sections: internals:internals-tracer-trace-child-tasks

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id	page	ref	title	content	breadcrumbs	references
internals:internals-tracer-trace-child-tasks	internals	internals-tracer-trace-child-tasks	Tracing child tasks	If your code uses a mechanism such as asyncio.gather() to execute code in additional tasks you may find that some of the traces are missing from the display. You can use the trace_child_tasks() context manager to ensure these child tasks are correctly handled. from datasette import tracer with tracer.trace_child_tasks(): results = await asyncio.gather( # ... async tasks here ) This example uses the register_routes() plugin hook to add a page at /parallel-queries which executes two SQL queries in parallel using asyncio.gather() and returns their results. from datasette import hookimpl from datasette import tracer @hookimpl def register_routes(): async def parallel_queries(datasette): db = datasette.get_database() with tracer.trace_child_tasks(): one, two = await asyncio.gather( db.execute("select 1"), db.execute("select 2"), ) return Response.json( { "one": one.single_value(), "two": two.single_value(), } ) return [ (r"/parallel-queries$", parallel_queries), ] Adding ?_trace=1 will show that the trace covers both of those child tasks.	["Internals for plugins", "datasette.tracer"]	[]