Re: How to properly fix memory leak - Mailing list pgsql-general

On Fri, 2025-04-25 at 22:24 -0500, Igor Korot wrote:
> Hi, ALL,
>
> [code]
>     auto res = PQexec( m_db, m_pimpl->m_myconv.to_bytes( query.c_str()
> ).c_str() );      /* ask for binary results */
>     if( PQresultStatus( res ) != PGRES_TUPLES_OK )
>     {
>         auto err = m_pimpl->m_myconv.from_bytes( PQerrorMessage( m_db ) );
>         errorMsg.push_back( L"Update validation table: " + err );
>         result = 1;
>     }
>     else
>     {
>         for( int i = 0; i < PQntuples( res ); i++ )
>         {
>             auto temp1 = m_pimpl->m_myconv.from_bytes( PQgetvalue(
> res, i, 1 ) );
>             m_tablespaces.push_back( temp1 );
>         } // this line gives a leak according to VLD
>     }
>     PQclear( res );
>     return result;
> [/code]
>
> I ran this code on MSVC 2017  with VLD and according to the VLD report I have
> a memory leak on the line indicated.
>
> Should I call PQclear() on every iteration of the loop?
>
> And I hope I handle the error cae properly...

No, PQclear() would cause an error (double free).

If it is not a spurious complaint, the leak would have to be in m_tablespaces.push_back().

Yours,
Laurenz Albe