[SERVER-9630] Mongos crashes by few seconds of DB locking (or network delay). Created: 09/May/13  Updated: 10/Dec/14  Resolved: 29/Jul/13

Status: Closed
Project: Core Server
Component/s: Sharding, Stability
Affects Version/s: 2.0.9, 2.2.4, 2.4.3
Fix Version/s: None

Type: Bug Priority: Major - P3
Reporter: Hiroaki Assignee: Unassigned
Resolution: Duplicate Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified
Environment:

CentOS release 6.4 (Final) x86_64


Issue Links:
Duplicate
duplicates SERVER-1714 multiplex mongos -> mongod connecions... Closed
Operating System: ALL
Participants:

 Description   

I run Mongos on each WEB servers.
And I set timeout to 1 seconds for each query due to peculiar and general form of the WEB.

I'm suffering from sudden mongos death.
It seems like caused by delay of the query from mongos to Mongod.

Mongos will create a thread per mongos-mongod connections.
When some queries delayed, Mongos will create new connection and thread to handle the request from APP.
But these new connection will be delayed while DB locking.

So Mongos continue to create threads , and die in the end.

I confirmed that the number of the Mongos's threads exceed more than 300 when minor network delay (less than 10 seconds).

I think that the "thread model of Mongos" is unlikely to work well in severe situation.



 Comments   
Comment by Stennie Steneker (Inactive) [ 29/Jul/13 ]

Hi,

Thank you for your feedback. We are working on making a number of improvements to the connection handling between mongos and mongod.

For more information and related issues please see SERVER-1714.

Regards,
Stephen

Comment by Hiroaki [ 10/May/13 ]

Mongos creates per mongos-mongod ACTIVE REQUEST, not per mongos-mongod connections.

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