Maxim, In the addition to my answer, I propose to divide the whole task into 2 steps: 1) Physical consistency recovery before PME. 2) Logical consistency recovery before PME.
The first step can be done before the discovery manager start, as it no needs any information about caches, it operates only with pages binary data. On this step, we can do points a) and b) from answer 3) and fsync the state of the page memory. The second step is much harder to implement as it requires major changes in Discovery SPI. Discovery node join event is triggered on coordinator after node successfully joins to the cluster. To avoid it, we should introduce a new state of node and fire discovery event only after logical recovery has finished. I doubt that logical recovery consumes a lot of time of exchange, but physical recovery does, as it performs fsync on disk after restore. 2018-08-03 17:46 GMT+03:00 Pavel Kovalenko <jokse...@gmail.com>: > Hello Maxim, > > 1) Yes, Discovery Manager is starting after GridCacheProcessor, which > starts GridCacheDatabaseSharedManager which invokes readMetastorage on > start. > > 2) Before we complete the local join future, we create and add Exchange > future on local node join to ExchangeManager. So, when local join future > completes, first PME on that node should be already run or at least there > will be first Exchange future in Exchange worker queue. > > 3) I don't exactly understand what do you mean saying "update obsolete > partition counter", but the process is the following: > a) We restore page memory state (which contain partition update > counters) from the last checkpoint. > b) We repair page memory state using physical delta records from WAL. > c) We apply logical records since last checkpoint finish marker. > During this iteration, if we meet DataRecord we increment update counter on > appropriate partition. NOTE: This phase currently happens during exchange. > After that partition exchange starts and information about actual > update counters will be collected from FullMessage. If partition counters > are outdated, rebalance will start after PME end. > > 4) I think yes because everything that you need is cache descriptors of > currently started caches on the grid. Some information can be retrieved > from the static configuration. Information about dynamically started caches > can be retrieved from Discovery Data Bag received when a node joins to > ring. See org.apache.ignite.internal.processors.cache.ClusterCachesInfo# > onGridDataReceived > > 5) I think the main problem is that metastorage and page memory share one > WAL. But If this phase will happen before PME is started on all cluster > nodes, I think it's acceptable that they will use 2 WAL iterations. > > 2018-08-03 10:28 GMT+03:00 Nikolay Izhikov <nizhi...@apache.org>: > >> Hello, Maxim. >> >> > 1) Is it correct that readMetastore() happens after node starts> but >> before including node into the ring?> >> >> I think yes. >> You can have some kind of metainformation required on node join. >> >> > 5) Does in our final solution for new joined node readMetastore> and >> restoreMemory should be performed in one step? >> >> I think, no. >> >> Meta Information can be required to perform restore memory. >> So we have to restore metainformation in first step and restore whole >> memory as a second step. >> >> В Пт, 03/08/2018 в 09:44 +0300, Maxim Muzafarov пишет: >> > Hi Igniters, >> > >> > >> > I'm working on bug [1] and have some questions about the final >> > implementation. Probably, I've already found answers on some of >> > them but I want to be sure. Please, help me to clarify details. >> > >> > >> > The key problem here is that we are reading WAL and restoring >> > memory state of new joined node inside PME. Reading WAL can >> > consume huge amount of time, so the whole cluster stucks and >> > waits for the single node. >> > >> > >> > 1) Is it correct that readMetastore() happens after node starts >> > but before including node into the ring? >> > >> > 2) Is after onDone() method called for LocalJoinFuture on local >> > node happend we can proceed with initiating PME on local node? >> > >> > 3) After reading checkpoint and restore memory for new joined >> > node how and when we are updating obsolete partitions update >> > counter? At historical rebalance, right? >> > >> > 4) Should we restoreMemory for new joined node before PME >> > initiates on the other nodes in cluster? >> > >> > 5) Does in our final solution for new joined node readMetastore >> > and restoreMemory should be performed in one step? >> > >> > >> > [1] https://issues.apache.org/jira/browse/IGNITE-7196 >> > >
