Hello All,
We have a Pulsar cluster with a topic that uses 3 partitions.
We are using Pulsar as a queue, a shared subscription.
The number of consumers goes up and down constantly (we look at the size of
the queue to scale up and down our number of consumers)
We have observed that some messages are consumed extremely delayed (even
when the median age is just a few milliseconds)
The median age of the messages received is usually just a few milliseconds,
with some probably in a few seconds (caused by we need to scale up our
consumer cluster)
But some messages are consumed minutes or even hours after they have been
queued.
Our app usually starts consuming messages with a large age (redeliveries
=0) and then it eventually processes messages with an age of just a few
milliseconds.
I found that whenever the age was very very large (hours), it was a
redelivery. (therefore, the large age at least has an explanation)
My guess is that a new consumer is processing the entire history in the
topic, looking for messages that had not been acknowledged. (since the
initial position is set to Earliest)
a) How can I avoid these "gaps" of messages apparently not being consumed
timely? Why are these not being delivered to the consumers already up and
running?
b) How can I reduce the time taken for a message to be redelivered?
Here is how we create the Pulsar Consumer:
consumer =
client
.newConsumer(JSONSchema.of(Payload.class))
.topic(requestQueue)
.subscriptionType(SubscriptionType.Shared)
.subscriptionInitialPosition(SubscriptionInitialPosition.Earliest)
.subscriptionName("queue-sample")
.receiverQueueSize(1)
.subscribe();
Any pointers are welcome.
Thank you
