执行几分钟后，多线程perl脚本的执行会挂起

Question

我是Perl的新手并尝试多线程。我从数据库中提取数据并在这些输出上运行我的代码。我确实得到了输出，但过了一会儿，它只是停止执行，我得到错误。是因为我用过叉子吗？我不确定......请帮忙。这是我的代码。

use strict;
use DBI;

#db variables have been declared already
my $dbh = DBI->connect("DBI:mysql:$database;host=$host", $user, $pw);

my $sql = qq{
SELECT......
};
my $sth = $dbh->prepare($sql);
$sth->execute();

my $child1 = 1;
my @threadsArray = ();

while(my @request = $sth->fetchrow_array()){
    my $net = @request[0];

    my $pid = fork();
    if ($pid == -1) {
        errorUsageMsg("Failed: Fork error.\n");
        die;
    } elsif ($pid == 0) {
        exit(findPro($net,$child1));                
    }
    else {
        $child1++;
    }
}

$sth->finish();
$dbh->disconnect;

if(my $pid > 0)
{#this is to avoid zombie process
    while ( wait() != -1) { my $r = $? >> 8; 
    }
}

sub findPro
{
    my $net= shift;
    my $child_id = shift;
#in this portion, I have the code which calls an in-built function of an API say, func.

# created a session here to connect to the API say with my $session;

#calling the object which contains the in-built function, func say like...
 my in-built = $session->get(.....);
  my $obj = $in-built[0];

#after getting the result from that object, in the below line, I call func as shown.
my $result = $obj->func();
    print $result;

    while ( wait() != -1) 
    { 
        my $r = $? >> 8;

    }
}

我得到了一些数据的输出，而对于其他数据，执行速度变慢，我得到错误，说不能调用方法＆＃34; func＆＃34;在未定义的值上。