Track used database conns with an histogram #3829
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r? @smarnach (rust-highfive has picked a reviewer for you, use r? to override) |
The histogram should allow us to determine more accurately how many connections are used, as the older approach of taking a sample whenever metrics are scraped does not work well.
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| time_to_obtain_connection_metric, | ||
| } => time_to_obtain_connection_metric.observe_closure_duration(|| { | ||
| // Record the number of used connections before obtaining the current one. | ||
| let state = pool.state(); |
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I assume accessing pool.state() is an inexpensive operation?
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This just requires obtaining a mutex lock, so shouldn't be expensive.
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requires obtaining a mutex lock
sounds pretty expensive to me 😅
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LGTM too! @bors r=Turbo87 |
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…ietroalbini Revert "Track used database conns with an histogram" Reverts #3829 This has been causing issues in production: 
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While looking at the metrics, me and @jtgeibel noticed that the way we tracked used database connections before (sampling the current state every time metrics are scraped) is not really accurate, as the connections could be all used up until the scrape happens. This PR adds another metric recording the used database connections with an histogram.
This PR also refactors how histograms are defined in the source code, to account for different histograms needing different buckets.