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！
{"minconf", RPCArg::Type::NUM,  "1", "The minimum number of confirmations before payments are included."},
                    {"include_empty", RPCArg::Type::BOOL,  "false", "Whether to include labels that haven't received any payments."},
                    {"include_watchonly", RPCArg::Type::BOOL,  "true for watch-only wallets, otherwise false", "Whether to include watch-only addresses (see 'importaddress')"},
                },
                RPCResult{
                    RPCResult::Type::ARR, "", "",
                    {
                        {RPCResult::Type::OBJ, "", "",
                        {
                            {RPCResult::Type::BOOL, "involvesWatchonly", "Only returns true if imported addresses were involved in transaction"},
                            {RPCResult::Type::STR_AMOUNT, "amount", "The total amount received by addresses with this label"},
                            {RPCResult::Type::NUM, "confirmations", "The number of confirmations of the most recent transaction included"},
                            {RPCResult::Type::STR, "label", "The label of the receiving address. The default label is \"\""},
                        }},
                    }
                },
                RPCExamples{
                    HelpExampleCli("listreceivedbylabel", "")
            + HelpExampleCli("listreceivedbylabel", "6 true")
            + HelpExampleRpc("listreceivedbylabel", "6, true, true")
                },
            }.Check(request);
    
    
    pwallet->BlockUntilSyncedToCurrentChain();
    auto locked_chain = pwallet->chain().lock();
    LOCK(pwallet->cs_wallet);
    return ListReceived(*locked_chain, pwallet, request.params, true);
}
static void MaybePushAddress(UniValue & entry, const CTxDestination &dest)