#11 concurrent modification at conn.close()

[Bert Summers]

I just started using 2.1 from CVS and now I get the
following error:

java.util.ConcurrentModificationException at
java.util.HashMap$HashIterator.next(HashMap.java:736)
at java.util.WeakHashMap$1.hasNext
(WeakHashMap.java:369) at
java.util.AbstractMap$2.hasNext(AbstractMap.java:364)
at com.codestudio.sql.PoolManConnection.clean
(PoolManConnection.java:128) at
com.codestudio.util.JDBCPool.returnConnection
(JDBCPool.java:378) at
com.codestudio.util.JDBCPool.connectionClosed
(JDBCPool.java:216) at
com.codestudio.sql.PoolManConnection.sendCloseEvent
(PoolManConnection.java:180) at
com.codestudio.sql.PoolManConnectionHandle.close
(PoolManConnectionHandle.java:55) at

This happens as I call conn.close() at the end of my
jsp page.

[Jason Swartz]

Logged In: YES
user_id=69061

This is also happening to me, on RH Linux 7.1 with java
1.3.1-b24.

[Nobody/Anonymous]

Logged In: NO

Same thing with :
Win NT
Poolman 2.1B1
jdk 1.3.1
oracle thin jdbc drivers 8.1.7

[Nobody/Anonymous]

Logged In: NO

this is because you have open two more statement and
unclosed them when you close the connection.

here is the test program.

String sDriver = "com.codestudio.sql.PoolMan";
String sURL = "jdbc:poolman";

try {
Class.forName(sDriver).newInstance() ;
conn = DriverManager.getConnection(sURL);

stmt = conn.createStatement();
stmt = conn.createStatement();
} catch (Exception se) {
cat.debug("Exception occured.", se);
} finally {
try {
conn.close(); // Exception occured.
} catch(SQLException se) {
}
}

[Jason Swartz]

Logged In: YES
user_id=69061

Yup, I wasn't closing all my statements. When I fixed that,
this error went away. Thanks to nobody! Well, it'd be nice if
poolman could report this problem and handle it safely.

[Bert Summers]

Logged In: YES
user_id=219308

Call me crazy but I thought that when I closed the
connection that the statements would get closed for me.

[Nobody/Anonymous]

Logged In: NO

The problem is in PoolManConnection.clean(). A fix follows:

for (Iterator iter = openstatements.iterator(); iter.hasNext
();)
{
// automatically cleans open ResultSets as well
PoolManStatement sst = (PoolManStatement) iter.next();
iter.remove(); // add this to fix
//sst.clean(); // don't need this (the following line
will do the clean)
// The following line calls back to
removeOpenStatement,
// which will alter the openstatements map and cause a
// ConcurrentModificationException here if we haven't
// Already removed the statement.
JDBCPool.closeStatement(sst);
}