Navigation:  WebOffice > Best Practices > Optimizing Performance - Impact of Minimum and Maximum Number of Instances

A pooled ArcGIS Server Service has a specific count of related process instances needed for performing asynchronous processing of requests in parallel.

 

The minimum and maximum number of instances count have big impact on the overall performance of a WebOffice 10 R3 project (project load/start up time as well as for server round trip time).

Depending on the count of data frames used in a published ArcMap document (.mxd) and the estimated count of concurrent users (users accessing  WebOffice 10 R3in the same period of time, more precise in the same minute), the minimum and maximum number of instances must be increased accordingly.

 

Recommended minimal setting (opposed to Esri ArcGIS Server defaults) for at maximum five concurrent users and an ArcMap document with one (1) data frame is

 

•Minimum number of instances: 2

•Maximum number of instances: 3

 

 

 

Note: The calculation of number of instances below is a rough ‘thumb rule’-like calculation and may not provide good results in specific configurations/scenarios. E.g. if only dynamic map services are used (no caching) then the probability for concurrent requests will increase – as a logical consequence the number of instances will need to be increased.

 

For each three additional data frames in a published ArcMap document, the overall instance count should be increased by at least 1.

For each five additional concurrent users (i.e. within peak load time hour of the day, within time interval of one (1) minute, five additional users access WebOffice 10 R3), the overall instance count should be increased by at least 1.

 

E.g. if an ArcGIS Server service used in a WebOffice 10 R3 project contains 7 data frames, and an estimated count of 10 concurrent users access the WebOffice 10 R3 project using the ArcGIS Server service, then the recommended minimum instance count would be 5:

Base count + (Overall data frame count -1) / 3 + (Overall concurrent users per minute - 5) / 5

2 + (7 - 1)  /  3 + (10 – 5) / 5 = 2 + 2 + 1 = 5

 

Using the Maximum number of instances parameter it is possible to better cope with load peaks. Thus if you have very high load peaks but a small base load, then you may e.g. increase the maximum number of instances by one or two counts.