prodash is a dashboard for displaying progress of concurrent applications.
It's easy to integrate thanks to a pragmatic API, and comes with a terminal user interface by default.
How to use…
Be sure to read the documentation at https://docs.rs/prodash, it contains various examples on how to get started.
Or run the demo application like so cd prodash && cargo run --example dashboard
.
Features
- fast insertions and updates for transparent progress tracking of highly concurrent programs
- a messages buffer for information about success and failure
- a terminal user interface for visualization, with keyboard controls and dynamic re-sizing
- unicode and multi-width character support
Limitations
- it does copy quite some state each time it displays progress information and messages
- The underlying sync data structure,
dashmap
, does not document every use of unsafe- I also evaluated
evmap
, which has 25% less uses of unsafe, but a more complex interface. - Thus far it seemed 'ok' to use, who knows… we are getting mutable pieces of a hashmap from multiple threads, however, we never hand out multiple handles to the same child which should make actual concurrent access to the same key impossible.
- I also evaluated
- If there are more than 2^16 tasks
- then
- running concurrently on a single level of the tree, they start overwriting each other
- over its lifetime, even though they do not run concurrently, eventually new tasks will seem like old tasks (their ID wrapped around)
- why
- on drop, they never decrement a child count used to generate a new ID
- fix
- make the id bigger, like u32
- we should do that once there is a performance test
- then
Lessons Learned
drop()
is not garantueed to be called when the future returns Ready and is in the futures::executor::ThreadPool- Workaround: drop and cleanup explicitly, prone to forgetting it.
- This is also why
futures::future::abortable()
works (by stopping the polling), but doesn't as cleanup is not performed, even though it clearly would be preferred. - fix
- Use a join handle and await it - this will drop the future properly
select()
might not work with complex futures - these should then beboxed()
ifUnpin
isn't implemented.