After generating the heap dump and analyzing those as given in link https://wiki.jenkins-ci.org/display/JENKINS/I'm+getting+OutOfMemoryError
I found the below instances and a lot of them
this - value: groovy.lang.GroovyClassLoader #28
<- delegate - class: groovy.lang.GroovyClassLoader$InnerLoader, value: groovy.lang.GroovyClassLoader #28
<- <classLoader> - class: get_oas_releases$_run_closure5, value: groovy.lang.GroovyClassLoader$InnerLoader #50
<- klazz - class: org.codehaus.groovy.reflection.ClassInfo, value: get_oas_releases$_run_closure5 class get_oas_releases$_run_closure5
<- value - class: org.codehaus.groovy.reflection.GroovyClassValuePreJava7$EntryWithValue, value: org.codehaus.groovy.reflection.ClassInfo #2204
<- [10548] - class: java.lang.Object[], value: org.codehaus.groovy.reflection.GroovyClassValuePreJava7$EntryWithValue #2198
<- table - class: org.codehaus.groovy.reflection.GroovyClassValuePreJava7$GroovyClassValuePreJava7Segment, value: java.lang.Object[] #563500
<- [9] - class: org.codehaus.groovy.util.AbstractConcurrentMapBase$Segment[], value: org.codehaus.groovy.reflection.GroovyClassValuePreJava7$GroovyClassValuePreJava7Segment #7
<- segments - class: org.codehaus.groovy.reflection.GroovyClassValuePreJava7$GroovyClassValuePreJava7Map, value: org.codehaus.groovy.util.AbstractConcurrentMapBase$Segment[] #1
<- map - class: org.codehaus.groovy.reflection.GroovyClassValuePreJava7, value: org.codehaus.groovy.reflection.GroovyClassValuePreJava7$GroovyClassValuePreJava7Map #1
<- globalClassValue - class: org.codehaus.groovy.reflection.ClassInfo, value: org.codehaus.groovy.reflection.GroovyClassValuePreJava7 #1
<- [1632] - class: java.lang.Object[], value: org.codehaus.groovy.reflection.ClassInfo class ClassInfo
<- elementData - class: java.util.Vector, value: java.lang.Object[] #32667
<- classes (Java frame) - class: org.eclipse.jetty.webapp.WebAppClassLoader, value: java.util.Vector #14
this - value: groovy.lang.GroovyClassLoader #39
<- delegate - class: groovy.lang.GroovyClassLoader$InnerLoader, value: groovy.lang.GroovyClassLoader #39
<- <classLoader> - class: Script1, value: groovy.lang.GroovyClassLoader$InnerLoader #61
<- klazz - class: org.codehaus.groovy.reflection.ClassInfo, value: Script1 class Script1
<- value - class: org.codehaus.groovy.reflection.GroovyClassValuePreJava7$EntryWithValue, value: org.codehaus.groovy.reflection.ClassInfo #987
<- [1] - class: java.lang.Object[], value: org.codehaus.groovy.reflection.GroovyClassValuePreJava7$EntryWithValue #2129
<- [6906] - class: java.lang.Object[], value: java.lang.Object[] #825722
<- table - class: org.codehaus.groovy.reflection.GroovyClassValuePreJava7$GroovyClassValuePreJava7Segment, value: java.lang.Object[] #563500
<- [9] - class: org.codehaus.groovy.util.AbstractConcurrentMapBase$Segment[], value: org.codehaus.groovy.reflection.GroovyClassValuePreJava7$GroovyClassValuePreJava7Segment #7
<- segments - class: org.codehaus.groovy.reflection.GroovyClassValuePreJava7$GroovyClassValuePreJava7Map, value: org.codehaus.groovy.util.AbstractConcurrentMapBase$Segment[] #1
<- map - class: org.codehaus.groovy.reflection.GroovyClassValuePreJava7, value: org.codehaus.groovy.reflection.GroovyClassValuePreJava7$GroovyClassValuePreJava7Map #1
<- globalClassValue - class: org.codehaus.groovy.reflection.ClassInfo, value: org.codehaus.groovy.reflection.GroovyClassValuePreJava7 #1
<- [1632] - class: java.lang.Object[], value: org.codehaus.groovy.reflection.ClassInfo class ClassInfo
<- elementData - class: java.util.Vector, value: java.lang.Object[] #32667
