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https://issues.apache.org/jira/browse/ACCUMULO-2743?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13983289#comment-13983289
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Josh Elser commented on ACCUMULO-2743:
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The easiest approach that doesn't involve touching a bunch of other code would
be to add some new methods on the API which can work around this. Since things
like setting an iterator can present stale data to both the client or the
server, we could implement something that invalidates the local cache to force
a fresh read. This would not be very scalable though.
To solve the issue for clients, we could add a boolean option to bypass the
cache and force a read from zookeeper, but this has the downside of lots of new
API methods which have that extra boolean argument.
Neither of these seem ideal, but I'm not coming up with something that is,
either.
> Improve stale-reads with ZooKeeper-backed data
> ----------------------------------------------
>
> Key: ACCUMULO-2743
> URL: https://issues.apache.org/jira/browse/ACCUMULO-2743
> Project: Accumulo
> Issue Type: Improvement
> Reporter: Josh Elser
> Fix For: 1.7.0
>
>
> Writing test code against Accumulo, especially via MiniAccumuloCluster, can
> be extremely frustrating. ZooKeeper is used for managing table
> configurations, among other things, to allow all tabletservers to be aware of
> the state of a table.
> The problem is that each tabletserver uses a Watcher to see when updates
> occur, and then it updates an internal cache of these properties. This is a
> problem even on an instance with a single tserver when setting a table
> property (configuring an iterator is a good example). The setTableProperty
> command is implemented via the Master, not a tserver like fetching the table
> configuration is implemented, which means that you're racing against the
> Watcher in the tserver.
> The cause of this is that test code gets riddled with code like the following:
> {code}
> String myProperty = tableConfiguration.getProperty("myProperty");
> for (int i = 0; i < retries && null == myProperty; i++) {
> myProperty = tableConfiguration.getProperty("myProperty");
> Thread.sleep(some_millis);
> }
> // Hope that you actually saw the update
> Assert.assertNotNull(myProperty)
> {code}
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