From: Ben Gribaudo <rubytalk@...>
Date: 2005-04-14T23:31:18+09:00
Subject: EINTR Error Causing Failure in E-mail Sending Script

Hello,

The corporation I work for runs a paid mailing list powered by a Ruby
1.8.2 script running on a dual-processor Intel Pentium II Debian Woody
R4 server (kernal 2.4.19*)*.

Occasionally, we encounter a "Errno::EINTR Interrupted system call"
exception coming from /usr/lib/ruby/1.8/net/protocol.rb:197:in
`sysread'. This is the method of our application's code that calls the
Ruby library method which sometimes results in the error.
    def mail(message)
        Net::SMTP.start("localhost", 25) do |smtp|
            smtp.sendmail(message.to_s, message.from.address,
message.to.address)
        end
    end

Some digging in the ruby-talk archives and on Google (found
http://www.delorie.com/gnu/docs/glibc/libc_498.html) make me think that
this error may be related to a threading/multi-tasking issue. (Note that
our mailer app does not create multiple threads but is run on a
multi-processor server.)

The impression I received from the ruby-talk archives on how to resolve
this issue is to catch the Errno::EINTR exception and retry the block
until the the code succeeds. Like:
    def mail(message)
        begin
            Net::SMTP.start("localhost", 25) do |smtp|
                smtp.sendmail(message.to_s, message.from.address,
message.to.address)
            end           
        rescue Errno::EINTR
            retry
        end   
    end

Does this sound like a wise* and re*asonable solution? Can any of you
shed more light as to why we encounter the EINTR error? Is it a
threading/signal handling issue in Ruby or something we are doing in our
application or ... ?

Thank you,
Ben Gribaudo