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Manuel Molaschi commented on JCR-2892:
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We have a different problem with the same cause... We experience a big performance loss on
an app built on Magnolia CMS and starting on Tomcat (configured with xmx at 1024m)
After a long investigation we assumed that this behaviour was caused by jvm spending a lot
of time in GC (cpu usage was always very high)
These are the startup time on different jr versions / fetch size
with jr 2.2.1: 129 sec
with jr 2.2.8 (fetch size 10000): > 1h
with jr 2.2.8 (patch applied on ConnectionHelper to comment out stmt.setFetchSize): 135 sec
> Large fetch sizes have potentially deleterious effects on VM memory requirements when
using Oracle
> --------------------------------------------------------------------------------------------------
>
> Key: JCR-2892
> URL: https://issues.apache.org/jira/browse/JCR-2892
> Project: Jackrabbit Content Repository
> Issue Type: Bug
> Components: jackrabbit-core, sql
> Affects Versions: 2.2.2
> Environment: Oracle 10g+
> Reporter: Christopher Elkins
>
> Since Release 10g, Oracle JDBC drivers use the fetch size to allocate buffers for caching
row data.
> cf. http://www.oracle.com/technetwork/database/enterprise-edition/memory.pdf
> r1060431 hard-codes the fetch size for all ResultSet-returning statements to 10,000.
This value has significant, potentially deleterious, effects on the heap space required for
even moderately-sized repositories. For example, the BUNDLE table (from 'oracle.ddl') has
two columns -- NODE_ID raw(16) and BUNDLE_DATA blob -- which require 16 b and 4 kb of buffer
space, respectively. This requires a buffer of more than 40 mb [(16+4096) * 10000 = 41120000].
> If the issue described in JCR-2832 is truly specific to PostgreSQL, I think its resolution
should be moved to a PostgreSQL-specific ConnectionHelper subclass. Failing that, there should
be a way to override this hard-coded value in OracleConnectionHelper.
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