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https://issues.apache.org/jira/browse/HDFS-1557?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Ivan Kelly updated HDFS-1557:
-----------------------------
Status: Patch Available (was: Open)
Addressed Suresh's comments.
{quote}
NNStorage use synchronized method errorDirectory() to notify listeners of
error. The listener implement synchrnonized method to handle the error. Is it
possible for listeners (say FSImage) to be calling from its synchronized
section, a synchronized method on NNStorage? This could cause dead locks.
{quote}
NNStorage now using CopyOnWriteArrayLists now, so errorDirectory is no longer
synchronised. (see below)
{quote}
format(), registerListener() should this be synchronized as it manipulates
listeners?
{quote}
listeners is now a CopyOnWriteArrayList.
{quote}
Storage#storageDirs are manipulated in NNStorage and Storage. The way it is
done is not thread safe. Perhaps the existing code is thread safe it self. This
could be addressed in a separate jira.
{quote}
Well spotted. I dont think any of this is threadsafe, given that storageDirs is
modified in numerous places, and is being constantly being iterated over which
could trigger a concurrent modification exception.
I've made storageDirs and removedStorageDirs a CopyOnWriteArrayList now.
{quote}
Consider making the following method package private: isPreUpgradableLayout(),
setRestoreFailedStorage() (both variants), attemptResotreRemovedStorage()...
The are other methods that could only be used with in the package. This makes
sure this is not a class for outside consumption. I would further consider
making NNStorage non public class.
{quote}
Tightened up all the access privileges which I could on that class now to
package private. Unfortunately, NNStorage itself must remain public because of
UpgradeUtilities in testing being in a different package.
> Separate Storage from FSImage
> -----------------------------
>
> Key: HDFS-1557
> URL: https://issues.apache.org/jira/browse/HDFS-1557
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: name-node
> Affects Versions: 0.21.0
> Reporter: Ivan Kelly
> Assignee: Ivan Kelly
> Fix For: 0.23.0
>
> Attachments: HDFS-1557-branch-0.22.diff, HDFS-1557-branch-0.22.diff,
> HDFS-1557-trunk.diff, HDFS-1557-trunk.diff, HDFS-1557-trunk.diff,
> HDFS-1557.diff, HDFS-1557.diff, HDFS-1557.diff, HDFS-1557.diff, HDFS-1557.diff
>
>
> FSImage currently derives from Storage and FSEditLog has to call methods
> directly on FSImage to access the filesystem. This JIRA is to separate the
> Storage class out into NNStorage so that FSEditLog is less dependent on
> FSImage. From this point, the other parts of the circular dependency should
> be easy to fix.
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