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！
HelpExampleCli("setwalletflag", "avoid_reuse")
                  + HelpExampleRpc("setwalletflag", "\"avoid_reuse\"")
                },
            }.Check(request);
    std::string flag_str = request.params[0].get_str();
    bool value = request.params[1].isNull() || request.params[1].get_bool();
    if (!WALLET_FLAG_MAP.count(flag_str)) {
        throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("Unknown wallet flag: %s", flag_str));
    }
    auto flag = WALLET_FLAG_MAP.at(flag_str);
    if (!(flag & MUTABLE_WALLET_FLAGS)) {
        throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("Wallet flag is immutable: %s", flag_str));
    }
    UniValue res(UniValue::VOBJ);
    if (pwallet->IsWalletFlagSet(flag) == value) {
        throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("Wallet flag is already set to %s: %s", value ? "true" : "false", flag_str));
    }
    res.pushKV("flag_name", flag_str);
    res.pushKV("flag_state", value);
    if (value) {
        pwallet->SetWalletFlag(flag);
    } else {
        pwallet->UnsetWalletFlag(flag);
    }
    if (flag && value && WALLET_FLAG_CAVEATS.count(flag)) {
        res.pushKV("warnings", WALLET_FLAG_CAVEATS.at(flag));
    }
    return res;
}
static UniValue createwallet(const JSONRPCRequest& request)