ResetSession not clearing memory

ParaView Support
1

Hello,

I’ve been trying to use the ResetSession() function to clear memory in my paraview script, but that doesn’t seem to be working. Am I misunderstanding how memory is managed in paraview? Should I be using a different function? Delete() or del didn’t help at all either.

Thank you

2

How do you check memory usage ? The OS is pretty lazy when it comes to reclaiming freed memory. If it doesnt need it, it will still show up as being used although it is available.

3

I’ve just been using the top command on linux, but the issue comes in when my script eventually crashes due to a lack of memory and I get:
error: exception occurred: Subprocess killed

4

Do you reset session in your script ?

Please share a demo script to reproduce the issue.

5

I had previously opened an issue here (Paraview ResetSession causing crashes - #3 by ihelt) about ResetSession() causing a crash which had a similar minimally working example (in case this looks familiar), but the code below creates a new layout, which was a remedy suggested in issue 22831 (https://gitlab.kitware.com/paraview/paraview/-/issues/22831).

from paraview.simple import *
import os

class pv:
    def __init__(self,casename):
        print('Initializing...')
        self.enReader = EnSightReader(registrationName='case1', CaseFileName=casename)

        # Create layout: Remedy to ResetSession crashing (Paraview issue 22831)
        layout = CreateLayout()
        self.renderView = GetActiveViewOrCreate('RenderView')
        AssignViewToLayout(view=self.renderView, layout=layout)

    def __del__(self):
        print('deleting...')
        Delete(self.enReader)
        ResetSession()

    def makeBlock(self):
        print('Making block...')
        self.extractBlock = ExtractBlock(registrationName='block', Input=self.enReader)
        self.extractBlockDisplay = Show(self.extractBlock, self.renderView, 'UnstructuredGridRepresentation')
        self.extractBlock.Selectors = ['booster']
        
    def makePicture(self,picName):
        pic_path = './'+picName+'.png'
        print('Saving '+picName+'...')
        
        layout = GetLayout()
        layout.SetSize(1400,200)
        if os.path.exists(pic_path):
            os.remove(pic_path)
        SaveScreenshot(pic_path, self.renderView, ImageResolution=[1400, 200], OverrideColorPalette='BlackBackground')
        


def main():

    # NOTE: "error: exception occurred: Subprocess killed" is a result of all memory being used by CPU
    casename1 = /path/to/file.case'

    i = 1
    while i < 10:
        print('-----------------------------------')
        pvi = pv(casename1)
        pvi.makeBlock()
        pvi.makePicture('pic{0:d}'.format(i))
        pvi.__del__()
        del pvi
        print('pv{0:d} done'.format(i))
        i = i+1


    print('done')

if __name__ == '__main__':
    main()

Executing this code gives me the following output:

user:> pvpython --mesa replicateCrash.py
-----------------------------------
Initializing...
VisRTX 0.1.6, using devices:
 0: Quadro P2000 (Total: 5.3 GB, Available: 5.1 GB)
Making block...
Saving pic1...
deleting...
deleting...
pv1 done
-----------------------------------
Initializing...
Making block...
Saving pic2...
deleting...
deleting...
pv2 done
-----------------------------------
Initializing...
Making block...
Saving pic3...
deleting...
deleting...
pv3 done
-----------------------------------
Initializing...
Making block...
error: exception occurred: Subprocess killed

where the crash coincides with my memory usage being completely full.

6

Make sure you delete the python handles and call the garbage collector, eg:

        Delete(self.enReader)
        ResetSession()
        import gc
        gc.collect()
1 Like
7

Thank you Mathieu! This seemed to do it:

import gc

def __del__(self):
        print('deleting...')
        Delete(self.enReader)
        Delete(self.renderView)
        Delete(self.extractBlock)
        Delete(self.extractBlockDisplay)
        ResetSession()
        gc.collect()

There still appears to be a bit of residual memory usage even after the destructor is called, but I’m not worried about it for the moment

1 Like
8

Shouldn’t ResetSession delete all of these objects? Isn’t this a defect in ResetSession?

9

ResetSession is reseting the ParaView session, but It definitely should not cleanup python objects.

That being said, maybe it makes sense to add a ResetSessionAndCleanNameSpace to simple.py ?