Re: puzzle of split() running under mod_perl
Ok, before heading off for the evening, here's a guess which may be totally wrong. JY - June Young said: We are running CSWS1.2 (based on Apache 1.3.6) on Open VMS V7.3-1 and CSWS_PERL V1.1 based on Mod_Perl V1.25. Main assumption ( this is buggy and not real apache/mod_perl ) - (as buggy as compaq (on disk) bioses, and all the compaq hardware, I've ever used, with the exception of the Dec Alpha (which was DEC at the time)). We have a function that changes the directory format from Unix to VMS, and this function is used in almost every script of our CGIs. Whenever the CGI that invokes this function get requested twice, the server process dies after the page comes out. Only on the second request? We noticed that it is the regex argument of function split causes the problem. We took this split statement out into a simple CGI script, and that CGI script works fine in mod_perl. Not sure about the syntax, by the outermost symbols should become delimiters for your reg.exp. (ie the quotes in your case) After adding quotes outside of the regex of split function in sub VMSify, the error went away. We could not figure out why the statement bombs out in our VMSify function and why adding quotes fixed it. The following are the test script and output in the browser. Adding the 's, simply makes it try and split on the symbol sequence /\// which doesn't exist in the string you're matching against, returning the whole string again. At least, that is my observed behaviour in 5.6.1. and the way I use them. My completely unsupported guess, which is what I'd look for given the circumstances, is this: 1) Given that: i) The original script segfaults the apache-clone ii) Your little cgi doesn't segfault anything. 2) Assuming: i) You're using 's in your 'original' live script ii) The split is returning an array of size 1, containing the original string in an your 'original' live script (because of the /\//). iii) Your test cgi script, as stated, is only trying to test out the SPLIT. iv) *the major assumption* You take this converted path on your vms system (as generated in step 2.ii) and are trying to access some 'real' file path with it / and open or stat or something. 3) Results in: (Complete Assumption) i) The apache-'clone' segfaulting/throwing a fatal/exploding on some attempt to read this real file path, which 'wasn't' really split in your live application and is still a unix path. ii) Compaq do it again and it's all their fault. iii) On a second read of your mail, 'adding' the quotes may have done this in reverse somehow and may still lead to either avoiding a syscall to open/read/stat/whatever a real file path. Although this is based on lots of assumptions, I think it might explain the segfault, which was fixed by removing(or was it adding?) your quotes. My thought was that fixing the server crash (which is what you wanted to explain?) came out of your avoiding a system call with a weird path to a real file. I don't know VMS, so I'm assuming nasties. I'm probably 90% wrong and it's that 10% of hope (and hmmm.. the I'd look 'there' factor) which I offer you. Hmmm. I'd also look at unclearly scroped variables which remain persistent between hits (given your two hit problem - if that really is the case). Might help, who knows? Not I. Byebye.
RE: puzzle of split() running under mod_perl
Hi June, JY - June Young said: with/without double quotes on the regexp. The print of the dir after= shows that split correctly parsed the input string. The only difference is that the server dies upon global destruction? As a matter of fact, I am very confused by the error message of global destruction. When does global destruction happen in mod_perl? Does my code causes server process die and then the process tries to do global destruction ? Or global destruction at some stage causes the process die. I thought mod_perl provide persistent environment, and no global destruction should happen until a process served enough requests and reached the end of lifecycle. My understanding was that it happend with a child process exiting after it hit its max requests .. of if you shutdown. What I might try if you're really curious is trying to run it through strace or truss (well your vms equivs) with httpd -X, unless someone else can give you an immediate answer, it often proved itself a useful approach. Might give you an idea of what is causing the process to die. Last night's enthusiasm has worn off. :) All the best. R.
puzzle of split() running under mod_perl
Title: Message
Hi,
We arerunning
CSWS1.2(based on Apache 1.3.6) on Open VMS V7.3-1 and
CSWS_PERL V1.1 based on Mod_Perl V1.25.
We have a function that changes the
directory format from Unix to VMS, and this function is used in almost every
script of our CGIs. Whenever the CGI that invokes this function get requested
twice, the server process dies after the page comes out.
In a single threaded server, we get Fatel
error in the error log file.
Fatal VMS error (status=36) at
ROOT$:[PERL5_006_01]VMS.C;2, line 802 during global destruction.
In a multi threaded server, we get a notice
in the error log file
[notice] child pid ab26 exit
signal Bad system call.
We noticed that it is the regex argument of
function split causes the problem.
We took this
split statement out into a simpleCGI script, and that CGI script works
fine in mod_perl.
Afteradding quotes outside of the
regex of split function in
subVMSify, the error went away.We could not figure out why the statement bombs out in our VMSify
functionand why adding quotes fixed
it. The following are the test script and output in the browser.
Thanks in advance for all
helps.
test.cgi
***
use strict;print "content-type:text/html\n\n";print
"head/headbody\n";
Test();
sub Test{ foreach (@::INC)
{ VMSify($_); }}
sub VMSify{ my @subDirs; my
$directory=uc(shift);
$directory=~s/^\/|\/$//g;
print "dir=$directory\nbr";#
@subDirs=split("/\//",$directory);
@subDirs=split(/\//,$directory);
$directory=undef; if(defined
$ENV{$subDirs[0]}){
$directory=shift(@subDirs).':'; }elsif(scalar(@subDirs)==1
$subDirs[0] eq '.'){ # Special case
for current directory
@subDirs=(); $directory='[]';
} if(scalar(@subDirs)){
$directory.='[';
$directory.=join('.',@subDirs);
$directory.=']';
} print "dir after=$directory\nbr";
return $directory;}
***
The output in the web brower is
dir=DYM$DISK/DYMAX/PERL/DYLIB dir
after=DYM$DISK:[DYMAX.PERL.DYLIB] dir=PERL_ROOT/LIB/VMS_AXP/5_6_1 dir
after=PERL_ROOT:[LIB.VMS_AXP.5_6_1] dir=PERL_ROOT/LIB dir
after=PERL_ROOT:[LIB] dir=PERL_ROOT:[LIB.SITE_PERL.VMS_AXP] dir
after=[PERL_ROOT:[LIB.SITE_PERL.VMS_AXP]] dir=PERL_ROOT:[LIB.SITE_PERL]
dir after=[PERL_ROOT:[LIB.SITE_PERL]] dir=PERL_ROOT/LIB/SITE_PERL
dir after=PERL_ROOT:[LIB.SITE_PERL] dir=. dir after=[]
dir=APACHE$ROOT dir after=APACHE$ROOT: dir=APACHE$ROOT/LIB/PERL
dir after=APACHE$ROOT:[LIB.PERL]
June Young, Software
Development
bus: (902)422-1973 x144Dymaxion Research Ltd., 5515 Cogswell
St., fax: (902)421-1267Halifax, Nova Scotia,
B3J 1R2
Canadamailto:
[EMAIL PROTECTED]http://www.dymaxion.ca
