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Posted to dev@tomcat.apache.org by bu...@apache.org on 2016/12/19 03:54:33 UTC
[Bug 60497] New: JSP custom tags returned to the tag pools to be
reused without executing the doEndTag method
https://bz.apache.org/bugzilla/show_bug.cgi?id=60497
Bug ID: 60497
Summary: JSP custom tags returned to the tag pools to be reused
without executing the doEndTag method
Product: Tomcat 8
Version: 8.5.5
Hardware: PC
OS: All
Status: NEW
Severity: critical
Priority: P2
Component: Jasper
Assignee: dev@tomcat.apache.org
Reporter: wklo@destinysolutions.com
Target Milestone: ----
As a result of the modification made in the change set "1754112 Improve the
error handling for custom tags to ensure that the tag is returned to the pool
or released and destroyed once used", Tomcat server version 8.5.5 (or higher up
to 8.5.9) will return a JSP custom tag instance back to the tag pool for reuse,
even after the execution of the tag's doStartTag method throws an exception.
This violates the JSP specification that specifies that JSP tags should never
be reused in case of an exception.
We ran into a problem when running a Struts 1 application that makes use of the
Struts Nested tag library under Tomcat 8.5.5. (We have similar problems for the
DisplayTag as well.) Here is a simplified example to illustrate the problem.
Consider the following three simple Java classes, namely, Form.java,
Parent.java, and Child.java:
public class Form {
private List<Parent> parents;
public List<Parent> getParents() {
return parents;
}
public void setParents(List<Parent> parents) {
this.parents = parents;
}
}
public class Parent {
private String name;
private List<Child> children;
public Parent(String name) {
this.name = name;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public List<Child> getChildren() {
return children;
}
public void setChildren(List<Child> children) {
this.children = children;
}
}
public class Child {
private String name;
private Parent parent;
public Child(String name){
this.name = name;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Parent getParent() {
return parent;
}
public void setParent(Parent parent) {
this.parent = parent;
}
}
Suppose we have two JSPs, say page1.jsp and page2.jsp, such that page1.jsp
includes page2.jsp and that both page1.jsp and page2.jsp include a
nested:iterate tag for rendering information contained in a Form instance.
page1.jsp
---------
<nested:iterate id="parent" name="form" property="parents" indexId="id">
<jsp:include page="/page2.jsp"/>
</nested:iterate>
page2.jsp
---------
<nested:iterate id="child" property="children" indexId="id">
... code that makes use of child ....
</nested:iterate>
Based on the current tag pool implementation, Tomcat will maintain two distinct
tag pools for the nested:iterate tag, one for page1.jsp and the other for
page2.jsp.
Under normal execution, i.e., without exception, the object referenced by the
nested:iterate tag defined on page2.jsp from which the "children" property will
be retrieved is a Parent instance, which is initialized by the nested:iterate
tag defined on page1.jsp. However, if the execution of the nested:iterate tag's
body defined on page2.jsp throws an exception, the name property of the tag
instance will be incorrectly and permanently set to be "form", after the tag
instance is returned back to the pool (associated with page2.jsp) to be reused.
As a result, all subsequent executions of page2.jsp that make use of the
corrupted nested:iterate tag instance will throw an exception, since the
Form.java class does not contain a property named "children".
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[Bug 60497] JSP custom tags returned to the tag pools to be reused
without executing the doEndTag method
Posted by bu...@apache.org.
https://bz.apache.org/bugzilla/show_bug.cgi?id=60497
--- Comment #5 from Wai-Kau Lo <wk...@destinysolutions.com> ---
I think the JSP spec clearly states that we should not reuse a JSP tag instance
if its doStartTag method execution raises an exception, as I explained in my
previous comment.
Also, this is clearly a regression issue introduced by changset set 1754112 in
Tomcat 8.5.5, which fortunately has not been ported back to the Tomcat 9.0
release branch. I am hoping we can roll back this changeset in the Tomcat 8.5
release branch.
Finally, JSP Custom Tag Pooling has been highlighted in the "Jasper 2 JSP
Engine How To" section as a significant performance booster.
JSP Custom Tag Pooling - The java objects instantiated for JSP Custom Tags can
now be pooled and reused. This significantly boosts the performance of JSP
pages which use custom tags.
Since our application depends heavily on custom tags, I am just hesitant to
simply turn off tag pooling with conducting some performance tests first.
In the meantime, I guess the only recourse is to compile my own Jasper engine.
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[Bug 60497] JSP custom tags returned to the tag pools to be reused
without executing the doEndTag method
Posted by bu...@apache.org.
https://bz.apache.org/bugzilla/show_bug.cgi?id=60497
--- Comment #7 from Wai-Kau Lo <wk...@destinysolutions.com> ---
Created attachment 34543
--> https://bz.apache.org/bugzilla/attachment.cgi?id=34543&action=edit
Test web application
Attached is a self-contained web application that can be used to replicate the
issue.
After deploying the test.war file on a Tomcat Server of version 8.5.5 (or
higher up to 8.5.9), access the following two URLs in sequence:
1) http://localhost:8080/test/test/page1.jsp
You will receive a NullPointerException from page2.jsp as expected.
java.lang.NullPointerException
org.apache.jsp.test.page2_jsp._jspService(page2_jsp.java:151)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
........................
