Re: dbpool problem

Hi,

It is to be expected. You need to synchronize your threads with a mutex. You are changing len or pos at another part of the program and you violate the assertion. Or better use gwlist_consume & gwlist_append, which lock pos.

BR,
Nikos
  ----- Original Message ----- 
  From: Esteban Cacavelos 
  To: devel Devel 
  Sent: Thursday, January 28, 2010 8:02 PM
  Subject: dbpool problem


  Hi Developers, i've been prooving the dbpool of kannel in the following scenario and i've found some problems

  static DBPool *pool3 = NULL; //GLOBAL

  //DATA BASE INIT
  void voDBInitalization()
  {
      CfgGroup *grp;
      Octstr *host, *username, *password, *database;
      long port;

      grp = cfg_get_single_group(cfg, octstr_imm("Database"));

      if((host = cfg_get(grp, octstr_imm("Host")))==NULL)
              panic(0, "Host");
      if((username = cfg_get(grp, octstr_imm("User")))==NULL)
              panic(0, "User");
      if((password = cfg_get(grp, octstr_imm("Password")))==NULL)
              panic(0, "passl");
      if((database = cfg_get(grp, octstr_imm("DBName")))==NULL)
              panic(0, "db");
      if (cfg_get_integer(&port, grp, octstr_imm("Port")) == -1)
              panic(0, "port");

          db_conf = gw_malloc(sizeof(DBConf));
      
          gw_assert(db_conf != NULL);
      
         db_conf->mysql = gw_malloc(sizeof(MySQLConf));
    
      gw_assert(db_conf->mysql != NULL);
    
          db_conf->mysql->host = host;
          db_conf->mysql->port = port;
          db_conf->mysql->username = username;
          db_conf->mysql->password = password;
          db_conf->mysql->database = database;

    

          pool = dbpool_create(DBPOOL_MYSQL, db_conf, 2);
    
      gw_assert(pool != NULL);
   }







  //MAIN
  int main (){

    threads[j++] = gwthread_create(thread1,&stParam);
                  threads[j++] = gwthread_create(thread2,&stParam);

  for (i = 0; i < j; ++i)
                          gwthread_join(threads[i]);
  } 





   thread1 and thread2 share the pool and try the query when dbpool_check returns >=1. 

  Both threads check the pool with dbpool_check(pool)  and its works correctly a few minutes but then the program throw panic because the function dbpool_check call
  pconn = gwlist_get(p->pool, i);  AND THE FOLLOWING CONDITION DOESN'T MATCH gw_assert(pos < list->len); in gwlist_get 


  I supose something like this is happening:  one thread get the len of the pool and then the other deletes one element when the dbpool_check try to re-establish some connection, so, the first thread has a inconsitent len of the pool.   



  i hope that i have explained the problem in the right way and sorry for the mistakes. 





  -- 
  Esteban L. Cacavelos de Amoriza
  Cel: 0981 220 429