[...] sqlite_orm is doing some thread-unsafe calls that it doesn't have to do, and could definitely use some improvement in this area. For example, there is lots of code that looks like this:

if(sqlite3_step(stmt) == SQLITE_DONE) {
    //  done..
} else {
    throw std::system_error(std::error_code(sqlite3_errcode(db), get_sqlite_error_category()),
                            sqlite3_errmsg(db));
}

which isn't thread safe because there's a race condition between the sqlite3_step(stmt) and the sqlite3_errcode(db)/sqlite3_errmsg(db) calls, which means the code and message in the exception aren't reliable when used multithreaded.

If I was writing it using raw libsqlite3, then I would write it to be thread-safe by writing it as:

auto rc = sqlite3_step(stmt);
if (rc == SQLITE_DONE) {
    // done..
} else {
    throw std::system_error(std::error_code(rc, get_sqlite_error_category()), sqlite3_errstr(rc));
}

but I can't currently get that thread safety with sqlite_orm.

Originally posted by @jagerman in #707