Python: ws.getInstrument holds onto memory

[Martyn Gigg]

Run the script below and then open up a process monitor. On windows it is using ~ 450Mb, click the 'Clear all memory' option and the usage doesn't change.

idf_file = 'LET_Definition.xml'
ws = LoadEmptyInstrument(idf_file)
instr = ws.getInstrument()

[Nick Draper]

Moved to iteration 33 at iteration 32 code freeze

[Nick Draper]

Moved at end of release 2.1

[Nick Draper]

Moved at the end of release 2.2

[Martyn Gigg]

So this is down to the fact that the getInstrument call returns a shared pointer so Python holds on to the memory. If you add a line instr = None at the end to drop it & then click clear the memory will be freed.

In this case we have to return a shared pointer because the getInstrument call creates a new parametrized instrument object so it needs to be kept alive by something. The real "problem" is that the parameterized instrument stores a shared pointer, if it stored a weak pointer then this wouldn't be a problem. However this would slow access to the base instrument pointer as each call to the weak one would have to check whether the other was still alive and temporarily promote it to a shared pointer, creating a lot of additional work.

[Russell Taylor]

Agreed.

[Stuart Campbell]

This ticket has been transferred to github issue ​5152