Report waiting time only for currently waiting clients #678
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drdrsh
changed the title
drdrsh
commented
Jan 18, 2024
src/stats/client.rs
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| @@ -41,6 +41,11 @@ pub struct ClientStats { | |||
| /// Maximum time spent waiting for a connection from pool, measures in microseconds | |||
| pub max_wait_time: Arc<AtomicU64>, | |||
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| // Time when the client started waiting for a connection from pool, measures in microseconds | |||
| // We use connect_time as the reference point for this value | |||
| // U64 can represent ~60 centuries in microseconds, so we should be fine | |||
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This is more like 5850 centuries, I got my math wrong.
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The pool
maxwaitmetric currently operates differently from Pgbouncer.The way it operates today is that we keep track of max_wait on each connected client, when
SHOW POOLSquery is made, we go over the connected clients and we get the max of max_wait times among clients. This means the pool maxwait will never reset, it will always be monotonically increasing until the client with the highestmaxwaitdisconnects.This PR changes this behavior, by keeping track of the wait_start time on each client, when a client goes into
WAITINGstate, we record the time offset fromconnect_time. When we either successfully or unsuccessfully checkout a connection from the pool, we reset the wait_start time.When
SHOW POOLSquery is made, we go over all connected clients and we only consider clients whosewait_startis non-zero, for clients that have non-zero wait times, we compare them and report the maximum waiting time asmaxwaitfor the pool.