Net::Server not closing

[Michael Grimm]

Hi --

I am experiencing an issue with hanging amavis processes. This started to happen a couple of months ago, and I couldn't find the cause, yet. There may be a week without any issue, sometimes there are only two days in between.

System:
        FreeBSD 9.1-RELEASE
        amavisd-new-2.8.0_2,1
        p5-Net-Server-2.007
        postfix-2.9.5,1
	(~1000 mails a day)

Amavis.conf:
        $max_servers = 2;
        $log_level = 5;
        (amavis will call spamassassin and clamav)

And that is what happens:

New mail arriving:
| Mar  4 10:19:50 mail postfix/smtpd[53746]: connect from xxx.xxx.xx[123.123.123.123]
| [...]
| Mar  4 10:19:50 mail amavis[53614]: Net::Server: 2013/03/04-10:19:50 CONNECT TCP Peer: "[10.10.10.1]:12724" Local: "[10.10.10.1]:10024"

Amavisd runs to completion, successfully:
| Mar  4 10:19:51 mail amavis[53614]: (53614-01) Amavis::DB::SNMP DESTROY called
| Mar  4 10:19:51 mail amavis[53614]: (53614-01) Net::Server: Child leaving (1)
| [...]
| Mar  4 10:19:51 mail amavis[53757]: Net::Server: Child Preforked (53757)
| Mar  4 10:19:51 mail amavis[53757]: entered child_init_hook

Next mail arrives, and amavis does processes that mail as usual including:
| Mar  4 10:28:50 mail amavis[53615]: (53615-01) Amavis::DB::SNMP DESTROY called
(no further amavis[.....] log entries until restart of amavis.)

BUT: Net::Server isn't closing ("Net::Server: Child leaving" line is missing!) and becomes a runaway process:
| KB-mail|root> ps -Af | grep amavis
| 53757 ??  RJ   119:13.73 /usr/local/sbin/amavisd (virgin child) (perl)

Now, every other arriving mail will become queued (deferred), and I do have to kill all amavisd processes (kill -9, not kill -15) and restart postfix for restart.

Does anyone has an idea how I could debug that issue? Or, is there a solution I didn't succeed to find at google?

Thanks and with kind regards,
Michael