topic Re: Number of connections to instance in Data Management Questions

Number of connections to instance

danbecker — Wed, 21 Mar 2012 14:04:14 GMT

installed SQLServer Express and enabled GDB storage using our ArcEditor (Desktop - Standard) License.

Few questions regarding the number of connections to the SQL Server instance, named "sqldb"

Lets say I create/publish a .mxd using data from a SDE gdb stored in sqldb.

How many clients can simultaneously connect to the service to view the data (read only)?

ArcGIS desktop -- client #1
ArcGIS online mapA -- client #2
ArcGIS online mapB -- client #3
JavascriptAPI custom map -- client #4 <---will this client receive the 'maximum number of connections to instance exceeded'?

thanks!

Re: Number of connections to instance

JakeSkinner — Wed, 21 Mar 2012 14:46:28 GMT

Hi Dan,

A database connection is made for each ArcGIS Server instance (ArcSOC.exe) that is created for the service(s). The min and max number of instances can be set by right-clicking on the service > Service Properties > Pooling tab. By default, the minimum number of instances is set to 1 and the maximum is set to 2. Therefore, when you start the service 1 connection is made to the SDE geodatabase.

By default, an instance is created as Pooled. This means when a request (ie pan/zoom in web app) is made to the service, an instance is taken from the pool, and then returned when the request is over. Once another request is made, say from another web app, that same instance can be used for that service request. So, multiple requests will need to be made at the same time in order for another instance to be created, thus creating another connection to the SDE geodatabase. This will not exceed the maximum number of instances, so by default a service can never exceed two connections to the geodatabase unless this paramter is increased. If the max number of instances is exceeded, the client will have to wait until an instance is returned to the pool before their request is returned.

Say the max instances of a service is set to two and both are being used, creating two connections to the SDE geodatabase. Then one of the users is finished accessing the service. The second SDE connection will remain until the idle time expires (set within the Services Properties > Pooling tab). Once the idle time expires, the instance will be removed from the server and the connection deleted from the SDE geodatabase.

Re: Number of connections to instance

danbecker — Wed, 21 Mar 2012 16:10:14 GMT

Hi Dan,

A database connection is made for each ArcGIS Server instance (ArcSOC.exe) that is created for the service(s). The min and max number of instances can be set by right-clicking on the service > Service Properties > Pooling tab. By default, the minimum number of instances is set to 1 and the maximum is set to 2. Therefore, when you start the service 1 connection is made to the SDE geodatabase.

By default, an instance is created as Pooled. This means when a request (ie pan/zoom in web app) is made to the service, an instance is taken from the pool, and then returned when the request is over. Once another request is made, say from another web app, that same instance can be used for that service request. So, multiple requests will need to be made at the same time in order for another instance to be created, thus creating another connection to the SDE geodatabase. This will not exceed the maximum number of instances, so by default a service can never exceed two connections to the geodatabase unless this paramter is increased. If the max number of instances is exceeded, the client will have to wait until an instance is returned to the pool before their request is returned.

Say the max instances of a service is set to two and both are being used, creating two connections to the SDE geodatabase. Then one of the users is finished accessing the service. The second SDE connection will remain until the idle time expires (set within the Services Properties > Pooling tab). Once the idle time expires, the instance will be removed from the server and the connection deleted from the SDE geodatabase.

thanks for the reply.

Now I see why the max. # of instances is set to 2 by default.

total connections to personal SDE gdb = 3; ArcSOC gets 2, one left for local editing in desktop envir.

Re: Number of connections to instance

danbecker — Mon, 16 Apr 2012 16:22:56 GMT

Still having 'max number of connections to instance exceeded' problems...

At the time I originally posted, I was using the ArcGIS-Desktop Standard License for the ArcSDE install; thus, I only had ArcSDE Personal with 3 connection limit.

Since then, I activated ArcSDE using the ArcGIS-Server Standard License and now, right click/properties on the db server in ArcCatalog, it displays "Class: ArcSDE Workgroup Server", which I *think* gets 10 connections?

