Tuning the monitoring and access logging settings for the HTTP server instances that handle client requests are important parts of ensuring peak GlassFish Server performance.
The following topics are addressed here:
Disabling the collection of monitoring statistics can increase overall GlassFish Server performance. You can enable or disable monitoring statistics collection for the HTTP service using either the Administration Console or asadmin subcommands.
Refer to Chapter 8, Administering the Monitoring Service, in Oracle GlassFish Server 3.1 Administration Guide for complete instructions on configuring the monitoring service using asadmin subcommands.
If using the Administration Console, click the Configurations->configuration-name->Monitoring node for the configuration for which you want to enable or disable monitoring for selected components. Refer to the Administration Console online help for complete instructions.
For instructions on viewing comprehensive monitoring statistics using asadmin subcommands, see Viewing Comprehensive Monitoring Data in Oracle GlassFish Server 3.1 Administration Guide. If using the Administration Console, you can view monitoring statistics by navigating to the server (Admin Server) node, and then clicking the Monitor tab. Refer to the online help for configuring different views of the available monitoring statistics.
When viewing monitoring statistics, some key performance-related information to review includes the following:
The DNS cache caches IP addresses and DNS names. The DNS cache is disabled by default. In the DNS Statistics for Process ID All page under Monitor in the web-based Administration interface the following statistics are displayed:
If the DNS cache is disabled, the rest of this section is not displayed.
By default, the DNS cache is off. Enable DNS caching in the Administration Console by clicking the Configurations->configuration-name->Network Config->http-listener-name node. Click the HTTP tab and enable the DNS Lookup option.
The number of current cache entries and the maximum number of cache entries. A single cache entry represents a single IP address or DNS name lookup. Make the cache as large as the maximum number of clients that access your web site concurrently. Note that setting the cache size too high is a waste of memory and degrades performance.
Set the maximum size of the DNS cache by entering or changing the value in the in the Administration Console by clicking the Configurations->configuration-name->Network Config->http-listener-name node. Click the File tab and set the desired options.
The hit ratio is the number of cache hits divided by the number of cache lookups.
This setting is not tunable.
Note - If you turn off DNS lookups on your server, host name restrictions will not work and IP addresses will appear instead of host names in log files.
It is possible to also specify whether to cache the DNS entries. If you enable the DNS cache, the server can store hostname information after receiving it. If the server needs information about the client in the future, the information is cached and available without further querying. specify the size of the DNS cache and an expiration time for DNS cache entries. The DNS cache can contain 32 to 32768 entries; the default value is 1024. Values for the time it takes for a cache entry to expire can range from 1 second to 1 year specified in seconds; the default value is 1200 seconds (20 minutes).
Do not use DNS lookups in server processes because they are resource-intensive. If you must include DNS lookups, make them asynchronous.
If asynchronous DNS is disabled, the rest of this section will not be displayed.
The number of name lookups (DNS name to IP address) that have been done since the server was started. This setting is not tunable.
The number of address loops (IP address to DNS name) that have been done since the server was started. This setting is not tunable.
The current number of lookups in progress.
The file cache caches static content so that the server handles requests for static content quickly. The file-cache section provides statistics on how your file cache is being used.
For information about tuning the file cache, see File Cache Settings.
The Monitoring page lists the following file cache statistics:
Number of Hits on Cached File Content
Number of Cache Entries
Number of Hits on Cached File Info
Heap Space Used for Cache
Number of Misses on Cached File Content
Cache Lookup Misses
Number of Misses on Cached File Content
Max Age of a Cache Entry
Max Number of Cache Entries
Max Number of Open Entries
Is File Cached Enabled?
Maximum Memory Map to be Used for Cache
Memory Map Used for cache
Cache Lookup Hits
Open Cache Entries: The number of current cache entries and the maximum number of cache entries are both displayed. A single cache entry represents a single URI. This is a tunable setting.
Maximum Heap Space to be Used for Cache
The following are statistics related to the Keep Alive system. The most important settings you can tune here relate to HTTP Timeout. See Timeout for more information.
Connections Terminated Due to Client Connection Timed Out
Max Connection Allowed in Keep-alive
Number of Hits
Connections in Keep-alive Mode
Connections not Handed to Keep-alive Thread Due to too Many Persistent Connections
The Time in Seconds Before Idle Connections are Closed
Connections Closed Due to Max Keep-alive Being Exceeded
Total Connections Queued: Total connections queued is the total number of times a connection has been queued. This includes newly accepted connections and connections from the keep-alive system.
Average Queuing Delay: Average queueing delay is the average amount of time a connection spends in the connection queue. This represents the delay between when a request connection is accepted by the server, and a request processing thread (also known as a session) begins servicing the request.
Accessing Logging can be tuned using several asadmin subcommands. Refer to Chapter 8, Administering the Monitoring Service, in Oracle GlassFish Server 3.1 Administration Guide for information about using these subcommands.
If using the Administration Console, Access Logging is configured from the Configurations->configuration-name->HTTP Service page. Refer to the Administration Console online help for complete instructions about the options on this page.
To enable or disable access logging, check or uncheck the Access Logging Enabled checkbox. Access Logging is disabled by default.
When performing benchmarking, ensure that Access Logging is disabled. If Access Logging is enabled, it is recommended that you also enable Rotation to ensure that the logs do not run out of disk space.