Concurrent Query Execution in EDG 7.8

[bostoM]

Hello,

I am reaching out because we have encountered an issue with EDG version 7.8. It appears that we cannot execute multiple queries simultaneously; instead, each query must wait for the previous one to finish. I believe this limitation was not present in version 5.

Could you please confirm whether the inability to execute simultaneous queries in EDG 7.8 is an intentional limitation or simply a configuration issue on our side?

Thank you for your assistance.

Best,

[Holger Knublauch]

Hello,

No, EDG can definitely run multiple queries in parallel, especially read-only queries.

What in particular are you running in parallel? Queries against the SPARQL endpoint? Are some of them UPDATEs?

Holger

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[bostoM]

Hi Holger and thank's for your answer.

   Yes queries against the sparql-endoint and no updates onyl RO queries ?

Best

[Holger Knublauch]

I would encourage you to submit this to our support portal so that our support team can better understand why this would happen in your setup.

Thanks

Holger

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[Bernd Johannes]

Hi everybody,

just to add our observation: at least in a mixed mode, where write and read queries happen in parallel, we also see this kind of behavior, that the system "seems" to serialize accesses in some way under certain circumstances. I say "seems", as we can only judge from the blocking behavior of the UI.

This is especially obvious, when EDG queries available collections for a user (e.g. when the user for the first time opens the collection dropdown). When this somewhat costly operation runs, many operations of other users seem to get serialized, and the world has to wait, until that one operation has finished (which takes ~36 seconds in our case - that's why it got so obvious).

We see this (in the UI) by the spinning IO indicator - and it affects read and write operations (not only writes).

However, we cannot exclude that this is not blocking, but just a tremendous slowdown of parallel running queries, which might seem like blocking.

Maybe this observation helps to pinpoint potential causes.

LG Bernd