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https://issues.apache.org/jira/browse/IGNITE-19519?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Vadim Pakhnushev updated IGNITE-19519:
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Summary: Deployment unit removal (was: Add remove verification after
restart )
> Deployment unit removal
> -----------------------
>
> Key: IGNITE-19519
> URL: https://issues.apache.org/jira/browse/IGNITE-19519
> Project: Ignite
> Issue Type: New Feature
> Reporter: Mikhail Pochatkin
> Assignee: Vadim Pakhnushev
> Priority: Major
> Labels: iep-103, ignite-3
>
> h3. Deployment unit removal process
> The deployment unit must be removed from all cluster nodes. In order to
> achieve this the following must be implemented:
> # Change {{clusterDURecord.status}} to {{OBSOLETE}} value. This operation
> could fail because another process has already changed status to {{OBSOLETE}}
> or {{REMOVING}} value. It is also impossible to start an undeployment process
> in case the deployment process is still in progress.
> After this step the deployment unit is not available for new code execution.
> Code execution in progress still can use this deployment unit.
> # Meta storage event must be fired to all target nodes due to a change of
> {{{}clusterDURecord.status{}}}.
> # After receiving this event by the target node the system must change
> {{nodeDURecord.status}} to{{ }}{{OBSOLETE}} value.
> # The node waits for finishing of all code executions in progress that
> depend on this deployment unit. As soon as all code executions are finished
> {{nodeDURecord.status}} must be changed to {{REMOVING}} value.
> From this point it is impossible to use the deployment unit for code
> execution neither for new tasks nor for old tasks (the second is impossible
> due to the invariant that all old tasks are finished).
> # For each change of {{nodeDURecord.status}} to {{REMOVING}} value the
> system is able to receive an event from meta storage and check that all nodes
> have {{{}nodeDURecord.status == REMOVING{}}}. If the condition is met then
> {{clusterDURecord.status}} must be changed to {{REMOVING}} too.
> # Now the deployment unit can be removed from each target node and, after
> it, remove corresponding status records.
> # For each removal of {{nodeDURecord}} record from meta storage the system
> is able to receive an event from meta storage and check that there are no any
> {{nodeDURecord}} records for the given deployment unit. Now the system must
> remove the {{clusterDURecord}} record for the deployment unit.
>
> Note that If the deployment unit was removed then there are no any class
> loaders associated with this deployment unit. Eventually the class loader
> should be collected by GC and all classes must be unloaded from JVM. It is
> the critical requirement in order to avoid memory leaks related to multiple
> class loading/unloading.
> h3. Node restart during unit removal process
> If a target node was restarted during deployment unit removal process then
> the node must find all deployment units with clusterDURecord.status ==
> OBSOLETE or clusterDURecord.status == REMOVING for restarted node and finish
> deployment unit removal process as described in the previous section.
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