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grpc/load_balancing: Sticky TF for pick_first - #3028
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nathanielford wants to merge 1 commit into
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Motivation
Once
pick_firstreportsTRANSIENT_FAILURE, it should keep reporting it until a subchannel becomes READY (stickyTRANSIENT_FAILURE, gRFC A62). Instead, when a new address list starts a connection attempt, pick_first reportsCONNECTING. RPCs that were failing fast start queueing instead, and the channel can switch back and forth between the two states.Solution
When a connection attempt starts while pick_first is reporting
TRANSIENT_FAILURE, keep reportingTRANSIENT_FAILUREinstead ofCONNECTING. The attempt still starts immediately.Test:
test_pick_first_resolver_update_in_transient_failure_starts_connecting_immediately. After a resolver error puts the policy inTRANSIENT_FAILURE, a valid address list starts connecting at once without reportingCONNECTING, and the policy reportsREADYonce a subchannel connects. The test fails without the fix.Notes
Resolved on #2784.