+1 (non-binding) Thanks, Zike Yang
On Thu, Feb 9, 2023 at 5:28 PM PengHui Li <codelipeng...@gmail.com> wrote: > > +1 (binding) > > Penghui > > > On Feb 9, 2023, at 17:24, Nozomi Kurihara <nkuri...@apache.org> wrote: > > > > +1 > > > > The LTS plan seems clear and helpful for users. > > > > Thanks, > > Nozomi > > > > 2023年2月9日(木) 5:44 Matteo Merli <matteo.me...@gmail.com>: > > > >> https://github.com/apache/pulsar/issues/15966 > >> > >> > >> ---------------------------------------------------------------------------------------- > >> > >> > >> ## Motivation > >> > >> In PIP-47 ( > >> https://github.com/apache/pulsar/wiki/PIP-47:-Time-Based-Release-Plan), we > >> have adopted a time-based release plan. This was the first attempt at > >> establishing a new principle on how releases should b > >> > >> The main two benefits of this approach have been: > >> > >> 1. Clarity for users and developers on when to expect a release > >> 2. Breaking a hard relationship between feature and release: a particular > >> feature will be included in the release if it is completed in time. > >> Otherwise, it will be bubbled up to the next release. > >> > >> The motivation for the current proposal is to extend the existing process > >> to address the issues that we have seen and that were left out of the scope > >> of PIP-47. > >> > >> ## Summary of existing issues in the process > >> > >> ### Short maintenance cycles for releases > >> > >> Since we're doing a 3 months release cycle, we are ending with 4 releases > >> done per year, even though it's more close to 3 releases. > >> > >> There is a high cost to maintain a lot of old releases, backport bug fixes, > >> and security patches. In general, we actively support the last 3 minor > >> releases while continuing to develop the next release. E.g., 2.8, 2.9, and > >> 2.10, while 2.11 is under development. > >> > >> The result is that a user adopting a particular release is forced to > >> upgrade in a < 1-year timeframe to keep up to date and use a supported > >> release. This timeframe is too short for many users as it imposes a lot of > >> forced upgrades, for which they are not prepared in terms of available time > >> and required effort. > >> > >> ### Live Upgrade/Downgrade compatibility path > >> > >> In Pulsar, we guarantee that users have a way to do live upgrades and > >> downgrades with zero downtime. > >> > >> This is very powerful because it gives them the freedom to upgrade to a new > >> release with the assurance of being able to roll back to the previous > >> release in case any functional or performance regressions are encountered. > >> > >> Today, this compatibility is guaranteed across minor versions. Eg: I can do > >> `2.7 -> 2.8 -> 2.7` as a live upgrade. > >> > >> What is not guaranteed is to "skip" releases. E.g.: `2.7 -> 2.9` might work > >> or not, but it's not guaranteed. In that case an intermediated upgrade > >> would be required: `2.7 -> 2.8 -> 2.9`. > >> > >> The reasons for which the "skip" upgrade might not work are multiple: > >> 1. Incompatible upgrade of some dependency (e.g., ZooKeeper) that might > >> not be compatible with an older version. > >> 2. Adoption of a new metadata format or data format on disk. > >> Every time we introduce a new incompatible format change (outside of a > >> regular Protobuf field addition), we do it in a 2 steps way: > >> - In a new release, we introduce the new feature/format, disabled by > >> default. The new release can read both old and new formats, though it keeps > >> writing the old format by default. > >> - In a subsequent release, we change the default to the new format > >> > >> Note that this consideration is separate from the compatibility between > >> clients and brokers, where we ***never*** break compatibility. The oldest > >> available Pulsar client can still talk with the newest Pulsar broker, and > >> vice versa, a new client, will be perfectly fine with an older broker > >> (except the new features won't be working). > >> > >> ### Releases getting delayed > >> > >> Another problem we have been experiencing is that release cycles have been > >> stretching considerably. Part of this has been because we have been > >> reaching the end of the release window, preparing a candidate, and then > >> taking a long time to flush out all issues found at the last minute in the > >> new release. > >> > >> We need to ensure that we have a date set in stone to