python
14 minPython Runtime Advanced: Native Memory, ASGI Lifecycles, and Worker Failure
Debug memory outside Python objects, choose ASGI worker boundaries, and find silent hangs in background consumers.
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python
17 minPython Async Runtime Advanced: GIL, ASGI Lifecycles, and Safe Concurrency
Understand event-loop scheduling, CPU versus I/O concurrency, ASGI worker lifecycles, per-request sessions, and cancellation-safe background work.
Q&A
Q&AHow do async def and standard def routes differ in FastAPI?
Async routes run on the event loop; sync routes are generally dispatched to a worker thread pool.
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An async route can yield during nonblocking I/O, allowing the event loop to serve other work. A normal def route is typically run in a thread pool. Calling blocking I/O inside async def blocks the event loop; using async syntax alone does not improve CPU-bound work. Choose an execution model based on the library and bottleneck.
http
5 minReliable API Clients: Pagination, Conditional Requests, and Retry Budgets
Keep list traversal stable, validate cached representations, and bound retry work when networks fail at ambiguous points.
Q&A
Q&AWhat does casting JSON with as Order do at runtime?
Type assertions are erased. Treat untrusted data as unknown and validate its shape and domain constraints before relying on it.
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Type assertions are erased. Treat untrusted data as unknown and validate its shape and domain constraints before relying on it.
databases
6 minSQL keyset pagination: continue an order without promising a snapshot
Use a unique ordering tuple and a deliberate visibility policy for reliable page traversal.
Q&A
Q&AHow do you check whether a service is listening on a port?
Inspect local socket state and bind address before changing firewall policy.
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On Linux, `ss -lntup` lists listening sockets; `netstat` may be available via net-tools on older systems. Confirm the process, address, and network namespace. A service bound only to 127.0.0.1 is not externally reachable; also check container port mapping and host policy.
databases
10 minSQL Query Recipes: Joins, Grouping, Window Functions, and Safe Pagination
Build common analytics queries while avoiding duplicate rows, incorrect aggregates, unstable pages, and cross-dialect surprises.