[SERVER-15593] Initial autosplit heuristics are very aggressive when config servers are down Created: 09/Oct/14  Updated: 11/Jul/16  Resolved: 29/Oct/14

Status: Closed
Project: Core Server
Component/s: Sharding
Affects Version/s: 2.7.7
Fix Version/s: 2.8.0-rc0

Type: Bug Priority: Major - P3
Reporter: Randolph Tan Assignee: Randolph Tan
Resolution: Done Votes: 1
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Attachments: File insert.js    
Issue Links:
Depends
Related
is related to SERVER-18096 Shard primary incorrectly reuses clos... Closed
Tested
Operating System: ALL
Participants:

 Description   

The assumption is that lots of data will be inserted, and distributing chunks when the data size is small is much less expensive than later. However, on repeated failure, this may need to be reconsidered.



 Comments   
Comment by Githook User [ 29/Oct/14 ]

Author:

{u'username': u'renctan', u'name': u'Randolph Tan', u'email': u'randolph@10gen.com'}

Message: SERVER-15593 Initial autosplit heuristics are very aggressive when config servers are down
Branch: master
https://github.com/mongodb/mongo/commit/fbbb0d2a1d845728cd714272199a652573e2f27d

Comment by Randolph Tan [ 10/Oct/14 ]

The problem here has to do with the prepare method in SyncClusterConnection (aka scc, connections for 3 config servers - https://github.com/mongodb/mongo/blob/r2.6.4/src/mongo/client/syncclusterconnection.cpp#L76) that gets called before every write to the config server. The scc appears to keep the connections within it so whenever it tries to call fsync on the downed config server, it will trigger the auto-reconnect logic, which has a backOff (https://github.com/mongodb/mongo/blob/r2.6.4/src/mongo/client/dbclient.cpp#L994) that gets longer and longer (twice every time) until it reaches the max of 1 second.

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