The Linux kernel imposes a 15-byte limit on thread names[1]. This means
information that does not fit in this limit, e.g., the pipeline ID of
layout and script threads, is lost in a debugger and profiler (see the
first column of the table below).
This commit shortens the thread names used in Servo to maximize the
amount of information conveyed. It also rectifies some inconsistencies
in the names.
| Before | After |
|-------------------|-------------------|
| `BluetoothThread` | `Bluetooth` |
| `CanvasThread` | `Canvas` |
| `display alert d` | `AlertDialog` |
| `FontCacheThread` | `FontCache` |
| `GLPlayerThread` | `GLPlayer` |
| `HTML Parser` | `Parse:www.examp` |
| `LayoutThread Pi` | `Layout(1,1)` |
| `Memory profiler` | `MemoryProfiler` |
| `Memory profiler` | `MemoryProfTimer` |
| `OfflineAudioCon` | `OfflineACResolv` |
| `PullTimelineMar` | `PullTimelineDat` |
| `ScriptThread Pi` | `Script(1,1)` |
| `WebWorker for h` | `WW:www.example.` |
| `ServiceWorker f` | `SW:www.example.` |
| `ServiceWorkerMa` | `SvcWorkerManage` |
| `Time profiler t` | `TimeProfTimer` |
| `Time profiler` | `TimeProfiler` |
| `WebGL thread` | `WebGL` |
| `Choose a device` | `DevicePicker` |
| `Pick a file` | `FilePicker` |
| `Pick files` | `FilePicker` |
[1]: https://stackoverflow.com/questions/5026531/thread-name-longer-than-15-chars
This does not (yet) upgrade ./rust-toolchain
The warnings:
* dead_code "field is never read"
* redundant_semicolons "unnecessary trailing semicolon"
* non_fmt_panic "panic message is not a string literal, this is no longer accepted in Rust 2021"
* unstable_name_collisions "a method with this name may be added to the standard library in the future"
* legacy_derive_helpers "derive helper attribute is used before it is introduced" https://github.com/rust-lang/rust/issues/79202
This is used for two memory reporting improvements.
- It's used to distinguish "explicit" memory reports from others. This
mirrors the same categorization that is used in Firefox, and gives a single
tree that's the best place to look. It replaces the "pages" tree which
was always intended to be a temporary stand-in for "explicit".
- It's used to computed "heap-unclassified" values for both the jemalloc
and system heaps, both of which are placed into the "explicit" tree.
Example output:
```
| 114.99 MiB -- explicit
| 52.34 MiB -- jemalloc-heap-unclassified
| 46.14 MiB -- system-heap-unclassified
| 14.95 MiB -- url(file:///home/njn/moz/servo2/../servo-static-suite/wikipe
dia/Guardians%20of%20the%20Galaxy%20(film)%20-%20Wikipedia,%20the%20free%20encyc
lopedia.html)
| 7.32 MiB -- js
| 3.07 MiB -- malloc-heap
| 3.00 MiB -- gc-heap
| 2.49 MiB -- used
| 0.34 MiB -- decommitted
| 0.09 MiB -- unused
| 0.09 MiB -- admin
| 1.25 MiB -- non-heap
| 1.36 MiB -- layout-worker-3-local-context
| 1.34 MiB -- layout-worker-0-local-context
| 1.24 MiB -- layout-worker-1-local-context
| 1.24 MiB -- layout-worker-4-local-context
| 1.16 MiB -- layout-worker-2-local-context
| 0.89 MiB -- layout-worker-5-local-context
| 0.38 MiB -- layout-task
| 0.31 MiB -- display-list
| 0.07 MiB -- local-context
| 1.56 MiB -- compositor-task
| 0.78 MiB -- surface-map
| 0.78 MiB -- layer-tree
```
The heap-unclassified values dominate the "explicit" tree because reporter
coverage is still quite poor.
This puts the larger sub-trees first. E.g. this:
```
| 1.04 MiB -- url(http://en.wikipedia.org/wiki/Main_Page)
| 0.26 MiB -- display-list
| 0.78 MiB -- paint-task # new output line
| 0.78 MiB -- buffer-map # new output line
```
becomes this:
```
| 1.04 MiB -- url(http://en.wikipedia.org/wiki/Main_Page)
| 0.78 MiB -- paint-task # new output line
| 0.78 MiB -- buffer-map # new output line
| 0.26 MiB -- display-list
```
This matches how Firefox's about:memory works.
Now that this is done for all sub-trees, the ad hoc sorting done for
Linux segments is no longer necessary, and has been removed.
A rebuild after touching components/profile/mem.rs now takes 48 seconds (and
only rebuilds `profile` and `servo`) which is much lower than it used to be.
In comparison, a rebuild after touching components/profile_traits/mem.rs takes
294 seconds and rebuilds many more crates.
This change also removes some unnecessary crate dependencies in `net` and
`net_traits`.
