[SERVER-28564] How to maintain consistant connections on mongos Created: 30/Mar/17  Updated: 31/May/17  Resolved: 06/Apr/17

Status: Closed
Project: Core Server
Component/s: MMAPv1
Affects Version/s: 3.2.12
Fix Version/s: None

Type: Bug Priority: Major - P3
Reporter: Jing Wu Assignee: Mark Agarunov
Resolution: Done Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Attachments: PNG File ITS2#conn_current_1min.png    
Issue Links:
Related
related to SERVER-25027 Configurable connection pools size fo... Closed
Operating System: ALL
Participants:

 Description   

After upgrading Mongodb cluster and mongos to V3.2.12, we do see mongos connectoins behaviour changes. we see application read performance is impacted.

On March 20 afternoon, all mongos were upgraded to V3.2.12, mongos connections graph changed dramtically. Did the V3.2.12 mongos close connections more actively ?
How can we avoid this behaviour ?

Mongo Java Driver version is 3.3. Mongodb is V3.2.12 (MMAPv1)



 Comments   
Comment by Mark Agarunov [ 06/Apr/17 ]

Hello jing66wu@yahoo.com,

After looking into this issue a bit more, it appears to be related to SERVER-25027 where you can find the parameters to adjust the behavior of mongoS connections and descriptions of those parameters. Please note that SERVER project is for reporting bugs or feature suggestions for 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-user group.

Thanks,
Mark

Comment by Mark Agarunov [ 06/Apr/17 ]

Hello jing66wu@yahoo.com,

My apologies for the delay in response and any inconvenience this is causing. Unfortunately we are still investigating this behavior and do not yet have an update to this issue, but will provide more information as it becomes available,

Thanks,
Mark

Comment by Jing Wu [ 05/Apr/17 ]

Can you give some advise regarding how to maintain connections to mongod cluster ?

Thanks,

Jing

Comment by Jing Wu [ 03/Apr/17 ]

From application side, they are using `spring-data-mongodb 1.8.0.RELEASE` .

Comment by Jing Wu [ 03/Apr/17 ]

Ramon,

I upgrade mongod and config from V3.0.14 to V3.2.12 first , mongos V3.0.14 connections behavior didn't change, then upgrade mongos from V3.0.14 to V3.1.2, connection behavior changed and application started notice impacts. Right now, we had to rollback mongos to V3.0.14 and mongod and config are still V3.2.12 in order to reduce impact.

Do you know if it's V3.2 mongos change ? How can we configure mongos to maintain minimal connections from application ?

Thanks,

Jing

Comment by Ramon Fernandez Marina [ 03/Apr/17 ]

What version of mongos did you upgrade from? Did you also change your mongod versions? If so, from which to which?

Thanks,
Ramón.

Comment by Jing Wu [ 30/Mar/17 ]

we have total 50 app hosts running mongos.

each mongos has the following configurations:

<Parameter name="db.maxConnectionsPerHost" value="150" override="true" />
<Parameter name="db.threadsAllowedToBlockForConnectionMultiplier" value="20" override="true" />
<Parameter name="db.connectTimeout" value="30000" override="true" />
<Parameter name="db.socketTimeout" value="20000" override="true" />

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