.. DO NOT EDIT.
.. THIS FILE WAS AUTOMATICALLY GENERATED BY SPHINX-GALLERY.
.. TO MAKE CHANGES, EDIT THE SOURCE PYTHON FILE:
.. "gallery/example_long_multiprocessing.py"
.. LINE NUMBERS ARE GIVEN BELOW.

.. only:: html

    .. note::
        :class: sphx-glr-download-link-note

        :ref:`Go to the end <sphx_glr_download_gallery_example_long_multiprocessing.py>`
        to download the full example code.

.. rst-class:: sphx-glr-example-title

.. _sphx_glr_gallery_example_long_multiprocessing.py:


Multiprocessing - Parallel execution of multiple OpenDrift instances in distinct CPUs
======================================================================================

.. GENERATED FROM PYTHON SOURCE LINES 6-64

.. code-block:: Python


    from datetime import datetime
    import numpy as np
    import xarray as xr
    from opendrift.readers import reader_netCDF_CF_generic
    from opendrift.models.oceandrift import OceanDrift
    from multiprocessing import Pool
    import glob
    import opendrift

    def concatenate_outputs(input_files, output_file):
        """
        Concatenate OpenDrift NetCDF outputs from multiple workers into one single output file.

        """

        ds_list = []
        trajectory_offset = 0
        for f in input_files:
                dsi = xr.open_dataset(f)
                traj_vars = [var for var in list(dsi.variables) if "trajectory" in dsi[var].dims]
                ds_traj = dsi[traj_vars]
                ds_traj = ds_traj.assign_coords(trajectory=ds_traj.trajectory + trajectory_offset)

                trajectory_offset += ds_traj.dims["trajectory"]
                ds_list.append(ds_traj)

        ds_conc = xr.concat(ds_list, dim="trajectory")
        ds_conc.to_netcdf(output_file)

        return ds_conc

    def RunOceanDrift(pool_number):
        """
        Configure and run one OpenDrift instance

        """

        o = OceanDrift(loglevel=0, logfile="output_W"+str(pool_number)+".log", seed=0)

        reader_topaz4 = reader_netCDF_CF_generic.Reader("https://thredds.met.no/thredds/dodsC/topaz/dataset-topaz4-arc-myoceanv2-be")
        o.add_reader(reader_topaz4, variables=['x_sea_water_velocity', 'y_sea_water_velocity','sea_water_temperature','sea_water_salinity','sea_floor_depth_below_sea_level'])

        o.set_config('drift:horizontal_diffusivity', 50)

        time = datetime(2023,1,1)

        ntraj=500
        iniz=np.random.rand(ntraj) * -10. # seeding the chemicals in the upper 10m

        o.seed_elements(lat=positions[pool_number][0], lon=positions[pool_number][1], z=iniz, radius=2000, number=ntraj, time=time, origin_marker=np.ones(ntraj)*(pool_number))

        o.run(steps=7*4, time_step=3600*6, time_step_output=3600*6, outfile = "output_W"+str(pool_number)+".nc")


    positions=[(58.5,3),(58.2, 2.5),(58,1),(57.8,1.2),(57,1),(56.8,1.8),(56.5,2),(56,2.2)]
    pool_size=len(positions)


.. GENERATED FROM PYTHON SOURCE LINES 65-71

.. code-block:: Python

    with Pool(pool_size) as p:
        p.starmap(RunOceanDrift, [(i,) for i in range(pool_size)])

    concatenate_outputs(input_files=glob.glob("output_W*.nc"), output_file="output_total.nc")



.. GENERATED FROM PYTHON SOURCE LINES 72-75

.. code-block:: Python


    o0 = opendrift.open("output_W0.nc")


.. GENERATED FROM PYTHON SOURCE LINES 76-77

.. image:: /gallery/animations/example_multiprocessing_0.gif

.. GENERATED FROM PYTHON SOURCE LINES 77-87

.. code-block:: Python


    o0.animation(color='origin_marker',
                markersize=3,
                vmin=0,vmax=pool_size-1,
                colorbar=False,
                fast = True,
                lscale = 'l')

    o = opendrift.open("output_total.nc")


.. GENERATED FROM PYTHON SOURCE LINES 88-89

.. image:: /gallery/animations/example_multiprocessing_1.gif

.. GENERATED FROM PYTHON SOURCE LINES 89-96

.. code-block:: Python


    o.animation(color='origin_marker',
                markersize=3,
                vmin=0,vmax=pool_size-1,
                colorbar=False,
                fast = True,
                lscale = 'l')


.. _sphx_glr_download_gallery_example_long_multiprocessing.py:

.. only:: html

  .. container:: sphx-glr-footer sphx-glr-footer-example

    .. container:: sphx-glr-download sphx-glr-download-jupyter

      :download:`Download Jupyter notebook: example_long_multiprocessing.ipynb <example_long_multiprocessing.ipynb>`

    .. container:: sphx-glr-download sphx-glr-download-python

      :download:`Download Python source code: example_long_multiprocessing.py <example_long_multiprocessing.py>`

    .. container:: sphx-glr-download sphx-glr-download-zip

      :download:`Download zipped: example_long_multiprocessing.zip <example_long_multiprocessing.zip>`


.. only:: html

 .. rst-class:: sphx-glr-signature

    `Gallery generated by Sphinx-Gallery <https://sphinx-gallery.github.io>`_