Hourly aggregation uses too much memory

[mhidas]

When aggregating larger datasets, the hourly averaging codes (velocity and non-velocity) can run out of memory and fail.
In general it seems the process can easily eat up 4-5Gb of memory (and want more...)

[mhidas]

There are a few versions of errors I've seen related to this. They arise at different points in the code, but the underlying issue is probably the same (inefficient memory usage).

First reported error:

Traceback (most recent call last):
  File "/mnt/ebs/pipeline/lib/python3.5/site-packages/aodncore/pipeline/handlerbase.py", line 1038, in run
    self.trigger(transition['trigger'])
  File "/mnt/ebs/pipeline/lib/python3.5/site-packages/transitions/core.py", line 65, in _get_trigger
    return machine.events[trigger_name].trigger(model, *args, **kwargs)
  File "/mnt/ebs/pipeline/lib/python3.5/site-packages/transitions/core.py", line 405, in trigger
    return self.machine._process(func)
  File "/mnt/ebs/pipeline/lib/python3.5/site-packages/transitions/core.py", line 1073, in _process
    return trigger()
  File "/mnt/ebs/pipeline/lib/python3.5/site-packages/transitions/core.py", line 423, in _trigger
    return self._process(event_data)
  File "/mnt/ebs/pipeline/lib/python3.5/site-packages/transitions/core.py", line 433, in _process
    if trans.execute(event_data):
  File "/mnt/ebs/pipeline/lib/python3.5/site-packages/transitions/core.py", line 279, in execute
    machine.callback(func, event_data)
  File "/mnt/ebs/pipeline/lib/python3.5/site-packages/transitions/core.py", line 1031, in callback
    func(*event_data.args, **event_data.kwargs)
  File "/mnt/ebs/pipeline/lib/python3.5/site-packages/aodndata/moorings/products_handler.py", line 314, in preprocess
    self._make_hourly_timeseries()
  File "/mnt/ebs/pipeline/lib/python3.5/site-packages/aodndata/moorings/products_handler.py", line 266, in _make_hourly_timeseries
    opendap_url_prefix=OPENDAP_URL_PREFIX
  File "/mnt/ebs/pipeline/lib/python3.5/site-packages/aodntools/timeseries_products/hourly_timeseries.py", line 501, in hourly_aggregator
    df_temp = nc_clean.to_dataframe()
  File "/mnt/ebs/pipeline/lib/python3.5/site-packages/xarray/core/dataset.py", line 3088, in to_dataframe
    return self._to_dataframe(self.dims)
  File "/mnt/ebs/pipeline/lib/python3.5/site-packages/xarray/core/dataset.py", line 3077, in _to_dataframe
    for k in columns]
  File "/mnt/ebs/pipeline/lib/python3.5/site-packages/xarray/core/dataset.py", line 3077, in <listcomp>
    for k in columns]
MemoryError

More recently ...

Traceback (most recent call last):
  File "/mnt/ebs/pyenv/versions/3.5.2/envs/pipeline_prod_venv/lib/python3.5/site-packages/aodncore/pipeline/handlerbase.py", line 1054, in run
    self.trigger(transition['trigger'])
  File "/mnt/ebs/pyenv/versions/3.5.2/envs/pipeline_prod_venv/lib/python3.5/site-packages/transitions/core.py", line 899, in _get_trigger
    return event.trigger(model, *args, **kwargs)
  File "/mnt/ebs/pyenv/versions/3.5.2/envs/pipeline_prod_venv/lib/python3.5/site-packages/transitions/core.py", line 401, in trigger
    return self.machine._process(func)
  File "/mnt/ebs/pyenv/versions/3.5.2/envs/pipeline_prod_venv/lib/python3.5/site-packages/transitions/core.py", line 1188, in _process
    return trigger()
  File "/mnt/ebs/pyenv/versions/3.5.2/envs/pipeline_prod_venv/lib/python3.5/site-packages/transitions/core.py", line 426, in _trigger
    return self._process(event_data)
  File "/mnt/ebs/pyenv/versions/3.5.2/envs/pipeline_prod_venv/lib/python3.5/site-packages/transitions/core.py", line 435, in _process
    if trans.execute(event_data):
  File "/mnt/ebs/pyenv/versions/3.5.2/envs/pipeline_prod_venv/lib/python3.5/site-packages/transitions/core.py", line 272, in execute
    event_data.machine.callbacks(itertools.chain(event_data.machine.before_state_change, self.before), event_data)
  File "/mnt/ebs/pyenv/versions/3.5.2/envs/pipeline_prod_venv/lib/python3.5/site-packages/transitions/core.py", line 1123, in callbacks
    self.callback(func, event_data)
  File "/mnt/ebs/pyenv/versions/3.5.2/envs/pipeline_prod_venv/lib/python3.5/site-packages/transitions/core.py", line 1144, in callback
    func(*event_data.args, **event_data.kwargs)
  File "/mnt/ebs/pyenv/versions/3.5.2/envs/pipeline_prod_venv/lib/python3.5/site-packages/aodndata/moorings/products_handler.py", line 390, in preprocess
    self._make_hourly_timeseries()
  File "/mnt/ebs/pyenv/versions/3.5.2/envs/pipeline_prod_venv/lib/python3.5/site-packages/aodndata/moorings/products_handler.py", line 300, in _make_hourly_timeseries
    **self.product_common_kwargs)
  File "/mnt/ebs/pyenv/versions/3.5.2/envs/pipeline_prod_venv/lib/python3.5/site-packages/aodntools/timeseries_products/hourly_timeseries.py", line 427, in hourly_aggregator
    df_temp = df_temp.reset_index().set_index('TIME')
  File "/mnt/ebs/pyenv/versions/3.5.2/envs/pipeline_prod_venv/lib/python3.5/site-packages/pandas/core/frame.py", line 4146, in set_index
    frame = self.copy()
  File "/mnt/ebs/pyenv/versions/3.5.2/envs/pipeline_prod_venv/lib/python3.5/site-packages/pandas/core/generic.py", line 5804, in copy
    data = self._data.copy(deep=deep)
  File "/mnt/ebs/pyenv/versions/3.5.2/envs/pipeline_prod_venv/lib/python3.5/site-packages/pandas/core/internals/managers.py", line 734, in copy
    do_integrity_check=False)
  File "/mnt/ebs/pyenv/versions/3.5.2/envs/pipeline_prod_venv/lib/python3.5/site-packages/pandas/core/internals/managers.py", line 395, in apply
    applied = getattr(b, f)(**kwargs)
  File "/mnt/ebs/pyenv/versions/3.5.2/envs/pipeline_prod_venv/lib/python3.5/site-packages/pandas/core/internals/blocks.py", line 753, in copy
    values = values.copy()
MemoryError: Unable to allocate 456. MiB for an array with shape (4, 14931864) and data type float64