And waits for them. That's pointless.
{
    if (action_type == ActionLocks::PartsMerge)
        return merger_mutator.merges_blocker.cancel();
    if (action_type == ActionLocks::PartsTTLMerge)
        return merger_mutator.ttl_merges_blocker.cancel();
    if (action_type == ActionLocks::PartsFetch)
        return fetcher.blocker.cancel();
    if (action_type == ActionLocks::PartsSend)
    {
        auto data_parts_exchange_ptr = std::atomic_load(&data_parts_exchange_endpoint);
        return data_parts_exchange_ptr ? data_parts_exchange_ptr->blocker.cancel() : ActionLock();
    }
    if (action_type == ActionLocks::ReplicationQueue)
        return queue.actions_blocker.cancel();
    if (action_type == ActionLocks::PartsMove)
        return parts_mover.moves_blocker.cancel();
    return {};
}
void StorageReplicatedMergeTree::onActionLockRemove(StorageActionBlockType action_type)
{
    if (action_type == ActionLocks::PartsMerge || action_type == ActionLocks::PartsTTLMerge
        || action_type == ActionLocks::PartsFetch || action_type == ActionLocks::PartsSend
        || action_type == ActionLocks::ReplicationQueue)
        background_executor.triggerTask();
    else if (action_type == ActionLocks::PartsMove)
        background_moves_executor.triggerTask();
}
bool StorageReplicatedMergeTree::waitForShrinkingQueueSize(size_t queue_size, UInt64 max_wait_milliseconds)