13
Monitoring Performance

See Also: Oracle Application Server 10g Performance Guide for performance tuning tips

This chapter describes how to gather performance statistics with OracleAS Web Cache Manager and how to interpret them.

This chapter contains these topics:

• Monitoring OracleAS Web Cache Health

• Gathering OracleAS Web Cache Performance Statistics

• Gathering End-User Performance Data

• Gathering Origin Server Performance Statistics

You can use Oracle Enterprise Manager to monitor many of the same performance statistics described in this chapter. See Oracle Application Server 10g Administrator's Guide for further information about using Oracle Enterprise Manager to monitor OracleAS Web Cache.

Note: After making a Statistics port property change in the Operations Ports page (Ports > Operations Ports), ensure that the cache server process is restarted. If it is not, then the Monitoring pages (Web Cache Statistics, Health Monitor, Origin Server Statistics, and Popular Requests) report the following error: Failure obtaining statistics from Web Cache cache server: error in connect. Please check that the cache server is up and running. See "Task 12: Apply Changes and Restart OracleAS Web Cache" for instructions on applying configuration changes and restarting the cache server process with command-line tools or OracleAS Web Cache Manager.

Monitoring OracleAS Web Cache Health

OracleAS Web Cache provides a health monitor that enables you to quickly access information about overall cache performance.

To monitor overall cache health:

1. Start OracleAS Web Cache Manager.

   See Also: "Starting OracleAS Web Cache Manager"

2. In the navigator frame, select Monitoring > Health Monitor.

   The Health Monitor page appears in the right pane.

3. From the For Cache list, select the cache. Click View. If you have not configured a cache cluster, this field displays the current cache (the cache to which you are connected.)

4. From the Auto Refresh list, select the frequency at which you want the statistics refreshed and click Set.

   If you select Never, then the page will not be refreshed again. If you want the statistics refreshed now, click Refresh Now.

Table 13-1 through Table 13-3 describe the statistics for this page.

Table 13-1 describes the general statistics.

Table 13-1  OracleAS Web Cache Health Monitor: General Statistics

Statistic	Description
Current Time	The time when this page was generated
Current Web Cache Start Time	The time when OracleAS Web Cache was started
Time Since Start	The length of time that OracleAS Web Cache has been operating since it was started. Time is denoted in days/hours/minutes/seconds.
Total Number of Requests Served by Current Web Cache	Accumulated number of requests that OracleAS Web Cache has served since it was started See Also: "Gathering OracleAS Web Cache Performance Statistics" to view detailed statistics for OracleAS Web Cache

Table 13-2 describes the statistics shown in the Requests Served by Origin Servers table, which lists the number of requests served to the selected cache by the origin servers.

Table 13-2  Requests Served by Origin Servers

Statistic	Description
Requests Served by Origin Servers	Name of the origin server and the port number from which the origin server is listening for OracleAS Web Cache requests.
Proxy Server	YES specifies that the server is a proxy server. NO specifies that the server is an application Web server.
Up/Down	The status of the origin server at the time that OracleAS Web Cache last attempted to communicate with that origin server. (OracleAS Web Cache attempts to reach the origin server only for specific purposes, such as retrieving responses for a cache miss.) UP specifies that the last communication with the server was successful. DOWN specifies that the server is down. If this is the last server in a single or multiple server configuration, OracleAS Web Cache continues to forward requests. If this is not the last server, no new requests will be sent to server. However, OracleAS Web Cache will poll the server until it is back online.
Since	Date and time when the origin server was last known to be up or down.
Total Requests Served	Number of client requests, such as Web browser requests, resolved by this origin server.
Average Latency	Average amount of time for the client requests to be resolved.

Table 13-3 describes the statistics in the Serving Requests/Second Now table.

Table 13-3  Serving Requests/Second Now Statistics

Statistic	Description
Stale Serves from Current Web Cache	Documents in the cache that have expired or that have been invalidated, but have not yet been refreshed from the origin servers
Fresh Serves from Current Web Cache	Documents in the cache that are still valid The health bar provides a graphical view of the number of client requests resolved for each second.

Gathering OracleAS Web Cache Performance Statistics

To monitor OracleAS Web Cache performance:

1. Start OracleAS Web Cache Manager.

   See Also: "Starting OracleAS Web Cache Manager"

2. In the navigator frame, select Monitoring > Web Cache Statistics.

   The Web Cache Statistics page appears.