deliver the release > >> to users. > >> > >> ## Proposal > >> > >> The proposal to address the above issues is composed of 2 parts. > >> > >> ### 1. Establish Long Term Support releases > >> > >> We need to provide a way for users to quickly understand the expected > >> lifecycle timeline of a given release and for that timeline to be long > >> enough not to be a constant update mandate. > >> > >> At the same time, we need to ensure that we maintainers are not spending > >> all the time just maintaining a huge list of old releases. > >> > >> For that, we can use the established concept of "Long Term Releases" or > >> LTS. > >> > >> We will perform LTS releases at a fixed cadence every 18 months, and we > >> will keep doing regular feature releases every 3 months as we're currently > >> doing. > >> > >> The LTS releases will be identified by being a `.0` version. For example: > >> * `3.0` -> LTS > >> * `3.1` -> regular release > >> * `3.2` -> regular release > >> * `4.0` -> LTS > >> > >> The major version bump will not carry any special meaning in terms of "big > >> features" included in the release or breaking API changes. Instead, it > >> would simply signal the type of the release. > >> > >> #### Compatibility between releases > >> > >> It will be guaranteed to be able to do a live upgrade/downgrade between one > >> LTS and the next one. > >> > >> For example: > >> > >> * `3.0 -> 4.0 -> 3.0` : OK > >> * `3.2 -> 4.0 -> 3.2` : OK > >> * `3.2 -> 4.4 -> 3.2` : OK > >> * `3.2 -> 5.0` : Not OK > >> > >> #### Release support expectation > >> > >> We will publish clear guidelines on the Pulsar website regarding the > >> expected timeline for which each release is supported and when the new > >> feature and LTS releases will be available. > >> > >> The support model will be: > >> > >> * LTS > >> * Released every 18 months > >> * Support for 24 months > >> * Security patches for 36 months > >> * Feature releases > >> * Released every 3 months > >> * Support for 6 months > >> * Security patches for 6 months > >> > >> This can be translated into: > >> * We support the last 2 LTS releases and the last 2 feature releases > >> * Security patches are provided for the past 3 LTS releases and 2 > >> feature releases > >> > >> Users are therefore encouraged to stay in an LTS release until they are > >> ready to jump into the next LTS unless they want to have access to some of > >> the features included in the latest feature releases. > >> > >> ### 2. Introduce a code-freeze period in the release cycle > >> > >> To address the problem with delayed release cycles, we are introducing a > >> code freeze period that will give us time to stabilize the release code > >> while not blocking new changes from being merged into master for the > >> subsequent version. > >> > >> This code-freeze will only be adopted for LTS/feature releases, not for any > >> patch release. > >> > >> In a 3 months release cycle, the last 3 weeks will be marked as a code > >> freeze period. The release manager will branch off from master, and he will > >> be responsible for selecting the changes that will be cherry-picked in the > >> release branch. > >> > >> From the code-freeze point, to minimize the risk of delaying the release, > >> only bug fixes involving a regression of behavior compared to a previous > >> release should be allowed. Occasional exceptions will be possible after > >> higher scrutiny of the change. > >> > >> At the moment of the code freeze, the release manager will also prepare a > >> release candidate in the same way we are doing today. Committers, > >> contributors, and users will test this RC to detect issues as early as > >> possible. > >> > >> A formal vote by the PMC will not be required at this stage (though any > >> disagreement should be sent out ASAP). > >> > >> After 1 week, if there are any changes, the release manager will provide a > >> new RC release that the community will test again. > >> > >> After 1 more week, if there are any changes, a third RC will be prepared, > >> and this will be submitted to vote to the PMC. Otherwise, the vote will be > >> held on an earlier RC release if no issues are found. > >> > >> The last 1 week will be used for the voting process and for updating Pulsar > >> website and the blog post announcing the release, which should (hopefully) > >> happen on the scheduled day. > >> > >> > >> -- > >> Matteo Merli > >> <matteo.me...@gmail.com> > >> >
