Documentation
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Overview ¶
Package logio decouples log production from the log sink.
Motivation (2026-08-14, frozen-spin/quiet-stall stall family): the worker logs to stderr, which in the benchmark deploy is a pipe into journald. When journald stalls, the 64KB pipe fills, the next slog write blocks WHILE HOLDING the handler mutex, and every goroutine that logs parks behind it — a whole-process freeze that self-heals in one burst when journald catches up (validation run 20260814-002639: 190s freeze on one worker, liveness markers stopped, coordinator saw a 36-result burst on recovery). Execution must never be gated on the log sink.
Index ¶
Constants ¶
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Variables ¶
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Functions ¶
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Types ¶
type AsyncWriter ¶
type AsyncWriter struct {
// contains filtered or unexported fields
}
AsyncWriter is an io.Writer that hands records to a background drainer through a bounded channel. When the buffer is full, Write drops the record and counts it instead of blocking. Dropped totals are surfaced in-band by the drainer (at most once per second) so the log stream itself records the loss.
func NewAsyncWriter ¶
func NewAsyncWriter(sink io.Writer, depth int) *AsyncWriter
NewAsyncWriter starts the drainer. depth is the buffered record count; at a few hundred bytes per record, 8192 records ≈ 2-3 MB and absorbs many minutes of normal log volume during a sink stall.
func (*AsyncWriter) Close ¶
func (a *AsyncWriter) Close() error
Close stops accepting writes, drains the buffer to the sink, and returns. Safe to call once; further Writes after Close are dropped.
func (*AsyncWriter) Dropped ¶
func (a *AsyncWriter) Dropped() uint64
Dropped returns the number of records dropped so far.
func (*AsyncWriter) Write ¶
func (a *AsyncWriter) Write(p []byte) (int, error)
Write never blocks on the sink: it copies p (slog reuses its buffer) and enqueues, dropping on overflow. Always reports success to the caller — a dropped log line must not fail the operation that logged. The RLock guards the enqueue against a concurrent Close (send on closed channel); it is uncontended in steady state.
Source Files