~CCheckQueue assertion failure during unclean exits #25448

For testing, I am using this:

--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -2102,6 +2102,7 @@ OutputType CWallet::TransactionChangeType(const std::optional<OutputType>& chang
 void CWallet::CommitTransaction(CTransactionRef tx, mapValue_t mapValue, std::vector<std::pair<std::string, std::string>> orderForm)
 {
     LOCK(cs_wallet);
+    throw std::runtime_error(std::string(__func__) + ": Wallet db error, transaction commit failed");
     WalletLogPrintf("CommitTransaction:\n%s", tx->ToString()); /* Continued */
 
     // Add tx to wallet, because if it has change it's also ours,

To trigger it, you have to attempt to send a transaction.

This correctly displays an error dialog, then exits with:

************************
EXCEPTION: St13runtime_error       
CommitTransaction: Wallet db error, transaction commit failed       
bitcoin in QPushButton->SendCoinsDialog       

bitcoin-qt: ./checkqueue.h:204: CCheckQueue<CScriptCheck>::~CCheckQueue() [T = CScriptCheck]: Assertion `m_worker_threads.empty()' failed.
Aborted

This issue is related to the failed assertion during the unclean exit.

(Previously seen in #24953, and "fixed" by avoiding the unclean exit in that one scenario)

Yeah, this is a very old problem. It's not safe to destruct the queue while there's stil a thread running. Maybe it could wait instead of assert.

https://github.com/bitcoin/bitcoin/pull/18731

#18731

It is #26762 now :)