run_erl under Linux (was: erl_interface and ALIVE)

Vance Shipley <>
Fri Sep 8 20:58:14 CEST 2000


I did dresolve this problem.  Testing showed that select was
returning 0 yet it had not timed out yet.  The solution turned
out to be setting the define USE_SETPGRP_NOARGS.  The following
snippet from run_erl.c was the source of the problem:

    /* disassociate from control terminal */
#ifdef USE_SETPGRP_NOARGS       /* SysV */
    setpgrp();
#else
#ifdef USE_SETPGRP              /* BSD */
    setpgrp(0,getpid());
#else                           /* POSIX */
    setsid();
#endif

It had been using setsid().

	-Vance

}  Yes, but check out the times!  My buffers are filling up 
}  with these messages as they are produced many times a second.
}  
}  This seems to be produced by run_erl.  In run_erl.c:
}  
}    /* Enter the work loop */
}  
}    timeout.tv_sec  = LOG_ALIVE_MINUTES*60;
}    timeout.tv_usec = 0;
}    while (1) {
}      maxfd = MAX(rfd, mfd);
}      FD_ZERO(&readfds);
}      FD_SET(rfd, &readfds);
}      FD_SET(mfd, &readfds);
}      time(&last_activity);
}      ready = select(maxfd + 1, &readfds, NULL, NULL, &timeout);
}      if (ready < 0) {
}        /* Some error occured */
}        error("Error in select.");
}        exit(1);
}      } else {
}        /* Check how long time we've been inactive */
}        time_t now;
}        time(&now);
}        if(!ready || now - last_activity > LOG_ACTIVITY_MINUTES*60) {
}     /* Either a time out: 15 minutes without action, */
}     /* or something is coming in right now, but it's a long time */
}     /* since last time, so let's write a time stamp this message */
}     sprintf(buf, "\n===== %s%s", ready?"":"ALIVE ", ctime(&now));
}     write_to_log(&lfd, &lognum, buf, strlen(buf));
}        }
}      }
}  
}  
}  I believe that what is happening is that select is returning 0 at
}  these times.  It gets into a state where it gets stuck doing this.
}  It hasn't timed out though as it's been far, far less than a minute.
}  
}  I think I'll test and report errno and see what it says...
}  
}  	-Vance
}  
}  
}  }  >Another problem which I do not yet understand is that 
}  }  >sometimes the Erlang node will produce the following 
}  }  >messages in the logs:
}  }  >
}  }  >===== ALIVE Fri Sep  1 11:32:49 2000
}  }  >
}  }  >===== ALIVE Fri Sep  1 11:32:49 2000
}  }  >
}  }  >===== ALIVE Fri Sep  1 11:32:49 2000
}  }  
}  }  
}  }  These entries are written to mark that the node is up and running,
}  }  even though it is not outputting anything to the shell.
}  }  
}  }  /Uffe
}  
}  



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