phhttpd-HOWTO(1).pdf

PHHTTPD HTTP Accelerator HOWTO

Zach Brown

David C. Merrill

2001−04−24

Revision History

Revision 1.1 2001−04−24 Revised by: DCM

Converted to DocBook 4.1 article, with some minor language cleanup. Copyright passed from Zach Brown

to David C. Merrill.

Revision 1.0

2000

Revised by: ZB

Initial release.

This document explains the use of the phhttpd http server accelerator under Linux.

As of the later 2.3 kernels, and offically in 2.4 and later, the TUX http accelerator is included in the standard

Linux kernel tree. Therefore, this document should be considered obsolete for most users.

PHHTTPD HTTP Accelerator HOWTO

Table of Contents

1. Copyright and License. ...................................................................................................................................1

2. Introduction. ....................................................................................................................................................2

2.1. Architectural Overview. ....................................................................................................................2

2.2. Supported Systems. ...........................................................................................................................2

3. Configuration File. ..........................................................................................................................................3

3.1. Overview. ..........................................................................................................................................3

3.2. Global Config Section ......................................................................................................................3

3.3. Virtual Servers. .................................................................................................................................4

4. Logging.. ...........................................................................................................................................................6

4.1. Overview. ..........................................................................................................................................6

4.2. Configuration. ...................................................................................................................................6

4.3. Format and Strange Behaviour. ........................................................................................................6

5. Run Time Facilities. ........................................................................................................................................8

5.1. Overview. ..........................................................................................................................................8

5.2. Log Rotating. ....................................................................................................................................8

5.3. Status Reporting. ...............................................................................................................................8

1. Copyright and License

GNU Free Documentation License, which is hereby incorporated by reference.

1. Copyright and License

2. Introduction

phhttpd is an HTTP accelerator. It serves fast static HTTP fetches from a local file−system and passes slower

dynamic requests back to a waiting server. It features a lean networking I/O core and an aggressive content

cache that help it perform its job efficiently.

2.1. Architectural Overview

phhttpd features a very slim I/O core. It does all its networking work using non−blocking system calls driven

by whatever event model is most appropriate for the host operating system. This allows a single execution

context to handle as many client connections as the event model dictates.

phhttpd's job is to serve static content as quickly as it possibly can. To do this it maintains a cache of content

in memory. When a request is serviced, phhttpd saves a reference to the on disk content and whatever HTTP

headers are dependent on the content. The next time a request for this content is received, phhttpd can service

it very quickly. This cache can be prepopulated (populated at run time), or can be built dynamically as

requests come in. Its size may also be capped by the administrator so that it doesn't overwhelm a system.

phhttpd is a threaded stand alone daemon. The number of threads is currently statically defined at run time.

Incoming connections are evenly balanced among the running threads, regardless of what content they may

be serving. Connections are served by the thread that accepted them until the transfer is done.

2.2. Supported Systems

phhttpd is currently only expected to build and run on Linux systems using glibc2.1 under a kernel that

supports passing POLL* information over real−time SIGIO signals. This means later 2.3.x kernels or a 2.2.x

kernel that has been patched.

I badly want this to change. If you're interested in doing porting work to other Operating Systems, please do

let me know.

2. Introduction

3. Configuration File

3.1. Overview

phhttpd uses an XML config file format to express how it should behave while running. More information on

XML may be found near http://www.w3.org/XML/

phhttpd's configuration centers around the concept of virtual servers. For us, a virtual server may be thought

of as the merging of a document tree and the actions phhttpd takes while serving that content.

phhttpd.conf may be thought of as having two main sections. The global section, which defines properties

that are consistent across the entire running phhttpd server, and multiple virtual sections that describe

properties of that only apply to a virtual server. There will only be one global section while multiple virtual

sections are allowed.

3.2. Global Config Section

The global section defines properties of the running server that don't apply to a single virtual server. It should

be enclosed in

Global config entities

cache max=NUM

Sets the maximum number of cached responses that will be held in memory. Each cached responses

holds a minimal amount of memory. More importantly, each cached response holds an open file

descriptor to the file with real content and an mmap() ed region of that content. phhttpd will start

pruning the cache when it notices either of these two resources coming under pressure, but has no

way to easily deduce that its running low on memory. The administrator may set this value to set an

upper bound on the number of responses to keep in memory.

control file=PATH

This specifies the file that will be used to talk with phhttpd_ctl .

globallog file=PATH

This specifies the file to which global messages will be logged.

mime file=PATH

This specifies the file that contains the mapping of file extensions to MIME types. It should be of the

form:

text/sgml sgml sgm

video/mpeg mpeg mpg mpe

timeout inactivity=NUM

3. Configuration File

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