perf(grpc-js): avoid array allocation for single-value metadata headers - #3099
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murgatroid99 merged 1 commit intoSep 24, 2026
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Most gRPC metadata headers contain only a single value (such as authorization tokens, tracing headers, and request IDs). Previously, `toHttp2Headers` always called `.map()`, allocating a temporary array for every header key on every RPC. For single-value headers, we now assign the formatted value directly to the header object instead of wrapping it in an array. This eliminates unnecessary allocations and reduces garbage collection pressure on the RPC hot path.
murgatroid99
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Sep 24, 2026
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Most gRPC metadata headers contain only a single value (such as authorization tokens, tracing headers, and request IDs). Previously,
toHttp2Headersalways called.map(), allocating a temporary array for every header key on every RPC.For single-value headers, we now assign the formatted value directly to the header object instead of wrapping it in an array. This eliminates unnecessary allocations and reduces garbage collection pressure on the RPC hot path.