[Python-3000] Non-blocking I/O? (Draft PEP for New IO system) (original) (raw)
Greg Ewing greg.ewing at canterbury.ac.nz
Mon Mar 5 01:19:49 CET 2007
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I'm having trouble seeing what the use case is for the buffered non-blocking writes being discussed here.
Doing asynchronous I/O usually doesn't involve putting the file descriptor into non-blocking mode. Instead you use select() or equivalent, and only try to read or write when the file is reported as being ready.
For this to work properly, the select() needs to operate at the bottom of the I/O stack. Any buffering layers sit above that, with requests for data propagating up the stack as the file becomes ready.
In other words, the whole thing has to have the control flow inverted and work in "pull" mode rather than "push" mode. It's hard to see how this could fit into the model as a minor variation on how writes are done.
-- Greg
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