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Benedikt Ritter commented on LANG-739: -------------------------------------- Setting this to Review Patch > 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. -- This message was sent by Atlassian JIRA (v6.1#6144)