mleonhard

Why do you think this is a lot of water? What are the alternatives to pulling from the local water utility and are those alternatives preferable?

Holding a lock while waiting for IO can destroy a system's performance. With async Rust, we can prevent this by making the MutexGuard !Send, so it cannot be held across an await. Specifically, because it is !Send, it cannot be stored in the Future [2], so it must be dropped immediately, freeing the lock. This also prevents Futurelock deadlock.

This is how I wrote safina::sync::Mutex [0]. I did try to make it Send, like Tokio's MutexGuard, but stopped when I realized that it would become very complicated or require unsafe.

> You could imagine an unfair Mutex that always woke up all waiters and let them race to grab the lock again. That would not suffer from risk of futurelock, but it would have the thundering herd problem plus all the liveness issues associated with unfair synchronization primitives.

Thundering herd is when clients overload servers. This simple Mutex has O(n^2) runtime: every task must acquire and release the mutex, which adds all waiting tasks to the scheduler queue. In practice, scheduling a task is very fast (~600ns). As long as polling the lock-mutex-future is fast and you have <500 waiting tasks, then the O(n^2) runtime is fine.

Performance is hard to predict. I wrote Safina using the simplest possible implementations and assumed they would be slow. Then I wrote some micro-benchmarks and found that some parts (like the async Mutex) actually outperform Tokio's complicated versions [1]. I spent days coding optimizations that did not improve performance (work stealing) or even reduced performance (thread affinity). Now I'm hesitant to believe assumptions and predictions about performance, even if they are based on profiling data.

NGOs must constantly raise money to fund their operations. The money that an NGO spends on fund-raising & administration is called "overhead". The percentage of annual revenue spent on overhead is the overhead percentage. Most NGOs publish this metric.

When a big donor stops contributing, the NGO must cut pay or lay off people and cut projects. I've never heard of an NGO "succumbing to excessive staff costs" like a startup running out of money. Financial mismanagement does occasionally happen and boards do replace CEOs. Board members are mostly donors, so they tend to donate more to help the NGO recover from mismanagement, instead of walking away.

NGOs pay less than other organizations, so they mostly attract workers who care about the NGO's mission. These are people with intrinsic motivation to make the NGO succeed in its mission. Financial incentives are a small part of their motivations. For example, my supervisor at Opportunity International refused several raises.

> So they go around addressing individual problems, taking sad pictures, and avoid addressing systemic problems.

Work on individual problems is valuable. For example, the Carter Center has prevented many millions of people from going blind from onchocerciasis and trachoma [0].

The Carter Center is not directly addressing the systemic problems of poverty and ineffective government health programs. That would take different expertise and different kinds of donors.

The world is extremely complicated and interconnected. The Carter Center's work preventing blindness directly supports worker productivity in many poor countries. Productivity helps economic growth and reduces poverty. And with more resources, government health programs run better.

Being effective in charity work requires humility and diligence to understand what can be done now, with the available resources. And then it requires tenacity to work in dangerous and backward places. It's an extremely hard job. People burn out. And we are all better off because of the work they do.

When we ignore the value of work on individual problems, because it doesn't address systemic problems, we practice binary thinking [1]. It's good to avoid binary thinking.