2026-08-14 18:20:30 +00:00
20 changed files with 862 additions and 21 deletions
@@ -62,6 +62,9 @@ jobs:
          -Dcurl.executable=/usr/bin/curl
          -Dnghttp.executable=/usr/bin/nghttp
          -Dgrpcurl.executable=/tmp/grpcurl
+          -Djdk.tracePinnedThreads=full
+          -Pjmh
+          -Dflash.performance.gates=true
          clean verify
        env:
          MAVEN_USERNAME: ${{ secrets.MAVEN_USERNAME }}
@@ -0,0 +1,44 @@
+# HTTP performance baselines
+
+These numbers are regression controls, not cross-machine promises. They were measured on
+2026-08-13 under Linux 6.12/KVM, six exposed cores of an AMD Ryzen 7 1700X, Temurin 21.0.11 and
+JMH 1.37. CI uses short independent forks for allocation and sample latency so the sampling
+harness does not contaminate `gc.alloc.rate.norm`.
+
+## Gated hot paths
+
+| Benchmark | B/op | p50 ns | p99 ns | p999 ns | CI p99 ceiling ns |
+|---|---:|---:|---:|---:|---:|
+| h1 parse and route | 0.022 | 540 | 33,472 | 60,822 | 45,000 |
+| h2 pooled stream lifecycle | 0.010 | 530 | 2,138 | 37,724 | 2,900 |
+| h2 response encoding | 0.004 | 210 | 993 | 14,626 | 1,350 |
+| HPACK browser-request decode | 0.015 | 730 | 5,245 | 27,577 | 7,100 |
+| HPACK typical-response encode | 0.003 | 180 | 620 | 12,025 | 850 |
+| frame read/validate/discard | 0.006 | 70 | 1,999 | 90,508 | 2,700 |
+
+The sub-byte allocation values occur with no collection and are JMH/GC-profiler rate
+normalization noise. The CI allocation ceiling is 0.05 B/op. A benchmark exceeding it fails; a
+baseline or ceiling change requires an explicit edit and justification here.
+
+The table records the higher percentile observed across three consecutive controlled runs; this is
+important because short sample-mode runs on the shared KVM host showed visible scheduler noise.
+The p999 values expose those tails but are recorded rather than gated. The p99 ceilings are the
+worst observed p99 plus about 35% headroom.
+
+## HTTP/1 historical comparison
+
+The plan required a pre-Phase-1 number, but no benchmark was committed at that point. Phase 17
+reconstructed the current `RequestPipelineBenchmark.parseAndRoute` fixture against Phase 0 commit
+`db6e4a4` in a detached worktree and ran both revisions on the same host and JVM:
+
+| Revision | ns/op | B/op |
+|---|---:|---:|
+| Phase 0 (`db6e4a4`) | 976.195 ± 45.924 | 224.007 |
+| Phase 17 | 1,024.602 ± 50.744 | 0.007 |
+
+The hardened parser's mean is 5.0% higher and removes effectively all 224 B/op. The 99.9%
+confidence intervals overlap (`930.271–1,022.120` ns for Phase 0 and `973.858–1,075.345` ns for
+Phase 17), so this run does not establish a statistically significant latency regression. This is
+an honest reconstruction, not a claim that an absent historical run existed. Phase 17 recovered
+about 4.5% by having `RequestParser` populate `Http1HeaderMap`'s zero-copy index during the same
+validated header pass instead of rescanning every line; all security checks remain in that path.
@@ -1100,3 +1100,45 @@ a second h2-only cleartext listener solely to satisfy a tool assumption.
 against that listener too.

 ---
+
+## DEC-35 — Separate live-stream admission from final-write ownership
+
+**Context.** A stream becomes closed on the wire before the asynchronous serialized writer calls
+back for its final batch. Counting that object as live rejects legal replacement streams; pooling
+it before the callback lets the next stream mutate memory still referenced by the writer.
+
+**Decision.** Detach a wire-closed stream from the primitive live table immediately before its
+final batch is submitted, but retain the stream object until write completion. Bound the combined
+live and detached population to twice `MAX_CONCURRENT_STREAMS`; output congestion therefore
+remains bounded and eventually applies `REFUSED_STREAM` backpressure rather than growing memory.
+
+**Consequence.** The peer can use all advertised live-stream slots while final writes drain, and
+the callback always owns the correct object generation. The closed-stream tombstone is recorded
+at detach time, so protocol error classification is unchanged.
+
+**Revisit when.** If production traces show the two-generation object bound rejecting healthy
+traffic, measure writer-drain latency first; increasing the bound without evidence would only hide
+output backpressure.
+
+---
+
+## DEC-36 — Performance gates distinguish profiler noise, latency sampling, and load results
+
+**Context.** JMH's sampling mode allocates bookkeeping records, so combining `Mode.SampleTime`
+with `GCProfiler` falsely reports allocations on otherwise allocation-free operations. End-to-end
+h2load results also show that Flash does not outperform the reference server, so the plan's
+"unmatched" wording cannot honestly become a product claim.
+
+**Decision.** Run two independent forked CI passes over the same six hot paths: average-time plus
+`GCProfiler` for allocation, and sample-time without the allocation profiler for p50/p99/p999.
+Treat up to 0.05 B/op with zero observed collections as the profiler's measurement floor. Gate
+p99 with documented per-benchmark ceilings and keep h2load comparative results informational.
+
+**Consequence.** CI detects real allocation and latency regressions without measuring its own
+sampling machinery. Performance documentation reports Flash and nghttpd numbers directly and
+makes no "unmatched" claim.
+
+**Revisit when.** Recalibrate baselines deliberately on a controlled CI runner, or replace the
+noise floor if a profiler can distinguish harness allocation from benchmark allocation exactly.
+
+---
@@ -78,7 +78,7 @@ Status values: `not started` / `in progress` / `blocked` / `done`.
 | 14 — h2c prior knowledge + proxy support | done | `feature/core/http2` | Independent TLS/h2c gates, pooled proxy-oriented h2 client with TLS ALPN and h2c, bidirectional h1/h2 trailer relay, shared four-direction hop-by-hop policy and certificate-backed 421 handling complete. Real grpcurl h2c interop passes. 670/670 tests green from a clean `-Pjmh` build. |
 | 15 — RFC 8441 extended CONNECT (WS over h2) | done | `feature/core/http2` | SETTINGS_ENABLE_CONNECT_PROTOCOL, shared WS router/session, DATA flow control, >1 MiB message, h1/h2 parity and lifecycle hardening complete. EX-52/53 fixed; DEC-32 recorded. 675/675 tests green from a clean `-Pjmh` build; real grpcurl interop remains green. |
 | 16 — Compliance test suite | done | `feature/core/http2` | h2spec 2.6.0: TLS 146/146 and mixed-port h2c 145/145 applicable cases, zero skips/failures; invalid-preface protocol boundary documented and regression-tested. Deterministic bounded fuzz targets, exact wire corpus, 1,000-stream single-connection test, nightly 10-minute soak, curl/nghttp/Java/grpcurl matrix and release-browser checklist complete. EX-54–56 fixed; DEC-33/34 recorded. Clean `-Pjmh` gate: 690 tests, 0 failures/errors, 1 intentional conditional soak skip. |
-| 17 — Benchmarks, allocation gates, tuning | not started | — | — |
+| 17 — Benchmarks, allocation gates, tuning | done | `feature/core/http2` | Forked JMH allocation and true sampled-p99 gates wired into CI; h1/h2/frame/HPACK/body/multiplexing/writer coverage complete. Reconstructed Phase-0 h1 baseline: 1,024.602 ns now vs 976.195 ns then with overlapping 99.9% CIs, and 0.007 vs 224.007 B/op. h2load matrix against nghttpd recorded honestly (no unmatched claim); tuning and async-profiler CPU/allocation/lock pass documented. EX-57/58 and DEC-35/36 recorded. Clean pinned-thread build: 694 tests, zero failures/errors, eight intentional conditional skips. |
 | 18 — Documentation | not started | — | — |

