Horton

Re: libpq debug log

Alvaro Herrera <alvherre@alvh.no-ip.org>

View thread View on postgr.es
From: 'Alvaro Herrera' <alvherre@alvh.no-ip.org>
To: "tsunakawa.takay@fujitsu.com" <tsunakawa.takay@fujitsu.com>
Cc: "k.jamison@fujitsu.com" <k.jamison@fujitsu.com>, "iwata.aya@fujitsu.com" <iwata.aya@fujitsu.com>, "'pgsql-hackers@lists.postgresql.org'" <pgsql-hackers@lists.postgresql.org>
Date: 2021-02-02T14:20:45Z
Lists: pgsql-hackers 
On 2021-Jan-29, tsunakawa.takay@fujitsu.com wrote:

> (30)
> +/*
> + * Deallocate FE/BE message tracking memory.  We only do this because
> + * FE message can grow arbitrarily large, and skip it in the initial state,
> + * because it's likely pointless.
> + */
> +void
> +pqTraceUninit(PGconn *conn)
> +{
> +	if (conn->fe_msg &&
> +		conn->fe_msg->num_fields != DEF_FE_MSGFIELDS)
> +	{
> +		free(conn->fe_msg);
> +		conn->fe_msg = NULL;
> +	}
> 
> What does the second if condition mean?  If it's not necessary, change the comment accordingly.

The rationale for that second condition is this: if the memory allocated
is the initial size, we don't free memory, because it would just be
allocated of the same size next time, and that size is not very big, so
it's not a big deal if we just let it be, so that it is reused if we
call PQtrace() again later.  However, if the allocated size is larger
than default, then it is possible that some previous tracing run has
enlarged the trace struct to a very large amount of memory, and we don't
want to leave that in place.

-- 
Álvaro Herrera       Valdivia, Chile

Commits

  1. Rename PQtraceSetFlags() to PQsetTraceFlags().

  2. Suppress length of Notice/Error msgs in PQtrace regress mode

  3. Strip file names reported in error messages on Windows, too.

  4. Fix setvbuf()-induced crash in libpq_pipeline

  5. libpq_pipeline: Must strdup(optarg) to avoid crash

  6. Remove setvbuf() call from PQtrace()

  7. Initialize conn->Pfdebug to NULL when creating a connection

  8. Disable force_parallel_mode in libpq_pipeline

  9. libpq_pipeline: add PQtrace() support and tests

  10. Improve PQtrace() output format

  11. Re-simplify management of inStart in pqParseInput3's subroutines.