Is the AckPolicy object in M3 C++ equivalent to
SubscriptionSettings.autoAck in M4?
It appears AckPolicy has been discontinued for the M4 API, so I
"converted" my code as shown below. With the M4 code I run an experiment
that I also used with M3, but in M4 the broker crashes. Details
below.
// Old M3 Code
Session session = connection.newSession();
AckPolicy subscrptn_ack_policy(0);
SubscriptionManager subscriptions(session);
subscriptions.setAckPolicy(subscrptn_ack_policy);
subscriptions.subscribe(local_my_queue, my_queue_name, my_queue_name);
// M4 Code: Is this equiv to M3 code?
Session session = connection.newSession();
SubscriptionSettings subscrptn_setngs;
subscrptn_setngs.autoAck= 0;
SubscriptionManager subscriptions(session);
subscriptions.subscribe(local_my_queue, my_queue_name,
subscrptn_setngs, my_queue_name);
I started the broker as follows and both publisher (1) and consumers (4,
8, 16, or 32) connect via TCP and with no delay as well:
$ qpidd --auth no --default-queue-limit 4294967295 --tcp-nodelay
M4 Code yields this error message on the broker. This did not occur with
same experiment in M3.
resource-limit-exceeded: resource-limit-exceeded: Policy exceeded on
6ed11fcb-3477-4fea-981
b-719306be4fd8 by message 682489 of size 524288 , policy: size:
max=4294967295, current=429
4458544; count: unlimited; type=flow_to_disk
(qpid/broker/QueuePolicy.cpp:74)
Here is the experiment described: Sequentially send 10000 messages each
of the following byte sizes 1, 2, 4, 8 ,16, 32, 64, 128, 256, 512, 1024,
2048, 4096, 8192 to amq.fanout exchange. Continue sequential sending but
with 1000 measages each
of the following byte 16384, 32768, 65536, 131072, 262144 and 524288. The
crash happens during the sending of the 1000, 524288 byte sized messages.
This crash happens at same time/place whether I have 4, 8, 16, or 32
consumers bound to the broker.
My solution was to set subscrptn_setngs.autoAck= 1, and the problem does
not occur.
We were originally using a 0 ack policy setting in M3
in hopes of squeezing out faster performance, but it turns out M4 gives us
slightly better performance even with autoAck= 1.
Thanks in advance for any insights as what is happening and why the
difference between the 2 releases.
Greg
