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！
"                         so the new transaction will not be explicitly bip-125 replaceable (though it may\n"
            "                         still be replaceable in practice, for example if it has unconfirmed ancestors which\n"
            "                         are replaceable)."},
                            {"estimate_mode", RPCArg::Type::STR,  "UNSET", "The fee estimate mode, must be one of:\n"
            "         \"UNSET\"\n"
            "         \"ECONOMICAL\"\n"
            "         \"CONSERVATIVE\""},
                        },
                        "options"},
                },
                RPCResult{
                    RPCResult::Type::OBJ, "", "", {
                        {RPCResult::Type::STR, "psbt", "The base64-encoded unsigned PSBT of the new transaction. Only returned when wallet private keys are disabled."},
                        {RPCResult::Type::STR_HEX, "txid", "The id of the new transaction. Only returned when wallet private keys are enabled."},
                        {RPCResult::Type::STR_AMOUNT, "origfee", "The fee of the replaced transaction."},
                        {RPCResult::Type::STR_AMOUNT, "fee", "The fee of the new transaction."},
                        {RPCResult::Type::ARR, "errors", "Errors encountered during processing (may be empty).",
                        {
                            {RPCResult::Type::STR, "", ""},
                        }},
                    }
                },
                RPCExamples{
            "\nBump the fee, get the new transaction\'s txid\n" +
                    HelpExampleCli("bumpfee", "<txid>")
                },
            }.Check(request);
    RPCTypeCheck(request.params, {UniValue::VSTR, UniValue::VOBJ});
    uint256 hash(ParseHashV(request.params[0], "txid"));
    CCoinControl coin_control;