When i used the encrypted wallet to test transfer parallelly,i frequently got the trouble: The rpc server is not responding.My test script is like below:
#!/bin/sh
while [ 1 ]
do
./bitcoin-cli listaddressgroupings>null
./bitcoin-cli walletpassphrase "!@#$%^&*" 2
./bitcoin sendtoaddress "mhAW6mzs5DeCbzBUHXBi4U446Fdnr1z8U7" 0.01
done

When i open the dead lock trace macro and check the debug log,i found the last print is as below:
2018-12-17 08:27:58 ThreadRPCServer method=walletpassphrase
2018-12-17 08:27:58 LOCKCONTENTION: cs_main
2018-12-17 08:27:58 Locker: wallet/rpcwallet.cpp:2642
2018-12-17 08:27:58 LOCKCONTENTION: pWallet->cs_wallet
2018-12-17 08:27:58 Locker: wallet/rpcwallet.cpp:2607

The line no 2642 is walletpassphrase and 2607 is LockWallet. I checked the code,i found there is no log printed for this line in function "walletpassphrase":
"LogPrint(BCLog::RPC, "queue run of timer %s in %i seconds (using %s)\n", name, nSeconds, timerInterface->Name());" So i guess the reason may be:
When "walletpassphrase" is running and lock the cs_wallet,the last relock timer triggered and call "LockWallet"."LockWallet" want to lock the cs_wallet but it has been locked by "walletpassphrase",so "LockWallet" is blocked.When "walletpassphrase" run to call "RPCRunLater",the function will erase the timer from the std::map "deadlineTimers",but the timer's timeout call is blocked,so the dead lock take place.
Is my guess right?
How to reslove the issue?
Any help will be appreciative！
{
    std::shared_ptr<CWallet> const wallet = GetWalletForJSONRPCRequest(request);
    CWallet* const pwallet = wallet.get();
    if (!EnsureWalletIsAvailable(pwallet, request.fHelp))
        return NullUniValue;
            RPCHelpMan{"bumpfee",
                "\nBumps the fee of an opt-in-RBF transaction T, replacing it with a new transaction B.\n"
                "An opt-in RBF transaction with the given txid must be in the wallet.\n"
                "The command will pay the additional fee by reducing change outputs or adding inputs when necessary. It may add a new change output if one does not already exist.\n"
                "All inputs in the original transaction will be included in the replacement transaction.\n"
                "The command will fail if the wallet or mempool contains a transaction that spends one of T's outputs.\n"
                "By default, the new fee will be calculated automatically using estimatesmartfee.\n"
                "The user can specify a confirmation target for estimatesmartfee.\n"
                "Alternatively, the user can specify a fee_rate (" + CURRENCY_UNIT + " per kB) for the new transaction.\n"
                "At a minimum, the new fee rate must be high enough to pay an additional new relay fee (incrementalfee\n"
                "returned by getnetworkinfo) to enter the node's mempool.\n",
                {
                    {"txid", RPCArg::Type::STR_HEX, RPCArg::Optional::NO, "The txid to be bumped"},
                    {"options", RPCArg::Type::OBJ, RPCArg::Optional::OMITTED_NAMED_ARG, "",
                        {
                            {"confTarget", RPCArg::Type::NUM,  "wallet default", "Confirmation target (in blocks)"},
                            {"fee_rate", RPCArg::Type::NUM,  "fall back to 'confTarget'", "fee rate (NOT total fee) to pay, in " + CURRENCY_UNIT + " per kB\n"
            "                         Specify a fee rate instead of relying on the built-in fee estimator.\n"
                                     "Must be at least 0.0001 " + CURRENCY_UNIT + " per kB higher than the current transaction fee rate.\n"},
                            {"replaceable", RPCArg::Type::BOOL,  "true", "Whether the new transaction should still be\n"
            "                         marked bip-125 replaceable. If true, the sequence numbers in the transaction will\n"
            "                         be left unchanged from the original. If false, any input sequence numbers in the\n"
            "                         original transaction that were less than 0xfffffffe will be increased to 0xfffffffe\n"