R help - May 2009 - newbie: closing unused connection + readline

Hello;
I am new to R and trying to read a line from socket connection at a
time but at the end of script I am getting "closing unused connection"
warning. I am not able to understand how to solve this. I want to read
a line from socket and then use read.table/scan on that line but it
looks like I am opening multiple connections instead of just one.  I
think I am doing something wrong or not able to understand correct
method of doing this.

---------------------------code------------------------
# Create a socket from which to read lines - one at a time (record)
reader.socket <-   socketConnection( host = 'localhost', 5000,
                                     server = TRUE, blocking = TRUE,
                                     open = "r", encoding
getOption("encoding") );
# now read each record and split/validate it using read.table
repeat {
  # here for each line I am opening new connection! how to avoid it?
  line.raw <- textConnection(readLines( reader.socket, n = 1, ok = TRUE));
  line.raw <- read.table(line.raw, sep=",");

  if ( length(line.raw) <  1)
    break;

  print (showConnections());
  print(warnings());
}

Try explicitly closing it:

close(reader.socket)

or

closeAllConnections()

On Sat, May 16, 2009 at 8:34 AM, Aval Sarri <aval.sarri at gmail.com>
wrote:
> Hello;
> I am new to R and trying to read a line from socket connection at a
> time but at the end of script I am getting "closing unused
connection"
> warning. I am not able to understand how to solve this. I want to read
> a line from socket and then use read.table/scan on that line but it
> looks like I am opening multiple connections instead of just one. ?I
> think I am doing something wrong or not able to understand correct
> method of doing this.
>
> ---------------------------code------------------------
> # Create a socket from which to read lines - one at a time (record)
> reader.socket <- ? socketConnection( host = 'localhost', 5000,
> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? server = TRUE, blocking = TRUE,
> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? open = "r", encoding >
getOption("encoding") );
> # now read each record and split/validate it using read.table
> repeat {
> ?# here for each line I am opening new connection! how to avoid it?
> ?line.raw <- textConnection(readLines( reader.socket, n = 1, ok =
TRUE));
> ?line.raw <- read.table(line.raw, sep=",");
>
> ?if ( length(line.raw) < ?1)
> ? ?break;
>
> ?print (showConnections());
> ?print(warnings());
> }
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

On Sat, May 16, 2009 at 8:34 AM, Aval Sarri <aval.sarri at gmail.com>
wrote:
> # Create a socket from which to read lines - one at a time (record)
> reader.socket <- ? socketConnection( host = 'localhost', 5000,
> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? server = TRUE, blocking = TRUE,
> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? open = "r", encoding =
getOption("encoding") );
> # now read each record and split/validate it using read.table
> repeat {
> ?# here for each line I am opening new connection! how to avoid it?
> ?line.raw <- textConnection(readLines( reader.socket, n = 1, ok =
TRUE));
What is the function of textConnection here?  Is read.table
incompatible with socketConnection for some reason?
> ?line.raw <- read.table(line.raw, sep=",");
> ...at the end of script I am getting "closing unused connection"
warning....
This is not a problem in itself.  For some reason, R gives a warning
when connections are garbage collected.  Of course, that can be a
symptom of poor connection management, but not necessarily.

In the present case, you are creating many unnecessary
textConnections, and R correctly garbage collects them.

            -s