Andre Kohn created ARROW-12629:
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Summary: [C++] Configurable read-ahead in CSV and JSON readers
Key: ARROW-12629
URL: https://issues.apache.org/jira/browse/ARROW-12629
Project: Apache Arrow
Issue Type: Improvement
Components: C++
Reporter: Andre Kohn
We are compiling Arrow C++ to WebAssembly and ran into the following issue with
the CSV reader:
Browsers became very picky about the use of SharedArrayBuffers after the events
around Spectre and Meltdown.
As a result, you have to compile Arrow to WebAssembly without threads if you
don't want to run your website with very strict cross-origin isolation.
Unfortunately, the CSV reader seems to always spawn a thread for the read-ahead
in both, the SerialStreamingReader and the SerialTableReader independent of
whether use_threads is set.
Right now, this effectively means that you cannot use the CSV (and JSON)
readers in threadless WebAssembly builds.
[https://github.com/apache/arrow/blob/4363fefe46dc357a9013f0f4bcdc235e1e2e8124/cpp/src/arrow/csv/reader.cc#L839]
[https://github.com/apache/arrow/blob/4363fefe46dc357a9013f0f4bcdc235e1e2e8124/cpp/src/arrow/csv/reader.cc#L913]
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