Test killing a process with SIGINT after connecting to an Oracle database

dbd-oracle-sigint-fail.pl

#!/usr/bin/perl

use strict;
use warnings;
use DBI;
use POSIX ":sys_wait_h";

if(my $pid = fork){
  warn "forked $pid from $$, press <ENTER> when ready to try killing\n";
  my $ready = <STDIN>;
  for ( 1 .. 3 ) {
    kill( INT => $pid ) or warn "kill unsuccessful\n";
    my $kid;
    do {
      $kid = waitpid( -1, WNOHANG );
    } while $kid > 0;

    if ( kill( 0 => $pid ) ) {
      warn "process still present\n";
      sleep 1;
    } else {
      last;
    }
  }
  if(kill(0 => $pid)){
    warn "terminating...\n";
    kill TERM => $pid;
  }
} else {
  close(STDIN);
  warn "connecting... ($$)\n";
  my $dbh;
  {
    $dbh = DBI->connect('dbi:Oracle:mydb', 'user', 'password');
    warn "connected in child ($$)\n";
  }
  while(1){
    sleep(1);
  }
  exit;
}

dbd-oracle-sigint-works.pl

#!/usr/bin/perl

use strict;
use warnings;
use DBI;
use POSIX ":sys_wait_h";

if(my $pid = fork){
  warn "forked $pid from $$, press <ENTER> when ready to try killing\n";
  my $ready = <STDIN>;
  for ( 1 .. 3 ) {
    kill( INT => $pid ) or warn "kill unsuccessful\n";
    my $kid;
    do {
      $kid = waitpid( -1, WNOHANG );
    } while $kid > 0;

    if ( kill( 0 => $pid ) ) {
      warn "process still present\n";
      sleep 1;
    } else {
      last;
    }
  }
  if(kill(0 => $pid)){
    warn "terminating...\n";
    kill TERM => $pid;
  }
} else {
  close(STDIN);
  warn "connecting... ($$)\n";
  my $dbh;
  {
    local $SIG{INT};
    $dbh = DBI->connect('dbi:Oracle:mydb', 'user', 'password');
    warn "connected in child ($$)\n";
  }
  while(1){
    sleep(1);
  }
  exit;
}

strace-of-interrupted-process.txt

First the Perl code, and then the corresponding strace:

my $dbh = DBI->connect($oracle_dsn, $user, $pass);
local $| = 1;
while(1){
  sleep 1;
  print '.';
}

The strace snippet is just from the inside of the while loop. It shows two iterations, an attempt to <CTRL>-C and then another iteration:

rt_sigprocmask(SIG_BLOCK, [CHLD], [], 8) = 0
rt_sigaction(SIGCHLD, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
nanosleep({1, 0}, 0x7fff485f4770)       = 0
write(1, ".", 1)                        = 1
rt_sigprocmask(SIG_BLOCK, [CHLD], [], 8) = 0
rt_sigaction(SIGCHLD, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
nanosleep({1, 0}, 0x7fff485f4770)       = 0
write(1, ".", 1)                        = 1
rt_sigprocmask(SIG_BLOCK, [CHLD], [], 8) = 0
rt_sigaction(SIGCHLD, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
nanosleep({1, 0}, {0, 847251953})       = ? ERESTART_RESTARTBLOCK (To be restarted)
--- SIGINT (Interrupt) @ 0 (0) ---
rt_sigprocmask(SIG_BLOCK, [], NULL, 8)  = 0
rt_sigprocmask(SIG_UNBLOCK, [], NULL, 8) = 0
rt_sigreturn(0x1)                       = -1 EINTR (Interrupted system call)
write(1, ".", 1)                        = 1
rt_sigprocmask(SIG_BLOCK, [CHLD], [], 8) = 0
rt_sigaction(SIGCHLD, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
nanosleep({1, 0}, 0x7fff485f4770)       = 0