3. From the For Cache list, select the cache and click View.

   If you have not configured a cache cluster, this field displays the current cache (the cache to which you are connected.) If you select All Caches, the Cluster Web Cache Statistics page, which is discussed later in this section, is displayed.

4. From the For Site list, select the Web site for which to view statistics. Click View.

5. From the Auto Refresh list, select the frequency at which you want the statistics refreshed and click Set.

   If you select Never, then the page will not be refreshed again. If you want the statistics refreshed now, click Refresh Now.

Table 13-4 through Table 13-8 describe the statistics on this page.

Table 13-4 describes the general statistics about the cache.

Table 13-4  OracleAS Web Cache Statistics: General Statistics

Statistic	Description
Updated at	The time when this page was generated
Current Cache Start Time	The time when OracleAS Web Cache was started or restarted
Time Since Start	The length of time that OracleAS Web Cache has been operating since it was started or restarted. Time is denoted in days/hours/minutes/seconds.
Current Cache Reset Time	The time when the statistics were last reset
Time Since Reset	The length of time since the statistics were last reset

Table 13-5 describes the statistics provided by the Cache Overview table, which provides an overview of the cache.

Table 13-5  OracleAS Web Cache Statistics: Cache Overview

Statistic	Description
Number of Documents in Cache	Number of documents stored in OracleAS Web Cache, plus the number of documents in transit through the cache. The number includes documents that have expired or have been invalidated but that have not been deleted from the cache.
Size of Documents in Cache	Size of the contents of the documents currently in the cache. This size does not reflect the total size needed to cache the documents because it does not include document header information or document overhead.
Total Bytes Served	Total number of bytes served to clients, such as browsers
Total Bytes Saved by Compression	Additional bytes that would be sent to clients if in-cache compression is disabled
Current Number of Open Connections	Current number of incoming open connections to the OracleAS Web Cache server and outgoing open connections to the origin servers. You can adjust the limit of connections in the Resource Limits page (Properties > Resource Limits).
Configured Maximum Cache Size	The maximum cache size. You can adjust the maximum size of the cache in the Resource Limits page (Properties > Resource Limits).
Current Allocated Memory	The physical size of the cache. The physical size of the cache is the amount of data memory allocated by OracleAS Web Cache for cache storage and operation. This number is always smaller than the process size shown by operating system statistics because the OracleAS Web Cache process, like any user process, consumes memory in other ways, such as instruction storage, stack data, thread, and library data.
Current Action Limit	Ninety-five percent of the Configured Maximum Cache Size. This number is usually larger than the Current Allocated Memory. See "Cache Memory" for more information about the relationship among Current Action Limit, Configured Maximum Cache Size, and Current Allocated Memory.

Table 13-6 describes the Requests Served table. This table provides information about the number or percentage of requests OracleAS Web Cache: has served on average for each second for the last ten seconds (Recent column), has served since it was started (Since Start column), and has served since the metrics were reset (Since Reset column).

If you choose Detail Statistics, the table shows metrics for owned content and on-demand content. These metrics are valid in a cache cluster environment.

Table 13-6  OracleAS Web Cache Statistics: Requests Served

Statistic	Description
Total Requests Served	Accumulated number of client (such as browser), peer cache, and ESI requests that OracleAS Web Cache has served since it was started or restarted
Average Requests Served	Average number of client, peer cache, and ESI requests served for each second
Fresh Hits	Percentage of client requests resolved by documents in the cache This percentage should be high, except when documents are being invalidated.
Stale Hits	Percentage of client requests resolved by documents that have expired or have been invalidated, but for which updated version have not yet been retrieved from the origin servers. As documents are invalidated or expired, the percentage of stale hits will increase. The percentage will decrease as OracleAS Web Cache retrieves updated content from the origin servers. If the percentage does not decrease, it could indicate a bottleneck on the origin servers.
Cacheable Misses	Percentage of client requests for cacheable documents not served by OracleAS Web Cache. In a cache cluster, this includes requests from peer caches.
Noncacheable Misses	Percentage of client requests for non-cacheable documents not served by OracleAS Web Cache.
Refreshes	Percentage of documents that OracleAS Web Cache has refreshed from the origin servers
Compressed Hits	Percentage of total requests served by the cache in compressed form
Compressed Misses	Percentage of total requests retrieved from the origin server and compressed by OracleAS Web Cache before serving

Table 13-7 describes the Cache Errors table. The Cache Errors table provides metrics about the error pages served since OracleAS Web Cache was started (Since Start column) or when the metrics were reset (Since Reset column).

