Update styleguide about thd_ prefix for secondary-thread functions. #1350
Conversation
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| It is very important in Twisted to be able to distinguish functions that runs in the main-thread and functions that don't, as reactors and deferreds can only be used in the main thread. | ||
| To make this distinction clearer, every functions meant to be started in a secondary thread should be prefixed with ``thd_``. |
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Fixed, thanks for the quick review ! |
Update styleguide about thd_ prefix for secondary-thread functions.
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I am curious about the reason of this distinction. Can you elaborate or point to a documentation telling why this distinction is so important? |
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@stibbons I think the core of it is in the new text itself: Twisted's reactor is intended to run in the main thread, and calling reactor methods in non-main threads causes weird and subtle bugs. Back in the 0.8.2 days, we had some functions that ran in threads but fired deferreds. The result was running callbacks for those deferreds in a thread other than the main thread, in parallel to other callbacks running in the main thread. Suddenly all of the data-safety you get from Twisted goes out the window, you get fun race conditions, corruption, and crashes. Does that help? |
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