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POMixture of Hibernate and Raw JDBC app is locking up
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copied!<p>I took over a company's Java Web application that stands at 30k lines of code. There are about 20 users on the system. The application originally did raw jdbc sql queries. I have converted some of the SQL to hibernate, but because of time and budget constraints I have not converted all of it. My thinking was that I could do a mixture of the two db interaction methods (hibernate and raw jdbc), while I incrementally migrate the app to all hibernate. It's using c3p0 connection pooling. It uses two pools; one for hibernate and one for the raw jdbc queries. There are some raw jdbc update and insert queries, but they are now all using hibernate's <code>session.doWork(Work work)</code> hook. The db is Microsoft SQL Server '08 R2.</p> <p>The problems we experience with this approach always seem to manifest themselves as the app locking up. For the past month, I have been able to reduce the frequency of lock-ups by fixing obvious problems. I am at a point now, where the cause is not so obvious, and my boss and I suspect that there is something fundamentally wrong in our approach or configuration that would solve this problem entirely.</p> <p>One thing that is confusing to me is that if these lock-ups are db deadlocks, the thread dumps only seem to indicate that a write is blocking a read. However, the transaction isolation level is read-committed, so why would a write block a read?</p> <p>Are there any suggestions you can give? Any suggestions for better debugging analyis?</p> <p>Here are is the properties from my persistence.xml file</p> <pre><code><property name="hibernate.dialect" value="org.hibernate.dialect.SQLServerDialect"/> <property name="hibernate.archive.autodetection" value="class, hbm"/> <property name="hibernate.c3p0.min_size" value="20" /> <property name="hibernate.c3p0.max_size" value="300" /> <property name="hibernate.c3p0.timeout" value="300" /> <property name="hibernate.c3p0.max_statements" value="50" /> <property name="hibernate.c3p0.idle_test_period" value="3000" /> </code></pre> <p>I'm using the default c3p0 configuration for the raw jdbc select queries</p>

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