fix(ktor): gzip level 1 instead of default level 6

[BennyFranciscus]

Sets Deflater.BEST_SPEED (level 1) for gzip compression on /compression endpoint, matching the HttpArena test requirement.

The default GZIPOutputStream constructor uses Deflater.DEFAULT_COMPRESSION (level 6). This fix overrides it to level 1 via the def field.

Closes #107

[MDA2AV]

/benchmark compression

[github-actions]

🚀 Benchmark run triggered for ktor (profile: compression). Results will be posted here when done.

[github-actions]

Benchmark Results

Framework: ktor | Profile: compression

ktor / compression / 4096c (p=1, r=0, cpu=unlimited)
  Best: 10183 req/s (CPU: 12078.5%, Mem: 5.4GiB) ===

ktor / compression / 16384c (p=1, r=0, cpu=unlimited)
  Best: 9876 req/s (CPU: 11312.9%, Mem: 6.1GiB) ===

Full log

#5 [internal] load build context
#5 DONE 0.0s

#6 [build 1/6] FROM docker.io/library/gradle:8.12-jdk21@sha256:4c01ef2d5b57f88578b20891d8640dc799855731b977850940057c1ea37ba8a6
#6 resolve docker.io/library/gradle:8.12-jdk21@sha256:4c01ef2d5b57f88578b20891d8640dc799855731b977850940057c1ea37ba8a6 0.1s done
#6 DONE 0.1s

#7 [stage-1 1/3] FROM docker.io/library/eclipse-temurin:21-jre@sha256:9d4453b48613404e1fa6e5e7eabc687ea57edfb8a1ad413956c5168f84b66af9
#7 resolve docker.io/library/eclipse-temurin:21-jre@sha256:9d4453b48613404e1fa6e5e7eabc687ea57edfb8a1ad413956c5168f84b66af9 0.1s done
#7 DONE 0.1s

#5 [internal] load build context
#5 transferring context: 10.95kB done
#5 DONE 0.0s

#8 [build 2/6] WORKDIR /app
#8 CACHED

#9 [build 4/6] RUN gradle dependencies --no-daemon -q 2>/dev/null || true
#9 CACHED

#10 [build 5/6] COPY src ./src
#10 CACHED

#11 [build 6/6] RUN gradle buildFatJar --no-daemon -q
#11 CACHED

#12 [build 3/6] COPY build.gradle.kts settings.gradle.kts gradle.properties ./
#12 CACHED

#13 [stage-1 2/3] WORKDIR /app
#13 CACHED

#14 [stage-1 3/3] COPY --from=build /app/build/libs/ktor-httparena.jar .
#14 CACHED

#15 exporting to image
#15 exporting layers done
#15 exporting manifest sha256:f2ffd4b1669c467e243f095544b673c8c318be86eb1492dc55cd5cb5f866085c done
#15 exporting config sha256:334d401e1c8f84af70bfeae679e078b0c5460efe5f41aec80f04cd826c060f58 done
#15 exporting attestation manifest sha256:de6c7e9d83299924a0de5fab918022347e7549e2dbf22d52ce6d158aaa0f5912 0.0s done
#15 exporting manifest list sha256:35d524ddea8bf34e4ceb677040f7076b574edb7a263b7f87a0b1c2b1892384ee
#15 exporting manifest list sha256:35d524ddea8bf34e4ceb677040f7076b574edb7a263b7f87a0b1c2b1892384ee 0.0s done
#15 naming to docker.io/library/httparena-ktor:latest done
#15 unpacking to docker.io/library/httparena-ktor:latest 0.0s done
#15 DONE 0.1s

==============================================
=== ktor / compression / 4096c (p=1, r=0, cpu=unlimited) ===
==============================================
89687bf7108577dcc9045a76f4fce95dd0660e7fcad14d00a1db351383f34042
[wait] Waiting for server...
[ready] Server is up

[run 1/3]
gcannon — io_uring HTTP load generator
  Target:    localhost:8080/
  Threads:   64
  Conns:     4096 (64/thread)
  Pipeline:  1
  Req/conn:  unlimited (keep-alive)
  Expected:  200
  Duration:  5s


  Thread Stats   Avg      p50      p90      p99    p99.9
    Latency   429.44ms   394.80ms   550.50ms    1.14s    1.32s

  47244 requests in 5.00s, 45560 responses
  Throughput: 9.11K req/s
  Bandwidth:  1.99GB/s
  Status codes: 2xx=45560, 3xx=0, 4xx=0, 5xx=0
  Latency samples: 45560 / 45560 responses (100.0%)
  CPU: 10956.8% | Mem: 5.4GiB

[run 2/3]
gcannon — io_uring HTTP load generator
  Target:    localhost:8080/
  Threads:   64
  Conns:     4096 (64/thread)
  Pipeline:  1
  Req/conn:  unlimited (keep-alive)
  Expected:  200
  Duration:  5s


