[SERVER-14016] Record insertion time increased after upgrading to 2.6 Created: 21/May/14  Updated: 10/Dec/14  Resolved: 21/May/14

Status: Closed
Project: Core Server
Component/s: Performance, Write Ops
Affects Version/s: 2.6.1
Fix Version/s: None

Type: Question Priority: Major - P3
Reporter: Sooraj B Assignee: Unassigned
Resolution: Done Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Participants:

 Description   

Hello,

I have 3 mongodb servers running as replica set. The primary gets data at the rate of ~2.5K inserts per second. The data contains an array of around 2.5kb in size, upto 4 levels deep. The documents are being inserted in fire and forget mode from a php client.
With Mongo 2.4.10, the inserts used to happen in microseconds range(say 100us-800us). I upgraded to 2.6.1 and now single insert happens in millisecond range(1ms-400ms).
I frequently see this in my logs "command adb.$cmd command: insert

{ $msg: "query not recording (too large)" }

keyUpdates:0 numYields:0 locks(micros) w:98 reslen:33 606ms"
Any advice on fixing this ?

The 3 servers are running in 3 machines of same configuration with 32GB RAM. After upgrading i see an increased RAM consumption in the same machine. Is this expected?

Moreover, i see these in system logs:
php[4619]: segfault at 1 ip 00007f87ed26d1c7 sp 00007ffffbf6c938 error 6 in mongo.so (deleted)[7f87ed25d000+49000]

Kindly advice.



 Comments   
Comment by Sooraj B [ 22/May/14 ]

~bjori I had to downgrade to 2.4.10 immediately so cannot get the crash dump now. I will be doing some more tests and if I am able to re create it, I will file a ticket with all info and backtraces.

Comment by Hannes Magnusson [ 22/May/14 ]

soorajb could you generate a backtrace for the PHP segfault (see https://bugs.php.net/bugs-generating-backtrace.php) and create a PHP ticket for it?

Comment by Sooraj B [ 22/May/14 ]

Thank you for the prompt response Thomas & Jason.
I see that fire and forget mode is taken down in 2.6.1 and there is no other choice than downgrading to 2.4.10.

Thanks again guys.

Comment by J Rassi [ 21/May/14 ]

soorajb: the PHP crash in mongo.so is a separate issue unrelated to the performance problem you're reporting, and could be due to a bug in the PHP driver. Please file a ticket at <https://jira.mongodb.org/browse/PHP>, and include the version of the PHP driver you're using in the ticket description.

Comment by Thomas Rueckstiess [ 21/May/14 ]

Hi Soorja,

You may want to look at Bulk Inserts to improve the performance of your writes in 2.6+.

The SERVER project is for reporting bugs or feature suggestions for the MongoDB server.

For MongoDB-related support discussion please post on the mongodb-users group (http://groups.google.com/group/mongodb-user) or Stack Overflow with the "mongodb" tag. A question like this involving more discussion would be best posted on the mongodb-users group.

Regards,
Thomas

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