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From Michael Goulish <mgoul...@redhat.com>
Subject Re: [jira] [Created] (PROTON-2189) proactor C client has abnormally long pauses during message send
Date Sat, 04 Apr 2020 16:31:28 GMT
Ken --

I have a proactor client in Mercury and it handles timeouts differently
than your code.
I don't remember now exactly why this was necessary, but I do vaguely
recall weird
behavior before I fixed it, at aconway's suggestion.

I think that, in the PN_PROACTOR_TIMEOUT case in the event handler, in my
code
it was not correct to send at that time and then reset the timer. (As you
are doing.)

Instead, in that case all I did was to wake the cnx:
         pn_connection_wake ( context->connection );

You can then send, and reset the timer only when you get an event of type:
     PN_CONNECTION_WAKE:
         send_message ( context );
         pn_proactor_set_timeout ( context->proactor, context->throttle );

In my case, I am sending entire messages -- but this is how I get it to
'throttle' the send-rate, i.e. send 1 message per N msec.


I don't remember exactly what Bad Thing was happening to me before I
started doing it this way, but I have a Bad Feeling that it may have been
similar to what you describe.





On Sat, Apr 4, 2020 at 12:00 PM Ken Giusti (Jira) <jira@apache.org> wrote:

> Ken Giusti created PROTON-2189:
> ----------------------------------
>
>              Summary: proactor C client has abnormally long pauses during
> message send
>                  Key: PROTON-2189
>                  URL: https://issues.apache.org/jira/browse/PROTON-2189
>              Project: Qpid Proton
>           Issue Type: Bug
>           Components: proton-c
>     Affects Versions: proton-c-0.30.0
>          Environment: To compile the clients install qpid-proton-c-devel
> and simply compile:
>
> gcc  -O2 -g -Wall -lqpid-proton -lm -o clogger clogger.c
>
> To reproduce my test, build qdrouterd and run it in the background.
> You need to have a consumer attached.  There is a test receiver client in
> the qdrouterd build in <build-dir>/tests/test-receiver.  This receiver is
> designed to handle streaming messages (by default sent to 'test-address')
>
> Run the consumer in the background then run each clogger (default params
> are fine).
>
> You should observe that clogger-reactor runs smoothly (use PN_TRACE_FRM=1
> on qdrouterd as well).
>
> You'll see clogger-reactor send the message header, then nothing for
> awhile, then send the entire message.
>
> Use "-D" for debug output to see how many bytes have been written to
> pn_link_send()
>
>
>             Reporter: Ken Giusti
>          Attachments: clogger-proactor.c, clogger-reactor.c
>
> I have a proactor-based C test client that has the ability to slowly send
> extremely large messages slowly.  This is done by sending 'chunks' of body
> data with pauses in between.
>
> This client was designed to test large streaming messages against
> qdrouterd.
>
> The behavior of this client is unexpected - I would expect the message
> data to appear "on the wire" in bursts relatively quickly.  In reality the
> data is buffered - in some cases over 1 GB is buffered - before it is
> written (as indicated by the lack @transfer frames dumped by the client AND
> the qdrouterd).  In some cases it takes up to 30 seconds before the
> client's data starts being written to the client.
>
> I've refactored the client to use reactor instead and the data flows as
> expected.  There is minimal buffering and no abnormally long pauses.
>
> The clients are attached.
>
> It is quite likely the proactor client is incorrectly implemented, but I
> used the qdrouterd I/O loop as the model and cannot see what may be wrong.
>
>
>
>
>
> --
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