Beginning Web Development With Perl : From Novice to ... - Nabo

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206CHAPTER 11 ■ DEVELOPMENT WITH MOD_PERLPerlRunOnceSometimes, even Apache::PerlRun by itself won’t fix the problems. In such instances, you canalso invoke PerlRunOnce option. With PerlRunOnce enabled, the process responsible for executingthe Perl program is spawned only for the lifetime of that execution and dies thereafter. Ifyou believe that this would cause nontrivial performance degradation, you are correct.You set the PerlRunOnce option from within the Apache configuration, specifically withinthe mod_perl section. Recall the sample configuration for Apache and mod_perl from Chapter 10,now modified to use Apache::PerlRun:SetHandler perl-scriptPerlHandler Apache::PerlRunOptions +ExecCGIPerlSendHeader OnAllow from allTo enable PerlRunOnce, you use the PerlSetVar option:PerlSetVar PerlRunOnce OnThe configuration now looks like this:SetHandler perl-scriptPerlHandler Apache::PerlRunPerlSetVar PerlRunOnce OnOptions +ExecCGIPerlSendHeader OnAllow from allApache::RegistryApache::Registry is the better performing module of the two modules discussed here forserving content through PerlHandler configuration directive. Examples shown throughout theremainder of this chapter will assume the use of Apache::Registry.Each program executed through Apache::Registry is done so by each Apache child,which compiles the program only once. This initial compile may result in the very first loadof a program taking incrementally longer before the subsequent runs take advantage of thatprecompile.The Apache configuration to mod_perl with Apache::Registry is typically as follows(replace /home/suehring/perl with the appropriate location for your installation):Alias /perl/ /home/suehring/perl/SetHandler perl-scriptPerlHandler Apache::Registry
CHAPTER 11 ■ DEVELOPMENT WITH MOD_PERL 207Options +ExecCGIPerlSendHeader OnAllow from allPreloading Perl ModulesAnother area for optimization using mod_perl is to preload Perl modules, rather than loadingthem with each program. For example, the CGI module or the DBI module could be loaded byApache, thus giving even better performance for programs that use those modules.Preloading Apache::DBIAs you learned in Chapter 3, the DBI provides database access through Perl. You can preloadthe DBI, and even the database-dependent bits through the DBD, to enhance performance.However, in the case of the DBI, you employ another method for initialization, using a specializedmodule called Apache::DBI. You load this module by using the following line in theApache configuration file:PerlModule Apache::DBIWith that line in the Apache configuration file, the Apache::DBI module will be preloadedand will overload the DBI namespace, enabling your programs to forego the use DBI pragmaand also providing just that much more speed to the program.Resurrecting an example from Chapter 3, Listing 11-1 (Newdb.cgi) shows that the same codecan be used, but notice that the use DBI pragma is now missing from the program.Listing 11-1. Preloading the DBIuse strict;use CGI qw/:standard/;my $username = "dbuser";my $password = "dbpass";my $dsn = "dbi:mysql:mysql:192.168.1.10";my $dbh = DBI->connect($dsn,$username,$password)or die "Cannot connect to database: $DBI::errstr";my $sth = $dbh->prepare("SELECT host,user FROM mysql.user");$sth->execute()or die "Cannot execute sth: $DBI::errstr";print header,start_html('MySQL Hosts and Users'),table({-border=>1}),Tr({-align=>'CENTER',-valign=>'TOP'},
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Beginning Web Development with Perl
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PART 5 ■ ■ ■ Creating Web Tem
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■CONTENTSvii■CHAPTER 4 System I
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■CONTENTSixCreating a SOAP Listen
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■CONTENTSxiTemplate Toolkit Synta
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About the Author■STEVE SUEHRING i
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AcknowledgmentsThanks to James Lee
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xx■INTRODUCTIONThis book will use
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CHAPTER 1■ ■ ■The CGI ModuleT
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CHAPTER 1 ■ THE CGI MODULE 5for t
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CHAPTER 1 ■ THE CGI MODULE 7Obvio
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CHAPTER 1 ■ THE CGI MODULE 9exit;
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CHAPTER 1 ■ THE CGI MODULE 11Each
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CHAPTER 1 ■ THE CGI MODULE 13When
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CHAPTER 1 ■ THE CGI MODULE 15Upda
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CHAPTER 1 ■ THE CGI MODULE 17rese
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CHAPTER 1 ■ THE CGI MODULE 19prin
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CHAPTER 1 ■ THE CGI MODULE 21Sett
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CHAPTER 1 ■ THE CGI MODULE 23You
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CHAPTER 1 ■ THE CGI MODULE 25■C
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CHAPTER 1 ■ THE CGI MODULE 27No m
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CHAPTER 1 ■ THE CGI MODULE 29The
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CHAPTER 1 ■ THE CGI MODULE 31prin
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CHAPTER 1 ■ THE CGI MODULE 33Also
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CHAPTER 2■ ■ ■Popular CGI Mod
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CHAPTER 2 ■ POPULAR CGI MODULES 3
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50CHAPTER 3 ■ DATABASES AND PERLT
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52CHAPTER 3 ■ DATABASES AND PERLm
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54CHAPTER 3 ■ DATABASES AND PERLl
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56CHAPTER 3 ■ DATABASES AND PERLc
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58CHAPTER 3 ■ DATABASES AND PERLR
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62CHAPTER 3 ■ DATABASES AND PERLw
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64CHAPTER 3 ■ DATABASES AND PERLA
