[smg][ci] Add thread safety to ModelPool and GPUAllocator (#16674)

.github/workflows/pr-test-rust.yml

@@ -172,6 +172,7 @@ jobs:
             env_vars: ""
             reruns: ""
             upload_benchmarks: true
+            parallel_opts: ""  # No parallel for benchmarks (performance measurement)
           - name: response-api
             timeout: 32
             test_dirs: "e2e_test/e2e_response_api"
@@ -180,18 +181,21 @@ jobs:
             reruns: "--reruns 3 --reruns-delay 2"
             setup_oracle: true
             setup_brave: true
+            parallel_opts: ""  # Legacy tests, not yet migrated for parallel
           - name: grpc
             timeout: 32
             test_dirs: "e2e_test/e2e_grpc"
             extra_deps: ""
             env_vars: "SHOW_ROUTER_LOGS=1"
             reruns: "--reruns 3 --reruns-delay 2"
+            parallel_opts: ""  # Legacy tests, not yet migrated for parallel
           - name: e2e
             timeout: 45
             test_dirs: "e2e_test/router e2e_test/embeddings"
-            extra_deps: ""
+            extra_deps: "pytest-parallel py"  # py is required for pytest-parallel with newer pytest
             env_vars: "SHOW_WORKER_LOGS=0 SHOW_ROUTER_LOGS=1"
             reruns: "--reruns 2 --reruns-delay 5"
+            parallel_opts: "--workers 1 --tests-per-worker 4"  # Thread-based parallelism
     runs-on: 4-gpu-a10
     timeout-minutes: ${{ matrix.timeout }}
     steps:
@@ -286,7 +290,7 @@ jobs:
           bash scripts/killall_sglang.sh "nuk_gpus"
           cd sgl-model-gateway
           source "$HOME/.cargo/env"
-          ${{ matrix.env_vars }} ROUTER_LOCAL_MODEL_PATH="/home/ubuntu/models" pytest ${{ matrix.reruns }} ${{ matrix.test_dirs }} -s -vv -o log_cli=true --log-cli-level=INFO
+          ${{ matrix.env_vars }} ROUTER_LOCAL_MODEL_PATH="/home/ubuntu/models" pytest ${{ matrix.reruns }} ${{ matrix.parallel_opts }} ${{ matrix.test_dirs }} -s -vv -o log_cli=true --log-cli-level=INFO
 
       - name: Upload benchmark results
         if: matrix.upload_benchmarks && success()