file_upload demo: yield write() cb in body_producer #2149
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bdarnell
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Sep 23, 2017
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Yeah, this should be yielding the write futures. It could potentially make sense to use body_producer without yielding the write futures if generating the body is asynchronous (and is assumed to be slower than the network), but that's not the case here (and even if generating the body were slow there's no harm in also waiting for flow control).
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The documentation for
tornado.httpclient.HTTPRequestsays:In the simpler example in this demo,
raw_producer(), there are no yields (or awaits) at all. It doesn't make much sense to use abody_producercallback if it generates and writes the whole body all at once without ever yielding, you might as well have just generated the whole body up front. In the more complex example,multipart_producer(), it looks likeyield gen.momentwas thrown in to allow some of the body to be sent before more of the body is produced, but that seems less elegant than just yieldingwrite().It's possible I just don't understand the nuances, so consider this half-question half-proposal :)