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！
if (scriptPubKey.IsPayToScriptHash()) {
                    const CScriptID& hash = CScriptID(boost::get<ScriptHash>(address));
                    CScript redeemScript;
                    if (provider->GetCScript(hash, redeemScript)) {
                        entry.pushKV("redeemScript", HexStr(redeemScript.begin(), redeemScript.end()));
                        
                        CTxDestination witness_destination;
                        if (redeemScript.IsPayToWitnessScriptHash()) {
                            bool extracted = ExtractDestination(redeemScript, witness_destination);
                            CHECK_NONFATAL(extracted);
                            
                            const WitnessV0ScriptHash& whash = boost::get<WitnessV0ScriptHash>(witness_destination);
                            CScriptID id;
                            CRIPEMD160().Write(whash.begin(), whash.size()).Finalize(id.begin());
                            CScript witnessScript;
                            if (provider->GetCScript(id, witnessScript)) {
                                entry.pushKV("witnessScript", HexStr(witnessScript.begin(), witnessScript.end()));
                            }
                        }
                    }
                } else if (scriptPubKey.IsPayToWitnessScriptHash()) {
                    const WitnessV0ScriptHash& whash = boost::get<WitnessV0ScriptHash>(address);
                    CScriptID id;
                    CRIPEMD160().Write(whash.begin(), whash.size()).Finalize(id.begin());
                    CScript witnessScript;
                    if (provider->GetCScript(id, witnessScript)) {
                        entry.pushKV("witnessScript", HexStr(witnessScript.begin(), witnessScript.end()));
                    }
                }
            }