Hi,
I've got a system which can sometimes be a bit bursty, which would exhaust
system memory if the queues were left unchecked. Therefore I've been using ring
queues, which solve the problem quite nicely, apart from what happens to the
"excess" messages. Ideally I'd like to buffer them to disk and process them at
a later, quieter time. I've been digging around and can see a few options:
1) 0.24 will have flow to disk, which would be perfect but sometimes my
messages are quite big (eg. 10MB) and this requires messages to be smaller than
a page. Is this limitation likely to be removed soon?
2) 0.24 allows a "backup engine" to take over a loaded queue (QPID-4650), but
this looks like it'd require a fair bit of legwork to implement said engine.
3) alternate-exchanges. These look pretty good for my needs, but I can't seem
to get them to work! From reading some documentation, I thought they'd good
with a limit policy of reject - MRG 2 Installation & Configuration guide, 4.8.2
says for an alternate exchange specified for a queue: "Messages that are
acquired and then rejected by a message consumer". However if I run the test
below, messages only get routed to the alternate exchange when the queue is
destroyed while containing messages, and not when messages are rejected because
the queue is full. Presumably calling Session::reject would cause it to go to
the alternate exchange, but should a limit policy of reject be the same?
Any ideas very welcome!
Jimmy
--8<--
qpid-config add exchange headers test1
qpid-config add exchange headers test1-overflow
# drain for messages in normal case
./drain -f "normal; { create: receiver, node: {type: queue, x-declare:
{exclusive: True, alternate-exchange: 'test1-overflow', arguments:
{'qpid.max_size': 1024, 'qpid.policy_type': 'reject'}}, x-bindings: [{exchange:
test1, arguments:{x-match:any, data-format: xyz}}]}}"
# drain for messages in overflow case
./drain -f "overflow; { create: receiver, node: {type: queue, x-declare:
{exclusive: True, arguments: {'qpid.max_size': 1024000, 'qpid.policy_type':
'ring'}}, x-bindings: [{exchange: test1-overflow, arguments:{x-match:any,
data-format: xyz}}]}}"
./spout --content test -c 5 --property data-format=xyz test1
# works as expected, messages received by normal drain
./spout --content test -c 5 --property data-format=xyz test1-overflow
# works as expected, messages received by overflow drain
# Now ctrl-c normal drain, and queue will remain
# Send loads of messages, fills up q1
./spout --content test -c 500 --property data-format=xyz test1
# Blocks... and no messages sent to overflow drain
qpid-config del queue normal --force
# now messages appear in overflow drain
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
