Dear Chuck, dear Gordon, Thank you very much for your replies. Now it is clear that I have to return from the handler before being able to perform any I/O operation. Returning from it after sending each message with "pn_message_send()", as you suggested, and handling all the successive PN_DELIVERY callbacks, I was able to obtain the desired result, sending each message almost immediately.
Gordon, what I was noticing was actually a big TCP packet (which was also fragmented if needed), containing inside a certain number of different AMQP "transfer" messages (each with the "transfer" performative, one for each call to "pn_message_send()"). It was then followed by a series of different TCP messages, each containing a single "disposition" from the receiver. Thank you again for all your assistance! Il giorno lun 10 feb 2020 alle ore 12:38 Gordon Sim <g...@redhat.com> ha scritto: > On 10/02/2020 1:12 am, Chuck Rolke wrote: > > ----- Original Message ----- > >> From: "Francesco Raviglione" <francescorav.es...@gmail.com> > >> To: firstname.lastname@example.org > >> Sent: Saturday, February 8, 2020 5:36:39 AM > >> Subject: Avoiding aggregation of "transfer" messages in Qpid Proton > >> > >> Hello, > >> I'm sorry about the several questions I'm posting on the mailing list > >> during these days, but, unfortunately, I'm struggling a bit in the > usage of > >> Qpid Proton (in particular, on the C version). > >> > >> One issue I noticed, and that I was not able to solve, is related to the > >> fact that, when following and adapting the send.c example (available > inside > >> the C API reference: > >> > https://qpid.apache.org/releases/qpid-proton-0.30.0/proton/c/api/send_8c-example.html > ), > >> all the AMQP "transfer" messages are aggregated and if, for instance, I > >> send 200 messages, one every 100 ms (using an additional Linux timer), I > >> have to wait for 20 seconds before seeing them on the receiving side (an > >> ActiveMQ broker, in my case), as all the 200 transfers are aggregated > into > >> a single, very big, AMQP message, which is sent only at the end of the > >> process. > >> > >> This is something I would like to avoid, as it makes end-to-end message > >> delivery (from producer, to broker, to consumer) too slow. > >> > >> Is there a way in which I can avoid this behaviour and make messages > being > >> sent immediately? > >> > >> Thank you very much in advance. > >> > > > > While you are in the PN_LINK_FLOW loop the calls to send_message are > only queueing > > messages to proton. Proton can't start sending any of them until you > return from the > > flow handler. > > > > What you could do is send only so many (N) messages in the flow handler > and then exit. > > Later the PN_DELIVERY callback will be activated and you can send more > messages there > > to keep the N messages in flight. > > While it is certainly true that you need to return control to the event > loop to allow any IO to happen, multiple calls to pn_message_send should > never be coalesced into a single large message as that method should > call pn_link_advance which creates a separate distinct message. > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: users-unsubscr...@qpid.apache.org > For additional commands, e-mail: users-h...@qpid.apache.org > >