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From: "David G. Johnston" <david.g.johnston@gmail.com>
Date: Fri, 25 Apr 2025 20:48:00 -0700
Message-ID: <CAKFQuwZKp_FWZ0mi9H8th+fh70KeoV=4_6uB40TvQ9r1Q04UhA@mail.gmail.com>
Subject: Re: How to properly fix memory leak
To: Igor Korot <ikorot01@gmail.com>
Cc: "pgsql-generallists.postgresql.org" <pgsql-general@lists.postgresql.org>
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On Friday, April 25, 2025, Igor Korot <ikorot01@gmail.com> wrote:

>
>         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.


Seems like a false positive.


>
> Should I call PQclear() on every iteration of the loop?
>

Would make processing more than a single row impossible if you throw away
the result after processing one row.

David J.

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On Friday, April 25, 2025, Igor Korot &lt;<a href=3D"mailto:ikorot01@gmail.=
com">ikorot01@gmail.com</a>&gt; wrote:<br><blockquote class=3D"gmail_quote"=
 style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><b=
r>
=C2=A0 =C2=A0 =C2=A0 =C2=A0 for( int i =3D 0; i &lt; PQntuples( res ); i++ =
)<br>
=C2=A0 =C2=A0 =C2=A0 =C2=A0 {<br>
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 auto temp1 =3D m_pimpl-&gt;m_myco=
nv.from_bytes( PQgetvalue(<br>
res, i, 1 ) );<br>
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 m_tablespaces.push_back( temp1 );=
<br>
=C2=A0 =C2=A0 =C2=A0 =C2=A0 } // this line gives a leak according to VLD<br=
>
=C2=A0 =C2=A0 }<br>
=C2=A0 =C2=A0 PQclear( res );<br>
=C2=A0 =C2=A0 return result;<br>
[/code]<br>
<br>
I ran this code on MSVC 2017=C2=A0 with VLD and according to the VLD report=
 I have<br>
a memory leak on the line indicated.</blockquote><div><br></div><div>Seems =
like a false positive.</div><div>=C2=A0</div><blockquote class=3D"gmail_quo=
te" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"=
>
<br>
Should I call PQclear() on every iteration of the loop?<br>
</blockquote><div><br></div><div>Would make processing more than a single r=
ow impossible if you throw away the result after processing one row.</div><=
div><br></div><div>David J.</div><div><br></div>

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