Practical mod_perl

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• Practical mod_perl
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  • Preface
    • What You Need to Know
    • Who This Book Is For
    • How This Book Is Organized
    • Reference Sections
    • Filesystem Conventions
    • Apache and Perl Versions
    • Typographic Conventions
    • Command Interpreter Program (Shell) Conventions
    • Installing Perl Modules
      • Manual Installation
      • Prerequisites Needed to Install Perl Modules on Windows
      • Building a Perl Module
      • Using the CPAN Shell
      • Using the Perl Package Manager
    • How to Contact Us
    • Acknowledgments
  • I. mod_perl Administration
    • 1. Introducing CGI and mod_perl
      • 1.1. A Brief History of CGI
        • 1.1.1. The HTTP Protocol
        • 1.1.2. The Common Gateway Interface Specification
        • 1.1.3. Apache CGI Handling with mod_cgi
      • 1.2. The Apache 1.3 Server Model
        • 1.2.1. Forking
        • 1.2.2. CGI Scripts Under the Forking Model
        • 1.2.3. Performance Drawbacks of Forking
      • 1.3. The Development of mod_perl 1.0
        • 1.3.1. Running CGI Scripts with mod_perl
      • 1.4. Apache 1.3 Request Processing Phases
        • 1.4.1. Apache 1.3 Modules and the mod_perl 1.0 API
        • 1.4.2. mod_perl 1.0 and the mod_perl API
      • 1.5. References
    • 2. Getting Started Fast
      • 2.1. Installing mod_perl 1.0 in Three Steps
      • 2.2. Installing mod_perl on Unix Platforms
        • 2.2.1. Obtaining and Unpacking the Source Code
        • 2.2.2. Building mod_perl
        • 2.2.3. Installing mod_perl
      • 2.3. Configuring and Starting the mod_perl Server
      • 2.4. Installing mod_perl for Windows
        • 2.4.1. Installing mod_perl with the Perl Package Manager
      • 2.5. Preparing the Scripts Directory
      • 2.6. A Sample Apache::Registry Script
        • 2.6.1. Porting Existing CGI Scripts to mod_perl
      • 2.7. A Simple mod_perl Content Handler
      • 2.8. Is This All We Need to Know About mod_perl?
      • 2.9. References
    • 3. Installing mod_perl
      • 3.1. Configuring the Source
        • 3.1.1. Controlling the Build Process
        • 3.1.2. Activating Callback Hooks
        • 3.1.3. Activating Standard API Features
        • 3.1.4. Enabling Extra Features
        • 3.1.5. Reusing Configuration Parameters
        • 3.1.6. Discovering Whether a Feature Was Enabled
        • 3.1.7. Using an Alternative Configuration File
        • 3.1.8. perl Makefile.PL Troubleshooting
          • 3.1.8.1. A test compilation with your Makefile configuration failed...
          • 3.1.8.2. Missing or misconfigured libgdbm.so
          • 3.1.8.3. Undefined reference to `PL_perl_destruct_level
      • 3.2. Building mod_perl (make)
        • 3.2.1. What Compiler Should Be Used to Build mod_perl?
        • 3.2.2. make Troubleshooting
          • 3.2.2.1. Undefined reference to `Perl_newAV'
          • 3.2.2.2. Unrecognized format specifier for...
      • 3.3. Testing the Server (make test)
        • 3.3.1. Manual Testing
        • 3.3.2. make test Troubleshooting
          • 3.3.2.1. make test fails
          • 3.3.2.2. mod_perl.c is incompatible with this version of Apache
          • 3.3.2.3. make test......skipping test on this platform
          • 3.3.2.4. make test fails due to misconfigured localhost entry
      • 3.4. Installation (make install)
        • 3.4.1. Manually Building a mod_perl-Enabled Apache
      • 3.5. Installation Scenarios for Standalone mod_perl
        • 3.5.1. The All-in-One Way
        • 3.5.2. Building mod_perl and Apache Separately
        • 3.5.3. When DSOs Can Be Used
        • 3.5.4. Building mod_perl as a DSO via APACI
        • 3.5.5. Building mod_perl as a DSO via APXS
      • 3.6. Building mod_perl with Other Components
        • 3.6.1. Installing mod_perl with PHP
        • 3.6.2. Installing mod_perl with mod_ssl (+openssl)
        • 3.6.3. Installing mod_perl with Apache-SSL (+openssl)
        • 3.6.4. Installing mod_perl with Stronghold
      • 3.7. Installing mod_perl with the CPAN.pm Interactive Shell
      • 3.8. Installing mod_perl on Multiple Machines
      • 3.9. Installation into a Nonstandard Directory
        • 3.9.1. Installing Perl Modules into a Nonstandard Directory
        • 3.9.2. Finding Modules Installed in Nonstandard Directories
          • 3.9.2.1. Modifying @INC
          • 3.9.2.2. Using the PERL5LIB environment variable
        • 3.9.3. Using the CPAN.pm Shell with Nonstandard Installation Directories
        • 3.9.4. Making a Local Apache Installation
        • 3.9.5. Nonstandard mod_perl-Enabled Apache Installation
        • 3.9.6. Nonstandard mod_perl-Enabled Apache Installation with CPAN.pm
      • 3.10. How Can I Tell if mod_perl Is Running?
        • 3.10.1. Checking the error_log File
        • 3.10.2. Testing by Viewing /perl-status
        • 3.10.3. Testing via Telnet
        • 3.10.4. Testing via a CGI Script
        • 3.10.5. Testing via lwp-request
      • 3.11. General Notes
        • 3.11.1. How Do I Make the Installation More Secure?
        • 3.11.2. Can I Run mod_perl-Enabled Apache as suExec?
        • 3.11.3. Should I Rebuild mod_perl if I Have Upgraded Perl?
