I just upgraded to 6.3 on my development server, and it looks like the 
problem is just as bad if not worse....

Jacob

On Wednesday, October 31, 2018 at 11:52:25 AM UTC-5, kar...@gmail.com wrote:
>
> Hi all,
>
> We are running DSpace 5.9 XMLUI with Tomcat 7 and Java 8 on a RHEL 7 
> server, with a small-ish collection of items (about 20,000). We are running 
> production with Oracle 12, but I have replicated the same issue with 
> Postgresql 9.2.
>
> We have recently noticed some very long page load times. Any given 
> discover/search page can take 2-7 seconds to load, and when there is even a 
> moderate amount of traffic (e.g., when a bot is indexing the site at about 
> 10 requests per second), page load times can take 30-60 seconds or longer.
>
> We have made the changes suggested at 
> https://wiki.duraspace.org/display/DSDOC5x/Performance+Tuning+DSpace for 
> both Tomcat and PostgreSQL.
>
> Our production site has been customized extensively, but I was able to 
> replicate the issue with an untouched DSpace 5.9 build using the default 
> Mirage theme with XMLUI.
>
> The issue is the same with both Oracle and PostgreSQL (PostgreSQL seems a 
> little bit better). 
>
> I have tried changing from Java 8 to Java 7.
>
> I have bumped up the database connection pool size to 300.
>
> Digging through the logs is difficult, since the problem only really 
> emerges under (moderate) load.
>
> However, I was able to track a single page request (to /discover), and 
> noticed that there were over 9000 individual SQL queries (for a single page 
> load) that looked like:
>
> DEBUG org.dspace.storage.rdbms.DatabaseManager @ Running query "SELECT * 
> FROM MetadataValue WHERE resource_id= ? and resource_type_id = ? ORDER BY 
> metadata_field_id, place"  with parameters: 144458,0
>
> (The resource_type_id `0` is for bitstreams.)
>
> I *think* (but could be wrong) that this is the source of our performance 
> problem; that the database is just getting bogged down with so many 
> requests. Looking at PostgreSQL's slow query logging, some of these 
> individual queries are taking about 1 second.
>
> Our situation is perhaps unique in that we have dozens (sometimes 
> hundreds) of "dark" (non-ORIGINAL) archival files associated with an item, 
> and it looks like this discover page is trying to load metadata for all of 
> them.
>
> This doesn't happen with an equivalent query in JSPUI.
>
> Any suggestions or workarounds? Why does the search page need to get 
> metadata for all bitstreams? 
>
> Does anyone know if upgrading to DSpace 6 would resolve this issue?
>
> Thanks,
>
> Jacob
>
>
>

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