Here's my connection list to the SDE GDB:

gdb_A --- Rest Service 1 (instances in use/running: 0/1)
gdb_A --- Rest Service 2 (instances in use/running: 0/2)
gdb_A --- Attempt to connect to the sde gdb via ArcCatalog <---Failed to connect, Max. # of connections exceeded.

Why does this happen, I have ArcSDE Workgroup, shouldn't I get 10 connections? I can only total up 3 above, and the ArcCatalog connection would be 4 ??

thanks!

Re: Number of connections to instance

JakeSkinner — Tue, 17 Apr 2012 12:32:22 GMT

Execute the Setup.exe for ArcSDE and only check the option 'Enable geodatabase storage on SQL Server Express'. After you complete the wizard, detach and then reattach the database using ArcCatalog.

If you still cannot make more than 3 connections, try creating a new geodatabase and test to see if you can make more than 3 connections.

Re: Number of connections to instance

danbecker — Tue, 17 Apr 2012 13:13:45 GMT

The gdb I'm connecting to was created when I was using the SDE personal license; now, after i've switched to an SDE Workgroup license, it seems like the gdb still only accepts the max. # of personal license connections; almost as if this wasn't updated.

I'll try creating new gdb and see what happens.

Re: Number of connections to instance

KimPeter — Mon, 23 Apr 2012 21:54:31 GMT

The gdb I'm connecting to was created when I was using the SDE personal license; now, after i've switched to an SDE Workgroup license, it seems like the gdb still only accepts the max. # of personal license connections; almost as if this wasn't updated.

That's expected; the license doesn't get updated in individual geodatabases until you detach then re-attach them.

http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#/Changing_license_keys_for_database_servers_and_their_geodatabases/003n0000006v000000/

Re: Number of connections to instance

JeffersonFerreira_Ferreira — Thu, 23 Aug 2012 14:46:54 GMT

Dear Colleagues;

I've read a lot of topics in the ESRI's forums and I'm confused yet. When I try to use the data via Database Connections it returns the error "maximum number of instances exceeded". Let me give you a context information.
I have a map service running and consuming ArcSDE Geodatabase data. When I right-click at the Database Server Connection in Catalog>Properties we see "Class: ArcSDE Personal Server". So, when my colleague try to do the same she have yhis error message. But we have, theoretically, only 2 connections: my connection in catalog and the the connection of the map service running. What is wrong here? ArcSOC consume more than one instance of sql?

Please, any ideas will be appreciated.

My best regards.

Re: Number of connections to instance

JakeSkinner — Thu, 23 Aug 2012 14:52:15 GMT

SOC connections can consume as many connections that the service's max instance is set to. You can check this by right-clicking on the service > Service Properties > Pooling tab. If the max is set to 2, and two users are using the service concurrently, then this will spawn two SOC connections within the geodatabase. See my post above for a more in depth explanation.

Re: Number of connections to instance

JeffersonFerreira_Ferreira — Thu, 23 Aug 2012 17:24:08 GMT

SOC connections can consume as many connections that the service's max instance is set to. You can check this by right-clicking on the service > Service Properties > Pooling tab. If the max is set to 2, and two users are using the service concurrently, then this will spawn two SOC connections within the geodatabase. See my post above for a more in depth explanation.

Thanks JSkinn3.

So, if I set the pooled service maximum connections to 1 (one) it will use only one connection to database? If it is correct, so me and my colleague have read access to the database, right? The case is: I have this sql geodatabase that is consumed by the web map service, can we (me and one user) access it to read (and one of us write)?

Thanks in advance

Re: Number of connections to instance

JakeSkinner — Thu, 23 Aug 2012 17:27:22 GMT

Thanks JSkinn3.

So, if I set the pooled service maximum connections to 1 (one) it will use only one connection to database? If it is correct, so me and my colleague have read access to the database, right? The case is: I have this sql geodatabase that is consumed by the web map service, can we (me and one user) access it to read (and one of us write)?

