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！
RPCResult::Type::OBJ, "", "",
                    {
                        {RPCResult::Type::STR_HEX, "hex", "The resulting raw transaction (hex-encoded string)"},
                        {RPCResult::Type::STR_AMOUNT, "fee", "Fee in " + CURRENCY_UNIT + " the resulting transaction pays"},
                        {RPCResult::Type::NUM, "changepos", "The position of the added change output, or -1"},
                    }
                                },
                                RPCExamples{
                            "\nCreate a transaction with no inputs\n"
                            + HelpExampleCli("createrawtransaction", "\"[]\" \"{\\\"myaddress\\\":0.01}\"") +
                            "\nAdd sufficient unsigned inputs to meet the output value\n"
                            + HelpExampleCli("fundrawtransaction", "\"rawtransactionhex\"") +
                            "\nSign the transaction\n"
                            + HelpExampleCli("signrawtransactionwithwallet", "\"fundedtransactionhex\"") +
                            "\nSend the transaction\n"
                            + HelpExampleCli("sendrawtransaction", "\"signedtransactionhex\"")
                                },
    }.Check(request);
    RPCTypeCheck(request.params, {UniValue::VSTR, UniValueType(), UniValue::VBOOL});
    
    CMutableTransaction tx;
    bool try_witness = request.params[2].isNull() ? true : request.params[2].get_bool();
    bool try_no_witness = request.params[2].isNull() ? true : !request.params[2].get_bool();
    if (!DecodeHexTx(tx, request.params[0].get_str(), try_no_witness, try_witness)) {
        throw JSONRPCError(RPC_DESERIALIZATION_ERROR, "TX decode failed");
    }
    CAmount fee;
    int change_position;
    FundTransaction(pwallet, tx, fee, change_position, request.params[1]);
    UniValue result(UniValue::VOBJ);