core/txpool: guard nil head subscription#33970
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apetro2 wants to merge 1 commit intoethereum:masterfrom
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core/txpool: guard nil head subscription#33970apetro2 wants to merge 1 commit intoethereum:masterfrom
apetro2 wants to merge 1 commit intoethereum:masterfrom
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txpool.loopassumedSubscribeChainHeadEventalways returns a valid subscription and unconditionally deferredUnsubscribe().That assumption is unsafe:
SubscriptionScope.Trackmay returnnilafter the blockchain scope is closed, andtxpool.loopstarts in a goroutine, so a shutdown race can hit this path.This PR adds a nil guard before deferring
Unsubscribe(). It keeps normal behavior unchanged and prevents a panic in the race window.A focused test (
TestTxPoolLoopNilHeadSubscription) was added to exercise the nil-subscription case, andgo test ./core/txpoolpasses (including repeated runs of the new test).