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Re: [eclipselink-users] Read/write and caching
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Since I can't see all your code for thread 1, I can't tell for sure, but I
suspect the issue is that the object stay managed in the EntityManager held by
thread 1.
The cache settings you are setting is for the 2nd tier cache. JPA sets out
rules about how entities get held in an EntityManager. As long as you use the
same EntityManager and the entities stay managed, you will have to explicitly
refresh them to see updates. If you get a new EntityManager, or clear your
EntityManager and then do a query with the cache settings you have seen, you
should get the cached data.
-Tom
On 15/03/2012 2:57 AM, Sebastian Weber wrote:
Hi All,
…and post again. I have some trouble with my Mail-Server and
subcribe/notification/confirm messages from the mailing list.
I hope you see this post fort he first time. Thanks in advance for you help!
I still like to setup a simple EclipseLink example with MySQL Database and
EclipseLink Caching. I found enough information about how I can configure the
cache but my Example still not working.
My Example:
Entry DBTSIRS:
@Entity
@Cache(
type=CacheType.FULL,
size=200,
expiry=10000
)
@NamedQueries({
@NamedQuery(name = "getAllIRS",
query = "SELECT e FROM DBTSIRS e",
hints = {@QueryHint(name = QueryHints.CACHE_USAGE,
value = CacheUsage.CheckCacheThenDatabase)})
})
public class DBTSIRS implements Serializable {
/** */
private static final long serialVersionUID = 3937702217098914083L;
@Id
private int irsID;
@Column(columnDefinition = "VARCHAR(50)")
private String gpslongitude;
@Column(columnDefinition = "VARCHAR(50)")
private String gpslatitude;
…
}
Thread 1 Just read from DB and print:
List<DBTSIRS> irs2 = this.em.createQuery("SELECT r from DBTSIRS r WHERE r.irsID
= 1",
DBTSIRS.class).setHint(QueryHints.CACHE_USAGE,CacheUsage.CheckCacheByPrimaryKey).getResultList();
List<DBTSIRS> irs3 = this.em.createNamedQuery("getAllIRS",
DBTSIRS.class).getResultList();
Thread 2 change the position attributes in DBTSIRS:
this.em.getTransaction().begin();
DBTSIRS dbirs = this.em.find(DBTSIRS.class, 1);
int lng = Integer.parseInt(dbirs.getGpslongitude());
int lat = Integer.parseInt(dbirs.getGpslatitude());
dbirs.setGpslatitude(Integer.toString(++lat));
dbirs.setGpslongitude(Integer.toString(++lng));
this.em.merge(dbirs);
this.em.getTransaction().commit();
So these two Threats are running each 5 seconds. Each Thread ha a separate
EntityManager generated by the EntityManagerFactory. Thread 2 is modifying the
attributes. By the way String will not be the best data type to store position
information! Yes I know! Just for this test! After the Commit the position
attributes the DB show me the current valid position information (1,2,3,4,…)
The Thread 1 still print me the first read value (1).
I guess I do something wrong on the caching configuration. The modification
don’t affect to the EntityManager cache of Thread 1.
Can you give me a hint where I can find information about this “issue” or better
what I doing wrong.
Thanks a lot!
Sebastian
--
Freundliche Grüße / Best Regards
Sebastian Weber
----------------------------------------------------------------------------------------------
Sebastian Weber, M.Sc.
Kommunikationssysteme / Communication Systems
Fakultät für Ingenieurwissenschaften / School of Engineering
Hochschule für Technik und Wirtschaft des Saarlandes (HTW) /
University of Applied Sciences
Standort / Location:
HTW Hochschul-Technologie-Zentrum (HTZ)
Campus IT-Park (CIP)
Altenkesseler Strasse 17/D2
66115 Saarbruecken, Germany
Phone: +49 681 5867-663
Mobile: n.a.
Fax: +49 681 5867-671
E-Mail: sebastian.weber@xxxxxxxxxxxxxxx
URL: http://www.htw-saarland.de
----------------------------------------------------------------------------------------------
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