[CI] Deflake the multi-API-server metrics test and Mooncake PD ports (#59507)

Signed-off-by: khluu <khluu000@gmail.com>
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

tests/entrypoints/serve/dev/rlhf/test_weight_operation_metrics.py

@@ -21,8 +21,10 @@ from vllm.distributed.weight_transfer.ipc_engine import IPCTrainerInitInfo
 
 DURATION = "vllm:rl_weight_update_operation_duration_seconds"
 IN_FLIGHT = "vllm:rl_weight_update_operations_in_flight"
-# Enough requests that the kernel spreads them over both API servers.
-SYNCS = 8
+# The API servers accept from one shared listening socket, so the kernel may
+# hand one process most connections. Sync until both have recorded, within a cap.
+MIN_SYNCS = 8
+MAX_SYNCS = 64
 
 
 def scrape(url: str) -> dict[tuple[str, str], float]:
@@ -75,11 +77,15 @@ def test_weight_sync_metrics_aggregate_across_api_servers(tmp_path):
             client=HTTPVLLMWeightSyncClient(url),
             source=ModuleSource(trainer),
         )
-        for _ in range(SYNCS):
+        syncs = 0
+        while syncs < MIN_SYNCS or (
+            len(pids_that_recorded(tmp_path)) < 2 and syncs < MAX_SYNCS
+        ):
             engine.send_weights()
+            syncs += 1
         metrics = scrape(url)
 
-    calls = {"init": 1, "start": SYNCS, "update": SYNCS, "finish": SYNCS}
+    calls = {"init": 1, "start": syncs, "update": syncs, "finish": syncs}
     for operation, count in calls.items():
         assert metrics[(f"{DURATION}_count", operation)] == count, operation
         assert metrics[(IN_FLIGHT, operation)] == 0, operation

tests/v1/kv_connector/mooncake_integration/run_accuracy_test.sh

@@ -78,6 +78,20 @@ wait_for_server() {
     done" && return 0 || return 1
 }
 
+# b200-k8s pods use host networking, so a fixed port can already be taken by
+# another job on the node. Bind all the ports at once so they are distinct.
+free_ports() {
+  python3 - "$1" <<'EOF'
+import socket
+import sys
+
+socks = [socket.socket() for _ in range(int(sys.argv[1]))]
+for s in socks:
+    s.bind(("", 0))
+print(" ".join(str(s.getsockname()[1]) for s in socks))
+EOF
+}
+
 # Function to clean up previous instances
 cleanup_instances() {
   echo "Cleaning up any running vLLM instances..."
@@ -107,6 +121,9 @@ run_tests_for_model() {
 
   # Proxy args: repeated --prefill URL BOOTSTRAP_PORT and --decode URL.
   PROXY_ARGS=()
+  # Per prefiller: server and bootstrap. Per decoder: server. Then the proxy.
+  read -r -a PORTS <<< "$(free_ports $((2 * NUM_PREFILL_INSTANCES + NUM_DECODE_INSTANCES + 1)))"
+  PROXY_PORT=${PORTS[${#PORTS[@]} - 1]}
 
   # Start prefill instances
   for i in $(seq 0 $((NUM_PREFILL_INSTANCES-1))); do
@@ -119,10 +136,8 @@ run_tests_for_model() {
       GPU_ID="${GPU_ID},${NEXT_GPU}"
     done
 
-    # Calculate port number (base port + instance number)
-    PORT=$((8100 + i))
-    # Bootstrap server port for this prefiller. Avoid clash across instances.
-    BOOTSTRAP_PORT=$((8998 + i))
+    PORT=${PORTS[$((2 * i))]}
+    BOOTSTRAP_PORT=${PORTS[$((2 * i + 1))]}
 
     echo "Starting prefill instance $i on GPU $GPU_ID, port $PORT, bootstrap $BOOTSTRAP_PORT"
 
@@ -162,8 +177,7 @@ run_tests_for_model() {
       NEXT_GPU=$(((GPU_ID + j) % $(get_num_gpus)))
       GPU_ID="${GPU_ID},${NEXT_GPU}"
     done
-    # Calculate port number (base port + instance number)
-    PORT=$((8200 + i))
+    PORT=${PORTS[$((2 * NUM_PREFILL_INSTANCES + i))]}
 
     echo "Starting decode instance $i on GPU $GPU_ID, port $PORT"
 
@@ -205,16 +219,16 @@ run_tests_for_model() {
   done
 
   # Start the proxy server
-  echo "Starting proxy server on port 8192"
+  echo "Starting proxy server on port $PROXY_PORT"
   python3 "${GIT_ROOT}/examples/disaggregated/mooncake_connector/mooncake_connector_proxy.py" \
-    --port 8192 "${PROXY_ARGS[@]}" &
+    --port "$PROXY_PORT" "${PROXY_ARGS[@]}" &
 
   # Wait for the proxy to start
   sleep 5
 
   # Run lm eval for this model
   echo "Running tests for $model_name"
-  TEST_MODEL=$model_name python3 -m pytest -s -x \
+  TEST_MODEL=$model_name PROXY_PORT=$PROXY_PORT python3 -m pytest -s -x \
     "${GIT_ROOT}/tests/v1/kv_connector/mooncake_integration/test_accuracy.py"
 
   # Clean up before running next model

tests/v1/kv_connector/mooncake_integration/test_accuracy.py

@@ -5,7 +5,7 @@ import os
 import lm_eval
 import openai
 
-BASE_URL = "http://localhost:8192/v1"
+BASE_URL = f"http://localhost:{os.environ.get('PROXY_PORT', 8192)}/v1"
 NUM_CONCURRENT = 100
 TASK = "gsm8k"
 FILTER = "exact_match,strict-match"