수정본

backend/app/services/korea_investment_api.py

@@ -232,6 +232,7 @@ class KoreaInvestmentAPI:
 
         # httpx 싱글톤 클라이언트 (커넥션 풀 재활용 — 매 요청마다 TCP/TLS 핸드셰이크 방지)
         self._http_client: Optional[httpx.AsyncClient] = None
+        self._http_client_lock = asyncio.Lock()
 
         # 토큰 발급 Lock (중복 발급 방지)
         self._token_lock = asyncio.Lock()
@@ -250,7 +251,28 @@ class KoreaInvestmentAPI:
 
         # 캐시된 토큰 로드
         self._load_token_from_cache()
-    
+
+    async def _get_http_client(self) -> httpx.AsyncClient:
+        """싱글톤 httpx 클라이언트 반환. 없으면 생성."""
+        if self._http_client is None or self._http_client.is_closed:
+            async with self._http_client_lock:
+                if self._http_client is None or self._http_client.is_closed:
+                    self._http_client = httpx.AsyncClient(
+                        timeout=httpx.Timeout(10.0, connect=5.0),
+                        limits=httpx.Limits(
+                            max_connections=20,
+                            max_keepalive_connections=10,
+                            keepalive_expiry=30,
+                        ),
+                    )
+        return self._http_client
+
+    async def close(self) -> None:
+        """httpx 클라이언트 정리. 앱 종료 시 호출."""
+        if self._http_client and not self._http_client.is_closed:
+            await self._http_client.aclose()
+            self._http_client = None
+
     def _load_token_from_cache(self):
         """파일에서 토큰 로드 (앱 시작 시 동기 호출)"""
         try:
@@ -447,13 +469,13 @@ class KoreaInvestmentAPI:
                 # 타임아웃 설정
                 timeout = httpx.Timeout(self.timeout, connect=10.0)
                 
-                async with httpx.AsyncClient(timeout=httpx.Timeout(10.0, connect=5.0)) as client:
-                    response = await client.request(
-                        method,
-                        f"{self.base_url}{endpoint}",
-                        headers=headers,
-                        **kwargs
-                    )
+                client = await self._get_http_client()
+                response = await client.request(
+                    method,
+                    f"{self.base_url}{endpoint}",
+                    headers=headers,
+                    **kwargs
+                )
 
                     # 성공
                     if response.status_code == 200: