On Tue, Sep 25, 2012 at 11:24 AM, Vincent Massol <[email protected]> wrote:
> See below. > > On Sep 25, 2012, at 10:48 AM, Denis Gervalle <[email protected]> wrote: > > > On Tue, Sep 25, 2012 at 1:29 AM, Andreas Jonsson <[email protected]> > wrote: > > > >> 2012-09-24 17:26, Vincent Massol skrev: > >>> Hi devs, > >>> > >>> I was trying to make XEM work with HSQLDB and... I have succeeded :) > >>> > >>> The only problem I have is that DBCP doesn't seem to work with > >> Hibernate. For some weird reasons when we do a SET SCHEMA it makes > calls to > >> fail afterwards. In any case if I configure Hibernate to not use DBCP > all > >> work just fine. > >> > >> Funny coincidence! I was just trying to get it to work with > >> PostgreSQL. It mostly works, as already commented on the Jira issue. > >> The only thing that seems to work unreliably is the initial template > >> creation. It seems likely that it is the same issue. > >> > >> But having looked into this I'm a bit worried about the current XEM > >> implementation. > > > > > > You should, we really do scary stuff to support multiple DB, and also > > dynamic mapping. > > > > > >> I'm not an expert on Hibernate, but to me it seems that > >> entities are expected to be bound to specific tables at initialization > >> time. So I'm wondering, does Hibernate really support changing the > >> mappings by switching databases or schemas underneath? > > > > > > The tricks is that we do not really support multiple hibernate mapping. > All > > accessed DBs use the same mapping. These are serious limitations in > > multi-wiki mode for mapping related features. > > > > Hibernate does not even knows that we switch the DB under its feet. Even > > the pool provider is not aware. This is why we need to set the correct DB > > each time we open a session/transaction (always tight together), which > > means getting a connection from the pool. We do not support nested > > session/transaction, in particular to different DBs for the same reason. > > > > > >> What prevents it > >> from generating prepared queries for accessing the entities, which will > >> be resolved against the initial database/schema, and continue to use > >> these even after the database or schema changes? > >> > > > > Our config prevent using prepared statements on the DB server. > > > > > >> +1 for your action plan. > >> > >> Best Regards, > >> > >> /Andreas > >> > >>> > >>> I've googled around and found that there are lots of people complaining > >> about DBCP. > >>> > >>> I've googled for what connection pooling library to use and I've found > >> that most people are recommending BoneCP (http://jolbox.com/). > >>> > >>> See: > >>> * > >> > http://stackoverflow.com/questions/5640146/java-jdbc-connection-pool-library-choice-in-2011-2012 > >>> * http://www.jorambarrez.be/blog/2012/04/30/dbcp_vs_c3p0_bonecp/ > >>> * > >> > http://stackoverflow.com/questions/8057110/java-database-connection-pool-bonecp-vs-dbpool-vs-c3p0 > >>> > >>> The other thing is that we currently have some 300 line of code that we > >> shouldn't have at all and that we need in XWiki just for handling DBCP > (see > >> com.xpn.xwiki.store.DBCPConnectionProvider). > >>> > >>> The pro of BoneCP is that it seems to be the fastest, see > >> http://jolbox.com/benchmarks.html > >>> > >>> So here's what I'd like to propose: > >>> > >>> * We move DBCPConnectionProvider to a legacy module > >>> * We bundle the bonecp jar by default > >>> * We configure our hibernate.cfg.xml by default to use boneCP: > >>> > >>> <property name="bonecp.idleMaxAge">240</property> > >>> <property name="bonecp.idleConnectionTestPeriod">60</property> > >>> <property name="bonecp.partitionCount">3</property> > >>> <property name="bonecp.acquireIncrement">10</property> > >>> <property name="bonecp.maxConnectionsPerPartition">60</property> > >>> <property name="bonecp.minConnectionsPerPartition">20</property> > >>> <property name="bonecp.statementsCacheSize">50</property> > >>> <property name="bonecp.releaseHelperThreads">3</property> > >>> > >>> <property > >> > name="connection.provider_class">com.jolbox.bonecp.provider.BoneCPConnectionProvider</property> > >>> > >>> What