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！
"\"generate\"              Coinbase transactions received with more than 100 confirmations.\n"
                                "\"immature\"              Coinbase transactions received with 100 or fewer confirmations.\n"
                                "\"orphan\"                Orphaned coinbase transactions received."},
                            {RPCResult::Type::STR_AMOUNT, "amount", "The amount in " + CURRENCY_UNIT + ". This is negative for the 'send' category, and is positive\n"
                                "for all other categories"},
                            {RPCResult::Type::STR, "label", "A comment for the address/transaction, if any"},
                            {RPCResult::Type::NUM, "vout", "the vout value"},
                            {RPCResult::Type::STR_AMOUNT, "fee", "The amount of the fee in " + CURRENCY_UNIT + ". This is negative and only available for the\n"
                                 "'send' category of transactions."},
                        },
                        TransactionDescriptionString()),
                        {
                            {RPCResult::Type::BOOL, "abandoned", "'true' if the transaction has been abandoned (inputs are respendable). Only available for the \n"
                                 "'send' category of transactions."},
                        })},
                    }
                },
                RPCExamples{
            "\nList the most recent 10 transactions in the systems\n"
            + HelpExampleCli("listtransactions", "") +
            "\nList transactions 100 to 120\n"
            + HelpExampleCli("listtransactions", "\"*\" 20 100") +
            "\nAs a JSON-RPC call\n"
            + HelpExampleRpc("listtransactions", "\"*\", 20, 100")
                },
            }.Check(request);
    
    
    pwallet->BlockUntilSyncedToCurrentChain();
    const std::string* filter_label = nullptr;