.. currentmodule:: brian2

.. 03_standalone_joblib:

Example: 03_standalone_joblib
=============================


        .. only:: html

            .. |launchbinder| image:: http://mybinder.org/badge.svg
            .. _launchbinder: https://mybinder.org/v2/gh/brian-team/brian2-binder/master?filepath=examples/multiprocessing/03_standalone_joblib.ipynb

            .. note::
               You can launch an interactive, editable version of this
               example without installing any local files
               using the Binder service (although note that at some times this
               may be slow or fail to open): |launchbinder|_

        

This example use C++ standalone mode for the simulation and the
`joblib library <https://joblib.readthedocs.io>`_
to parallelize the code. See the previous example (``02_using_standalone.py``)
for more explanations.

::

    from joblib import Parallel, delayed
    from time import time as wall_time
    from brian2 import *
    import os
    
    
    def run_sim(tau):
        pid = os.getpid()
        directory = f"standalone{pid}"
        set_device('cpp_standalone', directory=directory)
        print(f'RUNNING {pid}')
    
        G = NeuronGroup(1, 'dv/dt = -v/tau : 1', method='euler')
        G.v = 1
    
        mon = StateMonitor(G, 'v', record=0)
        net = Network()
        net.add(G, mon)
        net.run(100 * ms)
        res = (mon.t/ms, mon.v[0])
    
        device.reinit()
    
        print(f'FINISHED {pid}')
        return res
    
    
    if __name__ == "__main__":
        start_time = wall_time()
        
        n_jobs = 4
        tau_values = np.arange(10)*ms + 5*ms
    
        results = Parallel(n_jobs=n_jobs)(map(delayed(run_sim), tau_values))
    
        print(f"Done in {wall_time() - start_time:10.3f}")
    
        for tau_value, (t, v) in zip(tau_values, results):
            plt.plot(t, v, label=str(tau_value))
        plt.legend()
        plt.show()
    

.. image:: ../resources/examples_images/multiprocessing.03_standalone_joblib.1.png