        • 3.11.4. mod_auth_dbm Nuances
      • 3.12. References
    • 4. mod_perl Configuration
      • 4.1. Apache Configuration
        • 4.1.1. Configuration Files
        • 4.1.2. Configuration Directives
        • 4.1.3. <Directory>, <Location>, and <Files> Sections
          • 4.1.3.1. <Directory directoryPath> ... </Directory>
          • 4.1.3.2. <Files filename > ... </Files>
          • 4.1.3.3. <Location URI> ... </Location>
        • 4.1.4. Merging <Directory>, <Location>, and <Files> Sections
        • 4.1.5. Subgrouping of <Directory>, <Location>, and <Files> Sections
        • 4.1.6. Options Directive Merging
        • 4.1.7. MinSpareServers, MaxSpareServers, StartServers, MaxClients, and MaxRequestsPerChild
      • 4.2. mod_perl Configuration
        • 4.2.1. Alias Configurations
          • 4.2.1.1. Running scripts located in the same directory under different handlers
        • 4.2.2. <Location /perl> Sections
        • 4.2.3. PerlModule and PerlRequire
        • 4.2.4. Perl*Handlers
        • 4.2.5. The handler( ) Subroutine
        • 4.2.6. Investigating the Request Phases
        • 4.2.7. Stacked Handlers
        • 4.2.8. Perl Method Handlers
        • 4.2.9. PerlFreshRestart
        • 4.2.10. PerlSetEnv and PerlPassEnv
        • 4.2.11. PerlSetVar and PerlAddVar
        • 4.2.12. PerlSetupEnv
        • 4.2.13. PerlWarn and PerlTaintCheck
      • 4.3. The Startup File
        • 4.3.1. A Sample Startup File
        • 4.3.2. Syntax Validation
        • 4.3.3. What Modules Should Be Added to the Startup File
        • 4.3.4. The Confusion with use( ) in the Server Startup File
      • 4.4. Apache Configuration in Perl
        • 4.4.1. Constructing <Perl> Sections
        • 4.4.2. Breaking Out of <Perl> Sections
        • 4.4.3. Cheating with Apache->httpd_conf
        • 4.4.4. Declaring Package Names in Perl Sections
        • 4.4.5. Verifying <Perl> Sections
        • 4.4.6. Saving the Perl Configuration
        • 4.4.7. Debugging
      • 4.5. Validating the Configuration Syntax
      • 4.6. The Scope of mod_perl Configuration Directives
      • 4.7. Apache Restarts Twice
      • 4.8. Enabling Remote Server Configuration Reports
      • 4.9. Tips and Tricks
        • 4.9.1. Publishing Port Numbers Other Than 80
        • 4.9.2. Running the Same Script from Different Virtual Hosts
      • 4.10. Configuration Security Concerns
        • 4.10.1. Using Only Absolutely Necessary Components
        • 4.10.2. Taint Checking
        • 4.10.3. Hiding Server Information
        • 4.10.4. Making the mod_perl Server Inaccessible from the Outside
        • 4.10.5. Protecting Private Status Locations
      • 4.11. General Pitfalls
      • 4.12. References
    • 5. Web Server Control, Monitoring, Upgrade, and Maintenance
      • 5.1. Starting the Server in Multi-Process Mode
      • 5.2. Starting the Server in Single-Process Mode
      • 5.3. Using kill to Control Processes
        • 5.3.1. kill Signals for Stopping and Restarting Apache
        • 5.3.2. Speeding Up Apache's Termination and Restart
        • 5.3.3. Finding the Right Apache PID
      • 5.4. Using apachectl to Control the Server
      • 5.5. Validating Server Configuration
      • 5.6. Setuid root Startup Scripts
        • 5.6.1. Introduction to setuid Executables
        • 5.6.2. Apache Startup Script's setuid Security
        • 5.6.3. Sample setuid Apache Startup Script
      • 5.7. Preparing for Machine Reboot
      • 5.8. Upgrading a Live Server
        • 5.8.1. Upgrading Intranet Servers
        • 5.8.2. Upgrading 24 × 7 Internet Servers
          • 5.8.2.1. The server cluster
          • 5.8.2.2. The single server
            • 5.8.2.2.1. Upgrading live server components by swapping machines
            • 5.8.2.2.2. Upgrading a live server with port forwarding
            • 5.8.2.2.3. Upgrading a live server with prepackaged components
            • 5.8.2.2.4. Upgrading a live server using symbolic links
            • 5.8.2.2.5. Upgrading Perl code
            • 5.8.2.2.6. Moving files and restarting the server
            • 5.8.2.2.7. Using CVS for code upgrades
        • 5.8.3. Disabling Scripts and Handlers on a Live Server
          • 5.8.3.1. Disabling code running under Apache::Registry
          • 5.8.3.2. Disabling code running under other handlers
          • 5.8.3.3. Disabling services with help from the frontend server
        • 5.8.4. Scheduled Routine Maintenance
      • 5.9. Three-Tier Server Scheme: Development, Staging, and Production
        • 5.9.1. Starting a Personal Server for Each Developer
      • 5.10. Web Server Monitoring
        • 5.10.1. Interactive Monitoring
        • 5.10.2. Apache::VMonitorThe Visual System and Apache Server Monitor
          • 5.10.2.1. Prerequisites and configuration
          • 5.10.2.2. Multi-processes and system overall status reporting mode
          • 5.10.2.3. Single-process extensive reporting system
        • 5.10.3. Automated Monitoring
          • 5.10.3.1. mod_perl server watchdogs
      • 5.11. Server Maintenance Chores
        • 5.11.1. Handling Log Files
          • 5.11.1.1. Scheduled log file rotation
          • 5.11.1.2. Non-scheduled emergency log rotation
          • 5.11.1.3. Centralized logging
        • 5.11.2. Swapping Prevention
        • 5.11.3. Limiting Resources Used by Apache Child Processes
          • 5.11.3.1. OS-specific notes
        • 5.11.4. Tracking and Terminating Hanging Processes
        • 5.11.5. Limiting the Number of Processes Serving the Same Resource
        • 5.11.6. Limiting the Request-Rate Speed (Robot Blocking)
      • 5.12. References
    • 6. Coding with mod_perl in Mind
      • 6.1. Before You Start to Code
        • 6.1.1. Accessing Documentation
        • 6.1.2. The strict Pragma
        • 6.1.3. Enabling Warnings
      • 6.2. Exposing Apache::Registry Secrets
        • 6.2.1. The First Mystery: Why Does the Script Go Beyond 5?
