Oximeter: jitter collection intervals.#10711
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As of this writing, the oximeter collector's database batcher can queue at most 100_000 samples. In realistic conditions, it can receive about 80_000 metrics at once: each mgs producer sends about 40_000 metrics per collection on a full rack, and with the two mgs producers sampled with the same interval and offset, we receive all their collected metrics at roughly the same time. As a result, even when overall metrics volume isn't particularly high, we can drop samples when too many arrive at once. To mitigate thundering herds of samples, this patch introduces a jittered offset to each collection task timer, offsetting by 0..interval. This doesn't save us from having to size the collector queue properly, but spreads out load over time on average. Part of #10552.
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As of this writing, the oximeter collector's database batcher can queue at most 100_000 samples. In realistic conditions, it can receive about 80_000 metrics at once: each mgs producer sends about 40_000 metrics per collection on a full rack, and with the two mgs producers sampled with the same interval and offset, we receive all their collected metrics at roughly the same time. As a result, even when overall metrics volume isn't particularly high, we can drop samples when too many arrive at once.
To mitigate thundering herds of samples, this patch introduces a jittered offset to each collection task timer, offsetting by 0..interval. This doesn't save us from having to size the collector queue properly, but spreads out load over time on average.
Part of #10552.