fix: eliminate ARM64 data race on Server.session pointer#328
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tomasz-tomczyk merged 2 commits intomainfrom Apr 21, 2026
Merged
fix: eliminate ARM64 data race on Server.session pointer#328tomasz-tomczyk merged 2 commits intomainfrom
tomasz-tomczyk merged 2 commits intomainfrom
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Replace the `session *Session` + `ready atomic.Bool` two-field pattern with `session atomic.Pointer[Session]`. The old pattern had a data race: SetSession wrote the pointer without synchronization, then stored true to the atomic bool. On weakly-ordered architectures (ARM64/Apple Silicon), a handler goroutine could observe ready=true but read a stale nil session pointer, since atomic.Bool.Store only orders the boolean itself. With atomic.Pointer, the session store is a single atomic operation. Readiness is derived from the pointer being non-nil, eliminating the race entirely. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Load session once instead of twice for consistency with other handlers. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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Summary
session *Session+ready atomic.Boolwithatomic.Pointer[Session]to fix a data race on ARM64 (Apple Silicon)atomic.Bool.Storedoesn't order the preceding pointer write, so a handler goroutine could seeready=truebut read a stale nils.sessions.session.Load() != nilTest plan
go vet ./...cleango test -race -count=1 ./...passes🤖 Generated with Claude Code