        • 6.2.2. The Second MysteryInconsistent Growth over Reloads
      • 6.3. Namespace Issues
        • 6.3.1. The @INC Array
        • 6.3.2. The %INC Hash
        • 6.3.3. Name Collisions with Modules and Libraries
          • 6.3.3.1. A first faulty scenario
          • 6.3.3.2. A second faulty scenario
          • 6.3.3.3. A quick but ineffective hackish solution
          • 6.3.3.4. A first solution
          • 6.3.3.5. A second solution
          • 6.3.3.6. A third solution
      • 6.4. Perl Specifics in the mod_perl Environment
        • 6.4.1. exit( )
        • 6.4.2. die( )
        • 6.4.3. Global Variable Persistence
        • 6.4.4. STDIN, STDOUT, and STDERR Streams
        • 6.4.5. Redirecting STDOUT into a Scalar Variable
        • 6.4.6. print( )
        • 6.4.7. Formats
        • 6.4.8. Output from System Calls
        • 6.4.9. BEGIN blocks
        • 6.4.10. END Blocks
      • 6.5. CHECK and INIT Blocks
        • 6.5.1. $^T and time( )
        • 6.5.2. Command-Line Switches
          • 6.5.2.1. Warnings
          • 6.5.2.2. Taint mode
        • 6.5.3. Compiled Regular Expressions
          • 6.5.3.1. Matching patterns repeatedly
      • 6.6. Apache::Registry Specifics
        • 6.6.1. _ _END_ _ and _ _DATA_ _ Tokens
        • 6.6.2. Symbolic Links
        • 6.6.3. Return Codes
      • 6.7. Transition from mod_cgi Scripts to Apache Handlers
        • 6.7.1. Starting with a mod_cgi-Compatible Script
        • 6.7.2. Converting into a Perl Content Handler
        • 6.7.3. Converting to use the mod_perl API and mod_perl-Specific Modules
      • 6.8. Loading and Reloading Modules
        • 6.8.1. The @INC Array Under mod_perl
        • 6.8.2. Reloading Modules and Required Files
          • 6.8.2.1. Restarting the server
          • 6.8.2.2. Using Apache::StatINC
          • 6.8.2.3. Using Apache::Reload
          • 6.8.2.4. Using dynamic configuration files
            • 6.8.2.4.1. Writing configuration files
            • 6.8.2.4.2. Reloading configuration files
            • 6.8.2.4.3. Dynamically updating configuration files
      • 6.9. Handling the "User Pressed Stop Button" Case
        • 6.9.1. Detecting Aborted Connections
        • 6.9.2. The Importance of Cleanup Code
          • 6.9.2.1. Critical section
          • 6.9.2.2. Safe resource locking and cleanup code
      • 6.10. Handling Server Timeout Cases and Working with $SIG{ALRM}
      • 6.11. Generating Correct HTTP Headers
      • 6.12. Method Handlers: The Browse and See, Browse and View Example
      • 6.13. References
  • II. mod_perl Performance
    • 7. Identifying Your Performance Problems
      • 7.1. Looking at the Big Picture
      • 7.2. Asking the Right Questions
      • 7.3. References
    • 8. Choosing a Platform for the Best Performance
      • 8.1. Choosing the Right Operating System
        • 8.1.1. mod_perl Support for the Operating System
        • 8.1.2. Stability and Robustness
        • 8.1.3. Good Memory Management
        • 8.1.4. Avoiding Memory Leaks
        • 8.1.5. Memory-Sharing Capabilities
        • 8.1.6. The Real Cost of Support
        • 8.1.7. Discontinued Products
        • 8.1.8. Keeping Up with OS Releases
      • 8.2. Choosing the Right Hardware
        • 8.2.1. Machine Strength Demands According to Expected Site Traffic
        • 8.2.2. A Single Strong Machine Versus Many Weaker Machines
        • 8.2.3. Getting a Fast Internet Connection
        • 8.2.4. Tuning I/O Performance
        • 8.2.5. How Much Memory Is Enough?
        • 8.2.6. Getting a Fault-Tolerant CPU
        • 8.2.7. Detecting and Avoiding Bottlenecks
        • 8.2.8. Solving Hardware Requirement Conflicts
      • 8.3. References
    • 9. Essential Tools for Performance Tuning
      • 9.1. Server Benchmarking
        • 9.1.1. ApacheBench
        • 9.1.2. httperf
        • 9.1.3. http_load
        • 9.1.4. Other Web Server Benchmark Utilities
      • 9.2. Perl Code Benchmarking
      • 9.3. Process Memory Measurements
      • 9.4. Apache::Status and Measuring Code Memory Usage
      • 9.5. Code Profiling Techniques
        • 9.5.1. Profiling with Devel::DProf
        • 9.5.2. Profiling with Devel::SmallProf
      • 9.6. References
    • 10. Improving Performance with Shared Memory and Proper Forking
      • 10.1. Sharing Memory
        • 10.1.1. Calculating Real Memory Usage
        • 10.1.2. Memory-Sharing Validation
          • 10.1.2.1. Variable unsharing caused by regular expressions
          • 10.1.2.2. Numerical versus string access to variables
        • 10.1.3. Preloading Perl Modules at Server Startup
        • 10.1.4. Preloading Registry Scripts at Server Startup
        • 10.1.5. Module Initialization at Server Startup
          • 10.1.5.1. Initializing DBI.pm
          • 10.1.5.2. Initializing CGI.pm
        • 10.1.6. Memory Preallocation
      • 10.2. Forking and Executing Subprocessesfrom mod_perl
        • 10.2.1. Forking a New Process
        • 10.2.2. Freeing the Parent Process
        • 10.2.3. Detaching the Forked Process
        • 10.2.4. Avoiding Zombie Processes
        • 10.2.5. A Complete Fork Example
        • 10.2.6. Starting a Long-Running External Program
        • 10.2.7. Starting a Short-Running External Program
        • 10.2.8. Executing system( ) or exec( ) in the Right Way
      • 10.3. References
    • 11. Tuning Performance by Tweaking Apache's Configuration
      • 11.1. Setting the MaxClients Directive
