This script launches 510 simultaneous/concurrent MS-Access database SQL queries, which the database Jet Engine can handle just fine with increased Threads configured to 510, default is 3. The calling script launches the 510 instances, then immediately exits without waiting for them to complete. If you run this from a command prompt, and open Windows Task Manager, you can watch the concurrent processing occuring since I have prints to the screen going on. CPU usage will hit 100%, and my RAM memory usage hit a high of 83% for a split second, then fell back down rapidly. I have a single Intel Celeron processor 2.2GHz, and 3-GIG RAM on my WIndows 7 Home Premium Laptop. The database hit, contains a table of Bible book names: Genesis thru Revelation (66 books). 510 output files are created witht the SQL report output. I used a File Compare routine to verify all the same output. This reporting process produces reliable SQL output every time. Way to go Jet Engine!

Calling script:

use Win32;
use Win32::Process;
$PWD=Win32::GetCwd();
for ($i=1; $i<=510; $i++) {
  Win32::Process::Create($POBJ,"$PWD\\RptUtl.exe","RptUtl $i",0,DETACH
+ED_PROCESS,"."); 
}
exit;
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---

Called script i.e. RptUtl.exe <-- compiled RptUtl.pl

use Win32::ODBC;
use Win32;
use IO::Handle;

$i=$ARGV[0];   #-- called from another Perl script that launches 1 to 
+510 Windows O/S "detached" background processes.
$PWD=Win32::GetCwd();

$outfile="$PWD\\BibleBooks_$i.txt";
open(OUT,"> $outfile");
OUT->autoflush(1); 

$USR=Win32::LoginName();    $NODE=Win32::NodeName(); 

print OUT "Working Directory=\n $PWD\n  User=$USR  Node=$NODE\n\n";

$FILEDSN="FILEDSN=$PWD\\Bible.dsn; PWD=xYz";
$db = new Win32::ODBC($FILEDSN);  

if (! $db) {
   $error  =  Win32::ODBC::Error();
   print OUT "$error\n";  die;
}

$ret=$db->Sql("SELECT * FROM BibleBook");
if ($ret) {
   $error  =  Win32::ODBC::Error();
   print OUT "$error\n";  die;
}

while ($db->FetchRow()) { 
   my(%data) = $db->DataHash();
   print OUT $data{'bk'} . "   " . $data{'name'} . "   " . $data{'shor
+t_name'} . "\n"; 
   print $data{'bk'} . "   " . $data{'name'} . "   " . $data{'short_na
+me'} . "\n"; 
}
  
print OUT "\nGoodbye.\n";
exit;

END {
   if ($db) {
     $db->Close(); undef $db;  
   }
   close(OUT);
}
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Contents of ODBC FILEDSN Bible.dsn which is referenced in the above code:

[[ODBC]]
Threads=512  
Driver=Microsoft Access Driver (*.mdb)
DBQ=.\Bible.mdb
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