Re: [Hibernate] bad performance during flush and help is needed.

[Gavin King]

So, let me get this straight:

you, *500 times*

(a) obtain a new JDBC connection
(b) start a transaction
(c) do some work
(d) commit the transaction and close the JDBC connection
and you are surprised that this is slow??

Why would you not do it all in one transaction? Starting and stopping 
transactions is one of _the_ most expensive operations you can do with a 
database.

jiesheng zhang wrote:

First I have a source class like this.
public class Source
{
        Transaction tx;
        List pendingRemovedItems;
        public void beginTransaction()
        {
                // here I use ThreadLocal pattern.
                tx= ThreadState.getSession().beginTransaction();
        }
        public void commit()
        {
                try
                {
                        // I need to explicitly delete all items that need
deletion.
                        for (Iterator iter= pendingRemovedItems.iterator();
                                iter.hasNext();
                                )
                        {
                                ThreadState.getSession().delete(iter.next());
                        }
                        tx.commit();
                        logger.info(" db source is commited");
                        pendingRemovedItems.clear();
                } finally
                {
                        tx= null;
                }
        }
        
        // other variables and methods in source.
}
My application code is like this
Source src=...;
// when control comes here, there are about 500
persistence objects in session.
1. src.beginTransaction();
2. // here an new transient object is persisted.
3. src.commit();
The code fragment 1, 2, and 3 will be run 300 to 500
times. 

The following is sql code dumped from hibernate. That
is exactly what I expected. I only show 2 of them. The
timestamp indicated that each insertion was about one
second.
I am happy to provide any extra information.

2003-9-12 12:31:02 ....
Info: found cached source
Hibernate: select seq_resourceID.nextval from dual
Hibernate: insert into contact (luid, dbId, guid,
namefirst, namelast, nameother, nameprefix,
namesuffix, title, role, orgname, orgunit, birthday,
url, nickname, timezone, note, binary, categories,
class, contactID) values (?, ?, ?, ?, ?, ?, ?, ?, ?,
?, ?, ?, ?, ?, ?, ?, ?, ?, ?, 'd', ?)
Hibernate: insert into phonenumber (contactID, num,
type) values (?, ?, ?)
Hibernate: insert into email (contactID, email, type)
values (?, ?, ?)
2003-9-12 12:31:03 ...
Info:  db source is commited
2003-9-12 12:31:03 ....
2003-9-12 12:31:03 ...
Info: found cached source
Hibernate: select seq_resourceID.nextval from dual
Hibernate: insert into contact (luid, dbId, guid,
namefirst, namelast, nameother, nameprefix,
namesuffix, title, role, orgname, orgunit, birthday,
url, nickname, timezone, note, binary, categories,
class, contactID) values (?, ?, ?, ?, ?, ?, ?, ?, ?,
?, ?, ?, ?, ?, ?, ?, ?, ?, ?, 'd', ?)
Hibernate: insert into email (contactID, email, type)
values (?, ?, ?)
Hibernate: insert into phonenumber (contactID, num,
type) values (?, ?, ?)
2003-9-12 12:31:04 ...
Info:  db source is commited
--- Gavin King <[EMAIL PROTECTED]> wrote:
 

the transaction. My code is like this

Tranaction tx=sessiob.beginTransaction();
foo.setField(newValue);
tx.commit();
     

Well, obviously it is not like that, since that code
does not
load any objects into the session.
   

1. When the commit() is called, will the hibernate
loop through every object in the session
and check for modification?
     

Yes.

   

2. If it does, is it an expensive operation?

     

No, not at all.

   

Any suggestion to solve the performance bottleneck
     

in
   

my situation is really appreacited.

     

Exactly what does your code *really* look like?

   



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