diff options
Diffstat (limited to 'src/runtime')
| -rw-r--r-- | src/runtime/metrics/sample.go | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/src/runtime/metrics/sample.go b/src/runtime/metrics/sample.go index 60189cb334..35534dd70d 100644 --- a/src/runtime/metrics/sample.go +++ b/src/runtime/metrics/sample.go @@ -30,6 +30,16 @@ func runtime_readMetrics(unsafe.Pointer, int, int) // The user of this API is encouraged to re-use the same slice between calls for // efficiency, but is not required to do so. // +// Note that re-use has some caveats. Notably, Values should not be read or +// manipulated while a Read with that value is outstanding; that is a data race. +// This property includes pointer-typed Values (e.g. Float64Histogram) whose +// underlying storage will be reused by Read when possible. To safely use such +// values in a concurrent setting, all data must be deep-copied. +// +// It is safe to execute multiple Read calls concurrently, but their arguments +// must share no underlying memory. When in doubt, create a new []Sample from +// scratch, which is always safe, though may be inefficient. +// // Sample values with names not appearing in All will have their Value populated // as KindBad to indicate that the name is unknown. func Read(m []Sample) { |