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("getaddressesbylabel", "\"tabby\"")
            + HelpExampleRpc("getaddressesbylabel", "\"tabby\"")
                },
            }.Check(request);
    LOCK(pwallet->cs_wallet);
    std::string label = LabelFromValue(request.params[0]);
    
    UniValue ret(UniValue::VOBJ);
    std::set<std::string> addresses;
    for (const std::pair<const CTxDestination, CAddressBookData>& item : pwallet->mapAddressBook) {
        if (item.second.name == label) {
            std::string address = EncodeDestination(item.first);
            
            
            
            bool unique = addresses.emplace(address).second;
            CHECK_NONFATAL(unique);
            
            
            
            
            ret.__pushKV(address, AddressBookDataToJSON(item.second, false));
        }
    }
    if (ret.empty()) {
        throw JSONRPCError(RPC_WALLET_INVALID_LABEL_NAME, std::string("No addresses with label " + label));
    }
    return ret;
}
static UniValue listlabels(const JSONRPCRequest& request)