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！
},
                RPCResult{
                    RPCResult::Type::OBJ, "", "",
                    {
                        {RPCResult::Type::ARR, "transactions", "",
                        {
                            {RPCResult::Type::OBJ, "", "", Cat(Cat<std::vector<RPCResult>>(
                            {
                                {RPCResult::Type::BOOL, "involvesWatchonly", "Only returns true if imported addresses were involved in transaction."},
                                {RPCResult::Type::STR, "address", "The bitcoin address of the transaction."},
                                {RPCResult::Type::STR, "category", "The transaction category.\n"
                                    "\"send\"                  Transactions sent.\n"
                                    "\"receive\"               Non-coinbase transactions received.\n"
                                    "\"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::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."},
                                {RPCResult::Type::STR, "label", "A comment for the address/transaction, if any"},
                                {RPCResult::Type::STR, "to", "If a comment to is associated with the transaction."},
                            })},
                        }},