Thread: BUG #1569: Threads don't see ecpg default connection

BUG #1569: Threads don't see ecpg default connection

From

"Gavin Scott"

Date:

03 April 2005, 04:07:27

The following bug has been logged online:

Bug reference:      1569
Logged by:          Gavin Scott
Email address:      gavin@ipalsoftware.com
PostgreSQL version: 8.0.1
Operating system:   Fedora Core 3
Description:        Threads don't see ecpg default connection
Details:

When using postgresql 8.0 compiled with --enable-thread-safety, new threads
no longer see the default ecpg connection.  That was not the case in 7.4.x
compiled with or without --enable-thread-safety.

TEST CASE

The program at the end of this mail sets up a database table named
"dbthreadtest" in the default database.  It then spawns 5 threads which each
do a select from that table using the default connection.

If the program is saved as dbthreadtest.pgc, compile with:

ecpg -t -o dbthreadtest.c dbthreadtest.pgc
gcc -Wall -o dbthreadtest dbthreadtest.c -lecpg -lpthread

Results under 7.4.x / 8.0 without --enable-thread-safety:

[gavin@hesse protocol_lib]$ psql --version
psql (PostgreSQL) 7.4.7
contains support for command-line editing
[gavin@hesse protocol_lib]$ ./dbthreadtest
got id = 1
got id = 1
got id = 1
got id = 1
got id = 1

Results under 8.0 with --enable-thread-safety:

[gavin@marquez protocol_lib]$ psql --version
psql (PostgreSQL) 8.0.1
contains support for command-line editing
[gavin@marquez protocol_lib]$ ./dbthreadtest
'No such connection NULL in line 76.', sqlcode = -220 select id

TEST PROGRAM

/* -*-C-*- */

#include <stdlib.h>
#include <pthread.h>

#define CHECK_SQL(fmt, args...)                \
do                            \
{                            \
  if (sqlca.sqlcode != ECPG_NO_ERROR)            \
    {                            \
      fprintf (stderr, "'%s', sqlcode = %ld " fmt "\n",    \
           sqlca.sqlerrm.sqlerrmc,            \
           sqlca.sqlcode, ## args);            \
      exit (1);                        \
    }                            \
 }                            \
while (0)

#define FATAL(fmt, args...)            \
do                        \
{                        \
  fprintf (stderr, fmt "\n", ## args);        \
  exit (1);                    \
}                        \
while (0)

pthread_mutex_t global_lock;
pthread_t global_threads[5];

void
setup_db ()
{
  exec sql begin declare section;
    const char *_user;
  exec sql end declare section;

  pthread_mutex_lock (&global_lock);

  _user = getenv ("LOGNAME");

  exec sql connect to :_user;
  CHECK_SQL ("connect");

  exec sql create table dbthreadtest (id int);
  CHECK_SQL ("create dbthreadtest");

  exec sql insert into dbthreadtest (id) values (1);
  CHECK_SQL ("insert 1");

  pthread_mutex_unlock (&global_lock);
}

void
teardown_db ()
{
  pthread_mutex_lock (&global_lock);

  exec sql drop table dbthreadtest;
  CHECK_SQL ("drop dbthreadtest");

  exec sql disconnect;
  CHECK_SQL ("disconnect");

  pthread_mutex_unlock (&global_lock);
}

void *query_db (void *ignorep)
{
  exec sql begin declare section;
    int _id;
  exec sql end declare section;

  pthread_mutex_lock (&global_lock);
  exec sql select id into :_id from dbthreadtest;
  CHECK_SQL ("select id");

  fprintf (stdout, "got id = %d\n", _id);
  pthread_mutex_unlock (&global_lock);

  return NULL;
}

int
main ()
{
  int i;

  pthread_mutex_init (&global_lock, NULL);

  setup_db ();

  for (i = 0; i < sizeof (global_threads) / sizeof (global_threads[0]);
++i)
    {
      if (pthread_create (&global_threads[i], NULL, query_db, NULL))
    FATAL ("pthread_create %d failed", i);
    }

  for (i = 0; i < sizeof (global_threads) / sizeof (global_threads[0]);
++i)
    {
      if (pthread_join (global_threads[i], NULL))
    FATAL ("pthread_join %d failed", i);
    }

  teardown_db ();

  return 0;
}

Re: BUG #1569: Threads don't see ecpg default connection

From

Bruce Momjian

Date:

07 May 2005, 18:17:13

Are you still seeing a failure in ecpg?  I ran your test here and got:

    got id = 0
    got id = 0
    got id = 0
    got id = 0
    got id = 0

This is with thread safety enabled and CVS HEAD, which matches 8.0.X.

