Hello,
I am running into an issue where a PostGIS datastore in geotools 2.7-RC2
does not seem to be releasing connections back to the server upon
FeatureReader.close(). if a DefaultTransaction is involved and I do not
understand why.
I have a very small test where I configured my postgres server with
max_connections to 1. Then I wrote a small test program to loop 10 times
and just fetch 1 feature each time.
the part I can't figure out is that if I remove the transaction from the
getFeatureReader call and just pass in NULL, it works fine and the program
terminates OK.
If instead I pass the transaction in (and I don't have the line
params.put("max connections", 1); ) the program crashes with:
java.lang.RuntimeException: Unable to obtain connection: FATAL: sorry, too
many clients already
at
org.geotools.jdbc.JDBCDataStore.createConnection(JDBCDataStore.java:1566)
at
org.geotools.jdbc.JDBCDataStore.getConnection(JDBCDataStore.java:1528)
at
org.geotools.jdbc.JDBCDataStore.getConnection(JDBCDataStore.java:1545)
at
org.geotools.jdbc.JDBCFeatureSource.getReaderInternal(JDBCFeatureSource.java:537)
at
org.geotools.jdbc.JDBCFeatureStore.getReaderInternal(JDBCFeatureStore.java:209)
at
org.geotools.data.store.ContentFeatureSource.getReader(ContentFeatureSource.java:483)
at
org.geotools.data.store.ContentDataStore.getFeatureReader(ContentDataStore.java:414)
at Main2.main(Main2.java:57)
Caused by: org.postgresql.util.PSQLException: FATAL: sorry, too many
clients already
at
org.postgresql.core.v3.ConnectionFactoryImpl.doAuthentication(ConnectionFactoryImpl.java:291)
at
org.postgresql.core.v3.ConnectionFactoryImpl.openConnectionImpl(ConnectionFactoryImpl.java:108)
at
org.postgresql.core.ConnectionFactory.openConnection(ConnectionFactory.java:66)
at
org.postgresql.jdbc2.AbstractJdbc2Connection.<init>(AbstractJdbc2Connection.java:125)
at
org.postgresql.jdbc3.AbstractJdbc3Connection.<init>(AbstractJdbc3Connection.java:30)
at org.postgresql.jdbc3.Jdbc3Connection.<init>(Jdbc3Connection.java:24)
at org.postgresql.Driver.makeConnection(Driver.java:393)
at org.postgresql.Driver.connect(Driver.java:267)
at
org.apache.commons.dbcp.DriverConnectionFactory.createConnection(DriverConnectionFactory.java:38)
However, if I do use transaction and include the line params.put("max
connections", 1);
The program hangs on the second iteration right at: featureReader =
datastore.getFeatureReader(q, transaction);
Below is the class I'm referring to, Any help would be appreciated as to
why not using the transaction seems to cause connections to be truly
released by the DataStore (or the underlying Connection Pool). Is there
any way that Transactions can be kept in there and the "max connections"
directive to be followed such that the program doesn't hang or run out of
connections?
public class Main2
{
public static void main(String[] args)
{
Map params = new HashMap();
params.put("dbtype", "postgis"); //must be postgis
params.put("host", "myhost"); //the name or ip address of
the machine running PostGIS
params.put("port", new Integer(5432)); //the port that
PostGIS is running on (generally 5432)
params.put("database", "spatial"); //the name of the
database to connect to.
params.put("user", "dbuser"); //the user to connect
with
params.put("passwd", "dbuser"); //the password of the
user.
params.put("max connections", 1);
DataStore datastore = null;
try
{
datastore = DataStoreFinder.getDataStore(params);
FeatureReader<SimpleFeatureType, SimpleFeature> featureReader =
null;
String[] columns = new String[]
{
"the_geom", "colblkst",
"colblkcou", "colblk"
};
for (int x = 0; x < 10; x++)
{
try
{
System.out.println("going once!");
String filterstr = "colblkst='01' and colblkcou='001'
and colblk='10163'";
Filter filter = CQL.toFilter(filterstr);
Transaction transaction = new DefaultTransaction();
DefaultQuery q = new DefaultQuery("collection_blocks",
filter, columns);
featureReader = datastore.getFeatureReader(q,
transaction /*null*/);
if (featureReader.hasNext())
{
SimpleFeature f = featureReader.next();
}
transaction.commit();
featureReader.close();
// Thread.sleep(100000);
}
catch (Exception ex)
{
ex.printStackTrace();
}
}
}
catch (IOException ex)
{
ex.printStackTrace();
System.exit(-1);
}
}
}
--
Signed,
Alessandro Ferrucci
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