When running walletpassphrase on a large wallet.dat (ie about 300,000 segwit P2SH addresses) the command sometimes takes a very long time, and if command is run multiple times at once (while running slow) it causes bitcoin core to freeze (stops syncing and requires kill -9 to stop/restart)

During the locked up walletpassphrase commands being run the following messages start to appear in the debug.log:

`018-01-24 01:01:04 socket sending timeout: 1201s`

Note that this problem is intermittent, so sometimes the command runs instantly, other times it takes a few minutes, and other times it completely freezes the node.
CDataStream ssValue(SER_DISK, CLIENT_VERSION);
            int ret = m_batch.ReadAtCursor(pcursor, ssKey, ssValue);
            if (ret == DB_NOTFOUND)
                break;
            else if (ret != 0)
            {
                pwallet->WalletLogPrintf("Error reading next record from wallet database\n");
                return DBErrors::CORRUPT;
            }
            
            std::string strType, strErr;
            if (!ReadKeyValue(pwallet, ssKey, ssValue, wss, strType, strErr))
            {
                
                
                if (IsKeyType(strType) || strType == DBKeys::DEFAULTKEY) {
                    result = DBErrors::CORRUPT;
                } else if (strType == DBKeys::FLAGS) {
                    
                    result = DBErrors::TOO_NEW;
                } else {
                    
                    fNoncriticalErrors = true; 
                    if (strType == DBKeys::TX)
                        
                        gArgs.SoftSetBoolArg("-rescan", true);
                }
            }
            if (!strErr.empty())
                pwallet->WalletLogPrintf("%s\n", strErr);