Problem of Toplink cache

Question

when we try to get a object form DB by Toplink, the number of sub-object is doubule or treble,
for example: object User and object Role are many-to-many Mapping relation,get User form DB,sometime returns 4 Roles,sometime 8 Roles or 12 Roles, but the correct result is 4 Roles.
I don't konw why.

Answer 1

Yes,have only 4 unique rows in the relation table,this problem doesn't happened debug in Eclipse,just appeared on OC4J,so i suspect this is cache problem,
the query code:
//get the ClientSession
ClientSession cs = getClientSession();
Expression exp = (new ExpressionBuilder()).get("oid").equal(oid);
User user= cs.readObject(User.class, exp);
the User class:
public class User extends BaseEntity {
     private String ID;
     private String localName;
     private String firstName;
     private String lastName;
     private String stat;
     private String email;
     private String phone;
     private String fax;
     private String sourceAppCode;
     private Date lastLoginRangeBegin;
     private Date lastLoginRangeEnd;
     private ArrayList roleList;
     public String getID() {
          return ID;
     public void setID(String id) {
          ID = id;
     public void setStat(String stat) {
          this.stat = stat;
     public String getStat() {
          return stat;
     public void setEmail(String email) {
          this.email = email;
     public String getEmail() {
          return email;
     public void setPhone(String phone) {
          this.phone = phone;
     public String getPhone() {
          return phone;
     public void setFax(String fax) {
          this.fax = fax;
     public String getFax() {
          return fax;
     public void setSourceAppCode(String sourceAppCode) {
          this.sourceAppCode = sourceAppCode;
     public String getSourceAppCode() {
          return sourceAppCode;
     public void setRoleList(ArrayList roleList) {
          this.roleList = roleList;
     public ArrayList getRoleList() {
          return roleList;
     public void setLastLoginRangeBegin(Date lastLoginRangeBegin) {
          this.lastLoginRangeBegin = lastLoginRangeBegin;
     public Date getLastLoginRangeBegin() {
          return lastLoginRangeBegin;
     public void setLastLoginRangeEnd(Date lastLoginRangeEnd) {
          this.lastLoginRangeEnd = lastLoginRangeEnd;
     public Date getLastLoginRangeEnd() {
          return lastLoginRangeEnd;
     public void setLocalName(String localName) {
          this.localName = localName;
     public String getLocalName() {
          return localName;
     public void setFirstName(String firstName) {
          this.firstName = firstName;
     public String getFirstName() {
          return firstName;
     public void setLastName(String lastName) {
          this.lastName = lastName;
     public String getLastName() {
          return lastName;
}