Preview Features

[preview_features]

A preview feature is a component of oneTBB introduced to gather early feedback from users.

The key properties of a preview feature are:

• It is off by default and must be explicitly enabled.

• It aims to provide high implementation quality.

• There is no guarantee of future existence or compatibility.

• It may have limited or no support in tools such as correctness analyzers, profilers, and debuggers.

• ABI compatibility between translation units is guaranteed only when all are built with the same version of the library and the same set of enabled preview features.

Caution

A preview feature is subject to change in the future. It might be removed or significantly altered in future releases. Changes to a preview feature do not require the usual deprecation and removal process. Therefore, using preview features in production code is strongly discouraged.

Unless explicitly stated in a preview feature page, enable a preview feature by defining the corresponding TBB_PREVIEW_-prefixed macro before including any headers. This requirement is strict because oneTBB may be included indirectly through other headers.

Flow Graph

Feature	Description	Enabling macro
Type-specified message keys for join_node	Enables join_node in key-matching mode to obtain keys directly from message types.	TBB_PREVIEW_FLOW_GRAPH_FEATURES
Helper Functions for Expressing Graphs	Adds make_edges, make_node_set, follows, and precedes helper functions for building graphs.	TBB_PREVIEW_FLOW_GRAPH_FEATURES
Waiting for Single Messages in Flow Graph	Adds try_put_and_wait to submit a message and wait only for its associated work to complete.	TBB_PREVIEW_FLOW_GRAPH_TRY_PUT_AND_WAIT
Resource Limiting in the Flow Graph	Coordinates node access to limited shared resources via resource_limiter and resource_limited_node.	TBB_PREVIEW_FLOW_GRAPH_RESOURCE_LIMITING

Task Scheduler

Feature	Description	Enabling macro
Task Bypass Support for task_group	Allows a task_group task body to return a task_handle to run next (scheduler bypass).	TBB_PREVIEW_TASK_GROUP_EXTENSIONS
task_completion_handle Class	Adds task_completion_handle to track completion of a submitted task_group task.	TBB_PREVIEW_TASK_GROUP_EXTENSIONS
task_group Dynamic Dependencies	Lets tasks add dependencies dynamically while a task_group runs.	TBB_PREVIEW_TASK_GROUP_EXTENSIONS
Waiting for Individual Tasks in task_group	Adds waiting for an individual task_group task through its handle.	TBB_PREVIEW_TASK_GROUP_EXTENSIONS
parallel_phase Interface for Task Arena	Extends task_arena with an explicit parallel_phase to control worker participation.	TBB_PREVIEW_PARALLEL_PHASE
Core Type Selector for Task Arena Constraints	Adds core-type constraints to task_arena for hybrid-CPU systems.	TBB_PREVIEW_TASK_ARENA_CORE_TYPE_SELECTOR

Containers

Memory Allocation

Feature	Description	Enabling macro
Scalable Memory Pools	Provides memory_pool and fixed_pool classes for scalable pooled allocation.	TBB_PREVIEW_MEMORY_POOL
Allocate Memory Interleaved between NUMA Nodes	Allocates memory interleaved across NUMA nodes.	TBB_PREVIEW_NUMA_ALLOCATION