[SERVER-12052] map-reduce froze for minutes on "Final Reduce" at 100% Created: 11/Dec/13  Updated: 10/Dec/14  Resolved: 07/Apr/14

Status: Closed
Project: Core Server
Component/s: MapReduce
Affects Version/s: 2.4.5
Fix Version/s: None

Type: Bug Priority: Minor - P4
Reporter: Julien Assignee: Stennie Steneker (Inactive)
Resolution: Done Votes: 1
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified
Environment:

Debian 7.2


Operating System: ALL
Participants:

 Description   

I frequently got :
"msg" : "m/r: (3/3) final reduce to collection M/R: (3/3) Final Reduce Progress: 1178/1178 100%",

For minutes, or tens of minutes, what happen ?



 Comments   
Comment by Thomas Rueckstiess [ 07/Apr/14 ]

Hi Julien,

We haven't heard back from you and don't have enough information to diagnose this further, so I'll go ahead and close this ticket now. If this is still an issue please feel free to reopen the ticket again and provide additional information.

Thanks,
Thomas

Comment by Stennie Steneker (Inactive) [ 18/Mar/14 ]

Hi Julien,

After the "final reduce to collection" message is displayed the remaining steps are to:

  • iterate over all sorted objects
  • apply finalize() function, if defined

Does your Map/Reduce job include a finalize() function?

If you have other write operations on the same database, it's also possible that your Map/Reduce job is yielding. You can check this using db.currentOp() and the numYields value for your Map/Reduce operation.

Regards,
Stephen

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