balancer/leastrequest: Cache atomic load and also add concurrent rpc test #6602
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huangchong94
reviewed
Sep 1, 2023
| continue | ||
| } | ||
| if sc.numRPCs.Load() < pickedSC.numRPCs.Load() { | ||
| if sc.numRPCs.Load() < pickedSCNumRPCs { |
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Should sc.numRPCS.Load() be cached too? to save one more Load
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Oh good point. Switched.
dfawley
approved these changes
Sep 5, 2023
Comment on lines
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| scNumRPCs := sc.numRPCs.Load() | ||
| if scNumRPCs < pickedSCNumRPCs { |
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Optional: these can be merged into a compound if if desired. Or even simpler:
sc := p.subConns[index]
n := sc.numRPCs.Load()
if pickedSC == nil || n < pickedSCNumRPCs {
pickedSC = &sc
pickedSCNumRPCs = n
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Ah, beautiful suggestion :D. I tried breaking it but it works and is much cleaner. Thanks.
| wg.Add(1) | ||
| go func() { | ||
| defer wg.Done() | ||
| testServiceClient.EmptyCall(ctx, &testpb.Empty{}) |
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Should these do several calls each, maybe, to make concurrent pick calls more likely? Just make sure it doesn't run too long.
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Good point. Made each goroutine perform 5 calls.
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This PR caches the atomic load of the picked SubConn in the picker algorithm in least request picker for efficiency reasons, rather than doing it per iteration. It also adds an e2e test which performs concurrent RPCs to check for a race condition.
Continuation of #6587. Needs to be backported to 1.58 alongside that bug fix PR.
RELEASE NOTES: N/A