[Ace-users] Using ACE_Svc_Handler::msg_queue() for buffering is slow

[azathoth]

If I limit the size of the message block to 10 bytes, and I want to
send 8192 bytes to the server: the send command will be called once
with 10 bytes, then again pulling the remaining data off the message
queue to send 8182 bytes. (provided the client is ready to receive it
all, which it almost always is).

If I comment out the code that uses the message block so it always
goes to into the queue, send will be called with 8192 bytes.

If I force the message block to 8192 bytes, send will again be called
with 8192 bytes.

The above approaches take the same amount of time, in fact the time
spent inside the handle_output function for a test run sending
10megabytes is less than a second. In the first two approahces, the
entire 10megs will take at least 2 minutes to send. Only in the final
case, the entire 10 megs will take about 2 seconds to send.

As far as I can tell profiling the program, next to no time is
actually being spent inside the code, it seems to be spending most of
it's time waiting. I almost suspect that putting thins in the Message
queue is somehow interacting with the reactor in a way to slow down
event dispatching. My next step is probably going to be putting
Message Blocks in a std::queue rather than the ACE one.

On Nov 4, 3:38 pm, schm... at dre.vanderbilt.edu (Douglas C. Schmidt)
wrote:
> Hi,
>
> >None, i.e. ACE_NULL_MUTEX
>
> Ok, great.  One more question - what's the size of the data that
> you're sending with each approach, i.e., are you sending an 8k
> buffer at one time with the first approach and 10 byte buffers at a
> time with the other?  I recommend you use strace or ethereal to see
> what's going on wrt the data entering/leaving your machine.
>
> Thanks,
>
>         Doug
>
> On Nov 3, 11:59 pm, schm... at dre.vanderbilt.edu (Douglas C. Schmidt)
>
>
>
> >wrote:
> >> Hi,
>
> >> > No, it uses the reactor the same amount. The ACE_Message_Queue is
> >> > used as a fallback if the ACE_Message_Block gets full. If the
> >> > 'buffer gets full it just puts all the data in the queue, when
> >> > handle_output is called it sends all the data it can from both the
> >> > buffer and the queue. handle_output is called the same number of
> >> > times regardless of method used.
>
> >> Ok, so what type of synchronization are you using for the ACE_Message_Queue?
>
> >> Thanks,
>
> >>         Doug
> >> --
> >> Dr. Douglas C. Schmidt                       Professor and Associate Chair
> >> Electrical Engineering and Computer Science  TEL: (615) 343-8197
> >> Vanderbilt University                        WEB:www.dre.vanderbilt.edu/~schmidt
> >> Nashville, TN 37203                          NET: d.schm... at vanderbilt.edu
>
> --
> Dr. Douglas C. Schmidt                       Professor and Associate Chair
> Electrical Engineering and Computer Science  TEL: (615) 343-8197
> Vanderbilt University                        WEB:www.dre.vanderbilt.edu/~schmidt
> Nashville, TN 37203                          NET: d.schm... at vanderbilt.edu