[SERVER-31123] Primary node of ReplicaSet constantly high cpu usage Created: 18/Sep/17  Updated: 09/Oct/17  Resolved: 18/Sep/17

Status: Closed
Project: Core Server
Component/s: Performance
Affects Version/s: 3.4.2
Fix Version/s: None

Type: Improvement Priority: Minor - P4
Reporter: Roie Yossef Assignee: Kelsey Schubert
Resolution: Done Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Attachments: File metrics.2017-09-17T20-02-23Z-00000     File mongo.currentOp    
Participants:

 Description   

Hi,
We use mongo replicaSet version 3.4.2 on our production environments. The replicaSet works with 6 nodes , one primary and 5 secondaries. Few weeks ago we have started to get alerts on high cpu consumption on the primary node. At the beginning we thought that we should separate the load between the members so we configured our service to make reads from secondaries and write to the primary.

Unfortunately we are still on the same point. The cpu of the primary node is between 70-100% even on idle times while the secondaries consumes maximum of 20%.

It is important to mention that we creates DB for each one of our customers with average of 9 indexes each - we have 1500DB's like that.

Attached a log of db.currentOp() , mongostat and diagnostic metrics. let me know if more information required.

Thanks,
Roie.



 Comments   
Comment by Kelsey Schubert [ 18/Sep/17 ]

Hi roiey,

Thanks for the report. From the provided diagnostic data, I do not see anything to indicate a bug in the MongoDB server. For MongoDB-related support discussion please post on the mongodb-user group or Stack Overflow with the mongodb tag. A question like this involving more discussion would be best posted on the mongodb-users group.

See also our Technical Support page for additional support resources.

Kind regards,
Kelsey

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