Update ray template

nemo_run/run/ray/templates/ray.sub.j2

@@ -28,17 +28,36 @@ DASHBOARD_AGENT_GRPC_PORT=${DASHBOARD_AGENT_GRPC_PORT:-53007}
 METRICS_EXPORT_PORT=${METRICS_EXPORT_PORT:-53009}
 
 # Ports for the head node
-PORT=${PORT:-6379}
+PORT=${PORT:-54514}
 RAY_CLIENT_SERVER_PORT=${RAY_CLIENT_SERVER_PORT:-10001}
 #REDIT_SHARD_PORTS=${REDIT_SHARD_PORTS:-"random"} ??
 DASHBOARD_PORT=${DASHBOARD_PORT:-8265}  # Also used by debugger
 DASHBOARD_AGENT_LISTEN_PORT=${DASHBOARD_AGENT_LISTEN_PORT:-52365}
+RAY_DEBUGGER_ARGS=
+if [ "${RAY_DEBUG:-}" = "legacy" ]; then
+  RAY_DEBUGGER_ARGS="--ray-debugger-external"
+fi
+
+# After ray>=2.47, this feature is enabled by default which creates uv venvs for any py_executable starting with `uv run`.
+# There is severe contention and performance issues with this enabled considering our dependencies are so large and occasionally
+# need to be compiled, so NeMo RL has an implementation in nemo_rl/utils/venv.py that does it once per node as opposed to once per task.
+export RAY_ENABLE_UV_RUN_RUNTIME_ENV=0
+
+# Setting ulimit is recommended by ray best practices page
+# @ https://docs.ray.io/en/latest/cluster/vms/user-guides/large-cluster-best-practices.html
+# It's session based and won't affect the system outside the script
+# Ensure that the soft limit isn't above the hard limit
+if [[ $(ulimit -Hn) == "unlimited" ]] || [[ 65535 -lt $(ulimit -Hn) ]]; then
+  ulimit -Sn 65535
+elif [[ $(ulimit -Hn) != "unlimited" ]] && [[ $(ulimit -Hn) -lt 65535 ]]; then
+  echo "[WARNING]: Cannot increase ulimit on file descriptors to 65535 according ray recommendation: https://docs.ray.io/en/latest/cluster/vms/user-guides/large-cluster-best-practices.html. Speak to cluster admins to increase, otherwise ray may crash unexpectedly."
+fi
 
 # On our clusters, the largest port range on an idle worker appeared between 52369-64607
 # (not including the other ports set by this script). So this range is chosen to be
 # somewhere in the middle
 MIN_WORKER_PORT=${MIN_WORKER_PORT:-54001}
-MAX_WORKER_PORT=${MAX_WORKER_PORT:-54257}
+MAX_WORKER_PORT=${MAX_WORKER_PORT:-54513}
 
 # Ray temp directory (inside container). Used by --temp-dir and log sync sidecar
 RAY_TEMP_DIR=${RAY_TEMP_DIR:-/ray-cluster}
@@ -82,13 +101,66 @@ gpus_per_node=8
 
 num_retries={{ num_retries }}
 
+# Track backgrounded srun client PIDs for head and workers
+declare -A SRUN_PIDS
+
+# Verify all backgrounded srun client processes are still alive; exit fast if any died
+check_srun_processes() {
+  for name in "${!SRUN_PIDS[@]}"; do
+    pid="${SRUN_PIDS[$name]}"
+    # Check if the process is still running
+    if ! kill -0 "$pid" 2>/dev/null; then
+      echo "[ERROR] Background srun '$name' died (pid=$pid). Could be a failure in startup or an issue with the node preventing the srun to start. Attempting to exit." >&2
+      # Signal sidecars inside containers to terminate ASAP
+      touch "$LOG_DIR/ENDED"
+      exit 1
+    fi
+  done
+}
+
 # Getting the node names and IP addresses in the SLURM allocation
 nodes=$(scontrol show hostnames "$SLURM_JOB_NODELIST")
 nodes_array=($nodes)
 ip_addresses_array=()
 
