Memory not released after getting last algorithm from history in Python

[martyngigg]

This was first noticed on SANS when running the add files section of the ISIS SANS scripts.

The following script will reproduce the problem:

#!python
def foo():
    wsName= 'AddFilesSumTempory'
    filename = "SANS2D00028546.nxs"
    outWs = Load(Filename=filename,OutputWorkspace=wsName)
    props = outWs.getHistory().lastAlgorithm()
    LoadEventNexus(Filename=filename, OutputWorkspace='AddFilesSumTempory', LoadMonitors=True)

    DeleteWorkspace('AddFilesSumTempory')
    DeleteWorkspace('AddFilesSumTempory_monitors')

for i in range(1):
    foo()

After execution you should see that no workspaces are left but checking the memory usage of the MantidPlot executable still shows a sizeable amount of memory being used. Note that this should be a generic problem and not limited to SANS files.

If you run "Clear All Memory" then the memory is returned as expected.

[martyngigg]

This issue was originally trac ticket 11589