1 - Add a metric to track the number of inlight arenas from the pool
2 - Script now use 2 arenas:
- An initial (small) one for the script
- A sized one for the body
Should result in less pressure on our limited .large arenas
3 - DOMPoint and DOMPointRO are now arena free (they live on the slab only)
4 - TextDecoder no longer accumulate garbage in its arena
5 - Response object is much better at picking its arena size, rather than just
using a .large
Report memory held by arenas which are waiting on v8 finalization to v8. This
acts as a hint to the v8 GC, so that it knows about external memory which is
being held up by it.
This is opt-in, code needs to getArena() -> getPinnedArena() and then needs to
report() where it makes sense (e.g. no point reporting XHR memory if the Zig-
side still needs to instance).
This isn't exhaustive, but it covers _most_ cases where we call v8 (and the
most important ones, e.g. from ScriptManager and EventManager).
There's also a Page counter which, in the future, I'd like to expose in some way
such as via a custom cdp command or in a fetch --dump json to provide insight
on the "health" of the page/result.
Adds a /metrics endpoint in serve mode. Can be disabled via --disable-metrics.
In fetch, dumps the metrics if --metrics is specified (defaults to false).
None of the metrics being collected are on a hot path, so they're just always
collected using atomic operations (i.e. no `if (!enabled) return;`). Because
the operations are cheap and infrequent enough not to matter.
The one place I want to add more metrics is in HttpClient (bytes, status,
counts, ...) but after the pending HttpClient-related PR is merged.
./lightpanda fetch --log-level fatal --metrics "https://lightpanda.io/"
```
build_info{version="1.0.0-dev.7837+70493ce35"} 1
cdp_connections_total 0
cdp_connection_limit_total 0
cdp_active_connections 0
cdp_commands_total 0
cdp_unknown_commands_total 0
js_heap_limits_total 0
script_errors_total 0
arena_hit_total{size="tiny"} 908
arena_hit_total{size="small"} 35
arena_hit_total{size="medium"} 0
arena_hit_total{size="large"} 27
arena_miss_total{size="tiny"} 193
arena_miss_total{size="small"} 31
arena_miss_total{size="medium"} 5
arena_miss_total{size="large"} 23
navigate_total{type="page"} 1
navigate_total{type="iframe"} 0
navigate_total{type="popup"} 0
js_heap_size_bytes_bucket{le="4194304"} 0
js_heap_size_bytes_bucket{le="8388608"} 0
js_heap_size_bytes_bucket{le="16777216"} 1
js_heap_size_bytes_bucket{le="33554432"} 1
js_heap_size_bytes_bucket{le="67108864"} 1
js_heap_size_bytes_bucket{le="134217728"} 1
js_heap_size_bytes_bucket{le="268435456"} 1
js_heap_size_bytes_bucket{le="536870912"} 1
js_heap_size_bytes_bucket{le="+Inf"} 1
js_heap_size_bytes_sum 11223040
js_heap_size_bytes_count 1
```
Karl Seguin