Re^3: Sharing DBI between threads

The problem is not Perl, and the problem is not thread support in Perl. Ikegami explained the real problem in Re: Sharing DBI between threads: A single database connection can not know which of the various threads sends commands, thus the database gets confused or damaged. You need a dedicated database connection for each single thread, period. (And you need it in every language that allows you to use threads and a database connection.)

DBI WARNS not to use a threaded perl in a production environment. This does not mean DBI does not work with a threaded perl. It means that there MAY BE some issues with a threaded perl. You should perhaps read that warning as a better-safe-than-sorry warning: "it will very probably work as well, but we can not guarantee that as well as for a non-threaded perl". Every recent perl for Windows (with faked fork() support) is threaded, as are most perls built by the various Linux distributions. And all of those perls run pretty well with the DBI.

Perl has really unsafe features - for example it allows interchange of HASH references and integers without any warning even with `use strict;`

This sounds pretty strange, like a misunderstanding of some essential concepts of Perl. If not, could you show us a working example, and a copy of perl -V that exhibits that problem?

Alexander

--
Today I will gladly share my knowledge and experience, for there are no sweeter words than "I told you so". ;-)

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Re^4: Sharing DBI between threads by BrowserUk (Patriarch) on Jan 23, 2010 at 20:07 UTC
it allows interchange of HASH references and integers I'm guessing that he means: `print $href, '-', 0+$href;; HASH(0xacaa0) - 707232` [download] But as you say misunderstands that you can't (easily) go the other way. Also, perhaps he forgets that C allows you to cast a pointer to an integer; but more significantly cast an integer to a pointer (to anything). Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice. "I'd rather go naked than blow up my ass"	[reply] [d/l]
Re^4: Sharing DBI between threads by bagent (Novice) on Jan 23, 2010 at 21:30 UTC
> This sounds pretty strange, > like a misunderstanding of > some essential concepts of Perl. > If not, could you show us a working example, > and a copy of perl -V that exhibits that problem? `#!/usr/bin/perl -w use strict; my %results = ( 'results' => [ [10, 13, 14] ], ); # Add array reference to integer number without a warning, # result is a big number, 10896017 on my architecture print 1 + $results{'results'}->[0], "\n"; # print number of elements in array + 1 print 1 + scalar(@{$results{'results'}->[0]}), "\n"; # forgot @{, produces big number (10896017) # very easy to do mistake # can lead to hours of bughunting print 1 + scalar($results{'results'}->[0]), "\n";` [download] Not sure why `perl -V` is needed but here it is: par@maxlance ~/projects $ perl -V Summary of my perl5 (revision 5 version 8 subversion 8) configuration: Platform: osname=linux, osvers=2.6.31-gentoo-r6, archname=x86_64-linux-threa +d-multi uname='linux maxlance.homelinux.org 2.6.31-gentoo-r6 #9 smp wed de +c 23 03:27:57 msk 2009 x86_64 amd athlon(tm) 64 x2 dual core processo +r 5400+ authenticamd gnulinux ' config_args='-des -Darchname=x86_64-linux-thread -Dcccdlflags=-fPI +C -Dccdlflags=-rdynamic -Dcc=x86_64-pc-linux-gnu-gcc -Dprefix=/usr -D +vendorprefix=/usr -Dsiteprefix=/usr -Dlocincpth= -Doptimize=-O2 -pip +e -march=athlon64 -Duselargefiles -Dd_semctl_semun -Dscriptdir=/usr/b +in -Dman1dir=/usr/share/man/man1 -Dman3dir=/usr/share/man/man3 -Dinst +allman1dir=/usr/share/man/man1 -Dinstallman3dir=/usr/share/man/man3 - +Dman1ext=1 -Dman3ext=3pm -Dinc_version_list=5.8.0 5.8.0/x86_64-linux- +thread-multi 5.8.2 5.8.2/x86_64-linux-thread-multi 5.8.4 5.8.4/x86_64 +-linux-thread-multi 5.8.5 5.8.5/x86_64-linux-thread-multi 5.8.6 5.8.6 +/x86_64-linux-thread-multi 5.8.7 5.8.7/x86_64-linux-thread-multi -Dc +f_by=Gentoo -Ud_csh -Dusenm -Dusethreads -Di_ndbm -Di_gdbm -Di_db -Du +srinc=/usr/include -Dlibpth=/usr/local/lib64 /lib64 /usr/lib64' hint=recommended, useposix=true, d_sigaction=define usethreads=define use5005threads=undef useithreads=define usemulti +plicity=define useperlio=define d_sfio=undef uselargefiles=define usesocks=undef use64bitint=define use64bitall=define uselongdouble=undef usemymalloc=n, bincompat5005=undef Compiler: cc='x86_64-pc-linux-gnu-gcc', ccflags ='-D_REENTRANT -D_GNU_SOURCE + -DTHREADS_HAVE_PIDS -fno-strict-aliasing -pipe -Wdeclaration-after-s +tatement -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -I/usr/include/gd +bm', optimize='-O2 -pipe -march=athlon64', cppflags='-D_REENTRANT -D_GNU_SOURCE -DTHREADS_HAVE_PIDS -fno-stri +ct-aliasing -pipe -Wdeclaration-after-statement -I/usr/include/gdbm' ccversion='', gccversion='4.3.4', gccosandvers='' intsize=4, longsize=8, ptrsize=8, doublesize=8, byteorder=12345678 d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=1 +6 ivtype='long', ivsize=8, nvtype='double', nvsize=8, Off_t='off_t', + lseeksize=8 alignbytes=8, prototype=define Linker and Libraries: ld='x86_64-pc-linux-gnu-gcc -O2 -pipe -march=athlon64', ldflags =' + -L/usr/local/lib64' libpth=/usr/local/lib64 /lib64 /usr/lib64 libs=-lpthread -lnsl -lgdbm -ldb -ldl -lm -lcrypt -lutil -lc perllibs=-lpthread -lnsl -ldl -lm -lcrypt -lutil -lc libc=/lib/libc-2.9.so, so=so, useshrplib=false, libperl=libperl.a gnulibc_version='2.9' Dynamic Linking: dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-rdynami +c' cccdlflags='-fPIC', lddlflags='-shared -L/usr/local/lib64' Characteristics of this binary (from libperl): Compile-time options: MULTIPLICITY PERL_IMPLICIT_CONTEXT PERL_MALLOC_WRAP THREADS_HAVE_PIDS USE_64_BIT_ +ALL USE_64_BIT_INT USE_ITHREADS USE_LARGE_FILES USE_PERLIO USE_REENTRANT_API Built under linux Compiled at Jan 14 2010 11:10:33 @INC: /etc/perl /usr/lib64/perl5/vendor_perl/5.8.8/x86_64-linux-thread-multi /usr/lib64/perl5/vendor_perl/5.8.8 /usr/lib64/perl5/vendor_perl /usr/lib64/perl5/site_perl/5.8.8/x86_64-linux-thread-multi /usr/lib64/perl5/site_perl/5.8.8 /usr/lib64/perl5/site_perl /usr/lib64/perl5/5.8.8/x86_64-linux-thread-multi /usr/lib64/perl5/5.8.8 /usr/local/lib/site_perl . par@maxlance ~/projects $ [download]	[reply] [d/l] [select]