Add thread safety to ActiveFile #229
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dmitriy-kiriyenko
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ActiveFile is not thread-safe, which results in the following: if the very first request to ActiveFile goes simultaneously from even two threads, the first one is going to return as if the data was empty. The second request will immediately fix that, but that unlucky thread will receive a bad value. It may store it in the database or memoize it, which will result in further problem escalation. We can't just synchronize it, because we check the variable very far from reload. While we must synchronize, it's not enough. We have to flag it as 'done' only after it's loaded. Another problem is that we touch `all` in process of reloading, which will check `data_loaded` flag and try to reload again. To counter that, I come out with a method that won't trigger reload, to use it in methods that work during reload.
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@zilkey any chance? |
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@zilkey If you have the time, Please see a bit little 🙏 |
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Thanks @dmitriy-kiriyenko I tested locally and confirmed this definitely fixes the issue @DRMNick saw in #159 |
adampal
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Jul 20, 2022
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ActiveFile is not thread-safe, which results in the following: if the very first request to ActiveFile goes simultaneously from even two threads, the first one is going to return as if the data was empty. The second request will immediately fix that, but that unlucky thread will receive a bad value. It may store it in the database or memoize it, which will result in further problem escalation.
We can't just synchronise it, because we check the variable very far from reload. While we must synchronise, it's not enough. We have to flag it as 'done' only after it's loaded.
Another problem is that we touch
allin process of reloading, which will checkdata_loadedflag and try to reload again. To counter that, I come out with a method that won't trigger reload, to use it in methods that work during reload.Resolves #159.