Re: [milo-dev] [Q] Timing for deleting Subscription and MonitoredItems

[Shigeru Ishida <ishida_shigeru@xxxxxxxxxxx>]

Here, Milo 0.1.6 based simulation server is running continuously.
This server is a light-weight server that handles hundreds of node items.
(It is different from server processing more than 10,000 node items)

Therefore, from the viewpoint of suppressing the occurrence of
OOME as much as possible, I will briefly show notes on my experience.

1) I think that the version of Netty is 4.0.x rather than 4.1.x.

2) When running the server on Apache Felix (OSGi framework),
  I think that version is 5.6.10 (latest) better than 4.6.1.
  (OSGi's request may be small)

This server is currently running without Felix for about 20 days.
Initially, Full GC occurred at intervals of about 30 minutes,
but now it is occurring at intervals of about 6 minutes.
In addition, OOME has not occurred yet.

T1) Start - 2 days: Full GC occurs at intervals of several hours
T2) After T1 - 14 days elapsed: Full GC occurs at intervals of about 30 minutes
T3) After T2 - To date: Full GC occurs at intervals of about 6 minutes

I made this simulation server simple, but I think that there is
still a possibility that OOME will occur in the future.

<ishida_shigeru@xxxxxxxxxxx> wrote, Wed, 17 Jan 2018 10:35:53 +0900 (JST)

> Thank you very much. I understood.
> 
> <kevinherron@xxxxxxxxx> wrote, Tue, 16 Jan 2018 17:18:43 -0800
> 
> > They should get deleted when the session either times out or is closed by
> > the client.
> > 
> > If the client is disconnecting without closing the session, and the session
> > timeout was significant, this could result in the number of orphaned
> > sessions (and the associated subscriptions and items) growing.
> > 
> > I'll take a look and make sure that session are timing out and being
> > cleaned up correctly as well, just in case.
> > 
> > On Tue, Jan 16, 2018 at 5:05 PM, Shigeru Ishida <ishida_shigeru@xxxxxxxxxxx>
> > wrote:
> > 
> > > Hi Kevin,
> > >
> > > When will information of Subscription and MonitoredItems created by
> > > the server be deleted ?
> > >
> > > Will the server automatically delete these information when default
> > > mechanism of Milo works when the client terminates the connection
> > > normally or when the client terminates unexpectedly ?
> > > (ex. kill -9 client-pid)
> > >
> > > Or is it necessary for the client to record the SubscriptionId previously
> > > used and throw a delete request to the server when the client is restarted
> > > ?
> > >
> > > Here, with Apache Felix removed, the server is running stably.
> > > Once the re-establishing process has been executed, createSubscription()
> > > and createMonitoredItems() are called and processing continues.
> > >
> > > Therefore, a simulation server assuming process lines, process units,
> > > and node items of a factory with a larger scale is also created and running
> > > continuously. The total number of node items of this simulation server is
> > > over 10,000.
> > >
> > > Another company's client product is connected to this server, and OOME has
> > > occurred on the server as a result of this client repeatedly connecting and
> > > disconnecting.
> > >
> > > Regards,
> > >
> > > --Shigeru
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