      • 11.2. Setting the MaxRequestsPerChild Directive
      • 11.3. Setting MinSpareServers, MaxSpareServers, and StartServers
      • 11.4. KeepAlive
      • 11.5. PerlSetupEnv
      • 11.6. Reducing the Number of stat( ) Calls Made by Apache
      • 11.7. Symbolic Links Lookup
      • 11.8. Disabling DNS Resolution
      • 11.9. Response Compressing
      • 11.10. References
    • 12. Server Setup Strategies
      • 12.1. mod_perl Deployment Overview
      • 12.2. Standalone mod_perl-Enabled Apache Server
      • 12.3. One Plain and One mod_perl-Enabled Apache Server
        • 12.3.1. Choosing the Target Installation Directories Layout
        • 12.3.2. Configuration and Compilation of the Sources
          • 12.3.2.1. Building the httpd_docs server
          • 12.3.2.2. Building the httpd_perl server
        • 12.3.3. Configuration of the Servers
          • 12.3.3.1. Basic httpd_docs server configuration
          • 12.3.3.2. Basic httpd_perl server configuration
      • 12.4. One Light Non-Apache and One mod_perl-Enabled Apache Server
      • 12.5. Adding a Proxy Server in httpd Accelerator Mode
      • 12.6. The Squid Server and mod_perl
        • 12.6.1. Pros and Cons
        • 12.6.2. Light Apache, mod_perl, and Squid Setup Implementation Details
        • 12.6.3. mod_perl and Squid Setup Implementation Details
      • 12.7. Apache's mod_proxy Module
        • 12.7.1. Concepts and Configuration Directives
          • 12.7.1.1. ProxyPass
          • 12.7.1.2. ProxyPassReverse
          • 12.7.1.3. Security issues
        • 12.7.2. Knowing the Proxypassed Connection Type
        • 12.7.3. Buffering Feature
        • 12.7.4. Closing Lingering Connections with lingerd
        • 12.7.5. Caching Feature
        • 12.7.6. Build Process
      • 12.8. mod_rewrite Examples
      • 12.9. Getting the Remote Server IP in the Backend Server in the Proxy Setup
      • 12.10. Frontend/Backend Proxying with Virtual Hosts
        • 12.10.1. Virtual Host Flavors
        • 12.10.2. Dual-Server Virtual Host Configuration
        • 12.10.3. Virtual Hosts and Main Server Interaction
        • 12.10.4. Frontend Server Configuration
        • 12.10.5. Backend Server Configuration
      • 12.11. HTTP Authentication with Two Servers and a Proxy
      • 12.12. When One Machine Is Not Enough for Your RDBMS DataBase and mod_perl
        • 12.12.1. Server Requirements
        • 12.12.2. The Problem
        • 12.12.3. The Solution
        • 12.12.4. Three Machine Model
      • 12.13. Running More than One mod_perl Server on the Same Machine
      • 12.14. SSL Functionality and a mod_perl Server
      • 12.15. Uploading and Downloading Big Files
      • 12.16. References
    • 13. TMTOWTDI: Convenience and Habit Versus Performance
      • 13.1. Apache::Registry PerlHandler Versus Custom PerlHandler
      • 13.2. Apache::args Versus Apache::Request::param Versus CGI::param
      • 13.3. Buffered Printing and Better print( ) Techniques
      • 13.4. Interpolation, Concatenation, or List
      • 13.5. Keeping a Small Memory Footprint
        • 13.5.1. "Bloatware" Modules
        • 13.5.2. Importing Symbols
      • 13.6. Object Methods Calls Versus Function Calls
        • 13.6.1. The Overhead with Light Subroutines
        • 13.6.2. The Overhead with Heavy Subroutines
        • 13.6.3. Are All Methods Slower Than Functions?
      • 13.7. Using the Perl stat( ) Call's Cached Results
      • 13.8. time( ) System Call Versus $r->request_time
      • 13.9. Printing Unmodified Files
      • 13.10. Caching and Pre-Caching
      • 13.11. Caching with Memoize
      • 13.12. Comparing Runtime Performance of Perl and C
        • 13.12.1. Building Perl Extensions with XS and h2xs
        • 13.12.2. The Benchmark
        • 13.12.3. Inline.pm
        • 13.12.4. Perl Extensions Conclusion
      • 13.13. References
    • 14. Defensive Measures for Performance Enhancement
      • 14.1. Controlling Your Memory Usage
        • 14.1.1. Defining the Minimum Shared Memory Size Threshold
          • 14.1.1.1. Potential drawbacks of memory-sharing restrictions
        • 14.1.2. Defining the Maximum Memory Size Threshold
        • 14.1.3. Defining the Maximum Unshared Memory Size Threshold
      • 14.2. Coding for a Smaller Memory Footprint
        • 14.2.1. Memory Reuse
        • 14.2.2. Big Input, Big Damage
        • 14.2.3. Small Input, Big Damage
        • 14.2.4. Think Production, Not Development
        • 14.2.5. Passing Variables
        • 14.2.6. Memory Leakage
      • 14.3. Conclusion
      • 14.4. References
    • 15. Improving Performance Through Build Options
      • 15.1. Server Size as a Function of Compiled-in Features
      • 15.2. mod_status and ExtendedStatus On
      • 15.3. DYNAMIC_MODULE_LIMIT Apache Build Option
      • 15.4. Perl Build Options
      • 15.5. Architecture-Specific Compile Options
      • 15.6. References
    • 16. HTTP Headers for Optimal Performance
      • 16.1. Date-Related Headers
        • 16.1.1. Date Header
        • 16.1.2. Last-Modified Header
        • 16.1.3. Expires and Cache-Control Headers
      • 16.2. Content Headers
        • 16.2.1. Content-Type Header
        • 16.2.2. Content-Length Header
        • 16.2.3. Entity Tags
      • 16.3. Content Negotiation
        • 16.3.1. The Vary Header
      • 16.4. HTTP Requests
        • 16.4.1. GET Requests
        • 16.4.2. Conditional GET Requests
        • 16.4.3. HEAD Requests
