A chord needs a result backend and is sensitive if one part fails.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 | # ====================================================================== # Q: What are chain, group and chord? Give an example. # # A chord needs a result backend and is sensitive if one part fails. For very # large fan-outs (e.g. 250,000 screens) I don't create one task per screen but # batches (e.g. 500 ids per task) so the broker doesn't fill up. # ====================================================================== from celery import chain, group, chord # chain: one after the other, the result is passed to the next chain(download_media.s(media_id), transcode.s(), make_thumbnail.s())() # group: in parallel group(push_update.s(screen_id) for screen_id in screen_ids)() # chord: in parallel, then a callback when all are done chord(render_report_part.s(i) for i in range(10))(merge_report.s(report_id)) |