 ---
@@ -855,6 +855,25 @@ connection `PROTOCOL_ERROR`. **Fix**: preface verification now distinguishes mat
 and invalid input; invalid input sends GOAWAY. The exact 24 bytes are in the regression corpus.
 **Phase**: 16.

+### EX-57 — Wire-closed streams occupied the live concurrency table until their final write callback
+
+Found by the Phase 17 h2load matrix at the advertised 64-stream concurrency. A response stream
+could be closed in protocol state while its final immutable write batch was still owned by the
+serialized writer. Keeping that object in the live table made a legal replacement stream receive
+`REFUSED_STREAM`; recycling it immediately would instead corrupt the pending write callback.
+**Fix**: detach a closed stream from live lookup before submitting its final batch, retain bounded
+object ownership until the callback, and cap live plus detached objects at twice the advertised
+live capacity. The regression test fills a one-entry table, detaches its final generation, admits
+the next stream, and proves both objects return to the pool. **Phase**: 17.
+
+### EX-58 — The upstream HTTP/2 client left Nagle enabled on synchronous exchanges
+
+Found while building the Phase 17 end-to-end benchmark. The proxy-oriented client sends small
+request and control frames and then synchronously waits for the response; with Nagle enabled this
+interacted with delayed ACKs and added roughly 40 ms to a local exchange. **Fix**: configure
+`TCP_NODELAY` on both cleartext and TLS sockets before protocol exchange. A socket-option
+regression test covers the shared configuration method. **Phase**: 17.
+
 ---

 # PART III — The phases
@@ -3122,11 +3141,14 @@ decisions and the rejected ones. Every claim in the project's marketing about pe
 be traceable to a number in this file.

 ### DoD
- [ ] Allocation gates green in CI and wired to fail the build.
- [ ] Latency baselines recorded.
- [ ] h1 performance is not worse than the pre-Phase-1 baseline.
- [ ] No carrier pinning anywhere.
- [ ] `flash/docs/http2/PERFORMANCE.md` complete with the comparison against a reference server.
+- [x] Allocation gates green in CI and wired to fail the build.
+- [x] Latency baselines recorded in `BASELINES.md`; CI reads JMH's actual `p0.99` secondary
+      result, not iteration-mean statistics.
+- [x] h1 performance is not statistically worse than the reconstructed pre-Phase-1 baseline:
+      the 99.9% confidence intervals overlap, while allocation falls from 224.007 to 0.007 B/op.
+- [x] No carrier pinning anywhere — full 694-test clean run with
+      `-Djdk.tracePinnedThreads=full`, zero pinning events.
+- [x] `flash/docs/http2/PERFORMANCE.md` complete with the comparison against nghttpd.

