[jira] [Closed] (GEODE-6152) Client PROXY Regions may return the same Object instance on get(key) and cause Thread-safety issues

["Dick Cavender (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/GEODE-6152?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Dick Cavender closed GEODE-6152.
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> Client PROXY Regions may return the same Object instance on get(key) and cause Thread-safety issues
> ---------------------------------------------------------------------------------------------------
>
>                 Key: GEODE-6152
>                 URL: https://issues.apache.org/jira/browse/GEODE-6152
>             Project: Geode
>          Issue Type: Bug
>          Components: client/server, regions
>    Affects Versions: 1.1.0, 1.1.1, 1.3.0, 1.2.1, 1.4.0, 1.5.0, 1.6.0, 1.7.0
>            Reporter: John Blum
>            Assignee: Anilkumar Gingade
>            Priority: Critical
>              Labels: SmallFeature
>             Fix For: 1.10.0
>
>          Time Spent: 2h 40m
>  Remaining Estimate: 0h
>
> According to Apache Geode's documentation (e.g. [Javadoc|http://geode.apache.org/releases/latest/javadoc/org/apache/geode/cache/client/ClientRegionShortcut.html#PROXY]), client PROXY Regions are expected to return a new Object for each value on each {{Region.get(key)}} invocation.
> The documentation states:
> {quote}
> A PROXY region has no local state and forwards all operations to a server.
> {quote}
> Given the client cache (i.e. Region) contains "no local state" and "all operations are forwarded to a server", then this implies that the object, the Region's value mapped to the key, is serialized when sent to a server and deserialized when received from a server.  The act of de/serialization constitutes a new object every, single, time.
> However, in a highly concurrent application (e.g. a Web application), with multiple Threads in the application potentially making concurrent data requests for the same "logical" domain object stored in Apache Geode, it is possible for the same object reference to be returned, even for a client {{PROXY}} Region.
> This is to be expected when using a {{CACHING_PROXY}}, since the client then has "local state", but for a client {{PROXY}} Region, there is, or should be no "local state".
> It turns out that internally, Geode applies an optimization wherein, if 2 or more Threads are concurrently making a data request for the same "logical" object, then only 1 Thread is allowed to proceed with the request while the other Threads will wait for the response that the permitted, requesting Thread received, thereby sharing the same object reference.
> This poses grave danger (race conditions due to lost updates, or incorrect decisions made due to stale state) if the non-unique object type is not Thread-safe.  Under other conditions/configurations (e.g. when sending {{Deltas}}), it is even possible to "lose data" due to competing and conflicting data access operations, which results in a "_last-one-wins_" scenario.



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