We tried few things to give the exact reproducer. What we figured is , Issue is reproducible when application is multi threaded.

In Multi threaded application , even after exiting the thread FDs are not freed.

Please find the reproducer scripts and steps below.

File1 : Sample.pm

package sample;

use strict;
use DBI;

my $count = 0;

sub showtime () {
   print "Starting loop \n";
   #while ( $count < 50 ) {

      $count++;
      print ("Connecting to DB \n");
      # Modify sid, user, password values.
      my $dbh = DBI->connect("DBI:Oracle:host=localhost;port=1521;sid=
+syno",'temipsyno','temipsyno',{PrintError => 1, RaiseError => 1, ora_
+envhp => 0});

      #my $cmd = "grep  VmRSS /proc/$$/status";
      # Check no. of fd's after connection to db.
      #my $cmd = "ls -l /proc/$$/fd | grep ocius";
      #print `$cmd`;
      sleep(1);
      print ("Disconnecting from DB \n");
      $dbh->disconnect or warn "Disconnection failed: $DBI::errstr\n";
   #}
   print "Ending script \n";
}
1;
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#!/usr/local/bin/perl

use threads;
use sample;


$ENV{'ORACLE_HOME'} = '/usr/opt/oracle';

sub worker() {

   my $count = 0;

   # Make it do some work (open and close DB 10 times).
   while ( $count < 2 ) {
      sample::showtime();
      $count = $count + 1 ;
      #my $cmd = "ls -l /proc/$$/fd | grep ocius";
      #print threads -> self() -> tid()  . " : " . `$cmd` ;
      sleep 3
   }
}

my $nthreads = 5;

for ( 1..$nthreads )
{
   threads->create(\&worker);
}

foreach my $thr (threads->list() )
{
   $thr->join();
}

print ("Check no. of fd's for ocius.msb using lsof -p $$. Sleeping 30s
+ \n");
print ("If no. of fd's > 0, then why there is still fd's not closed ev
+en after"
       . " threads have exited \n");

sleep(30);
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./scr1
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Starting loop
Connecting to DB
Starting loop
Connecting to DB
Starting loop
Connecting to DB
Starting loop
Connecting to DB
Starting loop
Connecting to DB
Disconnecting from DB
Ending script
Disconnecting from DB
Ending script
Disconnecting from DB
Ending script
Disconnecting from DB
Ending script
Disconnecting from DB
Ending script
Starting loop
Connecting to DB
Starting loop
Connecting to DB
Starting loop
Connecting to DB
Starting loop
Connecting to DB
Starting loop
Connecting to DB
Disconnecting from DB
Ending script
Disconnecting from DB
Ending script
Disconnecting from DB
Ending script
Disconnecting from DB
Ending script
Disconnecting from DB
Ending script
Check no. of fd's for ocius.msb using lsof -p 9940. Sleeping 30s
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