Read CSV strings in perspective-python #1447
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sc1f
commented
Jun 15, 2021
| // https://github.com/emscripten-core/emscripten/issues/8574 | ||
| #include <perspective/vendor/arrow_single_threaded_reader.h> | ||
| #else | ||
| #include <arrow/csv/reader.h> |
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@texodus I can enable the read_options.use_threads = false; to true a few lines down - I am assuming it should be safe given that the API is exposed by Arrow and we don't do any manual concurrency for this on our side.
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Arrow seems to use this implementation for populating the default worker pool, which will consume all hardware concurrency without proper env flags. We should probably figure out how to override these flags in the loaded env, and to respect what was asked for in set_num_threads().
Interesting though, we could easily reuse this static threadpool in place of TBB, looks like ParallelFor() is nearly a dropin replacement for PSP_PARALLEL_FOR ..
texodus
approved these changes
Jun 18, 2021
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This PR enables direct loading of CSV strings inside
perspective-pythonusing the Apache Arrow-based loader used inperspective.js. The CSV loader uses the version ofreader.ccshipped with Apache Arrow, and not the customsingle_threaded_reader.cppwhich is implemented for the WASM binding. During the loading of CSVs, as is the case with loading regular Arrow binaries, the GIL is released by the C++ binding.Changelog
"x,y\n1,"would cause a segfault when trying to read into an invalidnull_bitmap_datapointer.