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https://issues.apache.org/jira/browse/JENA-41?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Andy Seaborne resolved JENA-41.
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Resolution: Fixed
Marking as "fixed" because transactional TDB has been released a a prototype.
It provides MR+SW.
> Different policy for concurrency access in TDB supporting a single writer and
> multiple readers
> ----------------------------------------------------------------------------------------------
>
> Key: JENA-41
> URL: https://issues.apache.org/jira/browse/JENA-41
> Project: Jena
> Issue Type: New Feature
> Components: Fuseki, TDB
> Reporter: Paolo Castagna
> Assignee: Andy Seaborne
> Attachments: Transaction.java, TransactionHandle.java,
> TransactionHandler.java, TransactionManager.java,
> TransactionManagerBase.java, TransactionalDatasetGraph.java
>
>
> As a follow up to a discussion about "Concurrent updates in TDB" [1] on the
> jena-users mailing list, I am creating this as a new feature request.
> Currently TDB requires developers to use a Multiple Reader or Single Writer
> (MRSW) locking policy for concurrency access [2]. Not doing this could cause
> data corruptions.
> The MRSW is indeed a MR xor SW (i.e. while a writer has a lock, no readers
> are allowed and, similarly, if a reader has a lock, no writes are possible).
> This works fine in most of the situation, but there might be problems in
> presence of long writes or long reads.
> It has been suggested that a "journaled file access" could be used to solve
> the issue regarding a long write blocking reads.
> [1] http://markmail.org/message/jnqm6pn32df4wgte
> [2] http://openjena.org/wiki/TDB/JavaAPI#Concurrency
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