Motivation

Pulsar has the limit of max unacked messages at

• broker level
• subscription level
• consumer level

In the product environment(maxUnackedMessagesPerBroker > 0), we met the subscription blocked unexpectedly even if we have set the limit of max un-ack for subscription and consumer big enough.

After troubleshooting, this is caused by the wrong default value of maxUnackedMessagesPerSubscriptionOnBrokerBlocked which is 0.16 now.

For example, if set maxUnackedMessagesPerBroker to 60000, the BrokerService#maxUnackedMsgsPerDispatcher should be 60000 * 1/6 = 10000 by default, but now it's 600

 this.maxUnackedMessages = pulsar.getConfiguration().getMaxUnackedMessagesPerBroker();
            this.maxUnackedMsgsPerDispatcher = maxUnackedMessages
                    * pulsar.getConfiguration().getMaxUnackedMessagesPerSubscriptionOnBrokerBlocked() / 100;

Modifications

• correct the value of maxUnackedMsgsPerDispatcher
• modify the related tests

Verifying this change

• Make sure that the change passes the CI checks.

This change is already covered by existing tests, such as (please describe tests).

Does this pull request potentially affect one of the following parts:

If the box was checked, please highlight the changes

• Dependencies (add or upgrade a dependency)
• The public API
• The schema
• The default values of configurations
• The threading model
• The binary protocol
• The REST endpoints
• The admin CLI options
• The metrics
• Anything that affects deployment

Documentation

• doc
• doc-required
• doc-not-needed
• doc-complete

Matching PR in forked repository

PR in forked repository:

aloyszhang#22