Using Performance Buckets

Performance buckets allow you to define buckets and link them to various server functions. Every time one of these functions is invoked, the server collects statistical data and adds it to the bucket. For example, send-cgi and service-j2ee are functions used to serve the CGI and Java servlet requests respectively. You can either define two buckets to maintain separate counters for CGI and servlet requests, or create one bucket that counts requests for both types of dynamic content. The cost of collecting this information is minimal, and the impact on the server performance is usually negligible. This information can later be accessed using perfdump. The following information is stored in a bucket:

• Name of the bucket. This name associates the bucket with a function.

• Description. A description of the functions with which the bucket is associated.

• Number of requests for this function. The total number of requests that caused this function to be called.

• Number of times the function was invoked. This number might not coincide with the number of requests for the function, because some functions might be executed more than once for a single request.

• Function latency or the dispatch time. The time taken by the server to invoke the function.

• Function time. The time spent in the function itself.

  The default-bucket is predefined by the server. It records statistics for the functions not associated with any user-defined bucket.

Configuration

You must specify all configuration information for performance buckets in the magnus.conf and obj.conf files. Only the default-bucket is automatically enabled.

First, you must enable performance statistics collection and perfdump.

The following examples show how to define new buckets in magnus.conf:

Init fn="define-perf-bucket" name="acl-bucket" description="ACL bucket"

Init fn="define-perf-bucket" name="file-bucket" description="Non-cached responses"

Init fn="define-perf-bucket" name="cgi-bucket" description="CGI Stats"

The previous examples create three buckets: acl-bucket, file-bucket, and cgi-bucket. To associate these buckets with functions, add bucket=bucket-name to the obj.conf function for which to measure performance.

Example

PathCheck fn="check-acl" acl="default" bucket="acl-bucket"
...
Service method="(GET|HEAD|POST)" type="*~magnus-internal/*" 
fn="send-file" bucket="file-bucket"
...
<Object name="cgi">
ObjectType fn="force-type" type="magnus-internal/cgi"
Service fn="send-cgi" bucket="cgi-bucket"
</Object>

For more information, see The bucket Parameter in Sun Java System Web Server 7.0 Update 4 Administrator’s Configuration File Reference.

Performance Report

The server statistics in buckets can be accessed using perfdump. The performance buckets information is located in the last section of the report returned by perfdump.

The report contains the following information:

• Average, Total, and Percent columns give data for each requested statistic.

• Request Processing Time is the total time required by the server to process all requests it has received so far.

• Number of Requests is the total number of requests for the function.

• Number of Invocations is the total number of times that the function was invoked. This number differs from the number of requests because a function can be called multiple times while processing one request. The percentage column for this row is calculated in reference to the total number of invocations for all of the buckets.

• Latency is the time in seconds that Web Server uses to call the function.

• Function Processing Time is the time in seconds that Web Server spends inside the function. The percentage of Function Processing Time and Total Response Time is calculated with reference to the total Request Processing Time.

• Total Response Time is the sum in seconds of Function Processing Time and Latency.

The following is an example of the performance bucket information available through perfdump:

Performance Counters:
------------------------------------------------
                           Average         Total      Percent

Total number of requests:               62647125
Request processing time:    0.0343  2147687.2500

default-bucket (Default bucket)
Number of Requests:                     62647125    (100.00%)
Number of Invocations:                3374170785    (100.00%)
Latency:                    0.0008    47998.2500    (  2.23%)
Function Processing Time:   0.0335  2099689.0000    ( 97.77%)
Total Response Time:        0.0343  2147687.2500    (100.00%)