<- classes (Java frame) - class: org.eclipse.jetty.webapp.WebAppClassLoader, value: java.util.Vector #14
this - value: groovy.lang.GroovyClassLoader #106
<- delegate - class: groovy.lang.GroovyClassLoader$InnerLoader, value: groovy.lang.GroovyClassLoader #106
<- <classLoader> - class: get_oas_releases$_run_closure2, value: groovy.lang.GroovyClassLoader$InnerLoader #128
<- klazz - class: org.codehaus.groovy.reflection.ClassInfo, value: get_oas_releases$_run_closure2 class get_oas_releases$_run_closure2
<- value - class: org.codehaus.groovy.reflection.GroovyClassValuePreJava7$EntryWithValue, value: org.codehaus.groovy.reflection.ClassInfo #2146
<- [14122] - class: java.lang.Object[], value: org.codehaus.groovy.reflection.GroovyClassValuePreJava7$EntryWithValue #2113
<- table - class: org.codehaus.groovy.reflection.GroovyClassValuePreJava7$GroovyClassValuePreJava7Segment, value: java.lang.Object[] #577746
<- [8] - class: org.codehaus.groovy.util.AbstractConcurrentMapBase$Segment[], value: org.codehaus.groovy.reflection.GroovyClassValuePreJava7$GroovyClassValuePreJava7Segment #8
<- segments - class: org.codehaus.groovy.reflection.GroovyClassValuePreJava7$GroovyClassValuePreJava7Map, value: org.codehaus.groovy.util.AbstractConcurrentMapBase$Segment[] #1
<- map - class: org.codehaus.groovy.reflection.GroovyClassValuePreJava7, value: org.codehaus.groovy.reflection.GroovyClassValuePreJava7$GroovyClassValuePreJava7Map #1
<- globalClassValue - class: org.codehaus.groovy.reflection.ClassInfo, value: org.codehaus.groovy.reflection.GroovyClassValuePreJava7 #1
<- [1632] - class: java.lang.Object[], value: org.codehaus.groovy.reflection.ClassInfo class ClassInfo
<- elementData - class: java.util.Vector, value: java.lang.Object[] #32667
<- classes (Java frame) - class: org.eclipse.jetty.webapp.WebAppClassLoader, value: java.util.Vector #14
this - value: groovy.lang.GroovyClassLoader #145
<- delegate - class: groovy.lang.GroovyClassLoader$InnerLoader, value: groovy.lang.GroovyClassLoader #145
<- <classLoader> - class: Script1, value: groovy.lang.GroovyClassLoader$InnerLoader #167
<- klazz - class: org.codehaus.groovy.reflection.ClassInfo, value: Script1 class Script1
<- value - class: org.codehaus.groovy.reflection.GroovyClassValuePreJava7$EntryWithValue, value: org.codehaus.groovy.reflection.ClassInfo #1099
<- [5219] - class: java.lang.Object[], value: org.codehaus.groovy.reflection.GroovyClassValuePreJava7$EntryWithValue #883
<- table - class: org.codehaus.groovy.reflection.GroovyClassValuePreJava7$GroovyClassValuePreJava7Segment, value: java.lang.Object[] #557473
<- [15] - class: org.codehaus.groovy.util.AbstractConcurrentMapBase$Segment[], value: org.codehaus.groovy.reflection.GroovyClassValuePreJava7$GroovyClassValuePreJava7Segment #1
<- segments - class: org.codehaus.groovy.reflection.GroovyClassValuePreJava7$GroovyClassValuePreJava7Map, value: org.codehaus.groovy.util.AbstractConcurrentMapBase$Segment[] #1
<- map - class: org.codehaus.groovy.reflection.GroovyClassValuePreJava7, value: org.codehaus.groovy.reflection.GroovyClassValuePreJava7$GroovyClassValuePreJava7Map #1
<- globalClassValue - class: org.codehaus.groovy.reflection.ClassInfo, value: org.codehaus.groovy.reflection.GroovyClassValuePreJava7 #1
<- [1632] - class: java.lang.Object[], value: org.codehaus.groovy.reflection.ClassInfo class ClassInfo
<- elementData - class: java.util.Vector, value: java.lang.Object[] #32667
<- classes (Java frame) - class: org.eclipse.jetty.webapp.WebAppClassLoader, value: java.util.Vector #14
increase your jenkins memory size