---------------------------------------------------------------------------

Gavin Scott wrote:
>
> The following bug has been logged online:
>
> Bug reference:      1569
> Logged by:          Gavin Scott
> Email address:      gavin@ipalsoftware.com
> PostgreSQL version: 8.0.1
> Operating system:   Fedora Core 3
> Description:        Threads don't see ecpg default connection
> Details:
>
> When using postgresql 8.0 compiled with --enable-thread-safety, new threads
> no longer see the default ecpg connection.  That was not the case in 7.4.x
> compiled with or without --enable-thread-safety.
>
> TEST CASE
>
> The program at the end of this mail sets up a database table named
> "dbthreadtest" in the default database.  It then spawns 5 threads which each
> do a select from that table using the default connection.
>
> If the program is saved as dbthreadtest.pgc, compile with:
>
> ecpg -t -o dbthreadtest.c dbthreadtest.pgc
> gcc -Wall -o dbthreadtest dbthreadtest.c -lecpg -lpthread
>
> Results under 7.4.x / 8.0 without --enable-thread-safety:
>
> [gavin@hesse protocol_lib]$ psql --version
> psql (PostgreSQL) 7.4.7
> contains support for command-line editing
> [gavin@hesse protocol_lib]$ ./dbthreadtest
> got id = 1
> got id = 1
> got id = 1
> got id = 1
> got id = 1
>
> Results under 8.0 with --enable-thread-safety:
>
> [gavin@marquez protocol_lib]$ psql --version
> psql (PostgreSQL) 8.0.1
> contains support for command-line editing
> [gavin@marquez protocol_lib]$ ./dbthreadtest
> 'No such connection NULL in line 76.', sqlcode = -220 select id
>
> TEST PROGRAM
>
> /* -*-C-*- */
>
> #include <stdlib.h>
> #include <pthread.h>
>
> #define CHECK_SQL(fmt, args...)                \
> do                            \
> {                            \
>   if (sqlca.sqlcode != ECPG_NO_ERROR)            \
>     {                            \
>       fprintf (stderr, "'%s', sqlcode = %ld " fmt "\n",    \
>            sqlca.sqlerrm.sqlerrmc,            \
>            sqlca.sqlcode, ## args);            \
>       exit (1);                        \
>     }                            \
>  }                            \
> while (0)
>
> #define FATAL(fmt, args...)            \
> do                        \
> {                        \
>   fprintf (stderr, fmt "\n", ## args);        \
>   exit (1);                    \
> }                        \
> while (0)
>
> pthread_mutex_t global_lock;
> pthread_t global_threads[5];
>
> void
> setup_db ()
> {
>   exec sql begin declare section;
>     const char *_user;
>   exec sql end declare section;
>
>   pthread_mutex_lock (&global_lock);
>
>   _user = getenv ("LOGNAME");
>
>   exec sql connect to :_user;
>   CHECK_SQL ("connect");
>
>   exec sql create table dbthreadtest (id int);
>   CHECK_SQL ("create dbthreadtest");
>
>   exec sql insert into dbthreadtest (id) values (1);
>   CHECK_SQL ("insert 1");
>
>   pthread_mutex_unlock (&global_lock);
> }
>
> void
> teardown_db ()
> {
>   pthread_mutex_lock (&global_lock);
>
>   exec sql drop table dbthreadtest;
>   CHECK_SQL ("drop dbthreadtest");
>
>   exec sql disconnect;
>   CHECK_SQL ("disconnect");
>
>   pthread_mutex_unlock (&global_lock);
> }
>
> void *query_db (void *ignorep)
> {
>   exec sql begin declare section;
>     int _id;
>   exec sql end declare section;
>
>   pthread_mutex_lock (&global_lock);
>   exec sql select id into :_id from dbthreadtest;
>   CHECK_SQL ("select id");
>
>   fprintf (stdout, "got id = %d\n", _id);
>   pthread_mutex_unlock (&global_lock);
>
>   return NULL;
> }
>
> int
> main ()
> {
>   int i;
>
>   pthread_mutex_init (&global_lock, NULL);
>
>   setup_db ();
>
>   for (i = 0; i < sizeof (global_threads) / sizeof (global_threads[0]);
> ++i)
>     {
>       if (pthread_create (&global_threads[i], NULL, query_db, NULL))
>     FATAL ("pthread_create %d failed", i);
>     }
>
>   for (i = 0; i < sizeof (global_threads) / sizeof (global_threads[0]);
> ++i)
>     {
>       if (pthread_join (global_threads[i], NULL))
>     FATAL ("pthread_join %d failed", i);
>     }
>
>   teardown_db ();
>
>   return 0;
> }
>
> ---------------------------(end of broadcast)---------------------------
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>
>                http://archives.postgresql.org
>

--
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

Re: BUG #1569: Threads don't see ecpg default connection

From

Michael Meskes

Date:

08 May 2005, 09:12:21

On Sat, May 07, 2005 at 12:37:24PM -0400, Bruce Momjian wrote:
> Are you still seeing a failure in ecpg?  I ran your test here and got:
> ...

Bruce,

this is fixed AFAIK. I just never saw the original post on -bugs and
thus did not answer there either.

Michael

--
Michael Meskes
Email: Michael at Fam-Meskes dot De
ICQ: 179140304, AIM/Yahoo: michaelmeskes, Jabber: meskes@jabber.org
Go SF 49ers! Go Rhein Fire! Use Debian GNU/Linux! Use PostgreSQL!

Re: BUG #1569: Threads don't see ecpg default connection

From

Gavin Scott

Date:

09 May 2005, 02:07:57

On Sat, 2005-05-07 at 12:37 -0400, Bruce Momjian wrote:
> Are you still seeing a failure in ecpg?  I ran your test here and got:
>
>     got id = 0
>     got id = 0
>     got id = 0
>     got id = 0
>     got id = 0
>
> This is with thread safety enabled and CVS HEAD, which matches 8.0.X.

Hi Bruce,

This was fixed by r1.25 of pgsql/src/interfaces/ecpg/ecpglib/connect.c :

----------------------------
revision 1.25
date: 2005/04/14 10:08:57;  author: meskes;  state: Exp;  lines: +24 -7
Added patch by Philip Yarra <philip.yarra@internode.on.net> for a bug in
thread
support.
----------------------------

--
Gavin Scott
gavin@ipalsoftware.com