Revert this change. If compiled with NDEBUG (many release builds), anything inside of assertions isn't executed, so it will deserialize incorrectly.

Just remove unused code, don't comment it out.

Just remove, don't comment it out.

Just remove, don't comment it out.

Just remove, don't comment it out.

Just remove, don't comment it out.

Move the function implementations into the actual class definition. Otherwise, I think you'll have issues if trying to include this header in multiple places.

template <typename T>
class SharedQueue
{
public:
    SharedQueue() = default;
    ~SharedQueue() = default;

    T& front()
    {
        // implement here
    }

    void pop_front()
    {
        // implement here
    }

    void push_back(const T& item)
    {
        // implement here
    }

    void push_back(T&& item)
    {
        // implement here
    }

    int size()
    {
        // implement here
    }

    bool empty()
    {
        // implement here
    }

private:
    std::deque<T> queue_;
    std::mutex mutex_;
    std::condition_variable cond_;
};

Why is this class even needed? Does ConcurrentQueue not do what you need?

ConcurrentQueue is subject to race conditions between calls to empty, front and pop if there is more than one thread; we could either use SharedQueue class or edit the ConcurrentQueue class. More here https://www.justsoftwaresolutions.co.uk/threading/implementing-a-thread-safe-queue-using-condition-variables.html

This isn't correct. Since you aren't adding message to the queue, if something's already being written to the socket, we just drop message.

We had some users running older Debian instances, which is why we built with 16.04. We're probably good to update this to 18.04 now, but you should check with the channel first, if you haven't already.

Ubuntu 16.04 environment was removed on September 20, 2021 actions/runner-images#3287

I guess we don't really have a choice then. You'll want to mention that in the next release announcement.

Good catch