comprehensive-rust/src/concurrency/async-pitfalls.md

# Pitfalls

Async / await provides convenient and efficient abstraction for concurrent
asynchronous programming. However, the async/await model in Rust also comes with
its share of pitfalls and footguns. We illustrate some of them in this chapter.

{{%segment outline}}
Update Concurrency course with times (#2007) As I mentioned in #1536: * Break into segments at approximately the places @fw-immunant put breaks * Move all of the files into `src/concurrency` * Add timings and segment/session metadata so course outlines appear There's room for more work here, including some additional feedback from @fw-immunant after the session I observed, but let's do one step at a time :) 2024-04-23 09:26:41 -04:00			`# Pitfalls`
Add an "async" session (#496) * beginning of an Async section * address review comments * Add futures page (#497) NOTE: `mdbook test` does not allow code samples to reference other crates, so they must be marked as `compile_fail`; see #175. * Add Runtimes & Tasks (#522) These concepts are closely related, and there's not much else to know about runtimes other than "they exist". This removes the bit about futures being "inert" because it doesn't really lead anywhere. * Async chapter (#524) * Add async channels chapter * Async control flow * Async pitfalls * Separate in multiple chapters + add daemon section * Merge reentering threads in blocking-executor * async_trait * Async fixes (#546) * Async: some ideas for simplifying the content (#550) * Simplify the async-await slide * Shorten futures and move it up * Add a page on Tokio * Modifications to the async section (#556) * Modifications to the async section * Remove the "Daemon" slide, as it largely duplicates the "Tasks" slide. The introduction to the "Control Flow" section mentions tasks as a kind of control flow. * Reorganize the structure in SUMMARY.md to correspond to the directory structure. * Simplify the "Pin" and "Blocking the Executor" slides with steps in the speaker notes to demonstrate / fix the issues. * Rename "join_all" to "Join". * Simplify some code samples to shorten them, and to print output rather than asserting. * Clarify speaker notes and include more "Try.." suggestions. * Be consistent about where `async` blocks are introduced (in the "Tasks" slide). * Explain `join` and `select` in prose. * Fix formatting of section-header slides. * Add a note on async trait (#558) --------- Co-authored-by: sakex <alexandre@senges.ch> Co-authored-by: rbehjati <razieh@google.com> 2023-04-14 10:06:50 -04:00
Format all Markdown files with `dprint` (#1157) This is the result of running `dprint fmt` after removing `src/` from the list of excluded directories. This also reformats the Rust code: we might want to tweak this a bit in the future since some of the changes removes the hand-formatting. Of course, this formatting can be seen as a mis-feature, so maybe this is good overall. Thanks to mdbook-i18n-helpers 0.2, the POT file is nearly unchanged after this, meaning that all existing translations remain valid! A few messages were changed because of stray whitespace characters: msgid "" "Slices always borrow from another object. In this example, `a` has to remain " -"'alive' (in scope) for at least as long as our slice. " +"'alive' (in scope) for at least as long as our slice." msgstr "" The formatting is enforced in CI and we will have to see how annoying this is in practice for the many contributors. If it becomes annoying, we should look into fixing dprint/check#11 so that `dprint` can annotate the lines that need fixing directly, then I think we can consider more strict formatting checks. I added more customization to `rustfmt.toml`. This is to better emulate the dense style used in the course: - `max_width = 85` allows lines to take up the full width available in our code blocks (when taking margins and the line numbers into account). - `wrap_comments = true` ensures that we don't show very long comments in the code examples. I edited some comments to shorten them and avoid unnecessary line breaks — please trim other unnecessarily long comments when you see them! Remember we're writing code for slides :smile: - `use_small_heuristics = "Max"` allows for things like struct literals and if-statements to take up the full line width configured above. The formatting settings apply to all our Rust code right now — I think we could improve this with https://github.com/dprint/dprint/issues/711 which lets us add per-directory `dprint` configuration files. However, the `inherit: true` setting is not yet implemented (as far as I can tell), so a nested configuration file will have to copy most or all of the top-level file. 2023-12-31 00:15:07 +01:00			`Async / await provides convenient and efficient abstraction for concurrent`
			`asynchronous programming. However, the async/await model in Rust also comes with`
Update Concurrency course with times (#2007) As I mentioned in #1536: * Break into segments at approximately the places @fw-immunant put breaks * Move all of the files into `src/concurrency` * Add timings and segment/session metadata so course outlines appear There's room for more work here, including some additional feedback from @fw-immunant after the session I observed, but let's do one step at a time :) 2024-04-23 09:26:41 -04:00			`its share of pitfalls and footguns. We illustrate some of them in this chapter.`
Add an "async" session (#496) * beginning of an Async section * address review comments * Add futures page (#497) NOTE: `mdbook test` does not allow code samples to reference other crates, so they must be marked as `compile_fail`; see #175. * Add Runtimes & Tasks (#522) These concepts are closely related, and there's not much else to know about runtimes other than "they exist". This removes the bit about futures being "inert" because it doesn't really lead anywhere. * Async chapter (#524) * Add async channels chapter * Async control flow * Async pitfalls * Separate in multiple chapters + add daemon section * Merge reentering threads in blocking-executor * async_trait * Async fixes (#546) * Async: some ideas for simplifying the content (#550) * Simplify the async-await slide * Shorten futures and move it up * Add a page on Tokio * Modifications to the async section (#556) * Modifications to the async section * Remove the "Daemon" slide, as it largely duplicates the "Tasks" slide. The introduction to the "Control Flow" section mentions tasks as a kind of control flow. * Reorganize the structure in SUMMARY.md to correspond to the directory structure. * Simplify the "Pin" and "Blocking the Executor" slides with steps in the speaker notes to demonstrate / fix the issues. * Rename "join_all" to "Join". * Simplify some code samples to shorten them, and to print output rather than asserting. * Clarify speaker notes and include more "Try.." suggestions. * Be consistent about where `async` blocks are introduced (in the "Tasks" slide). * Explain `join` and `select` in prose. * Fix formatting of section-header slides. * Add a note on async trait (#558) --------- Co-authored-by: sakex <alexandre@senges.ch> Co-authored-by: rbehjati <razieh@google.com> 2023-04-14 10:06:50 -04:00
Update Concurrency course with times (#2007) As I mentioned in #1536: * Break into segments at approximately the places @fw-immunant put breaks * Move all of the files into `src/concurrency` * Add timings and segment/session metadata so course outlines appear There's room for more work here, including some additional feedback from @fw-immunant after the session I observed, but let's do one step at a time :) 2024-04-23 09:26:41 -04:00			`{{%segment outline}}`