Method decreaseWorkerThreads

src/server/server.cc:2079–2100

}

void Server::decreaseWorkerThreads(size_t delta) {
  auto current_worker_threads = worker_threads_.size();
  CHECK(current_worker_threads > delta);
  auto remain_worker_threads = current_worker_threads - delta;
  for (size_t i = remain_worker_threads; i < current_worker_threads; i++) {
    // Unix socket will be listening on the first worker,
    // so it MUST remove workers from the end of the vector.
    // Otherwise, the unix socket will be closed.
    auto worker_thread = std::move(worker_threads_.back());
    worker_threads_.pop_back();
    // Migrate connections to other workers before stopping the worker,
    // we use round-robin to choose the target worker here.
    auto connections = worker_thread->GetWorker()->GetConnections();
    for (const auto &iter : connections) {
      auto target_worker = worker_threads_[iter.first % remain_worker_threads]->GetWorker();
      worker_thread->GetWorker()->MigrateConnection(target_worker, iter.second);
    }
    worker_thread->Stop(10 /* graceful timeout */);
    // Don't join the worker thread here, because it may join itself.
    recycle_worker_threads_.push(std::move(worker_thread));
  }
}

void Server::cleanupExitedWorkerThreads(bool force) {
  std::unique_ptr<WorkerThread> worker_thread = nullptr;