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  1. Fix minor memory leak in pg_basebackup and pg_receivewal

  1. [PATHC] Fix minor memory leak in pg_basebackup

    Zhang, Jie <zhangjie2@cn.fujitsu.com> — 2020-04-15T10:06:52Z

    Hi all

In some cases , PGresult is not cleared.

File: src\bin\pg_basebackup\streamutil.c

bool
RetrieveWalSegSize(PGconn *conn)
{
	PGresult   *res;
......
	res = PQexec(conn, "SHOW wal_segment_size");
	if (PQresultStatus(res) != PGRES_TUPLES_OK)
	{
		pg_log_error("could not send replication command \"%s\": %s",
					 "SHOW wal_segment_size", PQerrorMessage(conn));

		PQclear(res); // *** res  is cleared  ***
		return false;
	}
......
	/* fetch xlog value and unit from the result */
	if (sscanf(PQgetvalue(res, 0, 0), "%d%s", &xlog_val, xlog_unit) != 2)
	{
		pg_log_error("WAL segment size could not be parsed");
		return false;    // *** res  is not cleared  ***
	}
......
	if (!IsValidWalSegSize(WalSegSz))
	{
		pg_log_error(ngettext("WAL segment size must be a power of two between 1 MB and 1 GB, but the remote server reported a value of %d byte",
							  "WAL segment size must be a power of two between 1 MB and 1 GB, but the remote server reported a value of %d bytes",
							  WalSegSz),
					 WalSegSz);
		return false;   ;    // *** res  is not cleared  ***
	}
......


Here is a patch.

Best Regards!

  2. Re: [PATHC] Fix minor memory leak in pg_basebackup

    Michael Paquier <michael@paquier.xyz> — 2020-04-16T06:30:36Z

    On Wed, Apr 15, 2020 at 10:06:52AM +0000, Zhang, Jie wrote:
> In some cases , PGresult is not cleared.
> 
> File: src\bin\pg_basebackup\streamutil.c
> 
> bool
> RetrieveWalSegSize(PGconn *conn)
> {
> 	PGresult   *res;

RetrieveWalSegSize() gets called only once at the beginning of
pg_basebackup and pg_receivewal, so that's not an issue that has major
effects, still that's an issue.  The first one PQclear() is needed
where you say.  Now for the second one, I would just move it once the
code is done with the query result, aka after calling PQgetvalue().
What do you think?  Please see the attached.
--
Michael

  3. RE: [PATHC] Fix minor memory leak in pg_basebackup

    Zhang, Jie <zhangjie2@cn.fujitsu.com> — 2020-04-16T10:54:09Z

    Hi  Michael

so much the better!

-----Original Message-----
From: Michael Paquier [mailto:michael@paquier.xyz] 
Sent: Thursday, April 16, 2020 2:31 PM
To: Zhang, Jie/张 杰 <zhangjie2@cn.fujitsu.com>
Cc: pgsql-hackers@lists.postgresql.org
Subject: Re: [PATHC] Fix minor memory leak in pg_basebackup

On Wed, Apr 15, 2020 at 10:06:52AM +0000, Zhang, Jie wrote:
> In some cases , PGresult is not cleared.
> 
> File: src\bin\pg_basebackup\streamutil.c
> 
> bool
> RetrieveWalSegSize(PGconn *conn)
> {
> 	PGresult   *res;

RetrieveWalSegSize() gets called only once at the beginning of pg_basebackup and pg_receivewal, so that's not an issue that has major effects, still that's an issue.  The first one PQclear() is needed where you say.  Now for the second one, I would just move it once the code is done with the query result, aka after calling PQgetvalue().
What do you think?  Please see the attached.
--
Michael

  4. Re: [PATHC] Fix minor memory leak in pg_basebackup

    Michael Paquier <michael@paquier.xyz> — 2020-04-17T01:47:44Z

    On Thu, Apr 16, 2020 at 10:54:09AM +0000, Zhang, Jie wrote:
> So much the better!

Thanks for confirming.  Fixed, then.
--
Michael