Re: Non-deterministic behavior of multithreaded software

Victor Bazarov <v.bazarov@comcast.invalid>
Fri, 05 Aug 2011 08:07:07 -0400
On 8/5/2011 5:40 AM, itt ium wrote:

I have recently modified a software from single threaded to
multithreaded design. In single threaded version, a connection fd was
read by single thread, so event were always delivered in order. Now
since multiple threads handle different events (on the same fd), the
events are sometimes delivered out of order.

"Delivered" by whom, to where? Handling of events is one thing,
delivering them is another. Do you need them processed in order, then
don't parallelise their processing. If your events can be processed out
of order but then need to be re-queued, then you need to mark each event
(see below) for reassembling of the queue.

 > Please note, on the

connection fd, events are received in proper order and this non-
deterministic behavior is introduced by my software only.

Following are my doubt

1. How to handle such a situation

Every event, when read from your 'fd' (whatever that is), needs to be
wrapped in a package with the assigned ordinal number so that after
processing it can be again placed in another queue _sorted_.

2. Is it a bad idea to have multiple threads for the same fd. If yes
than how to increase capacity of a software that receives large amount
of data on a single fd only.

Are you guessing what can and cannot be parallelized? It's better to do
a systematic analysis of your own software to see what improvement you
can make by adding multithreading to it. There are many good/decent
books on thread and designing for parallel execution, why don't you
start with them?

Because of the relevance I am posting the message to following groups.



No, you're not. I'm reading this in 'comp.lang.c++'. Perhaps you
multiposted, but that's a BAD IDEA(tm). If you have to use more than
one newsgroup, *cross-post*.

I do not respond to top-posted replies, please don't ask

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