I've inherited an old system for which I am trying to recreate parts using asp.net. I'm considering using NHibernate to act as the DAL but initial tests are producing some poor performance results. I'm confident that the mistake is all mine so if someone could point me in the right direction i'd appreciate it.
I've created a template using MyGeneration and have generated all my mappings and class files. Everything compiles and I can access my data as I wish to.
However the object graph I am using is quite large (385 objects) and i'm wondering if this is the cause of the performance issues.
Working with one of the larger objects "Job" which references many others Employee, Customer, Site, etc.. I use the following mapping
-----------------------------------------------------------------------
Mapping for Job
-----------------------------------------------------------------------
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="PS.Core" namespace="PS.Core.Domain">
<class name="Job" table="Job">
<id name="Jobid" column="JobID" type="Int32" unsaved-value="0">
<generator class="native"/>
</id>
<bag name="AttachmentViewerList" inverse="true" lazy="true" >
<key column="JobID" />
<one-to-many class="AttachmentViewer" />
</bag>
<bag name="InvoiceDetailList" inverse="true" lazy="true" >
<key column="JobID" />
<one-to-many class="InvoiceDetail" />
</bag>
<bag name="InvoiceHeaderList" inverse="true" lazy="true" >
<key column="JobID" />
<one-to-many class="InvoiceHeader" />
</bag>
<bag name="InvoiceLineList" inverse="true" lazy="true" >
<key column="JobID" />
<one-to-many class="InvoiceLine" />
</bag>
<bag name="JobJournalList" inverse="true" lazy="true" >
<key column="JobID" />
<one-to-many class="JobJournal" />
</bag>
<bag name="JobLinkList" inverse="true" lazy="true" >
<key column="JobID" />
<one-to-many class="JobLink" />
</bag>
<bag name="JobTechnicianList" inverse="true" lazy="true" >
<key column="JobID" />
<one-to-many class="JobTechnician" />
</bag>
<many-to-one name="SkillSetid" column="SkillSetID" class="SkillSet" />
<many-to-one name="Custid" column="CustID" class="Customer" />
<many-to-one name="Siteid" column="SiteID" class="Site" />
<property column="SiteName" type="String" name="SiteName" not-null="true" length="50" />
<property column="ContactID" type="Int32" name="Contactid" not-null="true" />
<property column="ContactName" type="String" name="ContactName" not-null="true" length="50" />
<property column="ContactPhone" type="String" name="ContactPhone" not-null="true" length="30" />
.......plus 50ish other properties
-----------------------------------------------------------------------
------------------------------------------------------------------------
Method to load Jobs by Status (Returns roughly 100 Jobs)
with customers preloaded.
------------------------------------------------------------------------
public IList<Job> GetJobsByStatus(Job.JobStatus jobStatus)
{
ICriteria criteria = base.NHibernateSession.CreateCriteria(typeof(Job));
criteria.SetFetchMode(Job.ColumnNames.Custid, FetchMode.Eager);
criteria.Add(Expression.Eq(Job.ColumnNames.Status, (byte)jobStatus));
return criteria.List<Job>();
}
------------------------------------------------------------------------
By using a profiler I can see the query that executes is perfect and includes the customer join and takes only a split second to execute.
However on the line....
return criteria.List<Job>();
...I have to wait about 30 seconds for my objects to be loaded.
Again using profiler during this time I can see that no other queries are run against the database.
If I instantly run the method again (on the same page) I can see the query hit the database again and run just as quickly. This time however the jobs are loaded along with the customer records in a split second.
My question is why does it take so long to populate my objects initially? What happens during the first use of nHibernate that is slowing me down. Is there anything I can do to decrease this initial load time. If someone could explain what i'm seeing it would be a big help. I have turned off logging and this did increase performance to the point that I am at now.
I am using the open session in view pattern.
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