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From Lorenz Quack <quack.lor...@gmail.com>
Subject Re: Flow to disk behavior with In Memory messages
Date Tue, 23 Aug 2016 08:08:12 GMT
Hi Ramayan,

That is not entirely correct.
Flow to Disk is only indirectly related to persistence.

Persistent messages are *always* written to the message store
before the message is acknowledged or the transaction completes.
However, for performance reasons the broker will keep a copy of
the message in memory.  When flow to disk kicks in two things
happen:

   1) The in memory copy of new persistent messages will be
      discarded

   2) New transient messages will also be written to the message
      store

Note that I always wrote that the messages will be written to the
message store and not to disk.  In case of a Memory Virtual Host
the message store is held in memory so there won't be any
persistence.  Not even for persistent messages.  And, yes,
eventually your broker will run out of memory.

Memory VirtualHost(Node)s are more for testing purposes than
anything else.


Kind Regards,
Lorenz


On 23/08/16 03:02, Ramayan Tiwari wrote:
> Hi all,
>
> As I understand, flow to disk tries to protect Direct Memory by sending new
> messages to disk when using some form of persistent.
>
> What is the behavior when virtual host node type is "Memory". I was looking
> at the implementation, StoredMemoryMessage doesn't seem to do anything in
> case of flowToDisk(). So does that mean that Broker will ultimately shut
> down with OOM if we keep sending messages ?
>
> Thanks
> Ramayan
>


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