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From:Magnus Blåudd Date:April 17 2013 11:37am
Subject:Re: Threads_connected
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On 04/15/2013 02:45 PM, Raymond Peachey wrote:
> Hello,
>
> Is it possible to actually monitor number of connected clients on your
> mysql cluster when you have cluster connection pooling enabled?
>
> For example, in our case we have a MySQL Cluster node with 32 cores, which
> we've allocated 30 to use ndb connection pooling. When running a mysqlslap
> with a concurrency of, say, 60, I do not see that value show in
> threads_connected. Nor, do I see it show processlist.
>
> When I remove the ndb connection pooling, I accurately see the processlist
> showing all connected clients. I assume this is because of how the ndb
> connection pooling, in essence (correct me if I'm wrong), a mysqld child
> process that is used to connect to the cluster, which maybe is retaining
> it's own counters?? Is my thinking correct here, or is there a documented,
> alternate way of monitoring connected clients when using ndb connection
> pooling?
>
> Thanks,
>
> -Ray
>

The option --ndb-cluster-connection-pool controls how many connections 
the MySQL Server uses when talking to the NDB data nodes. I.e like the 
manual says "mimicking several MySQL Servers"

https://dev.mysql.com/doc/refman/5.1/en/mysql-cluster-program-options-mysqld.html#option_mysqld_ndb-cluster-connection-pool

This should not affect how many connections or threads your client 
application(for example mysqlslap) uses when connecting to the MySQL Server.

Neither can I imagine that the values of threads_connected in any way is 
connected to the above configuration variable.


Show some queries and the exact values used..

Btw. I think that 30 is a high value... maybe too high? Check the MySQL 
Server log file for error messages while starting up and connecting to 
the cluster.

/ Magnus
Thread
Threads_connectedRaymond Peachey15 Apr
  • Re: Threads_connectedMagnus Blåudd17 Apr
    • Re: Threads_connectedRaymond Peachey17 Apr