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！
},
            }.Check(request);
    WalletRescanReserver reserver(pwallet);
    if (!reserver.reserve()) {
        throw JSONRPCError(RPC_WALLET_ERROR, "Wallet is currently rescanning. Abort existing rescan or wait.");
    }
    int start_height = 0;
    uint256 start_block, stop_block;
    {
        auto locked_chain = pwallet->chain().lock();
        Optional<int> tip_height = locked_chain->getHeight();
        if (!request.params[0].isNull()) {
            start_height = request.params[0].get_int();
            if (start_height < 0 || !tip_height || start_height > *tip_height) {
                throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid start_height");
            }
        }
        Optional<int> stop_height;
        if (!request.params[1].isNull()) {
            stop_height = request.params[1].get_int();
            if (*stop_height < 0 || !tip_height || *stop_height > *tip_height) {
                throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid stop_height");
            }
            else if (*stop_height < start_height) {
                throw JSONRPCError(RPC_INVALID_PARAMETER, "stop_height must be greater than start_height");
            }
        }
        
        if (locked_chain->findPruned(start_height, stop_height)) {
            throw JSONRPCError(RPC_MISC_ERROR, "Can't rescan beyond pruned data. Use RPC call getblockchaininfo to determine your pruned height.");