[Mondrian] Queries being executed in serial in mondrian 3.4

[Brian Hagan]

Pedro,

It does ring a bell. See http://jira.pentaho.com/browse/MONDRIAN-1080. Maybe you can try 3.4.3.

- Brian
On Jun 8, 2012, at 9:02 AM, Pedro Alves wrote:

> 
> 
> Hey there.
> 
> 
> I really don't know how to ask this. I'm not even sure there's an issue, 
> just a set of coincidences.
> 
> 
> As most of you know, we develop a lot of dashboards that rely on mdx. 
> Lately, we've been having a few complains that the dashboards are 
> incredibly slow.
> 
> 
> And we can't find, in the mondrian / sql logs reasons for that to be slow.
> 
> 
> Until we noticed somethng weird:
> 
> 1. User A accesses a dashboard that is not on cache
> 2. User B accesses a dashboard that should be on cache
> 3. We see on the logs the queries for user A
> 4. User B is stuck, no activity
> 5. User A's queries end, dashboard rendered
> 6. User B's dashboard is immediately rendered
> 
> 
> I saw this the first time 2 weeks ago in a mondrian over lucid. I 
> thought it had to do with lucid's connection polling.
> 
> 
> I saw this again *today* with mondrian with mysql.
> 
> 
> Common factor: They were both on pentaho 4.5 (with mondrian 3.4.1).
> 
> 
> Commented this with Jan Aertsen and he said "weird - someone mentioned 
> something very similar a few days ago".
> 
> 
> I'm not saying this is a regression cause I don't know what it is. I 
> know some work has been done on query execution. But it's definitely 
> something that was not there before (or all our dashboards would be 
> basically unusable).
> 
> 
> Does this ring any bells to anyone? We'll try to see if we can somehow 
> reproduce this, but it's incredibly hard to reproduce concurrency 
> issues.... :(
> 
> 
> 
> -pedro
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