 ---

@@ -0,0 +1,99 @@
+# HTTP/2 performance
+
+## Method
+
+Measurements were taken on 2026-08-13 under Linux 6.12/KVM with six exposed AMD Ryzen 7 1700X
+cores, Temurin 21.0.11, JMH 1.37 and nghttp2 1.59.0. JMH component benchmarks use prepared,
+reusable protocol state and forked JVMs. `h2load` exercises the real cleartext server on loopback;
+Flash and nghttpd run on the same host in alternating order. Results are snapshots, not promises
+for different hardware.
+
+No "unmatched throughput" claim is supported. nghttpd is normally faster in this matrix; Flash's
+numbers include framework routing, request-model assembly and handler dispatch that the static
+reference server does not.
+
+## Component results
+
+The CI-controlled allocation and percentile numbers are in `BASELINES.md`. Additional average
+time measurements from the same run were:
+
+| Scenario | Result |
+|---|---:|
+| h2 responses across 1 live stream | 74.405 ns |
+| h2 responses across 8 live streams | 705.368 ns |
+| h2 responses across 64 live streams | 5,591.368 ns |
+| h2 responses across 256 live streams | 28,961.681 ns |
+| h2 POST lifecycle with 1 KiB DATA | 741.031 ns, 0.005 B/op |
+| 1 MiB streaming response | 78,681.815 ns |
+
+The multiplexing benchmark reports one complete response-encoding pass across all live streams,
+not per-stream time. `Http2BodyBenchmark` separately covers the 1 KiB request-body shape and the
+1 MiB response shape. `FrameWriterBenchmark` retains the Phase 3 contention matrix and its
+per-write latency distribution.
+
+## End-to-end h2load comparison
+
+Each row uses at least 1,000 requests. Requested stream concurrency is capped first by Flash's
+advertised 64-stream setting and then to 4,096 aggregate active streams so the 1,000-connection
+rows remain bounded. Both requested and effective values are shown.
+
+| Connections | Requested/effective streams | Flash req/s | nghttpd req/s |
+|---:|---:|---:|---:|
+| 1 | 1 / 1 | 2,136.18 | 12,786.42 |
+| 1 | 10 / 10 | 18,396.56 | 83,521.26 |
+| 1 | 100 / 64 | 17,039.55 | 66,746.76 |
+| 10 | 1 / 1 | 11,247.08 | 37,838.66 |
+| 10 | 10 / 10 | 25,055.12 | 104,964.84 |
+| 10 | 100 / 64 | 3,878.28 | 67,303.81 |
+| 100 | 1 / 1 | 5,517.94 | 42,319.09 |
+| 100 | 10 / 10 | 1,818.52 | 26,732.25 |
+| 100 | 100 / 40 | 7,042.85 | 136,585.90 |
+| 1,000 | 1 / 1 | 1,393.17 | 3,877.62 |
+| 1,000 | 10 / 4 | 10,374.83 | 40,976.05 |
+| 1,000 | 100 / 4 | 49,622.10 | 85,344.40 |
+
+The matrix found a correctness issue before it produced these final numbers: closed streams still
+occupied live admission slots while their final write callback was pending. The bounded detach
+fix is recorded as EX-57 and covered by regression tests.
+
+## Tuning decisions
+
+| Knob | Measurement | Decision |
+|---|---|---|
+| 16 KiB / 64 KiB / 1 MiB response frame | 1 MiB stream: 104,071 / 97,996 / 98,769 ns in the non-Huffman sweep | Keep 16 KiB. The roughly 6% gain at 64 KiB does not justify 4x per-connection buffer exposure on this noisy host. |
+| 1 MiB initial receive window | 100 MiB Phase 11 transfer and the load matrix complete without flow stalls | Keep; it matches bounded receive capacity and changing it independently would not isolate a throughput claim. |
+| half-window WINDOW_UPDATE hysteresis | 1 MiB streaming and 100 MiB transfer complete with steady pooled reads | Keep; no per-frame update traffic and no demonstrated reason to weaken backpressure. |
+| 64 KiB inline body | 1 KiB inline materialization is one 1,040 B allocation; streaming steady state is ≈0 B/op | Keep the explicit one-array small-body tradeoff and stream larger bodies. |
+| 64 × 16 KiB DATA buffers | 1 MiB streaming is 78,682 ns with ≈0 B/op; h2load stays bounded | Keep; larger chunks did not produce a clear win beyond the frame-size sweep. |
+| `ScratchPool` bound | 64 objects per exposed CPU, capped at 4,096; full 1,000-connection matrix completes | Keep the capacity bound; it affects retained burst memory, not steady-state request instructions. |
+| word-at-a-time route compare | 14.289 ns versus 22.313 ns bytewise, 36.0% faster | Keep. |
+| SWAR header-end scan | 89.919 ns versus 128.460 ns scalar, 30.0% faster | Keep. |
+| `SlicePool` size 4 | Header/path/query view benchmarks remain allocation-free | Keep; size changes lifetime capacity, not lookup work, and four simultaneous borrowed views match the documented contract. |
+| runtime-value Huffman | representative response headers: 375.761 ns versus 180.129 ns at 16 KiB | Keep disabled by default; this header set is 109% slower to encode. |
+
+The frame-size/Huffman factorial produced counterintuitive variation in the body-only rows, so it
+was not used to claim a Huffman body effect: Huffman only prepares headers. This is treated as
+host noise rather than reverse-engineered into a preferred result.
+
+## Profiling
+
+async-profiler 4.4 was run against the representative browser HPACK decode. The top CPU leaves
+were `Huffman.decode` (72.67%), `HpackHeaderBlock.accept` (7.00%), `HpackDecoder.decode` (5.00%),
+JVM byte-array copy (4.00%), `HpackHeaderBlock.copy` (4.00%), `HpackStaticTable.name` (2.00%),
+`PooledSlice.reset` (1.00%), `PooledSlice.array` (0.67%), JVM byte-arraycopy (0.67%), and
+`HpackDecoder.decodeString` (0.67%). Each belongs to decoding, bounded arena ownership, or the
+copy that makes header lifetime independent of dynamic-table eviction; none is incidental
+locking or logging.
+
+The allocation profile produced no samples on the gated decode path. The realistic eight-writer
+lock profile produced no sampled contended locks; the writer benchmark measured 185.605 bursts/s,
+p50 1.2 µs, p99 5.3 µs and p999 41.6 µs. CPU, allocation and lock artifacts were generated under
+`/tmp/phase17-*` and are intentionally not committed.
+
+CI runs the complete suite with `-Djdk.tracePinnedThreads=full`. The forked allocation and p99
+gates run only under the Maven `jmh` profile; the h2load comparison remains informational and
+conditional because cross-runner throughput is not a stable correctness gate.
+
+The reconstructed Phase-0 HTTP/1 comparison is documented in `BASELINES.md`. Its confidence
+interval overlaps the Phase-17 result, while normalized allocation falls from 224.007 B/op to
+0.007 B/op.
@@ -0,0 +1,95 @@
+package dev.relism.flash.http2;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.util.Collection;
+import java.util.Map;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.condition.EnabledIfSystemProperty;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.profile.GCProfiler;
+import org.openjdk.jmh.results.Result;
+import org.openjdk.jmh.results.RunResult;
+import org.openjdk.jmh.runner.Runner;
+import org.openjdk.jmh.runner.options.ChainedOptionsBuilder;
+import org.openjdk.jmh.runner.options.Options;
+import org.openjdk.jmh.runner.options.OptionsBuilder;
+import org.openjdk.jmh.runner.options.TimeValue;
+
+/** Short, forked JMH gates used by CI; full publication runs retain each benchmark's annotations. */
+@EnabledIfSystemProperty(named = "flash.performance.gates", matches = "true")
+class PerformanceGateTest {
+  private static final double ALLOCATION_NOISE_FLOOR = 0.05;
+  private static final String INCLUDE =
+      "(RequestPipelineBenchmark.parseAndRoute"
+          + "|Http2StreamBenchmark.lifecycle"
+          + "|Http2ResponseWriterBenchmark.encodeResponse"
+          + "|HpackDecoderBenchmark.decodeTypicalBrowserRequest"
+          + "|HpackEncoderBenchmark.encodeTypicalResponse"
+          + "|FrameLayerBenchmark.readValidateAndDiscard)";
+
+  @Test
+  void allocationAndLatencyBaselinesHold() throws Exception {
+    Collection<RunResult> allocationResults = new Runner(allocationOptions()).run();
+    assertFalse(allocationResults.isEmpty(), "JMH did not discover the allocation gates");
+    for (RunResult run : allocationResults) {
+      String benchmark = shortName(run.getParams().getBenchmark());
+      Result<?> allocation = run.getSecondaryResults().get("gc.alloc.rate.norm");
+      assertTrue(allocation != null, "missing allocation measurement for " + benchmark);
+      assertTrue(
+          allocation.getScore() <= ALLOCATION_NOISE_FLOOR,
+          () -> benchmark + " allocated " + allocation.getScore() + " B/op");
+    }
+
+    Collection<RunResult> latencyResults = new Runner(latencyOptions()).run();
+    assertFalse(latencyResults.isEmpty(), "JMH did not discover the latency gates");
+    for (RunResult run : latencyResults) {
+      String benchmark = shortName(run.getParams().getBenchmark());
+      Double maximumNanos = MAXIMUM_P99_NANOS.get(benchmark);
+      assertTrue(maximumNanos != null, "missing latency baseline for " + benchmark);
+      Result<?> p99 = run.getSecondaryResults().get("p0.99");
+      assertTrue(p99 != null, "missing p99 measurement for " + benchmark);
+      double score = p99.getScore();
+      assertTrue(
+          score <= maximumNanos,
+          () -> benchmark + " p99 regressed to " + score + " ns/op; gate is " + maximumNanos);
+    }
+  }
+
+  private static Options allocationOptions() {
+    return commonOptions()
+        .mode(Mode.AverageTime)
+        .addProfiler(GCProfiler.class)
+        .build();
+  }
+
+  private static Options latencyOptions() {
+    return commonOptions().mode(Mode.SampleTime).build();
+  }
+
+  private static ChainedOptionsBuilder commonOptions() {
+    return new OptionsBuilder()
+        .include(INCLUDE)
+        .warmupIterations(2)
+        .warmupTime(TimeValue.milliseconds(250))
+        .measurementIterations(3)
+        .measurementTime(TimeValue.milliseconds(350))
+        .forks(1)
+        .shouldFailOnError(true);
+  }
+
+  private static String shortName(String benchmark) {
+    return benchmark.substring(benchmark.lastIndexOf('.') + 1);
+  }
+
+  // Filled from the controlled baseline run documented in BASELINES.md, with 35% CI headroom.
+  private static final Map<String, Double> MAXIMUM_P99_NANOS =
+      Map.of(
+          "parseAndRoute", 45_000.0,
+          "lifecycle", 2_900.0,
+          "encodeResponse", 1_350.0,
+          "decodeTypicalBrowserRequest", 7_100.0,
+          "encodeTypicalResponse", 850.0,
+          "readValidateAndDiscard", 2_700.0);
+}
@@ -1,6 +1,10 @@
 package dev.relism.flash.http2.hpack;

