In this work, we study progress conditions for commutativity-aware, linearizable implementations of shared objects. Motivated by the observation that commuting operations can be executed in parallel, we introduce conflict-obstruction-freedom: a process is guaranteed to complete its operation if it runs for long enough without encountering step contention with conflicting (non-commuting) operations. This condition generalizes obstruction-freedom and wait-freedom by allowing progress as long as step contention is only induced by commuting operations. We prove that conflict-obstruction-free universal constructions are impossible to implement in the asynchronous read-write shared memory model. This result exposes a fundamental limitation of conflict-aware universal constructions: the mere invocation of conflicting operations imposes a synchronization cost. Progress requires eventual resolution of pending conflicts.

翻译：在本研究中，我们探讨了共享对象的可交换性感知线性化实现中的进展条件。基于可交换操作可并行执行的观察，我们提出了冲突无阻塞自由性：若某进程在足够长的运行时间内未遭遇与冲突性（不可交换）操作引发的步骤竞争，则其操作必能完成。该条件通过允许仅当步骤竞争由可交换操作引发时仍能取得进展，从而推广了无阻塞自由与无等待自由。我们证明了在异步读写共享内存模型中，冲突无阻塞自由的通用构造不可能实现。这一结果揭示了冲突感知通用构造的根本局限：仅冲突操作的调用就会产生同步开销。进展要求待定冲突最终必须得到解决。