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go/doc/next/6-stdlib/1-time.md
Dmitri Shuralyov acc93dac83 doc/next: populate TODOs found with relnote todo
This is the first round of TODOs created based on relnote todo output.
There are many entries that need to be documented, expanded, reworded,
and this change makes progress on setting that up.

For this cycle, relnote todo implemented a simple heuristic of finding
CLs that mention accepted proposals (see issue 62376, or comment
https://go.dev/issue/62376#issuecomment-2101086794 specifically).
The "Items that don't need to be mentioned in Go 1.23 release notes but
are picked up by relnote todo." section in todo.md contains an attempt
at reviewing that list. The large number of items needed to be reviewed
made it impractical to spend much time on any individual one.

For #65614.

Change-Id: Id9d5f1795575a46df2ec4ed0088de07ee6075a90
Reviewed-on: https://go-review.googlesource.com/c/go/+/588015
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Carlos Amedee <carlos@golang.org>
2024-05-23 20:49:22 +00:00

1.5 KiB

Timer changes

Go 1.23 makes two significant changes to the implementation of [time.Timer] and [time.Ticker].

First, Timers and Tickers that are no longer referred to by the program become eligible for garbage collection immediately, even if their Stop methods have not been called. Earlier versions of Go did not collect unstopped Timers until after they had fired and never collected unstopped Tickers.

Second, the timer channel associated with a Timer or Ticker is now unbuffered, with capacity 0. The main effect of this change is that Go now guarantees that for any call to a Reset or Stop method, no stale values prepared before that call will be sent or received after the call. Earlier versions of Go used channels with a one-element buffer, making it difficult to use Reset and Stop correctly. A visible effect of this change is that len and cap of timer channels now returns 0 instead of 1, which may affect programs that poll the length to decide whether a receive on the timer channel will succeed. Such code should use a non-blocking receive instead.

These new behaviors are only enabled when the main Go program is in a module with a go.mod go line using Go 1.23.0 or later. When Go 1.23 builds older programs, the old behaviors remain in effect. The new GODEBUG setting asynctimerchan=1 can be used to revert back to asynchronous channel behaviors even when a program names Go 1.23.0 or later in its go.mod file.