 import java.util.concurrent.TimeUnit;
+import dev.relism.flash.bytes.ByteWriter;
+import java.nio.charset.StandardCharsets;
+import org.openjdk.jmh.annotations.Level;
+import org.openjdk.jmh.annotations.Setup;
 import org.openjdk.jmh.annotations.Benchmark;
 import org.openjdk.jmh.annotations.BenchmarkMode;
 import org.openjdk.jmh.annotations.Fork;
@@ -22,6 +26,25 @@ public class HpackDecoderBenchmark {
  private final HpackDecoder decoder = new HpackDecoder();
  private final HpackHeaderBlock headers = new HpackHeaderBlock();
  private final byte[] block = {(byte) 0x82, (byte) 0x87, (byte) 0x84, (byte) 0x88};
+  private byte[] browserBlock;
+
+  @Setup(Level.Trial)
+  public void setupTypicalBlock() {
+    ByteWriter encoded = new ByteWriter(256);
+    HpackEncoder.writeIndexed(encoded, 2);
+    HpackEncoder.writeIndexed(encoded, 7);
+    HpackEncoder.writeLiteralWithNameIndex(
+        encoded, 4, "/products?category=books".getBytes(StandardCharsets.US_ASCII), true);
+    HpackEncoder.writeLiteralWithNameIndex(
+        encoded, 1, "shop.example.com".getBytes(StandardCharsets.US_ASCII), true);
+    HpackEncoder.writeLiteralWithNameIndex(
+        encoded, 19, "text/html,application/xhtml+xml".getBytes(StandardCharsets.US_ASCII), true);
+    HpackEncoder.writeLiteralWithNameIndex(
+        encoded, 16, "gzip, deflate".getBytes(StandardCharsets.US_ASCII), true);
+    HpackEncoder.writeLiteralWithNameIndex(
+        encoded, 55, "Mozilla/5.0 benchmark".getBytes(StandardCharsets.US_ASCII), true);
+    browserBlock = java.util.Arrays.copyOf(encoded.array(), encoded.length());
+  }

  @Benchmark
  public int decodeStaticRequest() {
@@ -29,4 +52,11 @@ public class HpackDecoderBenchmark {
    decoder.decode(block, 0, block.length, headers);
    return headers.count();
  }
+
+  @Benchmark
+  public int decodeTypicalBrowserRequest() {
+    headers.reset();
+    decoder.decode(browserBlock, 0, browserBlock.length, headers);
+    return headers.count();
+  }
 }
@@ -0,0 +1,43 @@
+package dev.relism.flash.http2.hpack;
+
+import dev.relism.flash.bytes.ByteWriter;
+import java.nio.charset.StandardCharsets;
+import java.util.concurrent.TimeUnit;
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Fork;
+import org.openjdk.jmh.annotations.Measurement;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.annotations.OutputTimeUnit;
+import org.openjdk.jmh.annotations.Scope;
+import org.openjdk.jmh.annotations.State;
+import org.openjdk.jmh.annotations.Warmup;
+
+/** Measures a representative stateless response header block. */
+@State(Scope.Thread)
+@BenchmarkMode(Mode.AverageTime)
+@OutputTimeUnit(TimeUnit.NANOSECONDS)
+@Fork(2)
+@Warmup(iterations = 3, time = 1)
+@Measurement(iterations = 5, time = 1)
+public class HpackEncoderBenchmark {
+  private static final byte[] CONTENT_LENGTH = "1024".getBytes(StandardCharsets.US_ASCII);
+  private static final byte[] CONTENT_TYPE = "application/json".getBytes(StandardCharsets.US_ASCII);
+  private static final byte[] CACHE_CONTROL = "no-cache".getBytes(StandardCharsets.US_ASCII);
+  private static final byte[] ETAG_NAME = "etag".getBytes(StandardCharsets.US_ASCII);
+  private static final byte[] ETAG = "\"abc123\"".getBytes(StandardCharsets.US_ASCII);
+  private static final byte[] SERVER = "Flash".getBytes(StandardCharsets.US_ASCII);
+  private final ByteWriter output = new ByteWriter(128);
+
+  @Benchmark
+  public int encodeTypicalResponse() {
+    output.reset();
+    HpackEncoder.writeIndexed(output, 8);
+    HpackEncoder.writeLiteralWithNameIndex(output, 31, CONTENT_TYPE, true);
+    HpackEncoder.writeLiteralWithNameIndex(output, 28, CONTENT_LENGTH, false);
+    HpackEncoder.writeLiteralWithNameIndex(output, 24, CACHE_CONTROL, true);
+    HpackEncoder.writeLiteralWithNameIndex(output, 51, SERVER, true);
+    HpackEncoder.writeLiteral(output, ETAG_NAME, ETAG);
+    return output.length();
+  }
+}
@@ -28,6 +28,7 @@ public class Http2BodyBenchmark {
  private static final Http2RequestBody.ConsumptionListener NOOP = bytes -> {};

  private final byte[] payload = new byte[1024];
+  private final byte[] streamingPayload = new byte[1024 * 1024];
  private final byte[] target = new byte[1024];
  private DataBufferPool pool;
  private Http2RequestBody source;
@@ -35,6 +36,7 @@ public class Http2BodyBenchmark {
  private Response response;
  private Http2ResponseWriter responseWriter;
  private ResettableInputStream responseSource;
+  private ResettableInputStream largeResponseSource;

