Case 107: task_scheduler_init Removed (oneTBB historical break)¶
| Field | Value |
|---|---|
| Verdict | 🔴 BREAKING |
| Category | Breaking |
| Platforms | Linux, macOS, Windows |
| Flags | ABI break, API break |
Detected ChangeKinds |
func_removed, type_removed |
| Source files | browse on GitHub |
Category: Class Removal | Verdict: 🔴 BREAKING
What breaks¶
An entire publicly-exported class — task_scheduler_init — is removed in v2.
Every consumer that referenced the class (constructed it, called its members,
or held it by value) gets undefined symbol at load time, and source code
fails to compile against the new headers.
Why this is a oneTBB-flavored break¶
This is the single largest hard ABI break in TBB's history: classic TBB
deprecated tbb::task_scheduler_init in 2020 and removed it in oneTBB
2021.1, alongside the entire tbb::task low-level API. The replacements
(tbb::global_control, tbb::task_arena) have different lifetimes and
semantics.
Real-world consequence: every Boost build that linked TBB, every HPC code
using task_scheduler_init directly, and every downstream package had to
either pin to classic TBB or rewrite its initialization path.
Code diff¶
| v1 | v2 |
|---|---|
class task_scheduler_init { ... }; |
(removed) |
task_scheduler_init(int) |
(removed) |
terminate() / is_active() |
(removed) |
How abicheck catches it¶
The existing FUNC_REMOVED / TYPE_REMOVED detectors fire on every
public symbol the class exported. This case exists as a named regression
fixture so the canonical TBB removal pattern stays exercised in CI.
How to fix¶
Don't remove publicly-exported classes in a minor release. The oneTBB
migration showed the only safe path:
1. Major SONAME bump (libtbb.so.2 → libtbb.so.12).
2. Concurrent shipping of compatibility headers via a separate package
(tbb_preview) for a transition release.
3. Strong documentation of the migration with mechanical replacements.
References¶
Source files¶
See also: Examples overview · All BREAKING cases · Category: Breaking.