changefeedccl: Make kvevent.Event memory efficient #87718
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This change has been validated on a 15 node cluster, running TPC-E workload. Prior to this change, starting the changefeed resulted
With this change, SQL throughput briefly drops from 22k to 12k, but then recovers to 21K; while the latency,
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@nvanbenschoten : FYI |
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Fixes cockroachdb#84709 `kvevent.Event` structure is very inefficient in its use of pointers. The number of pointers in the structure makes go GC processes more expensive, resulting in loss of performance in the cluster. This is particularly clear during the initial scan, when changefeeds rapidly allocate large number of events, which are then (rapidly) releases -- putting pressure on the go runtime GC. This PR replaces the use of multiple pointers with a single `*roachpb.RangeFeedEvent`. The direct use of `*roachpb.RangeFeedEvent` is beneficial since this is the (already allocated) event we receive from rangefeed RPC once changefeed completes the initial scan. Release justification: significant reduction of the changefeed impact on the foreground SQL latency. Release note (enterprise change): Changefeeds are more efficient during initial scan and backfill. The impact on runtime GC signficantly reduced, resulting in significant reduction of the changefeed impact on the foreground SQL latency.
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This was referenced Sep 13, 2022
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Fixes #84709
kvevent.Eventstructure is very inefficient in its use of pointers. The number of pointers in the structure makes go GC processes more expensive, resulting in loss of performance in the cluster.This is particularly clear during the initial scan, when changefeeds rapidly allocate large number of events, which are then (rapidly) releases -- putting pressure on the go runtime GC.
This PR replaces the use of multiple pointers with a single
*roachpb.RangeFeedEvent. The direct use of*roachpb.RangeFeedEventis beneficial since this is the (already allocated) event we receive from rangefeed RPC once changefeed completes the initial scan.Release justification: significant reduction of the changefeed impact on the foreground SQL latency.
Release note (enterprise change): Changefeeds are more efficient during initial scan and backfill. The impact on runtime GC signficantly reduced, resulting in significant reduction of the changefeed impact on the foreground SQL latency.