  @Setup(Level.Trial)
  public void setup() throws IOException {
@@ -44,6 +46,7 @@ public class Http2BodyBenchmark {
    response = new Response(200, ContentType.BINARY);
    responseWriter = new Http2ResponseWriter();
    responseSource = new ResettableInputStream(payload);
+    largeResponseSource = new ResettableInputStream(streamingPayload);
    source.begin(-1, false, NOOP);
    source.offer(1, payload, 0, payload.length, payload.length);
    source.finish(1);
@@ -76,6 +79,20 @@ public class Http2BodyBenchmark {
    return responseWriter.length();
  }

+  @Benchmark
+  public int streamingResponseOneMiB() throws IOException {
+    largeResponseSource.rewind();
+    response.reset(200, ContentType.BINARY).stream(largeResponseSource, streamingPayload.length);
+    responseWriter.startFlowControlled(
+        response, 1, false, false, true, false, false, 16_384, 32_768, 16_384);
+    int wireBytes = responseWriter.length();
+    while (!responseWriter.finished()) {
+      responseWriter.resume(16_384, 16_384);
+      wireBytes += responseWriter.length();
+    }
+    return wireBytes;
+  }
+
  private static final class ResettableInputStream extends InputStream {
    private final byte[] source;
    private int position;
@@ -0,0 +1,117 @@
+package dev.relism.flash.http2.message;
+
+import dev.relism.flash.http.ContentType;
+import dev.relism.flash.models.PreEncodedHeader;
+import dev.relism.flash.models.Response;
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.concurrent.TimeUnit;
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Fork;
+import org.openjdk.jmh.annotations.Level;
+import org.openjdk.jmh.annotations.Measurement;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.annotations.OutputTimeUnit;
+import org.openjdk.jmh.annotations.Param;
+import org.openjdk.jmh.annotations.Scope;
+import org.openjdk.jmh.annotations.Setup;
+import org.openjdk.jmh.annotations.State;
+import org.openjdk.jmh.annotations.Warmup;
+
+/** Factorial measurements for the response knobs considered during tuning. */
+@State(Scope.Thread)
+@BenchmarkMode(Mode.AverageTime)
+@OutputTimeUnit(TimeUnit.NANOSECONDS)
+@Fork(2)
+@Warmup(iterations = 3, time = 1)
+@Measurement(iterations = 5, time = 1)
+public class Http2TuningBenchmark {
+  @Param({"false", "true"})
+  public boolean huffmanDynamicValues;
+
+  @Param({"16384", "65536", "1048576"})
+  public int maxFrameSize;
+
+  private final byte[] largeBody = new byte[1024 * 1024];
+  private Http2ResponseWriter writer;
+  private Response response;
+  private Response streamingResponse;
+  private ResettableInputStream source;
+
+  @Setup(Level.Trial)
+  public void setup() {
+    writer = new Http2ResponseWriter();
+    response =
+        new Response(200, "hello", ContentType.JSON)
+            .header(new PreEncodedHeader("cache-control", "private, max-age=60"))
+            .header(new PreEncodedHeader("x-request-id", "d7bca219-6dd4-4ef0-a881-f21931e249c7"));
+    source = new ResettableInputStream(largeBody);
+    streamingResponse = new Response(200, ContentType.BINARY).stream(source, largeBody.length);
+  }
+
+  @Benchmark
+  public int encodeResponseHeaders() {
+    writer.prepare(
+        response,
+        1,
+        false,
+        true,
+        true,
+        huffmanDynamicValues,
+        false,
+        maxFrameSize,
+        32_768,
+        65_535);
+    return writer.length();
+  }
+
+  @Benchmark
+  public int streamOneMiB() throws IOException {
+    source.rewind();
+    writer.startFlowControlled(
+        streamingResponse,
+        1,
+        false,
+        false,
+        true,
+        huffmanDynamicValues,
+        false,
+        maxFrameSize,
+        32_768,
+        maxFrameSize);
+    int wireBytes = writer.length();
+    while (!writer.finished()) {
+      writer.resume(maxFrameSize, maxFrameSize);
+      wireBytes += writer.length();
+    }
+    return wireBytes;
+  }
+
+  private static final class ResettableInputStream extends InputStream {
+    private final byte[] bytes;
+    private int position;
+
+    private ResettableInputStream(byte[] bytes) {
+      this.bytes = bytes;
+    }
+
+    private void rewind() {
+      position = 0;
+    }
+
+    @Override
+    public int read() {
+      return position == bytes.length ? -1 : bytes[position++] & 0xff;
+    }
+
+    @Override
+    public int read(byte[] target, int offset, int length) {
+      if (position == bytes.length) return -1;
+      int count = Math.min(length, bytes.length - position);
+      System.arraycopy(bytes, position, target, offset, count);
+      position += count;
+      return count;
+    }
+  }
+}
@@ -0,0 +1,77 @@
+package dev.relism.flash.http2.stream;
+
+import dev.relism.flash.bytes.ByteWriter;
+import dev.relism.flash.http2.hpack.HpackDecoder;
+import dev.relism.flash.http2.hpack.HpackEncoder;
+import java.nio.charset.StandardCharsets;
+import java.util.concurrent.TimeUnit;
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Fork;
+import org.openjdk.jmh.annotations.Level;
+import org.openjdk.jmh.annotations.Measurement;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.annotations.OutputTimeUnit;
+import org.openjdk.jmh.annotations.Param;
+import org.openjdk.jmh.annotations.Scope;
+import org.openjdk.jmh.annotations.Setup;
+import org.openjdk.jmh.annotations.State;
+import org.openjdk.jmh.annotations.Warmup;
+
+/** Measures one response pass across a connection with N simultaneously live request streams. */
+@State(Scope.Thread)
+@BenchmarkMode(Mode.AverageTime)
+@OutputTimeUnit(TimeUnit.NANOSECONDS)
+@Fork(2)
+@Warmup(iterations = 3, time = 1)
+@Measurement(iterations = 5, time = 1)
+public class Http2MultiplexingBenchmark {
+  private static final byte[] BODY = "ok".getBytes(StandardCharsets.US_ASCII);
+
+  @Param({"1", "8", "64", "256"})
+  public int liveStreams;
+
+  private Http2Stream[] streams;
+
+  @Setup(Level.Trial)
+  public void setup() {
+    Http2StreamTable table = new Http2StreamTable(liveStreams);
+    streams = new Http2Stream[liveStreams];
+    ByteWriter encoded = new ByteWriter(64);
+    HpackEncoder.writeIndexed(encoded, 2);
+    HpackEncoder.writeIndexed(encoded, 7);
+    HpackEncoder.writeLiteralWithNameIndex(
+        encoded, 4, "/get".getBytes(StandardCharsets.US_ASCII), false);
+    HpackEncoder.writeLiteralWithNameIndex(
+        encoded, 1, "localhost".getBytes(StandardCharsets.US_ASCII), false);
+    HpackDecoder decoder = new HpackDecoder();
+    for (int i = 0; i < streams.length; i++) {
+      Http2Stream stream = table.acquire(i * 2 + 1);
+      decoder.decode(encoded.array(), 0, encoded.length(), stream.headerBlock());
+      stream.assembleRequest(null, null);
+      streams[i] = stream;
+    }
+  }
+
+  @Benchmark
+  public int encodeAllLiveStreamResponses() {
+    int wireBytes = 0;
+    for (Http2Stream stream : streams) {
+      stream
+          .responseWriter()
+          .prepare(
+              stream.resetResponse().body(BODY),
+              stream.id(),
+              false,
+              false,
+              true,
+              false,
+              false,
+              16_384,
+              32_768,
+              65_535);
+      wireBytes += stream.responseWriter().length();
+    }
+    return wireBytes;
+  }
+}
@@ -26,11 +26,14 @@ import org.openjdk.jmh.annotations.Warmup;
@Measurement(iterations = 5, time = 1)
 public class Http2StreamBenchmark {
  private static final byte[] BODY = "pong".getBytes(StandardCharsets.US_ASCII);
+  private static final byte[] POST_BODY = new byte[1024];

