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！
}
            if (!FeeModeFromString(options["estimate_mode"].get_str(), coinControl.m_fee_mode)) {
                throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid estimate_mode parameter");
            }
        }
      }
    } else {
        
        coinControl.fAllowWatchOnly = ParseIncludeWatchonly(NullUniValue, *pwallet);
    }
    if (tx.vout.size() == 0)
        throw JSONRPCError(RPC_INVALID_PARAMETER, "TX must have at least one output");
    if (change_position != -1 && (change_position < 0 || (unsigned int)change_position > tx.vout.size()))
        throw JSONRPCError(RPC_INVALID_PARAMETER, "changePosition out of bounds");
    for (unsigned int idx = 0; idx < subtractFeeFromOutputs.size(); idx++) {
        int pos = subtractFeeFromOutputs[idx].get_int();
        if (setSubtractFeeFromOutputs.count(pos))
            throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("Invalid parameter, duplicated position: %d", pos));
        if (pos < 0)
            throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("Invalid parameter, negative position: %d", pos));
        if (pos >= int(tx.vout.size()))
            throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("Invalid parameter, position too large: %d", pos));
        setSubtractFeeFromOutputs.insert(pos);
    }
    std::string strFailReason;
    if (!pwallet->FundTransaction(tx, fee_out, change_position, strFailReason, lockUnspents, setSubtractFeeFromOutputs, coinControl)) {
        throw JSONRPCError(RPC_WALLET_ERROR, strFailReason);
    }
}
static UniValue fundrawtransaction(const JSONRPCRequest& request)