 for node in $nodes; do
-    ip_address=$(getent hosts "$node" | awk '{print $1}' | head -n1)
+    # Try multiple methods to get IP address - ENHANCED VERSION v2.0
+    echo "[DEBUG] Resolving hostname: $node using enhanced resolution methods"
+    ip_address=""
+
+    # Method 1: Try host command
+    echo "[DEBUG] Method 1: host command"
+    ip_address=$(host $node 2>/dev/null | awk '/has address/ { print $4 }' | head -1 || true)
+    echo "[DEBUG] host result: '$ip_address'"
+
+    # Method 2: If host fails, try getent
+    if [[ -z "$ip_address" ]]; then
+        echo "[DEBUG] Method 2: getent hosts"
+        ip_address=$(getent hosts $node 2>/dev/null | awk '{ print $1 }' | head -1 || true)
+        echo "[DEBUG] getent result: '$ip_address'"
+    fi
+
+    # Method 3: If getent fails, try nslookup
+    if [[ -z "$ip_address" ]]; then
+        echo "[DEBUG] Method 3: nslookup"
+        ip_address=$(nslookup $node 2>/dev/null | awk '/^Address: / { print $2 }' | head -1 || true)
+        echo "[DEBUG] nslookup result: '$ip_address'"
+    fi
+
+    # Method 4: If all DNS methods fail, try ping to extract IP
+    if [[ -z "$ip_address" ]]; then
+        echo "[DEBUG] Method 4: ping"
+        ip_address=$(ping -c 1 $node 2>/dev/null | grep "PING" | sed 's/.*(\([^)]*\)).*/\1/' || true)
+        echo "[DEBUG] ping result: '$ip_address'"
+    fi
+
+    # If still no IP, use the hostname itself (might work if it's already an IP or resolvable)
+    if [[ -z "$ip_address" ]]; then
+        echo "[WARNING] Could not resolve IP for $node, using hostname as fallback"
+        ip_address=$node
+    fi
+
+    echo "[INFO] Node: $node -> IP: $ip_address"
     # Add the IP address to the array
     ip_addresses_array+=("$ip_address")
 done
@@ -184,12 +256,13 @@ ray start --head \
     --ray-client-server-port=${RAY_CLIENT_SERVER_PORT} \
     --dashboard-port=${DASHBOARD_PORT} \
     \
-    --node-manager-port=${NODE_MANAGER_PORT} \
-    --object-manager-port=${OBJECT_MANAGER_PORT} \
-    --runtime-env-agent-port=${RUNTIME_ENV_AGENT_PORT} \
-    --dashboard-agent-grpc-port=${DASHBOARD_AGENT_GRPC_PORT} \
-    --dashboard-agent-listen-port=${DASHBOARD_AGENT_LISTEN_PORT} \
-    --metrics-export-port=${METRICS_EXPORT_PORT} \
+    --node-manager-port=$((${NODE_MANAGER_PORT} + 1)) \
+    --object-manager-port=$((${OBJECT_MANAGER_PORT} + 1)) \
+    --runtime-env-agent-port=$((${RUNTIME_ENV_AGENT_PORT} + 1)) \
+    --dashboard-agent-grpc-port=$((${DASHBOARD_AGENT_GRPC_PORT} + 1)) \
+    --dashboard-agent-listen-port=$((${DASHBOARD_AGENT_LISTEN_PORT} + 1)) \
+    --metrics-export-port=$((${METRICS_EXPORT_PORT} + 1)) \
+    $RAY_DEBUGGER_ARGS \
     \
     --block
 EOFINNER
@@ -207,6 +280,7 @@ exit 1
 EOF
 )
 srun {{ common_srun_args }} --container-name=ray-head --nodes=1 --ntasks=1 -w "$head_node" -o $LOG_DIR/{{ ray_log_prefix }}head.log bash -x -c "$head_cmd" &
+SRUN_PIDS["ray-head"]=$!
 
 # Wait for the head node container to start and for Ray to be ready
 elapsed_time=0
@@ -217,6 +291,7 @@ while ! (srun --overlap --nodes=1 --ntasks=1 -w $head_node test -f $LOG_DIR/STAR
     exit 1
   fi
   echo "[INFO][$(date)] Waiting for Ray head node container to start and be ready... ($elapsed_time/$RAY_HEAD_START_TIMEOUT seconds)"
+  check_srun_processes
   sleep 2
   elapsed_time=$((elapsed_time + 2))
 done
@@ -261,7 +336,6 @@ monitor-sidecar &
 sed -i 's/context\.py_executable = " "\.join(self\.nsight_cmd) + " python"/context.py_executable = " ".join(self.nsight_cmd) + f" {context.py_executable}"/g' /opt/nemo_rl_venv/lib64/python*/site-packages/ray/_private/runtime_env/nsight.py
 
 cat <<EOFINNER | tee /launch-worker.sh
-sleep 5
 ray start --address "$ip_head" \
           --disable-usage-stats \
           --resources="{\"worker_units\": $gpus_per_node, \"slurm_managed_ray_cluster\": 1}" \
@@ -274,6 +348,7 @@ ray start --address "$ip_head" \
           --dashboard-agent-grpc-port=${DASHBOARD_AGENT_GRPC_PORT} \
           --dashboard-agent-listen-port=${DASHBOARD_AGENT_LISTEN_PORT} \
           --metrics-export-port=${METRICS_EXPORT_PORT} \
+          $RAY_DEBUGGER_ARGS \
           \
           --block
 EOFINNER
@@ -293,6 +368,7 @@ EOF
     OVERLAP_HEAD_AND_WORKER_ARG="--overlap"
   fi
   srun {{ common_srun_args }} ${OVERLAP_HEAD_AND_WORKER_ARG:-} --container-name=ray-worker-$i --exact --nodes=1 --ntasks=1 --cpus-per-task=$((16 * gpus_per_node)) -w "$node_i" -o $LOG_DIR/{{ ray_log_prefix }}worker-$i.log bash -x -c "$worker_cmd" &
+  SRUN_PIDS["ray-worker-$i"]=$!
   sleep 3
 done
 
@@ -316,9 +392,10 @@ extract_worker_units() {
 while true; do
   worker_units=$(extract_worker_units)
   echo "[INFO] Number of actors online: $worker_units/$NUM_ACTORS"
-  if [ "$worker_units" -eq "$NUM_ACTORS" ]; then
+  if [[ "$worker_units" -eq "$NUM_ACTORS" ]]; then
     break
   fi
+  check_srun_processes
   sleep 2
 done