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！
return result;
}
static UniValue listwallets(const JSONRPCRequest& request)
{
            RPCHelpMan{"listwallets",
                "Returns a list of currently loaded wallets.\n"
                "For full information on the wallet, use \"getwalletinfo\"\n",
                {},
                RPCResult{
                    RPCResult::Type::ARR, "", "",
                    {
                        {RPCResult::Type::STR, "walletname", "the wallet name"},
                    }
                },
                RPCExamples{
                    HelpExampleCli("listwallets", "")
            + HelpExampleRpc("listwallets", "")
                },
            }.Check(request);
    UniValue obj(UniValue::VARR);
    for (const std::shared_ptr<CWallet>& wallet : GetWallets()) {
        if (!EnsureWalletIsAvailable(wallet.get(), request.fHelp)) {
            return NullUniValue;
        }
        LOCK(wallet->cs_wallet);
        obj.push_back(wallet->GetName());
    }
    return obj;
}
static UniValue loadwallet(const JSONRPCRequest& request)