Skip journal flush-trace loop when debug logging is disabled#4835
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zymap
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Jul 14, 2026
merlimat
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(cherry picked from commit bcb3e70)
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Motivation
After every journal flush, a second pass iterates the whole
toFlushlist purely to emit per-entry DEBUG trace lines. When DEBUG is disabled (the normal production configuration), the loop still runs: it allocates anIteratorper flush and walks the full list doing null checks for nothing.Changes
Wrap the trace loop in slog's lazy consumer form,
log.debug(e -> { ... }), which returns immediately without invoking the consumer when DEBUG is disabled — no iteration, no iterator. A local alias oftoFlushis captured since the field variable is reassigned after the hand-off to the force-write thread (not effectively final).Verified with
BookieJournalTestandBookieJournalForceTest(22/22 pass) and module checkstyle.