# Queue size, threading used for session message Handler?

**URL:** <https://forum.inductiveautomation.com/t/queue-size-threading-used-for-session-message-handler/84286>\
**Category:** Ignition\
**Tags:** ignition81, perspective\
**Created:** [January 15, 2024, 7:59pm UTC](https://forum.inductiveautomation.com/t/queue-size-threading-used-for-session-message-handler/84286 "2024-01-15T19:59:57Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![mazeyrat](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/mazeyrat/32/10955_2.png) [@mazeyrat](https://forum.inductiveautomation.com/u/mazeyrat)\
**Post date:** [January 15, 2024, 7:59pm UTC](https://forum.inductiveautomation.com/t/queue-size-threading-used-for-session-message-handler/84286/1 "2024-01-15T19:59:57Z")

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Hi @paul-griffith (if it's in your scope)  
Is there any queue size limit for Perspective Session Events message handler ?  
For one type of message, are there processed **in sequence or in parallel ?**

 ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/6/9/692546d100ce89e0154270efbb06d24acf0adf17.png)

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**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\
**Post date:** [January 15, 2024, 8:22pm UTC](https://forum.inductiveautomation.com/t/queue-size-threading-used-for-session-message-handler/84286/2 "2024-01-15T20:22:43Z")

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> [@mazeyrat](#):
>
> processed **in sequence or in parallel ?**

All other message handlers are sequential per handler--I'd expect Perspective sessions to do the same (but perhaps separately per session, like Vision clients).

If IA doesn't give a definite answer, some experiments would be welcome.

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**Author:** ![paul-griffith](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/paul-griffith/32/37249_2.png) [@paul-griffith](https://forum.inductiveautomation.com/u/paul-griffith)\
**Post date:** [January 16, 2024, 11:15pm UTC](https://forum.inductiveautomation.com/t/queue-size-threading-used-for-session-message-handler/84286/3 "2024-01-16T23:15:17Z")

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Sequentially, "aggregated" by project.