[ome-users] concurrent OMERO Java API login for multiple users?

[Josh Moore]

On Sun, Aug 13, 2017 at 3:13 PM, BioDataAnalysis // Mario Emmenlauer
<memmenlauer at biodataanalysis.de> wrote:
>
> Dear OME,

Hi Mario,


> Are there statics in the API that forbid multiple concurrent logins?

There are no known structures that would prevent multiple logins from
a single JVM. Any would count as a significant bug.


> How thread-safe is the API?

The only services that have concurrency constraints are those around
the StatefulServiceInterface:

https://github.com/openmicroscopy/openmicroscopy/blob/develop/components/blitz/resources/omero/ServicesF.ice#L36

The server itself will lock method calls that need protection, but
since the service maintains state for the client, ultimately
responsibility of sensible use falls on the caller. (For example, it
doesn't make sense for one thread to change the current image of a
service if another thread is still expecting to load planes or
thumbnails from the previous image)


> And how resource-hungry is a new login?
> I'd expect login to be rather slow because I assume it will initialize
> a number of resources. Am I mistaken?

Not horribly slow, but yes, there are a number of mostly security
checks which occur on session creation. I'd expect several dozen
within a minute or so to be acceptable. Several hundred in the same
time period will likely start to create issues, especially if
continued over a long-period of time; and several thousand would
almost certainly require server adjustments.


> Thanks and all the best,
>     Mario Emmenlauer

All the best,
~Josh.