max_ack_pending

This is the amount of QoS 1 messages the server can send to a subscription without receiving any PUBACK for those messages. The valid range is [0..65535].

The total of subscriptions' max_ack_pending on a given session cannot exceed 65535. Attempting to create a subscription that would bring the total above the limit would result in the server returning 0x80 in the SUBACK for this subscription.

Due to how the NATS Server handles the MQTT # wildcard, each subscription ending with # will use 2 times the max_ack_pending value. Note that changes to this option is applied only to new subscriptions.

• Default value: 100
• Hot reloadable: Yes
• Aliases: max_pending, max_inflight

Values