Table 13-7  OracleAS Web Cache Statistics: Cache Errors

Statistic	Description
Network Error	Number of error pages that OracleAS Web Cache has served to clients due to a network error
Site Busy Error	Number of error pages that OracleAS Web Cache has served to clients due to a busy Web site error
ESI Uncaught Exception	Number of errors that OracleAS Web Cache has returned to a client when an uncaught exception occurred in the cache during ESI parsing or processing
ESI Default Fragment	Number of error pages that OracleAS Web Cache has served when an uncaught exception occurs in the application during ESI parsing or processing

Table 13-8 describes the Invalidations table, which provides metrics on the invalidation requests served since OracleAS Web Cache was started (Since Start column) or when the metrics were reset (Since Reset column).

Table 13-8  OracleAS Web Cache Statistics: Invalidations

Statistic	Description
Total Invalidation Requests	The number of invalidation requests processed
Total Invalidation Documents	The total number of objects invalidated

If you select All Caches in the For Cache list, the Cluster Web Cache Statistics page is displayed. Table 13-9 describes the statistics for this page.

Table 13-9  Cluster Web Cache Statistics

Statistic	Description
Number of Documents in All Caches	Total number of documents stored in all caches in the cache cluster, plus the number of documents in transit through a cache. The number includes documents that have expired or have been invalidated but that have not been deleted from a cache.
Size of Documents in All Caches	Size of the contents of the documents currently in all caches in the cache cluster. This size does not reflect the total size needed to cache the documents because it does not include document header information or document overhead.
Total Requests Served by All Caches	Total accumulated number of client, peer cache, and ESI requests that all caches in the cache cluster have served since each cache was started or restarted
Current Hit Rate in All Caches	Percentage of total requests resolved by documents in all caches in the cache cluster
Current Miss Rate in All Caches	Percentage of total requests to all caches in the cache cluster that were retrieved from the origin server

Gathering End-User Performance Data

Using OracleAS Web Cache, you can monitor the response time of your applications by viewing information about how quickly the responses are delivered to the end users. From the time a user enters the Web site until they exit, you can monitor which URLs they view and view reports about the response times the end user has experienced.

See Also: "Enabling End-User Performance Monitoring" for information about configuring end-user performance monitoring.

With OracleAS Web Cache Manager, you can view the output in HTML or write it to a comma-separated file, which can be imported into spreadsheet tools for viewing and analysis. The output provides information about the URLs or domains accessed and the average, minimum, and maximum latency of the requests to each URL.

Note that generating the output may take several minutes or hours to complete, depending on the log file size. Because this operation is processed on the OracleAS Web Cache server, perform this operation during non-peak hours to maintain the performance of your cache.

To use this feature, take the following steps:

1. Configure the cache for end-user performance monitoring, as described in "Enabling End-User Performance Monitoring".

2. In the navigator frame of OracleAS Web Cache Manager, select Monitoring > End-User Performance Analysis.

   The End-User Performance Analysis page appears.

3. In the Specify Access Log File for Analysis field, specify the full file specification for the access log that you want to analyze.

4. Click Submit.

   OracleAS Web Cache Manager displays the Analyzing End-User Performance dialog box, which provides progress messages. Do not close this dialog box.

5. When the operation is complete, the Analyzing End-User Performance dialog box displays methods of viewing the results. Select one of the following:
   • To view the output in HTML, select View output in HTML. The output is displayed in a browser window. To specify how the information is sorted, select one of the following from the links in the browser window:
     • By URL: Access log entries are sorted by URL.

     • By Domain: Access log entries are sorted by domain.

     • By URL (Hourly): Access log entries are sorted by hour, then by URL.

     • By Domain (Hourly): Access log entries are sorted by hour, then by domain.

   • To download the output to a comma-separated (.csv) file, select one of the following:
     • By URL: Access log entries are sorted by URL.

