to reproduce:

put an object in the cache that is not a Serializable
 hangs in store

The code is:

try {
            fout = new FileOutputStream(file);
            oout = new ObjectOutputStream(fout);
            oout.writeObject(obj);
            oout.flush();
        } catch (Exception e) {
            while (file.exists() && !file.delete()) {
                ;
            }

throw new CachePersistenceException("Unable to write '" + file + "' in the cache. Exception: " + e.getClass().getName() + ", Message: " + e.getMessage());
        } finally {
            try {
                oout.close();
            } catch (Exception e) {
            try {
                fout.close();
            } catch (Exception e) {
        }

Problem is that in the catch clause when writeObject throws an exception, the code tries to delete the file that is still opened, which can't succeed (at least on XP/JDK 1.5)
Better:

try {
            fout = new FileOutputStream(file);
            try {
                oout = new ObjectOutputStream(fout);
                try {
                    oout.writeObject(obj);
                    oout.flush();
                } finally {
                    try {
                        oout.close();
                    } catch (Exception e) {
                    }
                }
            } finally {
                try {
                    fout.close();
                } catch (Exception e) {
                }
            }
        } catch (Exception e) {
            while (file.exists() && !file.delete()) {
                ;
            }

throw new CachePersistenceException("Unable to write '" + file + "' in the cache. Exception: " + e.getClass().getName() + ", Message: " + e.getMessage());
        }

fout needs its own finalize&close because ObjectOutputStream() might throw an exception.