        • 16.4.4. POST Requests
      • 16.5. Avoiding Dealing with Headers
      • 16.6. References
  • III. Databases and mod_perl
    • 17. Databases Overview
      • 17.1. Volatile Databases
        • 17.1.1. In-Memory Databases in a Single Process
        • 17.1.2. In-Memory Databases Across Multiple Processes
      • 17.2. Non-Volatile Databases
        • 17.2.1. Flat-File Databases
        • 17.2.2. Filesystem Databases
        • 17.2.3. DBM Databases
        • 17.2.4. Relational Databases
      • 17.3. References
    • 18. mod_perl Data-Sharing Techniques
      • 18.1. Sharing the Read-Only Data in and Between Processes
      • 18.2. Sharing Data Between Various Handlers
      • 18.3. References
    • 19. DBM and mod_perl
      • 19.1. mod_perl and DBM
      • 19.2. Resource Locking
        • 19.2.1. Deadlocks
        • 19.2.2. Exclusive Locking Starvation
      • 19.3. Flawed Locking Methods
      • 19.4. Locking Wrappers Overview
      • 19.5. Tie::DB_Lock
      • 19.6. Examples
        • 19.6.1. tie( )-ing Once and Forever
        • 19.6.2. Read/Write Access
        • 19.6.3. Storing Complex Data Structures
      • 19.7. References
    • 20. Relational Databases and mod_perl
      • 20.1. Persistent Database Connections with Apache::DBI
        • 20.1.1. Apache::DBI Connections
        • 20.1.2. When to Use Apache::DBI (and When Not to Use It)
        • 20.1.3. Configuring Apache::DBI
        • 20.1.4. Debugging Apache::DBI
        • 20.1.5. Caveats and Troubleshooting
          • 20.1.5.1. Database locking risks
          • 20.1.5.2. Transactions
          • 20.1.5.3. Opening connections with different parameters
          • 20.1.5.4. Cannot find the DBI handler
          • 20.1.5.5. The morning bug
          • 20.1.5.6. Apache:DBI does not work
          • 20.1.5.7. Skipping connection cache during server startup
      • 20.2. Improving Performance
        • 20.2.1. Preopening DBI Connections
        • 20.2.2. Improving Speed by Skipping ping( )
        • 20.2.3. Efficient Record-Retrieval Techniques
        • 20.2.4. mysql_use_result Versus mysql_store_result Attributes
        • 20.2.5. Running Two or More Relational Databases
        • 20.2.6. Caching prepare( ) Statements
      • 20.3. DBI Debug Techniques
      • 20.4. References
  • IV. Debugging and Troubleshooting
    • 21. Error Handling and Debugging
      • 21.1. Warnings and Errors Explained
        • 21.1.1. The Importance of Warnings
          • 21.1.1.1. The diagnostics pragma
        • 21.1.2. Curing "Internal Server Error" Problems
        • 21.1.3. Making Use of the error_log
        • 21.1.4. Displaying Errors to Users
      • 21.2. Debugging Code in Single-Server Mode
      • 21.3. Tracing System Calls
      • 21.4. Tracing mod_perl-Specific Perl Calls
      • 21.5. Debugging Perl Code
        • 21.5.1. Locating and Correcting Syntax Errors
        • 21.5.2. Using Apache::FakeRequest to Debug Apache Perl Modules
        • 21.5.3. Using print( ) for Debugging
        • 21.5.4. Using print( ) and Data::Dumper for Debugging
        • 21.5.5. The Importance of a Good, Concise Coding Style
        • 21.5.6. Introduction to the Perl Debugger
        • 21.5.7. Interactive Perl Debugging Under mod_cgi
        • 21.5.8. Noninteractive Perl Debugging Under mod_perl
        • 21.5.9. Interactive mod_perl Debugging
          • 21.5.9.1. ptkdb and interactive mod_perl debugging
      • 21.6. Analyzing Dumped core Files
        • 21.6.1. Getting Ready to Debug
        • 21.6.2. Creating a Faulty Package
        • 21.6.3. Dumping the core File
        • 21.6.4. Analyzing the core File
        • 21.6.5. Extracting the Backtrace Automatically
      • 21.7. Hanging Processes: Detection and Diagnostics
        • 21.7.1. Hanging Because of an Operating System Problem
        • 21.7.2. When a Process Might Hang
        • 21.7.3. Detecting Hanging Processes
        • 21.7.4. Determination of the Reason
          • 21.7.4.1. Using the Perl trace
          • 21.7.4.2. Using the system calls trace
          • 21.7.4.3. Using the interactive debugger
        • 21.7.5. mod_perl gdb Debug Macros
      • 21.8. Useful Debug Modules
        • 21.8.1. B::Deparse
        • 21.8.2. -D Runtime Option
        • 21.8.3. Devel::Peek and Apache::Peek
        • 21.8.4. Devel::Symdump and Apache::Symdump
        • 21.8.5. Apache::Debug
        • 21.8.6. Other Debug Modules
      • 21.9. Looking Inside the Server
        • 21.9.1. Apache::StatusEmbedded Interpreter Status Information
          • 21.9.1.1. Minimal configuration
          • 21.9.1.2. Extended configuration
          • 21.9.1.3. Usage
        • 21.9.2. mod_status
      • 21.10. References
    • 22. Troubleshooting mod_perl
      • 22.1. Configuration and Startup
        • 22.1.1. libexec/libperl.so: open failed: No such file or directory
        • 22.1.2. install_driver(Oracle) failed: Can't load `.../DBD/Oracle/Oracle.so' for module DBD::Oracle
        • 22.1.3. Invalid command `PerlHandler'...
        • 22.1.4. RegistryLoader: Translation of uri [...] to filename failed
      • 22.2. Code Parsing and Compilation
        • 22.2.1. Value of $x will not stay shared at - line 5
        • 22.2.2. Value of $x may be unavailable at - line 5
        • 22.2.3. Can't locate loadable object for module ...
        • 22.2.4. Can't locate object method "get_handlers" ...
        • 22.2.5. Missing right bracket at line ...
