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https://issues.apache.org/jira/browse/SLING-1975?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Justin Edelson closed SLING-1975.
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> ScriptEngineFactory implementations should declare their threading support
> --------------------------------------------------------------------------
>
> Key: SLING-1975
> URL: https://issues.apache.org/jira/browse/SLING-1975
> Project: Sling
> Issue Type: Improvement
> Components: Scripting
> Affects Versions: Scripting JSP 2.0.14, Scripting JavaScript 2.0.10,
> Scripting Java 2.0.0
> Reporter: Felix Meschberger
> Assignee: Felix Meschberger
> Fix For: Scripting JSP 2.0.16, Scripting JavaScript 2.0.12,
> Scripting Java 2.0.2
>
>
> Our main script engines should declare in their ScriptEngineFactory
> implementations their behaviour with respect to multi thread as described in
> Section SCR.4.3.5.2 Metadata Methods of the JSR-223 Java Script API
> specification:
> Multithreaded Engine
> Multi-threaded Evaluation - The implementation of the API and the engine
> itself are capable of supporting concurrent evaluations by multiple threads
> on a single engine instance. However the exact behavior of such concurrent
> execution is ultimately determined by the script or scripts themselves. An
> engine which supports concurrent execution is "multi-threaded" in the same
> sense that the Java language is "multi-threaded": Evaluation by concurrent
> threads is allowed and produces side effects that can be seen by other
> threads. The threads may interact or not interact, utilize synchronization or
> not utilize synchronization, in scripting language dependent ways.
> Thread-Isolated Engine
> Satisfies the requirements for Multithreaded. Also, the side-effects for
> threads are isolated from one another. Specifically, the isolation limits the
> visibility of changes to the state of variables in the engine scope of the
> interpreter. Each thread will effectively have its own thread-local engine
> scope for the engine instance. Note that this does not limit the visibility
> of side effects outside the engine scope - for example, mutation of
> application-level Java objects.
> Stateless Engine
> Satisfies the requirements for Thread-Isolated. In addition, the mappings in
> the Bindings used as the engine scope of the ScriptEngine are not modified by
> any ScriptExecution. The keys in the Bindings and their associated values are
> exactly the same before and after each script execution.
> From this description, I would say :
> JavaScript is Multithreaded because as of SLING-1972 the variables are
> written back to the Engine scope bindings of the ScriptEngine instance (to
> support the SLING-1111 use case)
> JSP is state less because the Engine scope bindings are not modified by the
> ScriptEngine
> Java is state less because the Engine scope bindings are not modified by
> the ScriptEngine
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