[SERVER-21672] Mongod consumes 100% cpu when drive out of space Created: 25/Nov/15  Updated: 07/Dec/15  Resolved: 07/Dec/15

Status: Closed
Project: Core Server
Component/s: None
Affects Version/s: 3.2.0-rc3
Fix Version/s: None

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

Attachments: PNG File mongo_cpu.png     PNG File rc4.png    
Participants:

 Description   

When mongod runs out of drive space on windows, it may sit and spin consuming 100% cpu. Although I haven't confirmed if this happens when the out of space scenario occurs, it seems to happen when a shutdown is initiated with no available space.



 Comments   
Comment by Kelsey Schubert [ 07/Dec/15 ]

Hi nick@innsenroute.com,

Thank you for testing this behavior on 3.2.0-rc4 as well as 3.2.0-rc3. I am closing this ticket as gone away since you reported a different result in the more recent version.

SERVER-13811 is scheduled to improve how mongoD handles running out of disk space. Please feel free to watch or vote for it.

Kind regards,
Thomas

Comment by Nick Judson [ 26/Nov/15 ]

I got a different result after upgrading to RC4 (see the screen cap).

Comment by Nick Judson [ 25/Nov/15 ]

I'm not sure - I only noticed it after ctrl-c. I can re-run the test tonight and let you know.

I would expect it to keep trying (sleeping between tries) until a shutdown is triggered, at which point, there is a max amount of time which will elapse before self-destruct (with an appropriate error). I also wouldn't expect the spinning cpu, just a try/sleep cycle.

Comment by Mark Benvenuto [ 25/Nov/15 ]

Was the mongod process spinning before shutdown started or only after shutdown was started by Ctrl-C?

How do you expect mongod to behave in this case? If we are out of disk space, we may not be able to flush all pending changes to disk for instance.

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