        • 22.2.6. Can't load `.../auto/DBI/DBI.so' for module DBI
      • 22.3. Runtime
        • 22.3.1. foo ... at /dev/null line 0
        • 22.3.2. Segfaults When Using XML::Parser
        • 22.3.3. exit signal Segmentation fault (11)
        • 22.3.4. CGI Code Is Returned as Plain Text Instead of Being Executed
        • 22.3.5. rwrite returned -1
        • 22.3.6. Global symbol "$foo" requires explicit package name
        • 22.3.7. Use of uninitialized value at (eval 80) line 12
        • 22.3.8. Undefined subroutine &Apache::ROOT::perl::test_2epl::some_function called at
        • 22.3.9. Callback called exit
        • 22.3.10. Out of memory!
        • 22.3.11. syntax error at /dev/null line 1, near "line arguments:"
      • 22.4. Shutdown and Restart
        • 22.4.1. Evil Things Might Happen When Using PerlFreshRestart
        • 22.4.2. [warn] child process 30388 did not exit, sending another SIGHUP
        • 22.4.3. Processes Get Stuck on Graceful Restart
    • 23. Getting Help and Online Resources
      • 23.1. How to Report Problems
        • 23.1.1. Getting the Backtrace from Core Dumps
        • 23.1.2. Spinning Processes
      • 23.2. Mailing List Etiquette
      • 23.3. Resources
        • 23.3.1. mod_perl
        • 23.3.2. mod_perl Mailing Lists
        • 23.3.3. Perl
        • 23.3.4. Perl/CGI
        • 23.3.5. Apache
        • 23.3.6. DBI and SQL
        • 23.3.7. Squid
        • 23.3.8. CVS
        • 23.3.9. Performance and Scalability
        • 23.3.10. Web Security
  • V. mod_perl 2.0
    • 24. mod_perl 2.0: Installation and Configuration
      • 24.1. What's New in Apache 2.0
      • 24.2. What's New in Perl 5.6.0-5.8.0
      • 24.3. What's New in mod_perl 2.0
        • 24.3.1. Thread Support
        • 24.3.2. Perl Interface to the APR and Apache APIs
        • 24.3.3. Other New Features
        • 24.3.4. Improved and More Flexible Configuration
        • 24.3.5. Optimizations
      • 24.4. Installing mod_perl 2.0
        • 24.4.1. Installing from Source
        • 24.4.2. Installing Binaries
      • 24.5. Configuring mod_perl 2.0
        • 24.5.1. Enabling mod_perl
        • 24.5.2. Accessing the mod_perl 2.0 Modules
        • 24.5.3. Startup File
        • 24.5.4. Perl's Command-Line Switches
        • 24.5.5. mod_perl 2.0 Core Handlers
          • 24.5.5.1. modperl
          • 24.5.5.2. perl-script
          • 24.5.5.3. A simple response handler example
        • 24.5.6. PerlOptions Directive
          • 24.5.6.1. Enable
          • 24.5.6.2. Clone
          • 24.5.6.3. Parent
          • 24.5.6.4. Perl*Handler
          • 24.5.6.5. AutoLoad
          • 24.5.6.6. GlobalRequest
          • 24.5.6.7. ParseHeaders
          • 24.5.6.8. MergeHandlers
          • 24.5.6.9. SetupEnv
        • 24.5.7. Thread-Mode-Specific Directives
          • 24.5.7.1. PerlInterpStart
          • 24.5.7.2. PerlInterpMax
          • 24.5.7.3. PerlInterpMinSpare
          • 24.5.7.4. PerlInterpMaxSpare
          • 24.5.7.5. PerlInterpMaxRequests
          • 24.5.7.6. PerlInterpScope
        • 24.5.8. Retrieving Server Startup Options
      • 24.6. Resources
    • 25. Programming for mod_perl 2.0
      • 25.1. Migrating to and Programming with mod_perl 2.0
        • 25.1.1. The Shortest Migration Path
        • 25.1.2. Migrating Configuration Files
          • 25.1.2.1. PerlHandler
          • 25.1.2.2. PerlSendHeader
          • 25.1.2.3. PerlSetupEnv
          • 25.1.2.4. PerlTaintCheck
          • 25.1.2.5. PerlWarn
          • 25.1.2.6. PerlFreshRestart
        • 25.1.3. Code Porting
        • 25.1.4. ModPerl::Registry Family
        • 25.1.5. Method Handlers
        • 25.1.6. Apache::StatINC Replacement
      • 25.2. New Apache Phases and Corresponding Perl*Handlers
        • 25.2.1. Server Configuration and Startup Phases
          • 25.2.1.1. PerlOpenLogsHandler
          • 25.2.1.2. PerlPostConfigHandler
          • 25.2.1.3. PerlChildInitHandler
          • 25.2.1.4. PerlChildExitHandler
        • 25.2.2. Connection Phases
          • 25.2.2.1. PerlPreConnectionHandler
          • 25.2.2.2. PerlProcessConnectionHandler
            • 25.2.2.2.1. Socket-based protocol module
            • 25.2.2.2.2. Bucket brigade-based protocol module
        • 25.2.3. HTTP Request Phases
      • 25.3. I/O Filtering
        • 25.3.1. I/O Filtering Concepts
          • 25.3.1.1. Two methods for manipulating data
          • 25.3.1.2. HTTP request versus connection filters
          • 25.3.1.3. Multiple invocations of filter handlers
          • 25.3.1.4. Blocking calls
        • 25.3.2. Filter Configuration
        • 25.3.3. Input Filters
          • 25.3.3.1. Bucket brigade-based connection input filter
          • 25.3.3.2. Bucket brigade-based HTTP request input filter
          • 25.3.3.3. Stream-based HTTP request input filter
