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31 lines
1.5 KiB
Markdown
31 lines
1.5 KiB
Markdown
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### Timer changes
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Go 1.23 makes two significant changes to the implementation of
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[`time.Timer`](/pkg/time#Timer) and [`time.Ticker`](/pkg/time#Ticker).
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First, `Timer`s and `Ticker`s that are no longer referred to by the program
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become eligible for garbage collection immediately, even if their
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`Stop` methods have not been called.
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Earlier versions of Go did not collect unstopped `Timer`s until after
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they had fired and never collected unstopped `Ticker`s.
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Second, the timer channel associated with a `Timer` or `Ticker` is
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now unbuffered, with capacity 0.
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The main effect of this change is that Go now guarantees
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that for any call to a `Reset` or `Stop` method, no stale values
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prepared before that call will be sent or received after the call.
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Earlier versions of Go used channels with a one-element buffer,
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making it difficult to use `Reset` and `Stop` correctly.
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A visible effect of this change is that `len` and `cap` of timer channels
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now returns 0 instead of 1, which may affect programs that
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poll the length to decide whether a receive on the timer channel
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will succeed.
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Such code should use a non-blocking receive instead.
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These new behaviors are only enabled when the main Go program
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is in a module with a `go.mod` `go` line using Go 1.23.0 or later.
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When Go 1.23 builds older programs, the old behaviors remain in effect.
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The new [GODEBUG setting](/doc/godebug) [`asynctimerchan=1`](/pkg/time/#NewTimer)
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can be used to revert back to asynchronous channel behaviors
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even when a program names Go 1.23.0 or later in its `go.mod` file.
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