Defer debugpy and psutil imports until they are actually needed - #1543
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Defer debugpy and psutil imports until they are actually needed#1543Carreau wants to merge 1 commit into
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Both imports were paid for on every kernel startup even though most sessions never debug or ask for usage information. * `IPythonKernel.debugger` is now a lazily-created property; the debugger (and the debugpy import) is only built on the first debug request. `poll_stopped_queue` is scheduled at that point rather than in `start()`. * `debugger_class` was a `Type` trait, which traitlets resolves — and therefore imports — as soon as the kernel is instantiated. It is replaced by a plain `debugger_class_name` string; `debugger_class` remains as a deprecated property, and subclasses still overriding it keep working with a DeprecationWarning. * `psutil` is imported through `_get_psutil()`, which caches the (possibly None) result on first use. On a local test (where I have optimisation in IPython and traitlets as well), this brings the startup time from 220ms to 170ms
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Both imports were paid for on every kernel startup even though most sessions never debug or ask for usage information.
IPythonKernel.debuggeris now a lazily-created property; the debugger (and the debugpy import) is only built on the first debug request.poll_stopped_queueis scheduled at that point rather than instart().debugger_classwas aTypetrait, which traitlets resolves — and therefore imports — as soon as the kernel is instantiated. It is replaced by a plaindebugger_class_namestring;debugger_classremains as a deprecated property, and subclasses still overriding it keep working with a DeprecationWarning.psutilis imported through_get_psutil(), which caches the (possibly None) result on first use.On a local test (where I have optimisation in IPython and traitlets as well), this brings the startup time from 220ms to 170ms