Date: Wed, 31 Mar 2021 19:09:20 -0300
From: "'alvherre@alvh.no-ip.org'" <alvherre@alvh.no-ip.org>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: "iwata.aya@fujitsu.com" <iwata.aya@fujitsu.com>,
	"tsunakawa.takay@fujitsu.com" <tsunakawa.takay@fujitsu.com>,
	'Kyotaro Horiguchi' <horikyota.ntt@gmail.com>,
	"k.jamison@fujitsu.com" <k.jamison@fujitsu.com>,
	"pgsql-hackers@lists.postgresql.org" <pgsql-hackers@lists.postgresql.org>
Subject: Re: libpq debug log
Message-ID: <20210331220920.GA23882@alvherre.pgsql>
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On 2021-Mar-31, Tom Lane wrote:

> I wrote:
> > That is weird - only test 4 (of 8) runs at all, the rest seem to
> > fail to connect.  What's different about pipelined_insert?
> 
> Oh ... there's a pretty obvious theory.  pipelined_insert is
> the only one that is not asked to write a trace file.
> So for some reason, opening the trace file fails.
> (I wonder why we don't see an error message for this though.)

.. oh, I think we forgot to set conn->Pfdebug = NULL when creating the
connection.  So when we do PQtrace(), the first thing it does is
PQuntrace(), and then that tries to do fflush(conn->Pfdebug) ---> crash.
So this should fix it.

-- 
Álvaro Herrera       Valdivia, Chile
<inflex> really, I see PHP as like a strange amalgamation of C, Perl, Shell
<crab> inflex: you know that "amalgam" means "mixture with mercury",
       more or less, right?
<crab> i.e., "deadly poison"

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diff --git a/src/interfaces/libpq/fe-connect.c b/src/interfaces/libpq/fe-connect.c
index a90bdb8ab6..56a8266bc3 100644
--- a/src/interfaces/libpq/fe-connect.c
+++ b/src/interfaces/libpq/fe-connect.c
@@ -3952,6 +3952,7 @@ makeEmptyPGconn(void)
 	conn->verbosity = PQERRORS_DEFAULT;
 	conn->show_context = PQSHOW_CONTEXT_ERRORS;
 	conn->sock = PGINVALID_SOCKET;
+	conn->Pfdebug = NULL;
 
 	/*
 	 * We try to send at least 8K at a time, which is the usual size of pipe

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