multiple threads using one connection - Mailing list pgsql-interfaces

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;
}