[jira] [Closed] (JCR-3888) Possible dead lock in SharedItemStateManager in clustered environment

["Davide Giannella (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/JCR-3888?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Davide Giannella closed JCR-3888.
---------------------------------

Bulk close for 2.11.0

> Possible dead lock in SharedItemStateManager in clustered environment
> ---------------------------------------------------------------------
>
>                 Key: JCR-3888
>                 URL: https://issues.apache.org/jira/browse/JCR-3888
>             Project: Jackrabbit Content Repository
>          Issue Type: Bug
>    Affects Versions: 2.10.1
>            Reporter: Unico Hommes
>            Assignee: Unico Hommes
>             Fix For: 2.10.2, 2.11.0
>
>
> When using clustering SharedItemStateManager#Update#begin sets a lock on the database (line 573) and subsequently a write lock is set (line 579):
> {code:java}
>             // let listener know about change
>             try {
>                 eventChannel.updateCreated(this); // line 573
>             } catch (ClusterException e) {
>                 throw new ItemStateException(e.getMessage(), e);
>             }
>             try {
>                 writeLock = acquireWriteLock(local); // line 579
>             } finally {
>                 if (writeLock == null) {
>                     eventChannel.updateCancelled(this); // line 582
>                 }
>             }
> {code}
> In SharedItemStateManager#Update#end the update is committed and the write lock released:
> {code:java}
>                 eventChannel.updateCommitted(this, path); // line 849
>                 setAttribute(ATTRIBUTE_UPDATE_SIZE, null);
>                 if (writeLock != null) {
>                     // exception occurred before downgrading lock
>                     writeLock.release();
>                     writeLock = null;
>                 } else if (readLock != null) {
>                     try {
>                         if (succeeded) {
>                             /* dispatch the events */
>                             events.dispatch();
>                         }
>                     } finally {
>                         readLock.release(); // 863
>                     }
>                 }
> {code}
> However, the implementation of eventChannel#updateCommitted in ClusterNode#WorkspaceUpdateChannel#updateCommitted has the following code:
> {code:java}
>                 long journalUpdateSize = record.update(); // line 700
>                 long recordRevision = record.getRevision();
>                 setRevision(recordRevision); // line 703
> {code}
> The database lock is freed during the call to update the record on line 700.
> If a contending thread now sets a database lock at SharedItemStateManager:573 before this thread can set the revision in the database at ClusterNode:703 we have a dead lock. This is because this thread holds the write lock in SharedItemStateManager causing the contending thread to wait at SharedItemStateManager:579 while the contending thread holds the database lock causing this thread to wait at ClusterNode:703



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