[BUG] Memory leaks - Model

[madkote]

I have discovered, that memory is leaking by using the model/decoder.

Scenario

Load model, use it, unload -> the memory is released partially.

def runner_model():
    mem_usage = memory_profiler.memory_usage(-1, interval=.1, timeout=.5)
    print('> %s > mem=%s' % ('load model', max(mem_usage)))
    #
    model = KaldiNNet3OnlineModel(
        MODELDIR,
        acoustic_scale=1.0,
        beam=7.0,
        frame_subsampling_factor=3,
    )
    #
    mem_usage = memory_profiler.memory_usage(-1, interval=.1, timeout=.5)
    print('> %s > mem=%s' % ('model loaded', max(mem_usage)))
    try:
        for i in range(3):
            mem_usage = memory_profiler.memory_usage(-1, interval=.1, timeout=.5)
            print('> %s > mem=%s' % (' ---> MODEL iteration #%s' % i, max(mem_usage)))
            #
            # do something
            #
            mem_usage = memory_profiler.memory_usage(-1, interval=.1, timeout=.5)
            print('> %s > mem=%s' % (' ###> MODEL iteration #%s' % i, max(mem_usage)))
    finally:
        mem_usage = memory_profiler.memory_usage(-1, interval=.1, timeout=.5)
        print()
        print('> %s > mem=%s' % ('delete model', max(mem_usage)))
        #
        del model
        #
        mem_usage = memory_profiler.memory_usage(-1, interval=.1, timeout=.5)
        print()
        print('> %s > mem=%s' % ('model deleted', max(mem_usage)))

def task():
    mem_usage = memory_profiler.memory_usage(-1, interval=.1, timeout=.5)
    print('> %s > mem=%s' % ('start task', max(mem_usage)))
    #
    runner_model()
    #
    mem_usage = memory_profiler.memory_usage(-1, interval=.1, timeout=.5)
    print('> %s > mem=%s' % ('finish task', max(mem_usage)))

the output:

> start task > mem=45.46875
> load model > mem=45.46875
> model loaded > mem=356.10546875
>  ---> MODEL iteration #0 > mem=356.10546875
>  ###> MODEL iteration #0 > mem=356.10546875
>  ---> MODEL iteration #1 > mem=356.10546875
>  ###> MODEL iteration #1 > mem=356.10546875
>  ---> MODEL iteration #2 > mem=356.10546875
>  ###> MODEL iteration #2 > mem=356.10546875
> delete model > mem=356.10546875
> model deleted > mem=255.890625
> finish task > mem=255.890625

I see that 200MB are not released back - cf. > start task > mem=45.46875 and > finish task > mem=255.890625