Post date: [November 22, 2022, 9:25am UTC](https://discourse.paraview.org/t/pvpython-and-multiprocess/10771/4 "2022-11-22T09:25:57Z")

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Thank you for your attention. Sure, I tested a little multiprocess script outside Paraview and it works. I found [this issue](https://gitlab.kitware.com/paraview/paraview/-/issues/21125) inside the paraview gitlab.  
Of course I could not test the same script outside paraview since it depends from it

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<div class="post-metadata">

### Author: ![mwestphal](https://discourse.paraview.org/user_avatar/discourse.paraview.org/mwestphal/32/17_2.png) [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [November 22, 2022, 9:40am UTC](https://discourse.paraview.org/t/pvpython-and-multiprocess/10771/5 "2022-11-22T09:40:32Z")

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@jourdain