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74CHAPTER 4 ■ SYSTEM INTERACTION
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76CHAPTER 4 ■ SYSTEM INTERACTIONt
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78CHAPTER 4 ■ SYSTEM INTERACTIONc
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80CHAPTER 4 ■ SYSTEM INTERACTIONA
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82CHAPTER 4 ■ SYSTEM INTERACTIONm
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84CHAPTER 4 ■ SYSTEM INTERACTIONs
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86CHAPTER 4 ■ SYSTEM INTERACTIONr
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CHAPTER 5■ ■ ■LWP ModulesLWP
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CHAPTER 5 ■ LWP MODULES 91HTTP Re
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CHAPTER 5 ■ LWP MODULES 93Get Fun
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CHAPTER 5 ■ LWP MODULES 95When ca
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CHAPTER 5 ■ LWP MODULES 97These a
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CHAPTER 5 ■ LWP MODULES 99Recall
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CHAPTER 5 ■ LWP MODULES 101which
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CHAPTER 5 ■ LWP MODULES 103For th
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CHAPTER 5 ■ LWP MODULES 105Obviou
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108CHAPTER 6 ■ NET:: TOOLSCreatin
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110CHAPTER 6 ■ NET:: TOOLSThe out
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112CHAPTER 6 ■ NET:: TOOLSmy $pop
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114CHAPTER 6 ■ NET:: TOOLSthe POP
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116CHAPTER 6 ■ NET:: TOOLS($messa
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118CHAPTER 6 ■ NET:: TOOLSListing
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120CHAPTER 6 ■ NET:: TOOLSFor the
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122CHAPTER 6 ■ NET:: TOOLSNet::SM
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124CHAPTER 6 ■ NET:: TOOLS$smtpco
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126CHAPTER 6 ■ NET:: TOOLSuse Net
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128CHAPTER 6 ■ NET:: TOOLSListing
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130CHAPTER 6 ■ NET:: TOOLSFor exa
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132CHAPTER 6 ■ NET:: TOOLSSending
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PART 3■ ■ ■XML and RSS
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138CHAPTER 7 ■ SOAP-BASED WEB SER
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Page 166 and 167: 154CHAPTER 8 ■ PERL AND RSSFigure
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Page 192 and 193: PART 4■ ■ ■PerformanceEnhance
Page 194 and 195: 184CHAPTER 10 ■ APACHE AND MOD_PE
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Page 242 and 243: CHAPTER 12■ ■ ■The Template T
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CHAPTER 12 ■ THE TEMPLATE TOOLKIT
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CHAPTER 13■ ■ ■Perl Web Sites
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CHAPTER 13 ■ PERL WEB SITES WITH
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284APPENDIX ■ PERL BASICSKeywords
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286APPENDIX ■ PERL BASICS$ perl n
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288APPENDIX ■ PERL BASICSAnd line
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290APPENDIX ■ PERL BASICSCan you
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292APPENDIX ■ PERL BASICSBy defau
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294APPENDIX ■ PERL BASICS#!/usr/b
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296APPENDIX ■ PERL BASICSThe last
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298APPENDIX ■ PERL BASICSThe NOT
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300APPENDIX ■ PERL BASICSprint "S
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302APPENDIX ■ PERL BASICSthe syst
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304APPENDIX ■ PERL BASICS$ perl s
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306APPENDIX ■ PERL BASICSThis cod
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308APPENDIX ■ PERL BASICS$a = 6 *
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310APPENDIX ■ PERL BASICS$a = "A9
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312APPENDIX ■ PERL BASICS#!/usr/b
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314APPENDIX ■ PERL BASICSmy $name
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316APPENDIX ■ PERL BASICSis short
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318APPENDIX ■ PERL BASICSLet’s
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320APPENDIX ■ PERL BASICSOther Te
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322APPENDIX ■ PERL BASICS}}}actio
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324APPENDIX ■ PERL BASICSNotice t
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326APPENDIX ■ PERL BASICSLooping
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328APPENDIX ■ PERL BASICSuse stri
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330APPENDIX ■ PERL BASICSuntil ($
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332APPENDIX ■ PERL BASICSuse stri
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334APPENDIX ■ PERL BASICSdoneAll
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336APPENDIX ■ PERL BASICS$ perl r
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338APPENDIX ■ PERL BASICSSummaryT
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340■INDEXmethods for retrieving r
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342■INDEXdo() method for, 62dumpi
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344■INDEXhello option for Net::SM
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346■INDEXNet::DNS module, 125-128
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348■INDEXrecord with Net::DNS mod
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350■INDEXstoring mail server in e
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352■INDEXlogging based on, 229pri
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