Sure. The errors I saw manifested themselves as unsuccessful results in View
Results Tree, etc. The statement
openDocument(null).getDocumentElement();
at about line 405 in WebServiceSampler.jar was throwing a null pointer
exception, because the call to XDB.parse() was failing inside openDocument()
(because document builders are not thread safe). The null pointer exception
was caught at line 595 of WebServiceSampler.java, resulting in a call to
RESULT.setSuccessful(false)--hence, the unsuccessful result.
I personally found it easier to reproduce the problem by hitting a very
simple web service on another machine from a basic multi-threaded test plan.
I guess the key is to spend as little time as possible invoking the web
service, so that proportionally more time is spent preparing the call--thus
increasing the odds of finding more than one thread in the problematic code.
I have to say that I'm mystified by the practice of catching exceptions and
failing silently as demonstrated in openDocument(). I hope that's just
temporary.
-- KiYun
-----Original Message-----
From: Peter Lin [mailto:[EMAIL PROTECTED]
Sent: Thursday, March 31, 2005 10:53 PM
To: JMeter Developers List
Subject: Re: WebSerivceSampler not thread safe
thanks for the patch, i'll take a look this weekend when I get a
chance. Out of curiousity, what kind of errors are you seeing. I've
tested and profiled the sampler on several occasions using OptimizeIt
and wasn't able to see any errors. any additional information you can
provide would help make sure the bug is really fixed.
thanks
peter
On Mar 31, 2005 9:38 PM, KiYun Roe <[EMAIL PROTECTED]> wrote:
> Hi,
>
> There's a comment at about line 108 of
org.apache.jmeter.protocol.http.sampler.WebServiceSampler.java expressing
concern that sharing a single DocumentBuilder might not be thread safe.
Well, it's not. This explains the intermittent, mysterious failures that
I've seen testing a web service from multiple JMeter threads.
>
> Here's a possible patch using a ThreadLocal to allocate one
DocumentBuilder per thread. I'm new to Jakarta. How do I get this into the
source distribution?
>
> Thanks.
>
> -- KiYun Roe
>
> Index:
src/protocol/http/org/apache/jmeter/protocol/http/sampler/WebServiceSampler.
java
> ===================================================================
> RCS file:
/home/cvspublic/jakarta-jmeter/src/protocol/http/org/apache/jmeter/protocol/
http/sampler/WebServiceSampler.java,v
> retrieving revision 1.17
> diff -b -u -w -r1.17 WebServiceSampler.java
> ---
src/protocol/http/org/apache/jmeter/protocol/http/sampler/WebServiceSampler.
java 6 Jan 2005 01:11:43 -0000 1.17
> +++
src/protocol/http/org/apache/jmeter/protocol/http/sampler/WebServiceSampler.
java 1 Apr 2005 02:16:39 -0000
> @@ -112,7 +112,14 @@
> * consider using Apache commons pool to create a pool of document
builders
> * or make sure XMLParserUtils creates builders efficiently.
> */
> - private static DocumentBuilder XDB = null;
> + private static ThreadLocal ThreadLocalXDB =
> + new ThreadLocal()
> + {
> + protected Object initialValue()
> + {
> + return XMLParserUtils.getXMLDocBuilder();
> + }
> + };
>
> private String FILE_CONTENTS = null;
>
> @@ -413,10 +420,7 @@
> */
> protected Document openDocument(String key)
> {
> - if (XDB == null)
> - {
> - XDB = XMLParserUtils.getXMLDocBuilder();
> - }
> + DocumentBuilder XDB = (DocumentBuilder)
ThreadLocalXDB.get();
> Document doc = null;
> // if either a file or path location is given,
> // get the file object.
>
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