Match runtime benchmark production heap

Author: Arbousier1

.github/workflows/upstream-runtime-comparison.yml

@@ -400,7 +400,7 @@ jobs:
           runner_sha=$(sha256sum tools/perf/run-upstream-runtime-once.sh | awk '{print $1}')
           protocol_source_sha=$(sha256sum tools/perf/phase2-protocol-client.js | awk '{print $1}')
           protocol_analyzer_sha=$(sha256sum tools/perf/analyze-phase2-protocol-trace.js | awk '{print $1}')
-          jvm_fingerprint='-Xms2G -Xmx2G -XX:+UseG1GC -XX:+AlwaysPreTouch -Xlog:gc*=info,safepoint=info:file=jvm-gc-safepoint.log:time,uptime,level,tags:filecount=0 -Dfile.encoding=UTF-8'
+          jvm_fingerprint='-Xms4G -Xmx4G -XX:+UseG1GC -XX:+AlwaysPreTouch -Xlog:gc*=info,safepoint=info:file=jvm-gc-safepoint.log:time,uptime,level,tags:filecount=0 -Dfile.encoding=UTF-8'
           jvm_sha=$(printf '%s' "$jvm_fingerprint" | sha256sum | awk '{print $1}')
           stack_sha=$(
             {
@@ -634,6 +634,8 @@ jobs:
               raise SystemExit("preflight runtime profile mismatch")
           if manifest.get("campaignKind") != "preflight":
               raise SystemExit("preflight campaign kind mismatch")
+          if manifest.get("serverHeapGiB") != 4:
+              raise SystemExit("preflight server heap mismatch")
           expected_shutdown = {
               "mode": "clean",
               "stopGraceSeconds": 120,
@@ -855,6 +857,7 @@ jobs:
               "clientCpuSet": expected_client_cpu_set,
               "runtimeProfile": runtime_profile,
               "campaignKind": campaign_kind,
+              "serverHeapGiB": 4,
               "requestedFlags": expected_requested_flags,
               "effectiveFlags": expected_effective_flags,
           }
@@ -1162,6 +1165,8 @@ jobs:
                   raise SystemExit(f"runtime profile drifted in {row['RunId']}")
               if run_manifest.get("networkTimeoutSeconds") != 300:
                   raise SystemExit(f"network timeout drifted in {row['RunId']}")
+              if run_manifest.get("serverHeapGiB") != 4:
+                  raise SystemExit(f"server heap drifted in {row['RunId']}")
               if run_manifest.get("campaignKind") != kind:
                   raise SystemExit(f"campaign kind drifted in {row['RunId']}")
               expected_forced_shutdown = (
@@ -1335,6 +1340,7 @@ jobs:
               f"restart-isolated independent runs: `{runs}`.",
               f"Runtime profile: `{runtime_profile}`; shared config requests "
               "`PacketOnlyStatic=true` and `EventDriven=true` for both artifacts.",
+              "Server heap: `4 GiB` for both artifacts; target tick rate remains vanilla `20 TPS`.",
               "Runtime assertion: A reports both flags as `unsupported-legacy`; "
               "B exposes both runtime fields as `true`.",
               ("Server shutdown evidence: "
@@ -1463,6 +1469,7 @@ jobs:
               "paperSha256": paper_sha,
               "stackSha256": stack_sha,
               "runtimeProfile": runtime_profile,
+              "serverHeapGiB": 4,
               "requestedFlags": {
                   "packetOnlyStatic": True,
                   "eventDrivenBlockUpdates": True,

tools/perf/run-upstream-runtime-once.sh

@@ -33,6 +33,9 @@ measure_seconds="$COMPARE_MEASURE_SECONDS"
 # This only prevents the synthetic observer from being kicked while the
 # official upstream stalls; it does not alter the server's 20 TPS target.
 network_timeout_seconds=300
+# Match the 4 GiB production server represented by the supplied Spark profile.
+# A and B always receive the same fixed heap.
+server_heap_gib=4
 server_port="${COMPARE_SERVER_PORT:-25565}"
 protocol_trace_enabled="${COMPARE_PROTOCOL_TRACE_ENABLED:-0}"
 protocol_trace_max_events="${COMPARE_PROTOCOL_TRACE_MAX_EVENTS:-500000}"
@@ -250,8 +253,8 @@ client_manifest_sha256="$(sha256sum "$client_root/client-build-manifest.json" |
 script_sha256="$(sha256sum "${BASH_SOURCE[0]}" | awk '{print $1}')"
 
 jvm_arguments=(
-  -Xms2G
-  -Xmx2G
+  "-Xms${server_heap_gib}G"
+  "-Xmx${server_heap_gib}G"
   -XX:+UseG1GC
   -XX:+AlwaysPreTouch
   "-Xlog:gc*=info,safepoint=info:file=$jvm_log_name:time,uptime,level,tags:filecount=0"
@@ -666,7 +669,8 @@ python3 - "$run_directory/run-manifest.json" "$run_id" "$scenario" "$variant" \
   "$protocol_trace_aggregate_packet_allowlist" \
   "$trace_window_start_epoch_ms" "$trace_window_end_epoch_ms" \
   "$available_cpu_count" "$server_cpu_set" "$client_cpu_set" \
-  "$runtime_profile" "$campaign_kind" "$network_timeout_seconds" "$metrics_path" <<'PY'
+  "$runtime_profile" "$campaign_kind" "$network_timeout_seconds" \
+  "$server_heap_gib" "$metrics_path" <<'PY'
 from pathlib import Path
 import json
 import sys
@@ -678,7 +682,8 @@ import sys
     trace_enabled, trace_packet_allowlist, trace_aggregate_packet_allowlist,
     trace_window_start_epoch_ms, trace_window_end_epoch_ms,
     available_cpu_count, server_cpu_set, client_cpu_set,
-    runtime_profile, campaign_kind, network_timeout_seconds, metrics_path,
+    runtime_profile, campaign_kind, network_timeout_seconds, server_heap_gib,
+    metrics_path,
 ) = sys.argv[1:]
 metrics = json.load(open(metrics_path, encoding="utf-8"))
 Path(output).write_text(json.dumps({
@@ -690,6 +695,7 @@ Path(output).write_text(json.dumps({
     "runtimeProfile": runtime_profile,
     "campaignKind": campaign_kind,
     "networkTimeoutSeconds": int(network_timeout_seconds),
+    "serverHeapGiB": int(server_heap_gib),
     "requestedFlags": metrics["requestedFlags"],
     "effectiveFlags": metrics["effectiveFlags"],
     "sceneSize": int(scene_size),