IBM Integration Bus, Version 10.0.0.9 Operating Systems: AIX, HP-Itanium, Linux, Solaris, Windows, z/OS


Configuring the XPath cache

The integration server XPath cache size might become a performance bottleneck for customers who use many XPath expressions. Altering the size of the XPath cache might improve message flow performance.

An integration server (or 'execution group' in WebSphere® Message Broker Version 8.0 and earlier versions) keeps a cache of compiled XPath expressions to help reduce the processor usage of parsing and re-creating XPath expressions that are used repeatedly during message flow execution. This cache is shared by all message flows within an integration server. The default size of this cache is 10000 elements, and this is expected to be sufficient for most customer configurations.

It might be necessary to alter the size of this cache for optimal message flow performance if hundreds or thousands of XPath expressions are created for each Message Flow invocation. From IBM® Integration Bus Version 10.0 onwards, the XPath cache has its own resource manager ComIbmXPathCache; run the following command to return the status:
mqsireportproperties <INode> -e default -o ComIbmXPathCache -r
where <INode> is your integration node. The following output is an example of that returned from the command:
ComIbmXPathCache
 uuid='ComIbmXPathCache'
 userTraceLevel=''
 traceLevel=''
 userTraceFilter=''
 traceFilter=''
 vrmfIntroducedAt=''
 resourceGroup=''
 maximumSize='10000'
 minimumSize='6000'
 currentSize='0'
The maximumSize property controls the maximum number of compiled XPath expressions that can be stored in the XPath cache. When the XPath cache reaches this limit of compiled XPath expressions, entries are evicted from the cache based on the following criteria: You can change the value of the maximumSize property with the following command:
mqsireportproperties <INode> -e default -o ComIbmXPathCache -n maximumSize -v 20000.
The minimumSize property controls the minimum number of compiled XPath expressions that can be stored in the XPath cache. When the XPath cache reaches this number of compiled XPath expressions, the number of entries does not fall any lower when entries are evicted from the cache. You can change the value of the minimumSize property with the following command:
mqsireportproperties <INode> -e default -o ComIbmXPathCache -n minimumSize -v 1000.

The currentSize property reports the number of compiled XPath expressions that are stored in the XPath cache. This property is read-only, and must not be set with the mqsichangeproperties command.


be22566_.htm | Last updated 2017-07-17 12:46:27