[improve][broker] Add a random value upto 5% to avoid rollover multiple cursor ledgers

[TakaHiR07]

Motivation

If topic has multiple subscriptions, the cursor ledgers of subscriptions may rollover at the same time, which may bring additional pressure on zk.

Topic ledger has added the random value to avoid rollover at the same time. While cursor ledger do not have this mechanism.

pulsar/managed-ledger/src/main/java/org/apache/bookkeeper/mledger/impl/ManagedLedgerImpl.java

Lines 411 to 412 in 6d9f9ce

	// Get the next rollover time. Add a random value upto 5% to avoid rollover multiple ledgers at the same time
	this.maximumRolloverTimeMs = getMaximumRolloverTimeMs(config);

Modifications

Also add the 5% random value in rollover cursor ledger.

Verifying this change

• Make sure that the change passes the CI checks.

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

[lhotari]

does this get called when the config changes?
Could we add a updateConfig method to ManagedCursorImpl and handle the logic there?
There's no need to add the method to ManagedCursor interface since ManagedLedgerImpl only includes ManagedCursorImpl instances.

[TakaHiR07]

You mean that we add a updateConfig method to ManagedCursorImpl, which involve updateRolloverThresholds() and setThrottleMarkDelete() ?

Currently I add updateRolloverThresholds() to ManagedCursorImpl. While setThrottleMarkDelete() is still in ManagedCursor interface

[lhotari]

You mean that we add a updateConfig method to ManagedCursorImpl, which involve updateRolloverThresholds() and setThrottleMarkDelete() ?

yes

[lhotari]

maybe configUpdated is a better method name, since the method is an event handler for config updates.

[TakaHiR07]

That is reasonable. I have modified.