[jira] [Updated] (AMBARI-4323) Add ability to an agent to clear the ActionQueue

["Mahadev konar (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/AMBARI-4323?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Mahadev konar updated AMBARI-4323:
----------------------------------

    Fix Version/s:     (was: 1.6.0)
                   1.7.0

> Add ability to an agent to clear the ActionQueue
> ------------------------------------------------
>
>                 Key: AMBARI-4323
>                 URL: https://issues.apache.org/jira/browse/AMBARI-4323
>             Project: Ambari
>          Issue Type: Improvement
>          Components: agent, controller
>    Affects Versions: 1.5.0
>            Reporter: Dmitry Lysnichenko
>            Assignee: Dmitry Lysnichenko
>             Fix For: 1.7.0
>
>
> h2. Implementation proposal:
> 1. Add a new command type CANCEL_COMMAND to agent-server protocol. CANCEL_COMMAND contains identifier (task_id + stage_id) of an exact command for cancellation and an arbitrary text string (reasoning for command cancelation).  So CANCEL_COMMAND looks like 
> {code}
> {
>   target_task_id: "4-3"
>   reason: "Aborted by user via API"
> }
> {code}
> 2. At the server side, commands of this type are issued automagically when tasks are considered timed out. I'm going to do that here: org.apache.ambari.server.actionmanager.ActionScheduler#processInProgressStage. Also we will implement (in a separate jira) an ability to cancel arbitrary order via server API. A new method addCancelCommandAction() at org/apache/ambari/server/controller/AmbariCustomCommandExecutionHelper.java will become the endpoint that forms up a new CANCEL_COMMAND.
> 3. At the agent side, CANCEL_COMMANDs are executed inside Controller.py right after arrival (they are not put into ActionQueue). If command mentioned by the CANCEL_COMMAND is not present in the ActionQueue (it is already in progress or completed) and command is not IN_PROGRESS, CANCEL_COMMAND is silently ignored. After executing  CANCEL_COMMAND, agent starts executing next EXECUTION_COMMAND from the ActionQueue.
> 4. Also, agent clears entire action queue on every registration (disconnected from the server or the re-registration is requested). I'm going to add an appropriate logic to src.main.python.ambari_agent.Controller.Controller#registerAndHeartbeat. The motivation for doing that is to make a recovery from the network/server fail more reliable and fast (agent will have an empty ActionQueue and will be able to execute new EXECUTION_COMMANDS and STATUS_COMMANDS immediately after registration). Currently, after re-registration agent is locked up and continues to execute stale EXECUTION_COMMANDS.
> Also I'll recheck that server discards tasks for host when heartbeat is lost
> 5.When appropriate CANCEL_COMMAND is received, EXECUTION_COMMAND is cancelled even if it is IN_PROGRESS (the process is killed). 
> 6. Agent forms up command reports for cancelled commands just like it is done for COMPLETE and FAILED commands. Command statuses for cancelled commands are set to FAILED. I did not find enough reasoning for adding a new command report state CANCELED, feedback is welcome. Reasoning text (why command has been cancelled) is appended to command stderr and to command stdout.
> So, cancelled command report looks like:
> {code}
> {
>   taskId: "4-3"
>   status : FAILED
>   stderr : ".... some text ... \n Command was aborted because of: Aborted by user via API "
>   stdout : ".... some text ... \n Command was aborted because of: Aborted by user via API "
>   exitcode: 999
> }
> {code}
> Also, I'm going to fix a naming issue at org.apache.ambari.server.actionmanager.ActionScheduler#processInProgressStage . Here, we pass a stage timeout as a parameter for org.apache.ambari.server.actionmanager.ActionScheduler#timeOutActionNeeded, but the variable name is misleading (taskTimeout)
> This implementation should also solve another related jira AMBARI-4324



--
This message was sent by Atlassian JIRA
(v6.2#6252)