iTP Secure WebServer System Administrator's Guide (iTPWebSvr 5.1+)

Planning the iTP Secure WebServer PATHMON
Environment
iTP Secure WebServer System Administrator’s Guide—522659-001
3-4
Threading Considerations for the httpd Server
are essential in the Compaq environment for the iTP Secure WebServer. The
configuration file creates a PATHMON process and configures the application servers
and the Distributor process.
Refer to Appendix A, Configuration Directives
, for detailed descriptions of all the
configuration directives you can specify in the server configuration file (httpd.config).
To understand the configuration file, you must know the basic NonStop TS/MP
architecture and characteristics of the PATHMON environment. If you are not already
familiar with the basics of using NonStop TS/MP, refer to the NonStop TS/MP System
Management Manual.
Threading Considerations for the httpd Server
There are two techniques you can use, individually or in combination, to allow the iTP
Secure WebServer to handle many requests in parallel. These techniques are as follows:
•
Allow for a large number of servers in the httpd server class.
•
Allow each server to handle multiple requests in parallel.
To allow for multiple servers, you use the Maxservers command in the Server directive.
This command specifies the total number of servers in the class. If you want each server
to be single-threaded, the value of Maxservers should be large enough to accommodate
the maximum number of concurrent requests your WebServer must be able to handle.
To allow for multithreading in each server process, you use the
TANDEM_RECEIVE_DEPTH environment variable. (The Env command in the Server
directive lets you specify environment variables.) The value of
TANDEM_RECEIVE_DEPTH is the maximum number of requests a single httpd
process can handle.
To increase the number of concurrent requests, you can define multiple servers in the
server class and use TANDEM_RECEIVE_DEPTH to make each server multithreaded.
In this case, you can determine the maximum number of simultaneous requests to a
server class by multiplying the value of TANDEM_RECEIVE_DEPTH by the value of
Maxservers.
In the configuration file delivered with the iTP Secure WebServer, the httpd server class
consists of multiple, multithreaded servers.
Assigning a smaller number of servers with a higher number of threads per server has
the following benefits:
•
In a process, all threads share system resources such as swap space and file opens,
including opens to cache files.
Note. Although the receive depth is conceptually similar to the NonStop TS/MP link depth, the
link depth is limited to 255 simultaneous requests per server class, whereas the receive depth
is limited to 255 simultaneous requests per process. Therefore, even if you specify a value of 1
for the Linkdepth command, the httpd process can simultaneously service as many requests
on that link as are specified by the value specified for the receive depth.