        • 25.3.4. Output Filters
          • 25.3.4.1. Stream-based HTTP request output filter
          • 25.3.4.2. Another stream-based HTTP request output filter
          • 25.3.4.3. Bucket brigade-based HTTP request output filter
  • VI. Appendixes
    • A. mod_perl Recipes
      • A.1. Emulating the Authentication Mechanism
      • A.2. Reusing Data from POST Requests
      • A.3. Redirecting POST Requests
      • A.4. Redirecting While Maintaining Environment Variables
      • A.5. Handling Cookies
      • A.6. Sending Multiple Cookies with the mod_perl API
      • A.7. Sending Cookies in REDIRECT Responses
      • A.8. CGI::params in the mod_perlish Way
      • A.9. Sending Email from mod_perl
      • A.10. mod_rewrite in Perl
      • A.11. Setting PerlHandler Based on MIME Type
      • A.12. Singleton Database Handles
      • A.13. Terminating a Child Process on Request Completion
      • A.14. References
    • B. Apache Perl Modules
      • B.1. Development-Stage Modules
        • B.1.1. Apache::ReloadAutomatically Reload Changed Modules
        • B.1.2. Apache::PerlVINCAllow Module Versioning in <Location> and <VirtualHost> blocks
        • B.1.3. Apache::DProfHook Devel::DProf into mod_perl
        • B.1.4. Apache::SmallProfHook Devel::SmallProf into mod_perl
        • B.1.5. Apache::FakeRequestFake Request Object for Debugging
        • B.1.6. Apache::testFacilitate Testing of Apache::* Modules
      • B.2. Modules to Aid Debugging
        • B.2.1. Apache::DBHooks for the Interactive Perl Debugger
        • B.2.2. Apache::DebugUtilities for Debugging Embedded Perl Code
        • B.2.3. Apache::DebugInfoSend Debug Information to Client
        • B.2.4. Apache::LeakModule for Tracking Memory Leaks in mod_perl Code
        • B.2.5. Apache::PeekA Data Debugging Tool for the XS Programmer
        • B.2.6. Apache::SymbolAvoid the Mandatory `Subroutine Redefined' Warning
        • B.2.7. Apache::SymdumpSymbol Table Snapshots
      • B.3. Control and Monitoring Modules
        • B.3.1. Apache::Watchdog::RunAwayHanging Processes Monitor and Terminator
        • B.3.2. Apache::VMonitorVisual System and Apache Server Monitor
        • B.3.3. Apache::SizeLimitLimit Apache httpd Processes
        • B.3.4. Apache::GTopLimitLimit Apache httpd Processes
        • B.3.5. Apache::TimedRedirectRedirect URLs for a Given Time Period
        • B.3.6. Apache::ResourceLimit Resources Used by httpd Children
        • B.3.7. Apache::StatusEmbedded Interpreter Status Information
      • B.4. Server Configuration Modules
        • B.4.1. Apache::ModuleConfigInterface to Configuration API
        • B.4.2. Apache::PerlSectionsUtilities for Working with <Perl> Sections
        • B.4.3. Apache::httpd_confGenerate an httpd.conf File
        • B.4.4. Apache::srcMethods for Locating and Parsing Bits of Apache Source Code
        • B.4.5. Apache::ConfigFileParse an Apache-Style httpd.conf Configuration File
      • B.5. Authentication-Phase Modules
      • B.6. Authorization-Phase Modules
      • B.7. Access-Phase Modules
        • B.7.1. Stonehenge::ThrottleLimit Bandwith Consumption by IP Address
      • B.8. Type Handlers
        • B.8.1. Apache::MimeXMLmod_perl Mime Encoding Sniffer for XML Files
        • B.8.2. Apache::MIMEMapperAssociates File Extensions with PerlHandlers
      • B.9. Trans Handlers
        • B.9.1. Apache::AddHostPathAdds Some or All of the Hostname and Port to the URI
        • B.9.2. Apache::ProxyPassimplement ProxyPass in Perl
        • B.9.3. Apache::ProxyPassThruSkeleton for Vanilla Proxy
        • B.9.4. Apache::ThrottleSpeed-Based Content Negotiation
        • B.9.5. Apache::TransLDAPTrans Handler Example
      • B.10. Fixup Handlers
        • B.10.1. Apache::RefererBlockBlock Request Based Upon "Referer" Header
        • B.10.2. Apache::UsertrackEmulate the mod_usertrack Apache Module
      • B.11. Generic Content-Generation Modules
        • B.11.1. Apache::Registry and Apache::PerlRun
        • B.11.2. Apache::RegistryNGApache::Registry New Generation
        • B.11.3. Apache::RegistryBBApache::Registry Bare Bones
        • B.11.4. Apache::Request (libapreq)Generic Apache Request Library
        • B.11.5. Apache::DispatchCall PerlHandlers with the Ease of Registry Scripts
      • B.12. Application-Specific Content-Generation Modules
        • B.12.1. Apache::AutoIndexPerl Replacement for the mod_autoindex and mod_dir Apache Modules
        • B.12.2. Apache::WAP::AutoIndexWAP Demonstration Module
        • B.12.3. Apache::WAP::MailPeekDemonstrate Use of WML Delivery
        • B.12.4. Apache::ArchiveExpose Archive Files Through the Apache Web Server
        • B.12.5. Apache::GatewayImplement a Gateway
        • B.12.6. Apache::NNTPGatewayNNTP Interface for a mod_perl-Enabled Apache Web Server.