  Thread Stats   Avg      p50      p90      p99    p99.9
    Latency   386.03ms   391.60ms   435.10ms   615.90ms   723.10ms

  50980 requests in 5.00s, 50916 responses
  Throughput: 10.18K req/s
  Bandwidth:  2.23GB/s
  Status codes: 2xx=50916, 3xx=0, 4xx=0, 5xx=0
  Latency samples: 50916 / 50916 responses (100.0%)
  CPU: 12078.5% | Mem: 5.4GiB

[run 3/3]
gcannon — io_uring HTTP load generator
  Target:    localhost:8080/
  Threads:   64
  Conns:     4096 (64/thread)
  Pipeline:  1
  Req/conn:  unlimited (keep-alive)
  Expected:  200
  Duration:  5s


  Thread Stats   Avg      p50      p90      p99    p99.9
    Latency   385.21ms   390.10ms   433.00ms   618.20ms   749.70ms

  50866 requests in 5.00s, 50866 responses
  Throughput: 10.17K req/s
  Bandwidth:  2.23GB/s
  Status codes: 2xx=50866, 3xx=0, 4xx=0, 5xx=0
  Latency samples: 50865 / 50866 responses (100.0%)
  CPU: 12000.2% | Mem: 5.4GiB

=== Best: 10183 req/s (CPU: 12078.5%, Mem: 5.4GiB) ===
  Input BW: 735.88KB/s (avg template: 74 bytes)
[dry-run] Results not saved (use --save to persist)
httparena-bench-ktor
httparena-bench-ktor

==============================================
=== ktor / compression / 16384c (p=1, r=0, cpu=unlimited) ===
==============================================
1758a7dbab97b6276e4fb057f3fff152cc68c3dc4e112f61de57ee37707c3629
[wait] Waiting for server...
[ready] Server is up

[run 1/3]
gcannon — io_uring HTTP load generator
  Target:    localhost:8080/
  Threads:   64
  Conns:     16384 (256/thread)
  Pipeline:  1
  Req/conn:  unlimited (keep-alive)
  Expected:  200
  Duration:  5s


  Thread Stats   Avg      p50      p90      p99    p99.9
    Latency    1.27s    1.37s    2.24s    3.36s    3.63s

  59573 requests in 5.00s, 43189 responses
  Throughput: 8.63K req/s
  Bandwidth:  1.89GB/s
  Status codes: 2xx=43189, 3xx=0, 4xx=0, 5xx=0
  Latency samples: 43189 / 43189 responses (100.0%)
  CPU: 10641.7% | Mem: 6.0GiB

[run 2/3]
gcannon — io_uring HTTP load generator
  Target:    localhost:8080/
  Threads:   64
  Conns:     16384 (256/thread)
  Pipeline:  1
  Req/conn:  unlimited (keep-alive)
  Expected:  200
  Duration:  5s


  Thread Stats   Avg      p50      p90      p99    p99.9
    Latency    1.19s    1.36s    1.73s    1.96s    2.45s

  65585 requests in 5.00s, 49201 responses
  Throughput: 9.84K req/s
  Bandwidth:  2.15GB/s
  Status codes: 2xx=49201, 3xx=0, 4xx=0, 5xx=0
  Latency samples: 49201 / 49201 responses (100.0%)
  CPU: 11884.6% | Mem: 6.1GiB

[run 3/3]
gcannon — io_uring HTTP load generator
  Target:    localhost:8080/
  Threads:   64
  Conns:     16384 (256/thread)
  Pipeline:  1
  Req/conn:  unlimited (keep-alive)
  Expected:  200
  Duration:  5s


  Thread Stats   Avg      p50      p90      p99    p99.9
    Latency    1.18s    1.34s    1.70s    2.00s    2.14s

  65768 requests in 5.00s, 49384 responses
  Throughput: 9.87K req/s
  Bandwidth:  2.16GB/s
  Status codes: 2xx=49384, 3xx=0, 4xx=0, 5xx=0
  Latency samples: 49384 / 49384 responses (100.0%)
  CPU: 11312.9% | Mem: 6.1GiB

=== Best: 9876 req/s (CPU: 11312.9%, Mem: 6.1GiB) ===
  Input BW: 713.70KB/s (avg template: 74 bytes)
[dry-run] Results not saved (use --save to persist)
httparena-bench-ktor
httparena-bench-ktor
[restore] Restoring CPU governor to powersave...

[BennyFranciscus]

Nice, ~10.1K req/s at 4096c with level 1 compression. That's a solid result for Ktor — Java's GZIPOutputStream isn't the fastest gzip impl out there but level 1 makes a big difference vs the default level 6.

Latency looks reasonable too, p99 around 600-620ms under load. The 16384c numbers dipping slightly to ~9.9K makes sense — more connections = more scheduling overhead on the JVM side.

Should be good to merge I think, this brings Ktor in line with what the other frameworks are doing for the compression profile.