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Posted to jira@arrow.apache.org by "Dewey Dunnington (Jira)" <ji...@apache.org> on 2022/03/03 18:15:00 UTC
[jira] [Created] (ARROW-15841) [R] Implement SafeCallIntoR to safely call the R API from another thread
Dewey Dunnington created ARROW-15841:
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Summary: [R] Implement SafeCallIntoR to safely call the R API from another thread
Key: ARROW-15841
URL: https://issues.apache.org/jira/browse/ARROW-15841
Project: Apache Arrow
Issue Type: Bug
Components: R
Reporter: Dewey Dunnington
In ARROW-9235 we have a problem where we need to evaluate code (may be C++ that calls the R API in a way that may allocate R memory or literal R code) on the R main thread. As discussed in the pull request ( https://github.com/apache/arrow/pull/12323#issuecomment-1054726309 ), there are other times that this has come up and will come up in the future (e.g., evaluating user-defined R functions from the query engine, implementing extension types from R).
After discussing with [~westonpace], it seems like it is worth investing in a {{SafeCallFromR()}} C++ function that lives in the R bindings. The initial approach (that may need to be altered as we go) will be to
- have a global object that is initialized at the beginning of a C++ call from R to specific functions (and released on exit) that maintains some list of tasks that need to run on the R main thread and an event loop to periodically evaluate them while background tasks are running.
- define a {{SafeCallFromR()}} C++ function that adds a task to the global object and waits for the result to come back.
(with apologies to Weston if I mischaracterized our conversation!)
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