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https://issues.apache.org/jira/browse/LANG-739?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13805299#comment-13805299
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Philippe Renon commented on LANG-739:
-------------------------------------
Had a quick look the patch and I think it has an issue.
Because the only reference to the IDKey is held by the WeakHashMap, there is a
risk that it gets garbage collected at any time...
Additionaly I think that the HashCodeBuilder does not use a WeakHashMap.
> ToStringBuilder leaks memory if toString method causes hash code to be changed
> ------------------------------------------------------------------------------
>
> Key: LANG-739
> URL: https://issues.apache.org/jira/browse/LANG-739
> Project: Commons Lang
> Issue Type: Bug
> Components: lang.builder.*
> Affects Versions: 2.3
> Reporter: Philippe Renon
> Fix For: Review Patch
>
> Attachments: LANG-739-patch.txt
>
>
> We have the following abstract class:
> {code}
> public class AbstractMessageItem {
> private String toString;
> public boolean equals(final Object obj) {
> return EqualsBuilder.reflectionEquals(this, obj);
> }
> public int hashCode() {
> return HashCodeBuilder.reflectionHashCode(this);
> }
> public String toString() {
> if (toString == null) {
> toString = ToStringBuilder.reflectionToString(this);
> }
> return toString;
> }
> }
> {code}
> We also have two concrete classes extending the above class and one of them
> has a reference to the other.
> Now, if we call toString() on the 1st one, this will in turn call toString()
> on the second one.
> The call to toString() on the second one will cause its hash code to be
> changed and as a consequence will also change the hashCode of the first one
> *while* computing its toString().
> This causes the _infinite loop avoidance_ mechanism (i.e. the registry) to
> fail to unregister some objects and memory will be leaked.
> I believe that this leak can be avoided by using the system identity hash
> code when registering objects (as is done in HashCodeBuilder) instead of the
> user hash code.
> I know the issue can be worked around by removing the toString field (and
> loosing a dubious "performance enhancement" hack) or by making it transient,
> but I think that other "mutating" toString() methods can happen in the field
> (sometimes for good reasons) and fixing ToStringBuilder can be of help in
> some cases.
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