Thanks in advance

Yes, that is correct.

If you are still receiving a max connections error, check the 'dbo.sde_process_information' table within SQL Server Management Studio to see if there are any orphaned connections. At 10.1, there is new functionality that allows you to see which users are connected to the geodatabase directly from the catalog window.

Re: Number of connections to instance

JeffersonFerreira_Ferreira — Thu, 23 Aug 2012 17:37:17 GMT

Thank you JSkinn3.
I will test it and give you a feedback soon.

Re: Number of connections to instance

JeffersonFerreira_Ferreira — Sat, 20 Oct 2012 14:24:27 GMT

Thank you JSkinn3.
I will test it and give you a feedback soon.

The issue is not yet solved. I restarted the ArcSOC, deleted the services that consume the sql database and the message "Maximum number of connections...." still appear.
I checked the dbo.sde_process_information table within SQL Server Management Studio and cant identify anything, see the attached figure.
Its a serious issue, very recurrent. Doesn't matter what I do, the connection are not closed. Please, if someone have a tip...

Re: Number of connections to instance

KimPeter — Mon, 22 Oct 2012 18:30:40 GMT

Are you sure the geodatabase was updated to be a Workgroup geodatabase? You should never see a max connections message with a workgroup geodatabase. Based on this:

When I right-click at the Database Server Connection in Catalog>Properties we see "Class: ArcSDE Personal Server".

...it doesn't sound like you have a workgroup geodatabase. Be sure to authorize the instance with a Server Workgroup license, then update the geodatabases as described in the topic on changing license keys that I referenced in April.

Publishing services from a Desktop database server (ArcSDE Personal Server) is not supported.

-Kim

Re: Number of connections to instance

JeffersonFerreira_Ferreira — Fri, 07 Dec 2012 17:01:22 GMT

My Friends;

This quite serious. I really dont know what happens. I Always get the message "maximum number...". I have 2 geodatabases (SQL Express / ArcSDE Workgroup Server), one for rasters other for vectors. In GIS Server I have a geometry service, a geodata service, 6 image services and 3 map services (2 of them consuming an image from the rasters geodatabase each one).

But the windows processes list (task manager>processes) I have 12 ArcSOC.exe *32 processes running. Thats all right, all working great. After some requests (by using the web application) the ArcSOC processes jump to 17. So I follow the work normally. In some point one of the rastes (usually on of them) becomes inaccessible (accessing it from the rest a message says "doenst exist or is inaccessible).

So it only returns to work normally if a restart the SOM and SOC. Thus, appear the SOCs processes are holding instances indefinitely until I restart the SOC and SOM.

What could be happens? If someone can give a tip, please... I dont know what to do anymore.
Thanks

Re: Number of connections to instance

JakeSkinner — Fri, 07 Dec 2012 18:16:27 GMT

If all of these services are accessing data from your SDE Workgroup geodatabases, you are at your maximum connections. Set your 'Maximum number of instance per machine' to 1. You can do this by right-clicking on each service > Service Properties > Pooling. This way an additional database connection is not attempted if a simultaneous request is made on a service.

Re: Number of connections to instance

JeffersonFerreira_Ferreira — Fri, 07 Dec 2012 18:27:59 GMT

If all of these services are accessing data from your SDE Workgroup geodatabases, you are at your maximum connections. Set your 'Maximum number of instance per machine' to 1. You can do this by right-clicking on each service > Service Properties > Pooling. This way an additional database connection is not attempted if a simultaneous request is made on a service.

Thanks JSkinn3. I Will try it and will let you know how it works. But, this will not impact th number of concurrent access in the web application? Or will be the same?

Other issue, let me understand this better. I have 2 geodatabases, I can make 10 connections to each one? Or I can make a total of 10 connections to all my sde databases?

Re: Number of connections to instance

AaronKreag2 — Mon, 31 Aug 2015 22:24:28 GMT

If you read the ESRI Master License Agreement....it says under footnote 28. that there is no connection limit with web mapping applications. Please see the image attached....