this means: > >>> * Existing users of XWiki will not have to change anything, it'll still > >> work > >>> * New users will use bonecp without knowing > >>> * Existing users can migrate to bonecp just by changing one line in > >> their hibernate.cfg.xml file > >>> > >>> I'd love to do this for 4.3 but we're already quite advanced in the 4.x > >> cycle. That said it's just a one line change in hibernate.cfg.xml in > case > >> of problem to go back to DBCP so we could do this for 4.3 which leaves > us > >> 4.3, 4.4 and 4.5 to test this out. And if later on we find an issue > we'll > >> always be able to release a 4.5.1 that has this one line change to go > back > >> to DBCP. > >>> > >>> WDYT? > >>> > >>> Here's my +1 for this action plan. > >> > > > > Unless BoneCP really provide proven improvements, and not only a > potential > > performance increase, that will probably not be tremendous, I am not > really > > in favor of changing a well-know Apache project for a project that as not > > really a great team of supporter. > > I understand. You should also consider that Apache DBCP is well known for: > * being slow > * being full of bugs > * having a stalled development > > At least that's what I keep seeing mentioned in all my google everywhere. > Sure, I have never said that DBCP is perfect. We are not discussing about choosing it, we are currently using it and unless you express other real concerns than hypothetical performance improvement, I would not change it for BoneCP. If we were starting from scratch, the comparison of those library would be different. I found BoneCP really appealing in regards to technical matters, but I do not see it as a well contributed project, and its "owner" seems to have other concerns now. > > I think you shouldn't think Apache == Good. At least not for Commons. > Commons libs can be very small and maintained by very few people. > > If you check http://commons.apache.org/dbcp/team-list.html you'll see > several committers. > But if you check > http://svnsearch.org/svnsearch/repos/ASF/search?view=plot&path=%2Fcommons%2Fproper%2Fdbcp&plotsort=commitsyou'll > see that only 2 committers have been active since > 2009. > Do not make me said what I have not. I think Apache projects get better reputations in regards to business users than a standalone project. There is also more chance to see a apache project taken over than a standalone project. But I am not a so big fan of Apache. > You should also note that Tomcat 7 has implemented its own connection > pooling thus dropping DBCP even though they're both in apache land… you > should ask why. I don't know the internal story but here's what they say: > > > http://stackoverflow.com/questions/520585/connection-pooling-options-with-jdbc-dbcp-vs-c3p0/3481821#3481821 Again, I am not against changing if we have real value for that change. Currently the value of BoneCP is not worst the risk incurred by its lack of maintenance. Improve the balance, and I will reconsider my vote. > > Thanks > -Vincent > > PS: I don't disagree with your analysis but we shouldn't be too fearful > either of making discoveries/changes. Provided we can control them and > revert easily it's not a bad thing to discover new stuff. > > PPS: BoneCP could not be the best choice. Maybe C3P0 is better now or > maybe the new Tomcat Connection Pool is better. > > PPPS: In any case I'm not going to make any change till I get to the > bottom of this issue with HSQLDB in virtual mode…. > PS: I think we are agreeing :) > > > From the project info page, I see only > > one name. From the forum, there seems to be serious rumors that the > project > > is no more supported by that guy since more than a year. > > > > So, currently, I am -1. > > > > > >>> > >>> Thanks > >>> -Vincent > _______________________________________________ > devs mailing list > [email protected] > http://lists.xwiki.org/mailman/listinfo/devs > -- Denis Gervalle SOFTEC sa - CEO eGuilde sarl - CTO _______________________________________________ devs mailing list [email protected] http://lists.xwiki.org/mailman/listinfo/devs
