+1 Penghui
On Wed, Dec 22, 2021 at 7:22 AM Matteo Merli <mme...@apache.org> wrote: > https://github.com/apache/pulsar/issues/13304 > > Following the discussion, I have updated the proposal to also include > the deprecation and renaming of the config setting name to > `metadataSessionExpiredPolicy`. > > > > ------- > ## Motivation > > After all the work done for PIP-45 that was already included in 2.8 and 2.9 > releases, it enabled the concept of re-acquirable resource locks and leader > election. > > Another important change was to avoid doing any deferrable metadata > operation > when we know that we are not currently connected to the metadata service. > > Finally, that enabled to stabilize in 2.9 the configuration setting that > allows > brokers to continue operating in a safe mode when the session with > ZooKeeper > expires. > > The way it works is that, when we lose a ZooKeeper session, the data plane > will > continue to work undisturbed, relying on the BookKeeper fencing to avoid > any > inconsistencies. > > New topics are not able to get started, but existing topics will see no > impact. > > The original intention for shutting down the brokers was to ensure that we > would automatically go back to a consistent state, with respect to which > resources are "owned" in ZooKeeper by a given broker. > > With the re-acquirable resource locks, that problem was solved and > thoroughly > tested to be robust. > > ## Proposed changes > > In 2.10 release, for the setting: > > ```properties > # There are two policies to apply when broker metadata session > expires: session expired happens, "shutdown" or "reconnect". > # With "shutdown", the broker will be restarted. > # With "reconnect", the broker will keep serving the topics, while > attempting to recreate a new session. > zookeeperSessionExpiredPolicy=shutdown > ``` > > Deprecate the old setting and rename it to > `metadataSessionExpiredPolicy`, with default value set to `reconnect`. >
