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Swapped Go GC metadata can turn a collection into a 40 ms pause

frn.sh 3 min read Editor score 8/10

Go’s garbage collector reads metadata outside the heap during a stop-the-world pause; if that metadata is swapped out, the collector can stall on page faults. Engineers running memory-heavy Go services should account for swap and GC metadata when diagnosing latency.

What

A Go garbage collector pause reached 40 ms when GC metadata was in swap.

How

During the worst pause, 39 ms went to 228 page faults while the stopped-the-world collector read metadata.

Why it matters

Engineers using swap to absorb memory spikes should account for GC metadata faults, which can stall all Go processes in the cgroup.

Read on frn.sh → Hacker News · 32 comments

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