[wp-trac] [WordPress Trac] #10611: Support Partial core upgrades

[WordPress Trac]

#10611: Support Partial core upgrades
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 Reporter:  dd32             |       Owner:  dd32          
     Type:  enhancement      |      Status:  new           
 Priority:  normal           |   Milestone:  Future Release
Component:  Upgrade/Install  |     Version:  2.9           
 Severity:  normal           |    Keywords:                
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Comment(by Denis-de-Bernardy):

 > One thing that many people are not sure about is where the main
 bottleneck is
 >  * Downloading the large Zip file
 >  * The Zip Decompression (This is mainly memory usage IMO)
 >  * The IO time
 >  * The 2nd IO time
 >
 > Personally i think its mainly the IO..

 Oh, I can give you some feedback on that. Keep in mind that my own zip is
 7M+. :-P

  * download takes a few seconds
  * cleaning up after a failed install is very very very slow (see #10913)
  * unzip is *very* slow and resource hungry
  * copying actually is pretty fast
  * cleaning up is, again, very very very slow

 What frequently happens on my end with WP 2.8.x sites one of the
 following:

  1. the zip gets downloaded
  2. unzipping occurs, takes a lot of time, FTP times out about when it's
 done
  3. WP starts to copy, fails due to the FTP time out, and bails
  4. WP can't clean-up
  5. User tries again
  6. the zip gets downloaded
  7. FTP times out during the clean-up
  8. User tries again
  9. the zip gets downloaded
  10. FTP finishes up the clean-up
  11. Return to step 2 (until user decides it's hopeless)

 The way I work around it is by hooking into update_feedback. On each
 feedback, I force flush the output so the user gets some kind of feedback.
 I then disconnect the FTP (some hosts disallow overriding time-outs,
 meaning that #10407 or the newer ticket needs more fixing), I reconnect
 the FTP, and I reconfigure the FTP so it times out after 10 minutes on the
 host where that works. So far it's pretty successful.

 I considered uploading partial zips, but it seemed too risky (can't trust
 the version sent by the site, especially after a failed upgrade); the same
 goes for having a special file with the md5 of every file. Keeping the md5
 in options is no good either -- if a manual upgrade occurs, it breaks.

 That is to say, I think it's more important to fix #10913, which is the
 main culprit for failed upgrades.

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Ticket URL: <http://core.trac.wordpress.org/ticket/10611#comment:6>
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