  private Http2StreamTable streams;
  private HpackDecoder decoder;
  private byte[] requestBlock;
  private int requestLength;
+  private byte[] postBlock;
+  private int postLength;

  @Setup
  public void setup() {
@@ -45,7 +48,19 @@ public class Http2StreamBenchmark {
        block, 1, "localhost".getBytes(StandardCharsets.US_ASCII), false);
    requestBlock = block.array();
    requestLength = block.length();
+    ByteWriter post = new ByteWriter(96);
+    HpackEncoder.writeIndexed(post, 3);
+    HpackEncoder.writeIndexed(post, 7);
+    HpackEncoder.writeLiteralWithNameIndex(
+        post, 4, "/ping".getBytes(StandardCharsets.US_ASCII), false);
+    HpackEncoder.writeLiteralWithNameIndex(
+        post, 1, "localhost".getBytes(StandardCharsets.US_ASCII), false);
+    HpackEncoder.writeLiteralWithNameIndex(
+        post, 28, "1024".getBytes(StandardCharsets.US_ASCII), false);
+    postBlock = post.array();
+    postLength = post.length();
    lifecycle();
+    postOneKiB();
  }

  @Benchmark
@@ -62,4 +77,32 @@ public class Http2StreamBenchmark {
    streams.release(stream);
    return bytes;
  }
+
+  /** Unary request shape: HPACK decode, one 1 KiB DATA payload, assembly and fixed response. */
+  @Benchmark
+  public int postOneKiB() {
+    Http2Stream stream = streams.acquire(1);
+    decoder.decode(postBlock, 0, postLength, stream.headerBlock());
+    stream.prepareRequestBody(null, false);
+    stream.receiveData(POST_BODY, 0, POST_BODY.length, POST_BODY.length);
+    stream.finishRequestBody();
+    stream.assembleRequest(null, null);
+    stream
+        .responseWriter()
+        .prepare(
+            stream.resetResponse().body(BODY),
+            1,
+            false,
+            false,
+            true,
+            false,
+            false,
+            16_384,
+            32_768,
+            65_535);
+    int bytes = stream.responseWriter().length();
+    streams.remove(1);
+    streams.release(stream);
+    return bytes;
+  }
 }
@@ -190,6 +190,7 @@ public class RequestParser {
        boolean transferEncodingSeen    = false;
        boolean transferEncodingChunked = false;
        int headerCount = 0;
+        headerMap.beginParsed(buffer, sectionStart, headerEndIdx);

        while (current < headerEndIdx) {
            // deprecates line folding and treating a folded continuation as part of the
@@ -232,6 +233,7 @@ public class RequestParser {
            if (lineEnd - valueStart > Http1Limits.MAX_HEADER_VALUE_LENGTH) {
                throw new MalformedRequestException(431, "Header value exceeds " + Http1Limits.MAX_HEADER_VALUE_LENGTH + " bytes");
            }
+            headerMap.addParsed(current, colon - current, valueStart, lineEnd - valueStart);

            if (ByteScan.equalsIgnoreCaseAscii(buffer, current, colon, "content-length")) {
                // parseLong, which silently accepted "5abc" as 5 and "-1" as 1.
@@ -270,8 +272,6 @@ public class RequestParser {
            if (!contentLengthSeen) contentLength = 0;
        }

-        headerMap.reset(buffer, sectionStart, headerEndIdx);
-
        // ── Body / pipelining accounting ─────────────────────────────────────

        int bodyStart = headerEndIdx + 4;
@@ -185,6 +185,7 @@ final class Http2StreamDispatcher implements Http2Stream.ResponseSink {
      if (!stream.beginResponseBatch()) {
        throw new IllegalStateException("response batch already in flight");
      }
+      detachFinalBatch(stream, responseWriter);
      frameWriter.write(responseWriter);
    } catch (Exception failure) {
      failAndRelease(stream, Http2ErrorCode.INTERNAL_ERROR, failure);
@@ -220,6 +221,7 @@ final class Http2StreamDispatcher implements Http2Stream.ResponseSink {
        flowController.refundSend(stream, reserved - used);
      }
      applyBatchTransition(stream, responseWriter);
+      detachFinalBatch(stream, responseWriter);
      frameWriter.write(responseWriter);
    } catch (Exception failure) {
      stream.endResponseBatch();
@@ -270,16 +272,22 @@ final class Http2StreamDispatcher implements Http2Stream.ResponseSink {
    }
    if (stream.responseWriter().finished()) {
      if (stream.state() == Http2StreamState.CLOSED) {
-        streams.retire(stream, streamId);
+        if (!streams.retire(stream, streamId)) streams.release(stream);
      }
      return;
    }
    scheduleResume(stream);
  }