2) http://localhost:8080/test/test/page1.jsp?childName=name
Instead of the expected response shown below
Parent Name: Parent1
Child Name: name contains 4 characters
you will receive the following JspException:
javax.servlet.jsp.JspException: No getter method for property: "children" of
bean: "form"
org.apache.struts.taglib.TagUtils.lookup(TagUtils.java:987)
org.apache.struts.taglib.logic.IterateTag.doStartTag(IterateTag.java:232)
org.apache.struts.taglib.nested.logic.NestedIterateTag.doStartTag(NestedIterateTag.java:73)
org.apache.jsp.test.page2_jsp._jspService(page2_jsp.java:135)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
..............
This is caused by the "corrupted" nested:iterate tag instance cached in the tag
pool after processing the first URL.
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[Bug 60497] JSP custom tags returned to the tag pools to be reused
without executing the doEndTag method
Posted by bu...@apache.org.
https://bz.apache.org/bugzilla/show_bug.cgi?id=60497
--- Comment #6 from Remy Maucherat <re...@apache.org> ---
Created attachment 34540
--> https://bz.apache.org/bugzilla/attachment.cgi?id=34540&action=edit
Change reuse logic
I'm not convinced by the explanation. Adding some more complexity to the
generated code if the issue is found to be legitimate. And for review too.
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[Bug 60497] JSP custom tags returned to the tag pools to be reused
without executing the doEndTag method
Posted by bu...@apache.org.
https://bz.apache.org/bugzilla/show_bug.cgi?id=60497
--- Comment #4 from Remy Maucherat <re...@apache.org> ---
I didn't find anything that was very clear either, which is why I asked. I'd
recommend you disable tag pooling for now, it's probably not that useful
anymore.
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[Bug 60497] JSP custom tags returned to the tag pools to be reused
without executing the doEndTag method
Posted by bu...@apache.org.
https://bz.apache.org/bugzilla/show_bug.cgi?id=60497
--- Comment #1 from Remy Maucherat <re...@apache.org> ---
(In reply to Wai-Kau Lo from comment #0)
> This violates the JSP specification that specifies
> that JSP tags should never be reused in case of an exception.
Can you provide the spec language which states this ?
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[Bug 60497] JSP custom tags returned to the tag pools to be reused
without executing the doEndTag method
Posted by bu...@apache.org.
https://bz.apache.org/bugzilla/show_bug.cgi?id=60497
Remy Maucherat <re...@apache.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |FIXED
Status|NEW |RESOLVED
--- Comment #9 from Remy Maucherat <re...@apache.org> ---
I applied the patch and it will be included in 9M16, 8.5.10, 8.0.40, 7.0.74 and
6.0.49. It is possible the new behavior gets reintroduced in 8.5 and 9 after it
is reviewed.
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[Bug 60497] JSP custom tags returned to the tag pools to be reused
without executing the doEndTag method
Posted by bu...@apache.org.
https://bz.apache.org/bugzilla/show_bug.cgi?id=60497
Michael Osipov <19...@gmx.net> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |1983-01-06@gmx.net
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[Bug 60497] JSP custom tags returned to the tag pools to be reused
without executing the doEndTag method
Posted by bu...@apache.org.
https://bz.apache.org/bugzilla/show_bug.cgi?id=60497
--- Comment #10 from M. Manna <ma...@gmail.com> ---
Hello,
We would like to go for TC 8.5.14 or 8.5.15. Will this patch be available
there?
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[Bug 60497] JSP custom tags returned to the tag pools to be reused
without executing the doEndTag method
Posted by bu...@apache.org.
https://bz.apache.org/bugzilla/show_bug.cgi?id=60497
--- Comment #3 from Wai-Kau Lo <wk...@destinysolutions.com> ---
Page 2-54 of the JavaServer Pages Specification version 2.0 describes the
lifecycle of a JSP tag instance using a state transition diagram, which I have
uploaded to this bug as an attachment (named JSP Tag Lifecycle Diagram) for
ease of reference. The state transitions are described as follows:
•[1] This transition is intended to be for releasing long-term data. no
guarantees are assumed on whether any properties have been retained or not.
•[2] This transition happens if and only if the tag ends normally without
raising
an exception
•[3] Some setters may be called again before a tag handler is reused. For
instance, setParent() is called if it’s reused within the same page but at a
different level, setPageContext() is called if it’s used in another page, and
attribute setters are called if the values differ or are expressed as
request-time attribute values.
Label [2] corresponds to the state transition caused by the execution of the
doEndTag method, after the doStartTag method is execution. This implies that
the doEndTag method should not be executed if the doStartTag method execution
raises an exception. Since the doEndTag method is not executed, the tag
instance will not be in a proper state for the next execution of the
doStartTag, implying that we should never reuse the tag instance if the
doStartTag method raises an exception during its execution.
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[Bug 60497] JSP custom tags returned to the tag pools to be reused
without executing the doEndTag method
Posted by bu...@apache.org.
https://bz.apache.org/bugzilla/show_bug.cgi?id=60497
Remy Maucherat <re...@apache.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Attachment #34540|0 |1
is obsolete| |
--- Comment #8 from Remy Maucherat <re...@apache.org> ---
Created attachment 34544
--> https://bz.apache.org/bugzilla/attachment.cgi?id=34544&action=edit
Reuse exclusion and try/finally for simple tags
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[Bug 60497] JSP custom tags returned to the tag pools to be reused
without executing the doEndTag method
Posted by bu...@apache.org.
https://bz.apache.org/bugzilla/show_bug.cgi?id=60497
--- Comment #2 from Wai-Kau Lo <wk...@destinysolutions.com> ---
Created attachment 34534
--> https://bz.apache.org/bugzilla/attachment.cgi?id=34534&action=edit
JSP Tag Lifecycle Diagram
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