[infinispan-issues] [JBoss JIRA] Commented: (ISPN-318) Locking could optionally be "fair"

[Sanne Grinovero (JIRA)]

    [ https://jira.jboss.org/jira/browse/ISPN-318?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12501548#action_12501548 ] 

Sanne Grinovero commented on ISPN-318:
--------------------------------------

Manik, I tried some ways this weekend, but it looks like following the same strategy of ReentrantLock.FairSync is quite hard and errorprone: to reuse the parent's code it is a requirement that the reentrancy key is of type Thread, which is not true in Infinispan's case, so much code needs to be written to reimplement the queue of waiting objects. I would probably need to copy and adapt large code snippets of JVM, which is legally not an option. 

I'm also not sure if it would be ok to "park" the requesting thread, anyway some more discussion would be required. 

In my opinion you can reject this or move to future releases, I'll find a better alternative for what I need.

> Locking could optionally be "fair"
> ----------------------------------
>
>                 Key: ISPN-318
>                 URL: https://jira.jboss.org/jira/browse/ISPN-318
>             Project: Infinispan
>          Issue Type: Feature Request
>          Components: Locking and Concurrency
>    Affects Versions: 4.0.0.CR3
>            Reporter: Manik Surtani
>            Assignee: Sanne Grinovero
>             Fix For: 4.0.0.GA
>
>
> Would require a number of changes:
> 1.  A new boolean field and getter/setter in Configuration.LockingType (follow patterns of other boolean flags here to ensure proper XSD and parser generation), perhaps called "useFairLocking", defaults to false.
> 2.  Modify LockManagerImpl to pass this flag into the LockContainer implementations (in LockManagerImpl#startLockManager())
> 3.  Modify the 4 concrete LockContainer implementations to use this flag when creating new locks.  Implementations that use JDK reentrant locks just need to pass the fairness flag into the ReentrantLock constructor.
> 4.  Modify OwnableReentrantLock to handle fairness.  Referring to the JDK's ReentrantLock.FairSync may help.  OwnableReentrantLock combines features of the JDK ReentrantLock and ReentrantLock.NonFairSync into a single class, so perhaps the best approach is to create a new OwnableFairReentrantLock.

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