        • B.12.7. Apache::PrettyPerlSyntax Highlighting for Perl Files
        • B.12.8. Apache::PrettyTextReformat .txt Files for Client Display
        • B.12.9. Apache::RandomLocationRandom File Display
        • B.12.10. Apache::StageManage a Staging Directory
        • B.12.11. Apache::RoamingA mod_perl Handler for Roaming Profiles
        • B.12.12. Apache::BackhandWrite mod_backhand Functions in Perl
      • B.13. Database Modules
        • B.13.1. Apache::DBIInitiate a Persistent Database Connection
        • B.13.2. Apache::OWAOracle's PL/SQL Web Toolkit for Apache
        • B.13.3. Apache::Sybase::CTlibPersistent CTlib Connection Management for Apache
      • B.14. Toolkits and Frameworks for Content-Generation and Other Phases
        • B.14.1. Apache::ASPActive Server Pages for Apache with mod_perl
        • B.14.2. Apache::AxKitXML Toolkit for mod_perl
        • B.14.3. HTML::EmbperlEmbed Perl into HTML
        • B.14.4. Apache::EmbperlChainProcess Embedded Perl in HTML in the OutputChain
        • B.14.5. Apache::ePerlEmbedded Perl 5 Language
        • B.14.6. Apache::iNcomE-Commerce Framework
        • B.14.7. Apache::MasonPerl-Based Web Site Development and Delivery System
        • B.14.8. Apache::PageKitWeb Applications Framework
        • B.14.9. Template ToolkitTemplate Processing System
      • B.15. Output Filters and Layering Modules
        • B.15.1. Apache::OutputChainChain Stacked Perl Handlers
        • B.15.2. Apache::Cleanmod_perl Interface Into HTML::Clean
        • B.15.3. Apache::FilterAlter the Output of Previous Handlers
        • B.15.4. Apache::GzipChainCompress HTML (or Anything) in the OutputChain
        • B.15.5. Apache::PassFileSend File via OutputChain
        • B.15.6. Apache::GzipAuto-Compress Web Files with gzip
        • B.15.7. Apache::CompressAuto-Compress Web Files with gzip
        • B.15.8. Apache::LayerLayer Content Tree Over One or More Others
        • B.15.9. Apache::SandwichLayered Document (Sandwich) Maker
        • B.15.10. Apache::SimpleReplaceSimple Template Framework
        • B.15.11. Apache::SSIImplement Server-Side Includes in Perl
      • B.16. Logging-Phase Handlers
        • B.16.1. Apache::RedirectLogFixCorrect Status While Logging
        • B.16.2. Apache::DBILogConfigLogs Access Information in a DBI Database
        • B.16.3. Apache::DBILoggerTracks What's Being Transferred in a DBI Database
        • B.16.4. Apache::DumpHeadersWatch HTTP Transaction via Headers
        • B.16.5. Apache::TrafficTrack Hits and Bytes Transferred on a Per-User Basis
      • B.17. Core Apache Modules
        • B.17.1. Apache::ModuleInterface to Apache C Module Structures
        • B.17.2. Apache::ShowRequestShow Phases and Module Participation
        • B.17.3. Apache::SubProcessInterface to Apache Subprocess API
        • B.17.4. Apache::ConnectionInterface to the Apache conn_rec Data Structure
        • B.17.5. Apache::ConstantsConstants Defined in httpd.h
        • B.17.6. Apache::ExtUtilsUtilities for Apache C/Perl Glue
        • B.17.7. Apache::FileAdvanced Functions for Manipulating Files on the Server Side
        • B.17.8. Apache::LogInterface to Apache Logging
        • B.17.9. Apache::LogFileInterface to Apache's Logging Routines
        • B.17.10. Apache::ScoreboardPerl Interface to Apache's scoreboard.h
        • B.17.11. Apache::ServerPerl Interface to the Apache server_rec Struct
        • B.17.12. Apache::TablePerl Interface to the Apache Table Struct
        • B.17.13. Apache::URIURI Component Parsing and Unparsing
        • B.17.14. Apache::UtilPerl Interface to Apache C Utility Functions
      • B.18. Other Miscellaneous Modules
        • B.18.1. Apache::SessionMaintain Session State Across HTTP Requests
        • B.18.2. Apache::RequestNotesEasy, Consistent Access to Cookie and Form Data Across Each Request Phase
        • B.18.3. Apache::CookieHTTP Cookies Class
        • B.18.4. Apache::IconLook Up Icon Images
        • B.18.5. Apache::IncludeUtilities for mod_perl/mod_include Integration
        • B.18.6. Apache::LanguagePerl Transparent Language Support for Apache Modules and mod_perl Scripts
        • B.18.7. Apache::MmapPerl Interface to the mmap(2) System Call
        • B.18.8. Apache::GD::GraphGenerate Graphs in an Apache Handler
        • B.18.9. Apache::MotdProvide motd (Message of the Day) Functionality to a Web Server
        • B.18.10. Apache::ParseLogObject-Oriented Perl Extension for Parsing Apache Log Files
        • B.18.11. Apache::RegistryLoaderCompile Apache::Registry Scripts at Server Startup
        • B.18.12. Apache::SIGOverride Apache Signal Handlers with Perl's Signal Handlers
        • B.18.13. Apache::TempFileAllocate Temporary Filenames for the Duration of a Request
        • B.18.14. XmmsPerl Interface to the xmms Media Player
        • B.18.15. Module::UseLog and Load Used Perl Modules
    • C. ISPs Providing mod_perl Services
      • C.1. Users Sharing a Single Web Server
      • C.2. Users Sharing a Single Machine
      • C.3. Giving Each User a Separate Machine (Colocation)
      • C.4. Giving Each User a Virtual Machine
    • D. The Template Toolkit
      • D.1. Fetching and Installing the Template Toolkit
      • D.2. Overview
      • D.3. Typical Uses
      • D.4. Template Toolkit Language
        • D.4.1. Simple Template Example
      • D.5. Processing Templates
      • D.6. Apache/mod_perl Handler
      • D.7. Apache::Template Module
      • D.8. Hangman Application
        • D.8.1. Hangman CGI Script
        • D.8.2. Hangman with Modular Templates
        • D.8.3. Hangman Plug-in
        • D.8.4. Self-Contained Hangman Template
      • D.9. References
    • E. The AxKit XML Application Server
      • E.1. Installing and Configuring AxKit
      • E.2. Your First AxKit Page
        • E.2.1. If Something Goes Wrong
        • E.2.2. How it Works?
        • E.2.3. XPath
      • E.3. Dynamic Content
        • E.3.1. Handling Form Parameters
        • E.3.2. Handling Cookies
        • E.3.3. Sending Email
        • E.3.4. Handling Exceptions
        • E.3.5. Utilities Taglib
        • E.3.6. Executing SQL
      • E.4. More XPathScript Details
        • E.4.1. The XPathScript API
          • E.4.1.1. Extracting values
          • E.4.1.2. Declarative templates
      • E.5. XSLT
        • E.5.1. Anatomy of an XSLT Stylesheet
        • E.5.2. Template Rules and Recursion
        • E.5.3. Learning More
      • E.6. Putting Everything Together
      • E.7. More Reasons to Use AxKit
    • F. HTTP Status Codes
      • F.1. HTTP/1.0 Status Codes
      • F.2. HTTP/1.1 Status Codes
      • F.3. References
  • Index
  • About the Authors
  • Colophon
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