multiple threads using one connection

Hi,

I have multi-thread application written in Ada which uses APQ. All
threads use the same connection (can't afford one connection per
thread). I compiled libpq with --enable-thread-safty option.
When two threads try to execute a query at the same time one of them is
blocked and even when the other one finishes it is not unblocked.

I wrote simple test in c to find out is it APQ fault. But the result was
the same. Am I doing something wrong?

My libpq version is 8.0.4 and here's the code of this test:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include "libpq-fe.h"
#include <pthread.h>

/* for ntohl/htonl */
#include <netinet/in.h>
#include <arpa/inet.h>

PGconn *conn;

static void
exit_nicely(PGconn *conn)
{
//PQfinish(conn);
}

void *run(void *ptr)
{
char *message;
PGresult *res;
message = (char *)ptr;
res = PQexec(conn, "select * from foo;");

if (PQresultStatus(res) != PGRES_TUPLES_OK)
{
fprintf(stderr, "select failed: %s\n", PQerrorMessage(conn));
PQclear(res);
exit_nicely(conn);
return;
}

PQclear(res);
printf ("%s completed\n", message);

}

int
main(int argc, char **argv)
{
const char *conninfo;
pthread_t thread1, thread2;
char *message1 = "Thread 1";
char *message2 = "Thread 2";
int iret1, iret2;

//TODO
conninfo = "dbname = user = password = ";

/* Make a connection to the database */
conn = PQconnectdb(conninfo);

/* Check to see that the backend connection was successfully made */
if (PQstatus(conn) != CONNECTION_OK)
{
fprintf(stderr, "Connection to database failed: %s",
PQerrorMessage(conn));
exit_nicely(conn);
}
else
{
fprintf(stderr, "Connected.\n");
}

PGresult *res;
res = PQexec(conn, "drop table foo;create table foo(id int);");

if (PQresultStatus(res) != PGRES_COMMAND_OK)
{
fprintf(stderr, "create table failed: %s\n", PQerrorMessage(conn));
PQclear(res);
exit_nicely(conn);
return;
}

iret1 = pthread_create( &thread1, NULL, run, (void*) message1);
iret2 = pthread_create( &thread2, NULL, run, (void*) message2);

pthread_join( thread1, NULL);
pthread_join( thread2, NULL);
/* close the connection to the database and cleanup */
PQfinish(conn);

return 0;
}