+  private void detachFinalBatch(Http2Stream stream, Http2ResponseWriter writer) {
+    if (writer.finished() && stream.state() == Http2StreamState.CLOSED) {
+      streams.detach(stream, stream.id());
+    }
+  }
+
  private void failAndRelease(Http2Stream stream, Http2ErrorCode error, Exception cause) {
    int streamId = stream.id();
-    if (!streams.removeIfSame(stream, streamId)) return;
+    if (!streams.removeIfSame(stream, streamId) && stream.id() != streamId) return;
    if (cause != null) log.error("HTTP/2 stream {} failed", streamId, cause);
    try {
      stream.cancel();
@@ -463,6 +463,7 @@ public final class Http2Client implements Closeable {
      if (!origin.secure) {
        Socket socket = new Socket();
        socket.connect(new InetSocketAddress(origin.host, origin.port), CONNECT_TIMEOUT_MS);
+        configureLowLatency(socket);
        return socket;
      }
      SSLContext context;
@@ -473,6 +474,7 @@ public final class Http2Client implements Closeable {
      }
      SSLSocket socket =
          (SSLSocket) context.getSocketFactory().createSocket(origin.host, origin.port);
+      configureLowLatency(socket);
      SSLParameters parameters = socket.getSSLParameters();
      parameters.setApplicationProtocols(new String[] {"h2"});
      parameters.setEndpointIdentificationAlgorithm("HTTPS");
@@ -486,6 +488,10 @@ public final class Http2Client implements Closeable {
    }
  }

+  static void configureLowLatency(Socket socket) throws IOException {
+    socket.setTcpNoDelay(true);
+  }
+
  private static final class Exchange {
    private final int streamId;
    private final MutableHeaderMap headers = new MutableHeaderMap();
@@ -16,6 +16,7 @@ public final class Http2StreamTable {
  private final Http2Stream[] values;
  private final int mask;
  private final int maxEntries;
+  private final int maxObjects;
  private final int[] closedIds;
  private final byte[] closedKinds;
  private int size;
@@ -42,6 +43,7 @@ public final class Http2StreamTable {
    values = new Http2Stream[capacity];
    mask = capacity - 1;
    this.maxEntries = maxEntries;
+    maxObjects = maxEntries * 2;
    this.dataBuffers = dataBuffers;
    closedIds = new int[maxEntries * 2];
    closedKinds = new byte[closedIds.length];
@@ -69,7 +71,7 @@ public final class Http2StreamTable {
      free = stream.poolNext;
      stream.poolNext = null;
    } else {
-      if (created == maxEntries) return null;
+      if (created == maxObjects) return null;
      stream = new Http2Stream(dataBuffers);
      created++;
    }
@@ -123,6 +125,13 @@ public final class Http2StreamTable {
    return true;
  }

+  /** Removes a wire-closed stream from live concurrency while retaining its in-flight buffer. */
+  public synchronized boolean detach(Http2Stream stream, int streamId) {
+    if (!removeIfSame(stream, streamId)) return false;
+    rememberClosed(streamId, CLOSED_NORMALLY);
+    return true;
+  }
+
  public synchronized void rememberReset(int streamId) {
    rememberClosed(streamId, CLOSED_BY_RESET);
  }
@@ -77,12 +77,33 @@ public class Http1HeaderMap implements HeaderView {
    private Slice valueSlice;

    public void reset(byte[] buffer, int sectionStart, int sectionEnd) {
-        this.buffer       = buffer;
-        this.sectionStart = sectionStart;
-        this.sectionEnd   = sectionEnd;
+        beginParsed(buffer, sectionStart, sectionEnd);
        buildIndex();
    }

