From: Robert Klemme <shortcutter@...>
Date: 2007-05-31T21:00:20+09:00
Subject: Re: Does this code spawn lots of objects?

On 31.05.2007 13:49, Ben Edwards wrote:
> I have the following code:-
> 
> dbh = DBI.connect('*', '*', '*')
> smtp = Net::SMTP.start('*')
> sql = open( "gw.sql", "r" ).read
> sth = dbh.execute( sql )
> sth.fetch_hash do |row|
>  mail         = MailFactory.new()
>  mail.to      = "ben.edwards@ingenta.com"
>  mail.from    = "ben.edwards@ingenta.com"
>  mail.subject = "file from ingenta"
>  mail.text    =  "Here is the file"
>  mail.attach( "./" + row["IDENTITYID"] + "_" + month + year + ".csv" );
>  smtp.send_message( mail.to_s(), mail.from, mail.to )
> end
> sth.finish
> smtp.finish
> dbh.disconnect
> 
> This code seems to cause a new object to be created for every
> iteration of the iterator.  However is it true that 'mail =
> MailFactory.new()' causes the previous Mailfactory object not to have
> a reference to it and therefore it can be garbage collected?
> 
> Is there a better way of coding the above?

Probably not much room for improvement.  One thing you can do for sure 
is to use the block form of those various connections / IO's you are 
using.  And you can read in a complete file by doing File.read("ge.sql").

Probably you can also reuse the MailFactory (from, to, subject and text 
don't change anyway).  But I have no idea whether that will create any 
improvement.  And I also do not know that class so take this advice with 
a grain of salt.

Another idea is to start a second thread for mail sending.  Connect both 
threads with a queue with limited size.  That way you may use IO 
resources more efficiently.

Kind regards

	robert