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！
}},
            }
            },
        RPCExamples{
            HelpExampleCli("getbalances", "") +
            HelpExampleRpc("getbalances", "")},
    }.Check(request);
    
    
    wallet.BlockUntilSyncedToCurrentChain();
    auto locked_chain = wallet.chain().lock();
    LOCK(wallet.cs_wallet);
    const auto bal = wallet.GetBalance();
    UniValue balances{UniValue::VOBJ};
    {
        UniValue balances_mine{UniValue::VOBJ};
        balances_mine.pushKV("trusted", ValueFromAmount(bal.m_mine_trusted));
        balances_mine.pushKV("untrusted_pending", ValueFromAmount(bal.m_mine_untrusted_pending));
        balances_mine.pushKV("immature", ValueFromAmount(bal.m_mine_immature));
        if (wallet.IsWalletFlagSet(WALLET_FLAG_AVOID_REUSE)) {
            
            
            const auto full_bal = wallet.GetBalance(0, false);
            balances_mine.pushKV("used", ValueFromAmount(full_bal.m_mine_trusted + full_bal.m_mine_untrusted_pending - bal.m_mine_trusted - bal.m_mine_untrusted_pending));
        }
        balances.pushKV("mine", balances_mine);
    }
    auto spk_man = wallet.GetLegacyScriptPubKeyMan();
    if (spk_man && spk_man->HaveWatchOnly()) {
        UniValue balances_watchonly{UniValue::VOBJ};