How can you configure, in a portable way, the number of threads used by a ManagedExecutorService?

Question

Options

• Aprogrammatically, using a ManagedExecutorService
• Busing the ManagedExecutors utility class to define the execution properties
• CThis cannot be done because this configuration is dependent on the Java EE Product Provider.
• Dconfiguring the thread pool info in the deployment descriptor

• A
  70% (14)
• B
  5% (1)
• C
  15% (3)
• D
  10% (2)

Explanation

Option A is correct because the Jakarta Concurrency specification provides the @ManagedExecutorDefinition annotation (introduced in Jakarta Concurrency 3.0 / Jakarta EE 10), which lets you programmatically declare a ManagedExecutorService with properties like maxAsync to control concurrency - this is spec-defined and therefore portable across all compliant application servers.

Why the distractors are wrong:

• B - ManagedExecutors is a utility class for wrapping tasks with identity context or ManagedTaskListener callbacks, not for defining thread pool properties.
• C - The spec explicitly provides portable configuration mechanisms, so this is false; vendor-specific tuning exists but portable options do too.
• D - Deployment descriptors (e.g., glassfish-resources.xml, jboss-web.xml) are vendor-specific, making them the opposite of portable.

Memory tip: Match "portable" to "programmatic/annotation-based" in Jakarta EE - just as @DataSourceDefinition portably defines a datasource in code, @ManagedExecutorDefinition portably defines your executor. If the format is a vendor file, it's not portable.

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