The number of messages in unacknowledged state for a subscription

[qwehjkadhaskjf]

background

right now, I see many metrics about unacknowledged messages or consume delay, but I haven't got a metric about 'The number of messages in unacknowledged state for a subscription'

metrics

• pulsar_subscription_back_log
  it's a entry level metric
• pulsar_storage_backlog_size
  it's a topic level, not subscription level

question

how can I get the number of messages in unacknowledged state for a subscription ?

[lhotari]

You can use the Pulsar Admin API's stats endpoint (In the pulsar-admin command line too pulsar-admin topics stats) to get the information. More details in https://pulsar.apache.org/docs/3.3.x/administration-stats/ .

unackedMessages	The number of unacknowledged messages for the subscription, where an unacknowledged message is one that has been sent to a consumer but not yet acknowledged. This field is only meaningful when using a subscription that tracks individual message acknowledgment.

[qwehjkadhaskjf]

thank U for your reply
it's helpful to me, however, I was told that this stat may cause greater pressure on pulsar ？

[lhotari]

thank U for your reply
it's helpful to me, however, I was told that this stat may cause greater pressure on pulsar ？

It depends on many factors. You could test it yourself and see how your use of the API performs.

[qwehjkadhaskjf]

Thank U very much