Method ForEach

include/Eigen/Eigen/src/ThreadPool/ThreadLocal.h:215–232

WARN: It's not thread safe to call it concurrently with `local()`.

  // WARN: It's not thread safe to call it concurrently with `local()`.
  void ForEach(std::function<void(std::thread::id, T&)> f) {
    // Reading directly from `data_` is unsafe, because only CAS to the
    // record in `ptr_` makes all changes visible to other threads.
    for (auto& ptr : ptr_) {
      ThreadIdAndValue* record = ptr.load();
      if (record == nullptr) continue;
      f(record->thread_id, record->value);
    }

    // We did not spill into the map based storage.
    if (filled_records_.load(std::memory_order_relaxed) < capacity_) return;

    // Adds a happens before edge from the last call to SpilledLocal().
    EIGEN_MUTEX_LOCK lock(mu_);
    for (auto& kv : per_thread_map_) {
      f(kv.first, kv.second);
    }
  }

  // WARN: It's not thread safe to call it concurrently with `local()`.
  ~ThreadLocal() {