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Problem(Abstract) |
The Server status page of IBM HTTP Server is a convenient
tool for monitoring HTTP Server active and idle connections. |
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Resolving the
problem |
When addressing problems with IBM WebSphere Application
Server, such as slow response time and apparent application "hangs", it is
useful to understand the state of the Web server as well as the
Application Server. This understanding can help determine where
bottlenecks occur.
Both Apache and the IBM HTTP Server offer a convenient tool for monitoring
HTTP connections. The Server status page displays a snapshot of
connections from the Web server perspective. The following list contains
valid states for the Web server connections:
"_" |
Waiting for connection |
"S" |
Starting up |
"R" |
Reading request |
"W" |
Sending reply |
"K" |
Keepalive (read) |
"D" |
DNS lookup |
"L" |
Logging |
"G" |
Gracefully finishing |
As you refresh the page, you see mostly "." (idle connections) or "_"
(connections that have not been started yet, but which are within the
maxclient settings), with a few "W", "K" "S", or "R" connections that
represent actual requests in progress. The number of in-progress
connections goes up and down as you refresh the page. If this number is
steadily rising, it can indicate a problem, unless you actually have
increasing traffic.
For example, connections staying in a "W" state can occur when clients
terminate a transaction in mid-write. These connections return to "."
after the HTTP timeout value.
A large number of "W" (writing) connections can indicate a problem
responding to clients that are interrupted or disconnected before
receiving a complete response.
Comparing the number of transactions in progress to the MaxClients
directive in the httpd.conf file, and to the max connections
setting of WebSphere Application Server servlet engines can also point to
a bottleneck.
To add more detailed information to the server status page, add the
ExtendedStatus On directive to your configuration file (outside of the
Location tags). This addition enables you to see the process IDs of
individual connections so that you can use other tools to investigate
them. In addition, the "SS" column indicates how many seconds have passed
since the Web server thread started processing the request. This is useful
when you see a connection listed in a "W" state for a long period of time.
Enabling the server status page
Make the following updates to the Web server httpd.conf file to
view the server status page for IBM HTTP Server:
For Microsoft Windows users:
- Uncomment the following line:
LoadModule status_module
modules/ApacheModuleStatus.dll |
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- Uncommment the server-status location section and change the "allow
from" to localhost client ipaddress or domain. Also, Uncomment or add the
"ExtendedStatus On" directive:
<Location /server-status>
SetHandler server-status
order deny,allow
deny from all
allow from localhost
</Location>
ExtendedStatus On |
This example shows how to limit access of the server-status page to a
browser running locally on the machine where the Web server is also
running. |
For UNIX users:
- Uncomment the following line:
LoadModule status_module
libexec/mod_status.so |
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- For Apache or IBM HTTP Server V1.3 releases only, uncomment the
following line or add this line if it is currently missing:
- Uncommment the server-status location section and change the "allow
from" to the localhost client ipaddress or domain. Also, uncomment or add
the "ExtendedStatus On" directive:
<Location /server-status>
SetHandler server-status
order deny,allow
deny from all
allow from ibm.com
</Location>
ExtendedStatus On |
This example shows how to grant anyone with access to the domain the
ability to see the page. See the previous Windows example for local access
only. |
After making these changes, restart the Web server, then browse the
http://domain-name/server-status page.
You can see a display of current connections and their states: reading,
responding, idle, and so forth.
To see an example of server-status display visit: http://www.apache.org/server-status |
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Cross Reference information |
Segment |
Product |
Component |
Platform |
Version |
Edition |
Application Servers |
Runtimes for Java Technology |
Java SDK |
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