From: Lee Kindness <lkindness@csl.co.uk>
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Message-ID: <16121.27884.841077.431930@kelvin.csl.co.uk>
Date: Wed, 25 Jun 2003 10:35:40 +0100
To: Philip Yarra <philip@utiba.com>
Subject: ECPG still having thread problems on Linux
In-Reply-To: <200306241825.32527.philip@utiba.com>
References: <200306241825.32527.philip@utiba.com>
Cc: Lee Kindness <lkindness@csl.co.uk>,
	pgsql-interfaces@postgresql.org


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Philip, both your SELECTs are using the same database connection (and
it's undefined which one it is) without any locking. You need to add
"AT clauses" to specify an explicit connection. See attached diff.

However, i've not tried it... I'll try and get some time!

L.

Philip Yarra writes:
 > Hi all, it looks like Lee's ECPG (and libpq) thread-safety patches
 > have been applied, and configure --with-threads is also added. I
 > have been doing some testing.
 > 
 > On FreeBSD 4.8, the attached sample app runs without a problem.
 > 
 > However, I still encounter a threading problem on Linux (RedHat 7.3).
 > 
 > I have done the following:
 > 1) cvs update
 > 2) ./configure --with-threads && make && su -c "make install"
 > 3) compiled cn.pgc as follows:
 >         a) ecpg -t cn.pgc
 >         b) gcc -I/usr/local/pgsql/include -L/usr/local/pgsql/lib \
 >                 -lecpg -lpgtypes -pthread cn.c
 > 4) ./a.out - one thread runs to completion (inserts 5 records),
 >         the other hangs (manages one insert, then blocks forever)


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*** cn.pgc	2003-06-25 10:29:55.000000000 +0100
--- cn.pgc.new	2003-06-25 10:29:45.000000000 +0100
***************
*** 36,46 ****
  	EXEC SQL END DECLARE SECTION;
  	EXEC SQL WHENEVER sqlerror sqlprint;
  	EXEC SQL CONNECT TO :cs AS test1;
! 	EXEC SQL SET AUTOCOMMIT TO ON;
  	for (i = 0; i < 5; i++)
  	{
  		printf("thread1 inserting\n");
! 		EXEC SQL INSERT INTO foo VALUES(:bar);
  		printf("==>thread1 insert done\n");
  	}
  	EXEC SQL DISCONNECT test1;
--- 36,46 ----
  	EXEC SQL END DECLARE SECTION;
  	EXEC SQL WHENEVER sqlerror sqlprint;
  	EXEC SQL CONNECT TO :cs AS test1;
! 	EXEC SQL AT test1 SET AUTOCOMMIT TO ON;
  	for (i = 0; i < 5; i++)
  	{
  		printf("thread1 inserting\n");
! 		EXEC SQL AT test1 INSERT INTO foo VALUES(:bar);
  		printf("==>thread1 insert done\n");
  	}
  	EXEC SQL DISCONNECT test1;
***************
*** 57,67 ****
  	EXEC SQL END DECLARE SECTION;
  	EXEC SQL WHENEVER sqlerror sqlprint;
  	EXEC SQL CONNECT TO :cs AS test2;
! 	EXEC SQL SET AUTOCOMMIT TO ON;
  	for (i = 0; i < 5; i++)
  	{
  		printf("thread2 inserting\n");
! 		EXEC SQL INSERT INTO foo VALUES(:bar);
  		printf("==>thread2 insert done\n");
  	}
  	EXEC SQL DISCONNECT test2;
--- 57,67 ----
  	EXEC SQL END DECLARE SECTION;
  	EXEC SQL WHENEVER sqlerror sqlprint;
  	EXEC SQL CONNECT TO :cs AS test2;
! 	EXEC SQL AT test2 SET AUTOCOMMIT TO ON;
  	for (i = 0; i < 5; i++)
  	{
  		printf("thread2 inserting\n");
! 		EXEC SQL AT test2 INSERT INTO foo VALUES(:bar);
  		printf("==>thread2 insert done\n");
  	}
  	EXEC SQL DISCONNECT test2;

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