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doc/go1.19: adjust runtime release notes

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This addresses comments from CL 410356.

For #48409.
For #51400.

Change-Id: I03560e820a06c0745700ac997b02d13bc03adfc6
Reviewed-on: https://go-review.googlesource.com/c/go/+/410735
Run-TryBot: Michael Pratt <mpratt@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Chris Hines <chris.cs.guy@gmail.com>
Reviewed-by: Russ Cox <rsc@golang.org>
This commit is contained in:
Michael Pratt 2022-06-06 17:32:03 -04:00
parent f3e051a184
commit 7a82c6859f
1 changed files with 34 additions and 19 deletions
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53
doc/go1.19.html
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@ -103,19 +103,26 @@ Do not send CLs removing the interior tags from such phrases.
<p><!-- https://go.dev/issue/48409 --><!-- CL 397018 -->
The runtime now includes support for a soft memory limit. This memory limit
includes all memory mapped and managed by the runtime, and excludes external
memory sources such as binary size, memory managed in other languages, and
memory held by the operating system on behalf of the Go program. This limit
may be managed via the <code>GOMEMLIMIT</code> environment variable or the
<code>SetMemoryLimit</code> function in the runtime/debug package. The limit
works in conjunction with <code>GOGC</code> and <code>SetGCPercent</code>,
includes the Go heap and all other memory managed by the runtime, and
excludes external memory sources such as mappings of the binary itself,
memory managed in other languages, and memory held by the operating system on
behalf of the Go program. This limit may be managed via
<a href="/pkg/runtime/debug/#SetMemoryLimit"><code>runtime/debug.SetMemoryLimit</code></a>
or the equivalent
<a href="/pkg/runtime/#hdr-Environment_Variables"><code>GOMEMLIMIT</code></a>
environment variable. The limit works in conjunction with
<a href="/pkg/runtime/debug/#SetGCPercent"><code>runtime/debug.SetGCPercent</code></a>
/ <a href="/pkg/runtime/#hdr-Environment_Variables"><code>GOGC</code></a>,
and will be respected even if <code>GOGC=off</code>, allowing Go programs to
always make maximal use of their memory limit, improving resource efficiency
in some cases. Please note that small memory limits, on the order of tens of
megabytes or less, are less likely to be adhered to due to external latency
factors, such as OS scheduling. See https://go.dev/issue/52433 for more
details. Larger memory limits, on the order of hundreds of megabytes or more,
are stable and production-ready.
in some cases. See <a href="https://go.dev/doc/gc-guide">the GC guide</a> for
a detailed guide explaining the soft memory limit in more detail, as well as
a variety of common use-cases and scenarios. Please note that small memory
limits, on the order of tens of megabytes or less, are less likely to be
respected due to external latency factors, such as OS scheduling. See
<a href="https://go.dev/issue/52433">issue 52433</a> for more details. Larger
memory limits, on the order of hundreds of megabytes or more, are stable and
production-ready.
</p>
<p><!-- CL 353989 -->
@ -123,7 +130,8 @@ Do not send CLs removing the interior tags from such phrases.
size approaches the soft memory limit, the Go runtime also attempts to limit
total GC CPU utilization to 50%, excluding idle time, choosing to use more
memory over preventing application progress. In practice, we expect this limit
to only play a role in exceptional cases, and the new runtime/metrics metric
to only play a role in exceptional cases, and the new
<a href="/pkg/runtime/metrics/#hdr-Supported_metrics">runtime metric</a>
<code>/gc/limiter/last-enabled:gc-cycle</code> reports when this last
occurred.
</p>
@ -667,20 +675,27 @@ Do not send CLs removing the interior tags from such phrases.
<dl id="runtime/metrics"><dt><a href="/pkg/runtime/metrics/">runtime/metrics</a></dt>
<dd>
<p><!-- https://go.dev/issue/47216 --><!-- CL 404305 -->
The new <code>/sched/gomaxprocs:threads</code> metric reports the current
<code>runtime.GOMAXPROCS</code> value.
The new <code>/sched/gomaxprocs:threads</code>
<a href="/pkg/runtime/metrics/#hdr-Supported_metrics">metric</a> reports
the current
<a href="/pkg/runtime/#GOMAXPROCS"><code>runtime.GOMAXPROCS</code></a>
value.
</p>
<p><!-- https://go.dev/issue/47216 --><!-- CL 404306 -->
The new <code>/cgo/go-to-c-calls:calls</code> metric reports the total
number of calls made from Go to C. This metric is identical to the <a
href="/pkg/runtime/#NumCgoCall"><code>runtime.NumCgoCall</code></a>
The new <code>/cgo/go-to-c-calls:calls</code>
<a href="/pkg/runtime/metrics/#hdr-Supported_metrics">metric</a>
reports the total number of calls made from Go to C. This metric is
identical to the
<a href="/pkg/runtime/#NumCgoCall"><code>runtime.NumCgoCall</code></a>
function.
</p>
<p><!-- https://go.dev/issue/48409 --><!-- CL 403614 -->
The new <code>/gc/limiter/last-enabled:gc-cycle</code> metric reports the
last GC cycle when the GC CPU limiter was enabled.
The new <code>/gc/limiter/last-enabled:gc-cycle</code>
<a href="/pkg/runtime/metrics/#hdr-Supported_metrics">metric</a>
reports the last GC cycle when the GC CPU limiter was enabled. See the
<a href="#runtime">runtime notes</a> for details about the GC CPU limiter.
</p>
</dd>
</dl><!-- runtime/metrics -->