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From "Igor Seliverstov (JIRA)" <j...@apache.org>
Subject [jira] [Comment Edited] (IGNITE-5714) Implementation of suspend/resume for pessimistic transactions
Date Sun, 09 Jun 2019 16:26:00 GMT

    [ https://issues.apache.org/jira/browse/IGNITE-5714?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16859149#comment-16859149
] 

Igor Seliverstov edited comment on IGNITE-5714 at 6/9/19 4:25 PM:
------------------------------------------------------------------

Rolling update is out of scope there since Ignite doesn't support it.

I meant you may use a thread local variable to hold explicit lock version (with a counter
represents how many locks you hold). At first lock operation you generate a new GridCacheVersion,
put it into the variable and use it for locking. On locks release you decrement the counter
and remove the version as soon as the counter becomes zero. So you have tx version and explicit
lock version at the hand. This way you don't need txFinishSync since there is nothing to defend
with it.

Possible some changes at message layer needed.


was (Author: gvvinblade):
Rolling update its or of scope there since Ignite doesn't support it.

I meant you may use a thread local variable to hold explicit lock version (with a counter
represents how many locks you hold). At first lock operation you generate a new GridCacheVersion,
put it into the variable and use it for locking. On locks release you decrement the counter
and remove the version as soon as the counter becomes zero. So you have tx version and explicit
lock version at the hand. This way you don't need txFinishSync since there is nothing to defend
with it.

Possible some changes at message layer needed.

> Implementation of suspend/resume for pessimistic transactions
> -------------------------------------------------------------
>
>                 Key: IGNITE-5714
>                 URL: https://issues.apache.org/jira/browse/IGNITE-5714
>             Project: Ignite
>          Issue Type: Sub-task
>          Components: general
>            Reporter: Alexey Kuznetsov
>            Assignee: Aleksey Plekhanov
>            Priority: Major
>              Labels: iep-34
>          Time Spent: 4h 10m
>  Remaining Estimate: 0h
>
> Support transaction suspend()\resume() operations for pessimistic transactions. Resume
can be called in another thread.
>    _+But there is a problem+_: Imagine, we started pessimistic transaction in thread
T1 and then perform put operation, which leads to sending GridDistributedLockRequest to another
node. Lock request contains thread id of the transaction. Then we call suspend, resume in
another thread and we also must send messages to other nodes to change thread id. 
> It seems complicated task.It’s better to get rid of sending thread id to the nodes.
> We can use transaction xid on other nodes instead of thread id. Xid is sent to nodes
in GridDistributedLockRequest#nearXidVer
>    _+Proposed solution+_ : On remote nodes instead of thread id of near transaction GridDistributedLockRequest#threadId
use its xid GridDistributedLockRequest#nearXidVer.
> Remove usages of near transaction's thread id on remote nodes.



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