RE: [C400-L] select()

[Srikanth_D <Srikanth_D@xxxxxxxxxx>]

thanks a lot bob, i was out on weekend so this delay in response.
i got your point.

i am still in dark regarding allocating a thread/worker thread, i am using
pthread_create() . what exactly is pthread_create(), a worker thread or am i
allocating a thread. to be honest i am a beginner in multithreaded
programming, if you can pass on URLs/any documents on multithreading on
AS/400 it will be of great help.

best rgds.,
srikanth d


> ----------
> From:         Bob Crothers[SMTP:bob@cstoneindy.com]
> Reply To:     c400-l@midrange.com
> Sent:         Friday, May 31, 2002 8:02 PM
> To:   c400-l@midrange.com
> Subject:      RE: [C400-L] select()
>
> Srikanth,
>
> If you make your server app multi-threaded, you wont have to mess with
> select() at all.
>
> Exactly how you structure your app will depend on many things like are
> the connections persistent or "connect, do a single transaction,
> disconnect"?
>
> If they are persistent, what kind of volume?
>
> Answers to these questions will help you determine your threading
> model.  Eg: Simply allocate a thread to service each client or use
> "worker" threads.  Allocating a thread per client works well when a)
> number of concurrent clients is small -or-b) volume from each client is
> high -or- c) you want to keep things simple and performance isn't an
> issue.
>
> Regardless of the thread model you use, the socket logic is fairly
> simple:
>
> In the main listener thread:
>
> 1) bind()
> 2) listen()           // wait for a new connection request
> 3) accept()   // get the new connect request
> 4) givedescriptor()   //set up to pass the socket to a thread
> 5)                    // depending on thread model, figure out what thread
> to send the
> socket over to
> 6) Go back up and do your listen() again and wait for next connect
> request.
>
> Then in the processing threads:
>
> 1) takedescriptor()
> 2) now act like the rest of the world doesn't exist.  Use blocking
> send/receives etc.
>
> If you are dealing with a lot of clients, the above logic will have to
> be modified somewhat, but the concept is similar.
>
> I use give/takedescriptor because when I wrote the socket my server
> that runs on the as/400, "threads" didn't exist in os/400.  So I had to
> use jobs instead of threads and the give/takedescriptor was the only
> way to pass the sockets between jobs.
>
> In the PC world, there are much easier ways to pass a socket between
> threads and if they are available for you to use on the AS/400, you
> should probably use them.
>
> Regards,
> Bob Crothers
> Cornerstone Communications
> http://www.cstoneindy.com
>
>
>
>
> -----Original Message-----
> From: c400-l-admin@midrange.com [mailto:c400-l-admin@midrange.com]On
> Behalf Of Srikanth_D
> Sent: Friday, May 31, 2002 4:34 AM
> To: c400-l@midrange.com
> Subject: [C400-L] select()
>
> hi all,
>
> i am a little confused on how to use select() in a socket program. here
> is
> the deal.
>
> client connects to a server to accomplish a transaction, let us say
> account
> balance enquiry. right now my code blocks on a send() and recv(), for
> e.g.
> client send()s the account number and blocks on a recv() to get the
> balance
> of the account. i would like to eliminate these blocking. i think using
> select() would be the choice for that, but what would be the basis to
> set
> values to the struct timeval which is the fifth parameter in select().
> can i
> use select() in a multithreaded environment. for complex transactions
> (like
> fund transfer between two accounts) i have various send() and recv(),
> do i
> need to code select() before each send() and recv().
>
> please help me on this.
>
> thanks in advance.
> -srikanth d
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