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Quickstart - cerebro.optstrategy() no result (3.7 Windows)

  • Hi, I'm new to python and to backtrader. Trying out the quickstart tutorial, everything worked fine, until the optimizer topic, the program does not execute bt.Strategy methods, I put some print values and it seens like the init or stop funcions doesn't execute.

    If I change the code to run once, just with cerebro.addstrategy(TestStrategy) it works fine.

    When I execute the code, It only prints "calling run()"

    from __future__ import (absolute_import, division, print_function,
    import datetime  # For datetime objects
    import os.path  # To manage paths
    import sys  # To find out the script name (in argv[0])
    # Import the backtrader platform
    import backtrader as bt
    # Create a Stratey
    class TestStrategy(bt.Strategy):
        params = (
            ('maperiod', 10),
            ('printlog', True),
        def log(self, txt, dt=None, doprint=True):
            ''' Logging function fot this strategy'''
            if self.params.printlog or doprint:
                dt = dt or self.datas[0]
                print('%s, %s' % (dt.isoformat(), txt))
        def __init__(self):
            print('init start')
            # Keep a reference to the "close" line in the data[0] dataseries
            self.dataclose = self.datas[0].close
            # To keep track of pending orders and buy price/commission
            self.order = None
            self.buyprice = None
            self.buycomm = None
            # Add a MovingAverageSimple indicator
            self.sma = bt.indicators.SimpleMovingAverage(
                self.datas[0], period=self.params.maperiod)
            print('init end')        
        def notify_order(self, order):
            if order.status in [order.Submitted, order.Accepted]:
                # Buy/Sell order submitted/accepted to/by broker - Nothing to do
            # Check if an order has been completed
            # Attention: broker could reject order if not enough cash
            if order.status in [order.Completed]:
                if order.isbuy():
                        'BUY EXECUTED, Price: %.2f, Cost: %.2f, Comm %.2f' %
                    self.buyprice = order.executed.price
                    self.buycomm = order.executed.comm
                else:  # Sell
                    self.log('SELL EXECUTED, Price: %.2f, Cost: %.2f, Comm %.2f' %
                self.bar_executed = len(self)
            elif order.status in [order.Canceled, order.Margin, order.Rejected]:
                self.log('Order Canceled/Margin/Rejected')
            # Write down: no pending order
            self.order = None
        def notify_trade(self, trade):
            if not trade.isclosed:
            self.log('OPERATION PROFIT, GROSS %.2f, NET %.2f' %
                     (trade.pnl, trade.pnlcomm))
        def next(self):
            # Simply log the closing price of the series from the reference
            self.log('Close, %.2f' % self.dataclose[0])
            # Check if an order is pending ... if yes, we cannot send a 2nd one
            if self.order:
            # Check if we are in the market
            if not self.position:
                # Not yet ... we MIGHT BUY if ...
                if self.dataclose[0] > self.sma[0]:
                    # BUY, BUY, BUY!!! (with all possible default parameters)
                    self.log('BUY CREATE, %.2f' % self.dataclose[0])
                    # Keep track of the created order to avoid a 2nd order
                    self.order =
                if self.dataclose[0] < self.sma[0]:
                    # SELL, SELL, SELL!!! (with all possible default parameters)
                    self.log('SELL CREATE, %.2f' % self.dataclose[0])
                    # Keep track of the created order to avoid a 2nd order
                    self.order = self.sell()
        def stop(self):
            self.log('(MA Period %2d) Ending Value %.2f' %
                     (self.params.maperiod,, doprint=True)
    if __name__ == '__main__':
        # Create a cerebro entity
        cerebro = bt.Cerebro()
        # Datas are in a subfolder of the samples. Need to find where the script is
        # because it could have been called from anywhere
        modpath = os.path.dirname(os.path.abspath(sys.argv[0]))
        datapath = 'C:\spy.CSV'
        # Create a Data Feed
        data = bt.feeds.YahooFinanceCSVData(
            # Do not pass values before this date
            fromdate=datetime.datetime(2000, 1, 1),
            # Do not pass values before this date
            todate=datetime.datetime(2020, 12, 31),
            # Do not pass values after this date
        # Add the Data Feed to Cerebro
        # Set our desired cash start
        # Add a FixedSize sizer according to the stake
        cerebro.addsizer(bt.sizers.FixedSize, stake=2)
        # Set the commission
        # Add a strategy
        strats = cerebro.optstrategy(
            maperiod=range(10, 15))    
        print('calling run()')
        # Run over everything

  • administrators

    Don't take this personally. It's clear you are new, else you wouldn't miss this at the top of each page in the community.

    For code/output blocks: Use ``` (aka backtick or grave accent) in a single line before and after the block. See:

    which has the effect of making your code readable.

    On the positive side you have let us know that you are running under Windows whilst playing with optimization. Further details would have cleared the situation, but the most obvious thing:

    • As a newbie you have been sold the benefits of using Jupyter or Spyder or something similar.

    Those shells hijack the Python core and eventually destroy the multiprocessing facilities of Python under Windows.

    See this for example:

    No, there is nothing which can be done, except that you use a proper shell for executing the scripts.

  • oh thanks!

    I didn't understood how to use the backtick, sorry, bad english. It's ok now

    I'll search for something to use multiprocessing on windows, I've never used Python, so just installed windows version and followed the tutorial.

    Thanks again!

  • I was using IDLE and running the script with F5

    It works OK when executed from the command line.

    As a suggestion, you could add a warning on the quickstart tutorial, just saying that the optimization uses multiprocessing.

    Thanks again!

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