+1 (non)
On 2022/01/14 03:23:37 mattison chao wrote: > +1 (non-binding) > > Best, > Mattison > > On Fri, 14 Jan 2022 at 11:19, Hang Chen <chenh...@apache.org> wrote: > > > +1 (binding) > > > > Best, > > Hang > > > > Zhanpeng Wu <wuzhanpeng.w...@gmail.com> 于2022年1月14日周五 10:37写道： > > > > > > This is the voting thread for PIP-129. It will stay open for at least 48 > > > hours. Pasted below for quoting convenience. > > > > > > ---- > > > > > > https://github.com/apache/pulsar/issues/13526 > > > > > > ---- > > > > > > ## Motivation > > > > > > Under the current ledger-trimming design in > > > > > `org.apache.bookkeeper.mledger.impl.ManagedLedgerImpl#internalTrimLedgers`, > > > we need to collect those ledgers that need to be deleted first, and then > > > perform the asynchronous deletion of the ledger concurrently, but we do > > not > > > continue to pay attention to whether the deletion operation is completed. > > > If the meta-information update has been successfully completed but an > > error > > > occurs during the asynchronous deletion, the ledger may not be deleted, > > but > > > at the logical level we think that the deletion has been completed, which > > > will make this part of the data remain in the storage layer forever (such > > > as bk). As the usage time of the cluster becomes longer, the residual > > data > > > that cannot be deleted will gradually increase. > > > > > > In order to achieve this goal, we can separate the logic of > > > meta-information update and ledger deletion. In the trimming process, we > > > can first mark which ledgers are deletable, and update the results to the > > > metadatastore. We can perform the deletion of marked ledgers > > asynchronously > > > in the callback of updating the meta information, so that the original > > > logic can be retained seamlessly. Therefore, when we are rolling upgrade > > or > > > rollback, the only difference is whether the deleted ledger is marked for > > > deletion. > > > > > > To be more specific: > > > 1. for upgrade, only the marker information of ledger has been added, and > > > the logical sequence of deletion has not changed. > > > 2. for rollback, some ledgers that have been marked for deletion may not > > be > > > deleted due to the restart of the broker. This behavior is consistent > > with > > > the original version. > > > > > > In addition, if the ledger that has been marked is not deleted > > > successfully, the marker will not be removed. So for this part of > > ledgers, > > > every time trimming is triggered, it will be deleted again, which is > > > equivalent to a check and retry mechanism. > > > > > > ## Goal > > > > > > We need to modify some logic in > > > > > `org.apache.bookkeeper.mledger.impl.ManagedLedgerImpl#internalTrimLedgers` > > > so that the ledger deletion logic in ledger-trimming is split into two > > > stages, marking and deleting. Once the marker information is updated to > > the > > > metadatastore, every trimming will try to trigger the ledger deletion > > until > > > all the deleteable ledgers are successfully deleted. > > > > > > ## Implementation > > > > > > This proposal aims to separate the deletion logic in ledger-trimming, so > > > that `ManagedLedgerImpl#internalTrimLedgers` is responsible for marking > > the > > > deletable ledgers and then perform actual ledger deletion according to > > the > > > metadatastore. > > > > > > Therefore, the entire trimming process is broken down into the following > > > steps: > > > > > > 1. mark deletable ledgers and update ledger metadata. > > > 2. do acutual ledger deletion after metadata is updated. > > > > > > For step 1, we can store the marker of deletable information in > > > `org.apache.bookkeeper.mledger.impl.ManagedLedgerImpl#propertiesMap`. > > When > > > retrieving the deleted ledger information, we can directly query by > > > iterating `propertiesMap`. If this solution is not accepted, maybe we can > > > create a new znode to store these information, but this approach will not > > > be able to reuse the current design. > > > > > > For step 2, we can perform the deletion of marked ledgers asynchronously > > in > > > the callback of updating the meta information. And every trimming will > > > trigger the check and delete for those deleteable ledgers. > > > > > > Related PR: https://github.com/apache/pulsar/pull/13575 > > >
