Explainer
Log uncaught exceptions in Python
Use sys.excepthook for top-level failures, threading.excepthook for worker threads, and explicit handling for functions and asynchronous tasks.
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Measure elapsed time in Python
Compare Python timing functions, measure elapsed work with perf_counter, and avoid confusing nanosecond units with clock resolution.
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Keep Nginx startup independent of upstream DNS availability
Avoid configuration-time hostname failures with runtime resolution, understand backup limits, and return a controlled maintenance response.
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Pad strings and numbers with zeros in Python
Use zfill for signed strings, numeric format specifications for integers, and rjust or ljust when you need literal character padding.
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Parse Nginx access logs for request analysis
Extract fields from combined access logs, count requests by status and second, and avoid misleading timing or time-window analysis.
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How Python passes arguments to functions
Understand shared objects, local rebinding, mutable defaults, and shallow copies when passing values to Python functions.
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Print literal braces in Python format strings
Escape braces in f-strings and str.format, combine literal braces with substitutions, and serialize JSON without hand-built templates.
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Pretty-print JSON files and responses in Python
Format JSON with indentation, preserve Unicode, validate API responses, and use Python’s json.tool from the command line.
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Print to standard error in Python
Send diagnostics to stderr with print or logging, keep them separate from stdout, and redirect each stream independently.
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Print without a newline in Python
Control print endings with end, separate arguments with sep, and flush progress output when it would otherwise remain buffered.
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Profile a Python script with cProfile
Find expensive functions with cProfile, sort saved statistics with pstats, and choose line profiling or timeit for more focused analysis.
Explainer
Raise and re-raise exceptions in Python
Choose appropriate Python exception types, preserve causes with raise from, and re-raise failures without relying on assertions for input validation.