When we retry after a 429, we get another 429.
I suspect a round-down issue.
In our scenario:
we do requests, and eventually get a 429 Too Many Request with Retry-After: 19
we wait 19 seconds, then try again:429 again, with Retry-After: 0
Now, can it be the actual values were 19.4 and 0.4 for example and they were rounded down for the Retry-After in the headers?
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Probably, should be an easy fix. Another starter task @erlend_sh ?
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dinomite
2018 年11 月 28 日 16:10
3
I’m not entirely sure where this is happening, but I suspect it has to do with use of Lua’s tonumber() in rate_limiter.rb —quoth Redis’ EVAL documentation :
Lua has a single numerical type, Lua numbers. There is no distinction between integers and floats. So we always convert Lua numbers into integer replies, removing the decimal part of the number if any.
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andrei
2021 年1 月 12 日 16:52
5
事实证明，问题并不出在 Lua 脚本的舍入上。Lua 脚本接收到的已经是舍入后的值。
此外，这根本不是舍入问题。即使使用未舍入的秒数，仍然有可能收到带有 Retry-After: 0 的 429 响应。
以下是针对主要问题的修复方案：
master ← AndrewPrigorshnev:fix/sliding-window-end-time-in-rate-limiter
merged 06:26PM - 12 Jan 21 UTC
If the sliding window size is N seconds, then a moment at the Nth second should … be considered as the moment outside of the sliding window.
Otherwise, if the sliding window is already full, at the Nth second, a new call wouldn't be allowed, but a time to wait before the next call would be equal to zero, which is confusing.
In other words, the end of the time range shouldn't be included in the sliding window. Let's say we start at the second 0, and the sliding window size is 10 seconds. In the current version of Rate Limiter, this sliding window will be considered as a time range `[0, 10]` (including the end of the range), which actually is 11 seconds in length.
After this fix, the time range will be considered as `[0, 10)` (excluding the end of the range), which is exactly 10 seconds in length.
以下是针对偶尔会导致相同错误的额外问题的修复方案：
master ← AndrewPrigorshnev:fix/use-the-same-time-moment-in-redis-calls
merged 08:09PM - 12 Jan 21 UTC
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