[Info-vax] Large mailboxes

Jan-Erik Söderholm jan-erik.soderholm at telia.com
Sat Nov 28 08:09:53 EST 2020


Den 2020-11-28 kl. 04:08, skrev Dave Froble:
> On 11/27/2020 9:00 PM, Jan-Erik Söderholm wrote:
>> Den 2020-11-27 kl. 23:41, skrev Arne Vajhøj:
>>> On 11/26/2020 1:27 PM, Arne Vajhøj wrote:
>>>> On 11/26/2020 11:30 AM, Marc Van Dyck wrote:
>>>>> So my question is, why this limitation ? Is it just because when this
>>>>> interface was written, noone imagined that there could ever be a
>>>>> mailbox with more than 64k outstanding messages ? Or am I really going
>>>>> to break something other than this counter if I try loading more
>>>>> than 64k messages ?
>>>>
>>>> I don't know.
>>>>
>>>> But it seems likely that noone imagined it being a problem.
>>>>
>>>> It uses non-paged pool. How big was available non-paged pool on
>>>> VAX systems?
>>>>
>>>> My guess is that available non-paged pool divided by a
>>>> normal message size would fit into 16 bit.
>>>
>>> I could add that as a rule of thumb I would
>>> only use VMS mailboxes (or Windows pipes or
>>> *nix unix sockets) to buffer hundreds or a
>>> few thousands of messages.
>>>
>>> If I needed hundreds of thousands or
>>> millions I would look for a message queue
>>> (and if I needed billions I would look at
>>> Kafka).
>>>
>>> Arne
>>>
>>
>> Isn't the normal way to use a VMS mailbox as an on-line interface
>> between one (or more) senders and one recevier? That is, the
>> mailbox as such is never intended to "store" anything apart from
>> a very short time during the transmission.
> 
> That is how I use them.  Trust the mailbox to hold data, and what happens 
> when there is a system crash?
> 
>> If the intention is to buffer 10000's or 100000's of messages,
>> VMS mailboxes looks as the wrong tool from the toolbox...
> 
> For that type of volume, perhaps a database?
> 

I thought more in a line of a messages queuing tool that have
persistent storage for the queue content. There are many, two
older ones are DEC/MessageQ and IBM/MQ. And there are a number
of open source tools today that serve the same purpose.



More information about the Info-vax mailing list