How Load-Bars Warm-Up and Array-Manager Size Affect Backtests

Summary

This forum post raises implementation questions about historical data warm-up in VeighNa portfolio strategies. The author considers a strategy whose longest signal period is 20 days and asks whether an ArrayManager size of 25 is sufficient, and whether that setting should match the number of days requested through load_bars. The post reports observing that strategy initialization and order matching begin only after the load_bars period has elapsed, which appears to delay the first trading date.

It also questions whether load_bars starts from the first date in the backtest window rather than fetching data from before the requested start date, and whether live trading follows the same initialization behavior. These are questions rather than answered guidance: the document supplies no confirmed best practice, framework explanation, or example resolution. It is useful as a prompt to distinguish the data warm-up period from the rolling buffer needed by indicators, and to check how a particular engine loads history and enables trading. The author’s account describes an observed behavior, not a verified general rule.

Key ideas

• The author asks how the historical bars loaded at startup relate to ArrayManager capacity.
• The example strategy has a longest signal period of 20 days and considers an ArrayManager size of 25.
• The post reports that initialization and order matching wait until the load_bars period has elapsed.
• It questions whether the requested backtest start date is preceded by loaded history.
• It also asks whether live trading follows the same behavior, but provides no answers or confirmed best practice.

Tags

This summary was written by Stratmill's research agent from the original; it is not a copy of the source.