     • By Domain: Access log entries are sorted by domain.

     • By URL (Hourly): Access log entries are sorted by hour, then by URL.

     • By Domain (Hourly): Access log entries are sorted by hour, then by domain.

     You are prompted to save or open the file. You can view the file in any application, such as Microsoft Excel, that supports comma-separated files.

Gathering Origin Server Performance Statistics

To monitor origin server performance:

1. Start OracleAS Web Cache Manager.

   See Also: "Starting OracleAS Web Cache Manager"

2. In the navigator frame, select Monitoring > Origin Server Statistics.

   The Origin Server Statistics page appears.

3. From the For Cache list, select the cache and click View.

   If you have not configured a cache cluster, this field displays the current cache (the cache to which you are connected.)

4. From the Auto Refresh list, select the frequency at which you want the statistics refreshed and click Set.

   If you select Never, then the page will not be refreshed again. If you want the statistics refreshed now, click Refresh Now.

Table 13-10 through Table 13-12 describe the statistics for this page.

Table 13-10 describes the general information about the origin servers, that is, application Web servers or proxy servers, displayed on this page.

Table 13-10  Origin Server Statistics

Statistic	Description
Origin Server: hostname	Name of the origin server and the port number from which the server is listening for OracleAS Web Cache requests.
Origin Server: proxy server	YES specifies that the server is a proxy server. NO specifies that the server is an application Web server.
Up/Down Time: up/down	The status of the origin server at the time that OracleAS Web Cache last attempted to communicate with that origin server. (OracleAS Web Cache attempts to reach the origin server only for specific purposes, such as retrieving responses for a cache miss.) UP specifies that the last communication with the server was successful. DOWN specifies that the server is down. If this is the last server in a single or multiple server configuration, OracleAS Web Cache keeps a connection open to the server for requests. If this is not the last server, then no new requests will be sent to server. However, other active servers will poll the downed server until it is back online.
Up/Down Time: since	Date and time when the origin server was last known to be up or down
Completed Requests: number/sec	Current number of requests that the origin server has processed per second. The number is the average for each second during the last ten-second interval.
Completed Requests: max/sec	Maximum number of requests that the origin server has processed for each second during the last ten-second interval.
Completed Requests: avg/sec	Average number of requests that the origin server has processed for each second.
Completed Requests: total	Accumulated number of requests that the origin server has processed.
Latency: avg this interval	Average latency, during the last 10-second interval, to process requests for OracleAS Web Cache.
Latency: avg since start	Average number of seconds to process requests for OracleAS Web Cache since the origin server started.
Load: now	Current number of connections from OracleAS Web Cache that the origin server has open. The number is the average for each second during the last ten-second interval.
Load: max	Maximum number of connections that the origin server has had open at one time. Note: Consider increasing the capacity of an origin server if the max connections is close to the server's capacity. You can increase capacity in the Origin Servers page (Origin Servers, Sites, and Load Balancing > Origin Servers).
Active Sessions: now	Current number of active sessions from OracleAS Web Cache to the origin servers. The number is the average for each second during the last ten-second interval.
Active Sessions: max	Maximum number of active sessions that the origin server has had open at one time.

Table 13-11 describes the type of errors listed in the Errors Served table, which lists the following for each type of errors served:

• Number this second: Current number error pages that OracleAS Web Cache is serving

• Total: Total number of error pages that OracleAS Web Cache has served since the cache was last restarted

  Table 13-11  Errors Served

  Type	Description
  Network Error	Error pages that OracleAS Web Cache has served to clients due to a network error
  Site Busy Error	Error pages that OracleAS Web Cache has served to clients due to a busy Web site error
  ESI Uncaught Exception	Number of errors that OracleAS Web Cache has returned to a client when an uncaught exception occurred during ESI parsing or processing
  ESI Default Fragment	Number of error pages that OracleAS Web Cache has served to a client when an uncaught exception occurs in the application during ESI parsing or processing

Table 13-12 describes the statistics in the Origin Server Backlog table.

Table 13-12  Origin Server Backlog Statistics

Type	Description
Now	Current number of requests for the cache that are awaiting processing by the application Web server. The number is the average for each second during the last ten-second interval.
Max	Maximum number of requests for the cache that are awaiting processing by the application Web server.