Go 1.21 is not yet released. These are work-in-progress release notes. Go 1.21 is expected to be released in August 2023.
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When printing very deep stacks, the runtime now prints the first 50 (innermost) frames followed by the bottom 50 (outermost) frames, rather than just printing the first 100 frames. This makes it easier to see how deeply recursive stacks started, and is especially valuable for debugging stack overflows.
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As always, there are various minor changes and updates to the library, made with the Go 1 promise of compatibility in mind. There are also various performance improvements, not enumerated here.
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The new WithoutCancel
function returns a copy of a context that is not canceled when the original
context is canceled.
The new WithDeadlineCause
and WithTimeoutCause
functions provide a way to set a context cancellation cause when a deadline or
timer expires. The cause may be retrieved with the
Cause function.
The new AfterFunc
function registers a function to run after a context has been cancelled.
In Go 1.21, ValueOf
no longer forces its argument to be allocated on the heap, allowing
a Value's content to be allocated on the stack. Most
operations on a Value also allow the underlying value
to be stack allocated.
The new OnceFunc,
OnceValue, and
OnceValues
functions capture a common use of Once to
lazily initialize a value on first use.