https://github.com/eBookingServices/mysql-lited/issues/4

Although, I would advise you not to store connections. Connection should be locked for as little amount of time as possible, so that they get back to the connection pool and get reused as much as possible.

I took the above from your link, so basically how do you close the connection there is lockConnection but no freeConnection or releaseConnection, basically what I wanted to achieve is that upon running the server, I will initialize the connectionpool and keep it running until I close the server... when I was using DDBC + mysql-native I can basically run -c100 -t10s without error, but when I use mysql-lited, I get "too many connections" error, bad file descriptors, connection refused etc, I know that each of it is caused by some other events on the system, which prompts me to think that the connection is not being reused instead the code is spawning a connection for every single request, because the connection is not closed properly upon exiting, or the query is not being finished because the next query force closed the old connection, I was thinking of something like this in the class wrapper 

auto insert(string[string] fv, string table){
   conn.lockConnection(); // lock connection
   scope(exit) conn.releaseConnection(); //release back to the pool on exit or error

   // query codes
   conn.execute("query here");
}

so that even if the code fails or error occurs, the connection will still be released as soon as it sees the closing bracket or as soon as the error occurs...

below is my source code for testing, afterwards i try to benchmark it using siege -c100 -t10s http://localhost:8080 and it fails... 

class Db {
	static MySQLClient client;
	private MySQLClient.LockedConnection conn;
	shared static this(){
		client = new MySQLClient("host=127.0.0.1;user=root;pwd=rootpassword;db=mewmew");
		this.conn = client.lockConnection();
	}

	static void query (string s=""){
		//conn = client.lockConnection();
		conn.execute("insert into users (name, email) values (?, ?)", "frank", "thetank@cowabanga.com");
	}
}

here is a similar insert using my class that is using ddbc + mysql-native 

class Db {
	static DataSource ds;
	MySQLDriver driver;

	static string[string] params;
	static string[string] config;
	static string url;

	shared static this(){		
		MySQLDriver driver;
	    driver = new MySQLDriver();
	    url = MySQLDriver.generateUrl(config["host"], std.conv.to!ushort(config["port"]), config["db"]);
	    params = MySQLDriver.setUserAndPassword(config["user"], config["pass"]);
	    ds = new ConnectionPoolDataSourceImpl(driver, url, params);
	}

	auto insert( string[string] values, string table ){
		if(values.length <= 0){
			return false;
		}
		else{
			string[] placeholders = new string[values.length];
			placeholders[] = "?";
			
			string sql = "INSERT INTO `" ~ table ~ "`(`" ~ join(values.keys, "`, `") ~ "`) VALUES (" ~ join(placeholders, ",") ~ ")";
			auto conn = ds.getConnection();
			scope(exit) conn.close();
			auto pstmt = conn.prepareStatement(sql);
			scope(exit) pstmt.close();
			int i=0;
			foreach(key, val; values){
				++i;
				pstmt.setString(i, val);
			}

			if(pstmt.executeUpdate()){
				return true;
			}
			else return false;
		}
	}

}

I like your approach on the mysql-lited, so I wanted to push through with it. I hope you could help me.