+    /**
+     * Starts an index populated by the request parser while it validates the same header lines.
+     * This avoids rescanning a validated section solely to recover offsets already known there.
+     */
+    public void beginParsed(byte[] buffer, int sectionStart, int sectionEnd) {
+        this.buffer = buffer;
+        this.sectionStart = sectionStart;
+        this.sectionEnd = sectionEnd;
+        headerCount = 0;
+    }
+
+    /** Adds one already-validated header to the current zero-copy index. */
+    public void addParsed(int nameOffset, int nameLength, int valueOffset, int valueLength) {
+        ensureIndexCapacity(headerCount + 1);
+        nameOffsets[headerCount] = nameOffset;
+        nameLengths[headerCount] = nameLength;
+        valueOffsets[headerCount] = valueOffset;
+        valueLengths[headerCount] = valueLength;
+        nameHashes[headerCount] =
+                ByteScan.hashNameIgnoreCaseAscii(buffer, nameOffset, nameLength);
+        headerCount++;
+    }
+
    private void buildIndex() {
        headerCount = 0;
        if (buffer == null) return;
@@ -92,13 +113,7 @@ public class Http1HeaderMap implements HeaderView {
            int colon   = findColon(i, lineEnd);
            if (colon != -1) {
                int vs = skipSpaces(colon + 1, lineEnd);
-                ensureIndexCapacity(headerCount + 1);
-                nameOffsets[headerCount]  = i;
-                nameLengths[headerCount]  = colon - i;
-                valueOffsets[headerCount] = vs;
-                valueLengths[headerCount] = lineEnd - vs;
-                nameHashes[headerCount]   = ByteScan.hashNameIgnoreCaseAscii(buffer, i, colon - i);
-                headerCount++;
+                addParsed(i, colon - i, vs, lineEnd - vs);
            }
            i = lineEnd + 2;
        }
@@ -0,0 +1,141 @@
+package dev.relism.flash.http2;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import dev.relism.flash.extension.FlashApp;
+import dev.relism.flash.extension.FlashConfiguration;
+import java.net.ServerSocket;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.time.Duration;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.TimeUnit;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.Tag;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.condition.EnabledIfSystemProperty;
+import org.junit.jupiter.api.io.TempDir;
+
+@Tag("benchmark")
+@EnabledIfSystemProperty(named = "h2load.executable", matches = ".+")
+@EnabledIfSystemProperty(named = "nghttpd.executable", matches = ".+")
+class H2LoadMeasurementTest {
+  private static final int[] CONNECTIONS = {1, 10, 100, 1_000};
+  private static final int[] STREAMS = {1, 10, 100};
+  private static final Pattern RATE = Pattern.compile("([0-9.]+) req/s");
+  private static final Pattern REQUESTS =
+      Pattern.compile("requests: (\\d+) total, .*? (\\d+) succeeded, (\\d+) failed");
+
+  private FlashApp app;
+  private Process reference;
+
+  @AfterEach
+  void stop() {
+    if (app != null) app.stop().join();
+    if (reference != null) reference.destroyForcibly();
+  }
+
+  @Test
+  void measureFlashAndNghttpdMatrix(@TempDir Path directory) throws Exception {
+    int flashPort = freePort();
+    app =
+        FlashApp.create(
+            FlashConfiguration.builder()
+                .host("127.0.0.1")
+                .port(flashPort)
+                .http2CleartextEnabled(true)
+                .h2MaxStreamsCreatedPerInterval(Integer.MAX_VALUE)
+                .h2MaxStreamsPerConnection(0)
+                .build());
+    app.get("/index.html", (request, response) -> "flash-load");
+    app.start();
+
+    int referencePort = freePort();
+    Files.writeString(directory.resolve("index.html"), "flash-load");
+    ProcessBuilder server =
+        new ProcessBuilder(
+            System.getProperty("nghttpd.executable"),
+            "--no-tls",
+            "--max-concurrent-streams=128",
+            "-d",
+            directory.toString(),
+            Integer.toString(referencePort));
+    applyLibraryPath(server);
+    reference = server.redirectErrorStream(true).start();
+    Thread.sleep(200);
+
+    System.out.println(
+        "implementation,connections,requested_streams,effective_streams,requests,requests_per_second");
+    for (int connections : CONNECTIONS) {
+      for (int streams : STREAMS) {
+        int requests = Math.max(1_000, connections * streams);
+        int effectiveStreams =
+            Math.max(
+                1,
+                Math.min(
+                    Math.min(streams, Http2Limits.MAX_CONCURRENT_STREAMS),
+                    4_096 / connections));
+        measure("flash", flashPort, connections, streams, effectiveStreams, requests);
+        measure("nghttpd", referencePort, connections, streams, effectiveStreams, requests);
+      }
+    }
+  }
+
+  private static void measure(
+      String implementation,
+      int port,
+      int connections,
+      int requestedStreams,
+      int effectiveStreams,
+      int requests)
+      throws Exception {
+    List<String> command = new ArrayList<>();
+    command.add(System.getProperty("h2load.executable"));
+    command.add("-n");
+    command.add(Integer.toString(requests));
+    command.add("-c");
+    command.add(Integer.toString(connections));
+    command.add("-m");
+    command.add(Integer.toString(effectiveStreams));
+    command.add("-t");
+    command.add(Integer.toString(Math.min(8, connections)));
+    command.add("http://127.0.0.1:" + port + "/index.html");
+    ProcessBuilder builder = new ProcessBuilder(command).redirectErrorStream(true);
+    applyLibraryPath(builder);
+    Process process = builder.start();
+    assertTrue(process.waitFor(Duration.ofMinutes(2).toMillis(), TimeUnit.MILLISECONDS));
+    String output = new String(process.getInputStream().readAllBytes(), StandardCharsets.UTF_8);
+    assertEquals(0, process.exitValue(), output);
+    Matcher requestsResult = REQUESTS.matcher(output);
+    assertTrue(requestsResult.find(), output);
+    assertEquals(requests, Integer.parseInt(requestsResult.group(1)), output);
+    assertEquals(requests, Integer.parseInt(requestsResult.group(2)), output);
+    assertEquals(0, Integer.parseInt(requestsResult.group(3)), output);
+    Matcher rate = RATE.matcher(output);
+    assertTrue(rate.find(), output);
+    System.out.printf(
+        "%s,%d,%d,%d,%d,%s%n",
+        implementation,
+        connections,
+        requestedStreams,
+        effectiveStreams,
+        requests,
+        rate.group(1));
+  }
+
+  private static void applyLibraryPath(ProcessBuilder builder) {
+    String path = System.getProperty("nghttp.library.path");
+    if (path != null) builder.environment().put("LD_LIBRARY_PATH", path);
+  }
+
+  private static int freePort() throws Exception {
+    try (ServerSocket socket = new ServerSocket(0)) {
+      return socket.getLocalPort();
+    }
+  }
+}
@@ -2,6 +2,8 @@ package dev.relism.flash.http2.client;

 import static org.junit.jupiter.api.Assertions.assertArrayEquals;
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;

 import dev.relism.flash.extension.FlashApp;
 import dev.relism.flash.extension.FlashConfiguration;
@@ -10,6 +12,7 @@ import dev.relism.flash.models.MutableHeaderMap;
 import dev.relism.flash.tls.TestKeystores;
 import dev.relism.flash.tls.TlsConfig;
 import java.net.ServerSocket;
+import java.net.Socket;
 import java.net.URI;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Path;
@@ -101,6 +104,15 @@ class Http2ClientTest {
    }
  }

+  @Test
+  void configuresConnectionsForRequestResponseLatency() throws Exception {
+    try (Socket socket = new Socket()) {
+      assertFalse(socket.getTcpNoDelay());
+      Http2Client.configureLowLatency(socket);
+      assertTrue(socket.getTcpNoDelay());
+    }
+  }
+
  private static MutableHeaderMap fields(String name, String value) {
    MutableHeaderMap headers = new MutableHeaderMap();
    byte[] nameBytes = name.getBytes(StandardCharsets.US_ASCII);
@@ -3,6 +3,8 @@ package dev.relism.flash.http2.stream;
 import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertNotSame;
 import static org.junit.jupiter.api.Assertions.assertSame;
 import static org.junit.jupiter.api.Assertions.assertTrue;

@@ -52,4 +54,20 @@ class Http2StreamTableTest {
    assertEquals(Http2StreamTable.CLOSED_BY_RESET, table.closedKind(3));
    assertEquals(Http2StreamTable.CLOSED_UNKNOWN, table.closedKind(5));
  }
+
+  @Test
+  void detachedFinalWriteDoesNotConsumeLiveStreamCapacity() {
+    Http2StreamTable table = new Http2StreamTable(1);
+    Http2Stream first = table.acquire(1);
+
+    assertTrue(table.detach(first, 1));
+    Http2Stream second = table.acquire(3);
+    assertNotNull(second);
+    assertNotSame(first, second);
+
+    table.release(first);
+    assertTrue(table.retire(second, 3));
+    assertEquals(2, table.createdCount());
+    assertEquals(2, table.freeCount());
+  }
 }