Connector crashes when attempting connections from multiple threads

#include <mariadb/conncpp.hpp>

#include <iostream>

#include <thread>

#include <string>

sql::Driver* driver = sql::mariadb::get_driver_instance();

sql::SQLString connectionUrl = "jdbc:mariadb://localhost:3306/the_database_name";

sql::Properties properties = {{"user", "the_username"}, {"password", "the_password"}};

int main()

{

    // simulate 2 concurrent connections each making 500 requests

    std::vector<std::function<void()>> t1cbs;

    std::vector<std::function<void()>> t2cbs;

    for(int i = 0; i < 500; i++) // if does not fail for you at 500 up the number until it does

    {

        t1cbs.push_back([&]{

            std::unique_ptr<sql::Connection> conn(driver->connect(connectionUrl, properties));

            std::cout << "t1:" << conn->getHostname().c_str() << std::endl;

        });

        // comment out this block to keep the second thread from executing, and you will see 

        // that no errors occur

        t2cbs.push_back([&]{

            std::unique_ptr<sql::Connection> conn(driver->connect(connectionUrl, properties));

            std::cout << "t2:" << conn->getHostname().c_str() << std::endl;

        });

    }

    std::thread t1([&]{

        for(auto& cb : t1cbs)

            cb();

    });

    std::thread t2([&]{

        for(auto& cb : t2cbs)

            cb();

    });

    t1.join();

    t2.join();

    return 0;

}