feat: 提升并发容量默认配置

ai_knowledge_base_v2/apps/backend/alembic/versions/0028_chat_concurrency_default.py

@@ -0,0 +1,84 @@
+"""raise the default chat concurrency to thirty
+
+Revision ID: 0028_chat_concurrency
+Revises: 0027_content_generation
+"""
+
+from __future__ import annotations
+
+from alembic import op
+import sqlalchemy as sa
+
+
+revision = "0028_chat_concurrency"
+down_revision = "0027_content_generation"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    config = sa.table(
+        "sys_system_config",
+        sa.column("config_key", sa.String(length=100)),
+        sa.column("config_value", sa.Text()),
+        sa.column("description", sa.String(length=255)),
+    )
+    connection = op.get_bind()
+    _set_default(
+        connection,
+        config,
+        key="chat_max_active_requests",
+        old_default="2",
+        new_default="30",
+        description="用户正式问答的全局执行上限；Redis 可用时由所有后端实例共享，超过后进入排队。",
+    )
+    _set_default(
+        connection,
+        config,
+        key="chat_max_queue_size",
+        old_default="20",
+        new_default="90",
+        description="超过最大并发后允许等待的请求数量。默认按并发数的 3 倍预留。",
+    )
+    _set_default(
+        connection,
+        config,
+        key="chat_queue_timeout_seconds",
+        old_default="60",
+        new_default="90",
+        description="请求在排队中超过该时间后自动结束。默认可覆盖约三轮请求释放。",
+    )
+
+
+def downgrade() -> None:
+    # 运行时配置可能已经被管理员调整，降级代码版本时不覆盖现场值。
+    pass
+
+
+def _set_default(
+    connection,
+    config,
+    *,
+    key: str,
+    old_default: str,
+    new_default: str,
+    description: str,
+) -> None:
+    current = connection.execute(
+        sa.select(config.c.config_value).where(config.c.config_key == key)
+    ).scalar_one_or_none()
+    if current is None:
+        connection.execute(
+            config.insert().values(
+                config_key=key,
+                config_value=new_default,
+                description=description,
+            )
+        )
+        return
+    if str(current).strip() == old_default:
+        connection.execute(
+            config.update()
+            .where(config.c.config_key == key)
+            .values(config_value=new_default, description=description)
+        )