DeleteWorkspace makes mantid hang for WISH data after NormaliseToMonitor (windows not IDAaaS)

[RichardWaiteSTFC]

Describe the bug Windows hangs when deleteing a WISH workspace above a certain memory threshold.

To Reproduce (1) Run this script

LoadRaw(Filename='WISH00043526.raw', OutputWorkspace='Vana', LoadMonitors='Separate') # 2021-11-10T16:30:01.487334000 execCount: 19
CropWorkspace(InputWorkspace='Vana', OutputWorkspace='Vana', XMin=6000, XMax=99000) # 2021-11-10T16:30:31.007140000 execCount: 20
NormaliseByCurrent(InputWorkspace='Vana', OutputWorkspace='Vana') # 2021-11-10T16:30:54.491781000 execCount: 21
ConvertUnits(InputWorkspace='Vana', OutputWorkspace='Vana', Target='Wavelength') # 2021-11-10T16:30:55.211130000 execCount: 22
NormaliseByCurrent(InputWorkspace='Vana_monitors', OutputWorkspace='Vana_monitors') # 2021-11-10T16:30:55.527786000 execCount: 23
CropWorkspace(InputWorkspace='Vana_monitors', OutputWorkspace='Vana_monitors', XMin=6000, XMax=99000) # 2021-11-10T16:30:55.532764000 execCount: 24
ConvertUnits(InputWorkspace='Vana_monitors', OutputWorkspace='Vana_monitors', Target='Wavelength') # 2021-11-10T16:30:55.537742000 execCount: 25
NormaliseToMonitor(InputWorkspace='Vana', OutputWorkspace='Vana_norm', MonitorWorkspace='Vana_monitors', MonitorWorkspaceIndex=3) # 2021-11-10T16:30:55.541725000 execCount: 26

(2) Delete the Vana workspace - it hangs on windows

(3) Load in a small section of WISH data (1 bank only) - it will no longer hang

LoadRaw(Filename='WISH00043526.raw', OutputWorkspace='Vana', LoadMonitors='Separate',
    SpectrumMin=1, SpectrumMax=19461)  # bank 1

Expected behavior It wouldn't hang and the delete workspace would execute successfully in ~5s

Screenshots

Platform/Version (please complete the following information):

• OS: Windows
• OS Version: 6.2 and nightly

Additional context

[RichardWaiteSTFC]

@thomashampson have core got any capacity to look into this next sprint? WISH have mentioned it again.

[thomashampson]

@thomashampson have core got any capacity to look into this next sprint? WISH have mentioned it again.

I can have a look at it.

[sf1919]

I've been unable to recreate this on v6.9 on Windows. The workspace deletes quickly with no hanging. Could @RichardWaiteSTFC and @thomashampson also check whether it's reproducable still?

[sf1919]

I've just tried deleting Vana_norm and that is hanging so there is definitely some issue still there

[RichardWaiteSTFC]

I've just tried deleting Vana_norm and that is hanging so there is definitely some issue still there

I've also had WISH scientists report the issue when deleting Vana_norm

[sf1919]

@RichardWaiteSTFC can we retry this on v6.10? I'm not sure I can recreate it so it might have been fixed?