I am used to close all recources when i am done with these but that seems not to be the case in app engine world.
Here is little method that gets all countries, adds these to List and closes PersistenceManager as its not needed anymore, we have all the data we need in List.
public List<Country> getCountries() {
PersistenceManager pm = PMF.get().getPersistenceManager();
String query = "select from " + Country.class.getName();
List<Country> countries = (List<Country>) pm.newQuery(query).execute();
pm.close();
return countries;
}
Countries are used in simple dataTable below, but when running this code app engine starts to complain “Object Manager has been closed”. To fix this issue pm.close(); can be commented out and hope that guys from google will close it eventually themselves. Google in its documentation does not recommend this though.
<h:dataTable value="#{countryBean.countries}" var="country">
<h:column>
</h:column>
</h:dataTable>
Probably appengine is lazy to actually get items from datastore to List but gets them only when particular item is used. So another way to fix it is to force appengine to force loading all entries from datastore by copying.
public List<Country> getCountries() {
PersistenceManager pm = PMF.get().getPersistenceManager();
String query = "select from " + Country.class.getName();
List<Country> countries = (List<Country>) pm.newQuery(query).execute();
List<Country> countries2=new ArrayList<Country>();
Collections.copy(countries, countries2);
pm.close();
return countries;
}
What i have not figured out yet is why all request take awful lot of CPU recource and how to reduce it. over 5000ms is like crazy
01-24 04:18AM 54.222 /faces/insertcountry.xhtml 200 930ms 5289cpu_ms 4570api_cpu_ms 0kb Mozilla/5.0 (X11; U; Linux x86_64; et; rv:1.9.1.7) Gecko/20100106 Ubuntu/9.10 (karmic) Firefox/3.5.7,gzip(gfe),gzip(gfe) ... 01-24 04:18AM 54.729 org.datanucleus.ObjectManagerImpl close: Outstanding nontx update being committed to datastore
An Error Occurred: Object Manager has been closed +- Stack Trace Read the rest of this entry »
