sboag 01/01/09 14:41:39
Modified: java/src/org/apache/xalan/transformer TransformerImpl.java
Log:
At least for now, I commented out the m_reportInPostExceptionFromThread stuff
altogether. I'm a little worried that this could cause problems with
diagnostics from piped transforms, but hopefully the call to setExceptionThrown
to the input handler should cover this. In any case, the setting of
m_reportInPostExceptionFromThread seemed pretty funky to me.
Response to note sent by Nicola Brown <[EMAIL PROTECTED]>
01/08/2001 08:36 AM
=====
Get the transformer thread via createTransformerThread. From email
on this subject:
In response to this I've created the following method in
org.apache.xalan.TransformerImpl:
/**
* Create a thread for the transform. This can be overridden by derived
* implementations to provide their own thread, for thread pooling and the
* like.
*
* @return thread suitable to use for the transformation.
*/
public Thread createTransformThread()
{
return new Thread(this);
}
Someone who is using XalanJ2 in an EJB environment or the like can set the
javax.xml.transform.TransformerFactory system property to provide a derivation
from TransformerImpl, and provide a thread suitable for the environment.
I don't know if this will do the trick. Please advise.
-scott
"Roytman, Alex" <[EMAIL PROTECTED]> 01/07/2001 12:14 AM Please respond
to xalan-dev To: "'[email protected]'" <[email protected]>
cc: "'[email protected]'" <[email protected]>, (bcc:
Scott Boag/CAM/Lotus) Subject: Xalan2 in server environment (was Xalan2 Stree
Module spans sec ond thread to do transform?)
Scott,
Thank you very much for your reply.
One part which is sensitive to thread origin in my opinion is Extensions
In extensions people can do all sorts of things. I am not very experienced
with EJB implementation but I can imagine that many things (transactional
context, bean environment, etc.) depend on threads and some static variables
which helps with setting /switching context for beans being managed by the
server.
Example: in J2EE it is recommended to create JNDI initial context using
default constructor InitialContext(). The result of the instantiation
depends on the context where it was executed and the context is set by the
server for the thread on which your component is running. So if you call new
InitialContext() in your extension (in sql extension to get JDBC DataSource
for example ) it might fail.
Do extension run on the second (created by Xalan) thread?
I will forward your message to Tomcat news group lets see what Tomcat
developers think.
Alex
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Sent: Saturday, January 06, 2001 11:39 PM
To: [email protected]
Subject: Re: Xalan2 Stree Module spans second thread to do transform?
> In many
> cases component should not attempt to create its own threads.
> For example thread's ContextClassLoader or ThreadLocal variables might
need
> to be initialized by the server.
> Also it defeats thread pooling done by the server etc.
>
> Could you please comment on this issue
Yeah, I've been a bit worried about this. However, I've not yet heard of
any problems that have been caused by it, and XalanJ1 has long had a two
threaded system (though not as effective as in XalanJ2). Ultimately, I
would rather use a pull model for this, and only have one thread, but a)
there is no standard "pull" API for XML parsers, and b) this doesn't work
anyway when SAX events are used, for whatever reason.
I'm open to any input to how Xalan might request the thread from the
servlet environment, though it has to be able to be run outside a servlet
environment too. Also, it would be good if someone with deep knowledge of
EJB's and the like could comment. I talked this over in a hallway
conversation with someone who is fairly familiar with EJB's, and he didn't
think there was a problem, though I forget why. It seems insane/crazy to
me that a component can't use a thread in it's internal modules.
-scott
"Roytman,
Alex" To:
"'[email protected]'" <[email protected]>
<[EMAIL PROTECTED] cc: (bcc: Scott
Boag/CAM/Lotus)
etech.com> Subject: Xalan2 Stree Module
spans second thread to do transform?
01/06/2001
10:48 PM
Please respond
to xalan-dev
Dear Xalan developers,
I have a question about using upcoming Xalan2 in server env.
In Xalan2 design specs it is said:
"The Stree module implements the default Source Tree for Xalan, that is to
be transformed. It implements read-only DOM2 interfaces, and provides some
information needed for fast transforms, such as document order indexes. It
also attempts to allow a streaming transform by launching the transform on
a
secondary thread as soon as the SAX2 StartDocument event has occurred."
In server environment server usually controls threads creation. In many
cases component should not attempt to create its own threads.
For example thread's ContextClassLoader or ThreadLocal variables might need
to be initialized by the server.
Also it defeats thread pooling done by the server etc.
Could you please comment on this issue
Thank you very much in advance
Alex Roytman
Revision Changes Path
1.73 +32 -17
xml-xalan/java/src/org/apache/xalan/transformer/TransformerImpl.java
Index: TransformerImpl.java
===================================================================
RCS file:
/home/cvs/xml-xalan/java/src/org/apache/xalan/transformer/TransformerImpl.java,v
retrieving revision 1.72
retrieving revision 1.73
diff -u -r1.72 -r1.73
--- TransformerImpl.java 2001/01/09 18:14:42 1.72
+++ TransformerImpl.java 2001/01/09 22:41:38 1.73
@@ -231,15 +231,17 @@
m_textformat = new OutputProperties(Method.Text);
}
- /**
- * Flag to let us know if an exception should be reported inside the
- * postExceptionFromThread method. This is needed if the transform is
- * being generated from SAX events, and thus there is no central place
- * to report the exception from. (An exception is usually picked up in
- * the main thread from the transform thread in [EMAIL PROTECTED]
#transform(Source source)}
- * from [EMAIL PROTECTED] #getExceptionThrown()}. )
- */
- private boolean m_reportInPostExceptionFromThread = true;
+ // Commenteded out in response to problem reported by
+ // Nicola Brown <[EMAIL PROTECTED]>
+// /**
+// * Flag to let us know if an exception should be reported inside the
+// * postExceptionFromThread method. This is needed if the transform is
+// * being generated from SAX events, and thus there is no central place
+// * to report the exception from. (An exception is usually picked up in
+// * the main thread from the transform thread in [EMAIL PROTECTED]
#transform(Source source)}
+// * from [EMAIL PROTECTED] #getExceptionThrown()}. )
+// */
+// private boolean m_reportInPostExceptionFromThread = false;
/** A node vector used as a stack to track the current
* ElemTemplateElement. Needed for the
@@ -393,7 +395,7 @@
// For now, reset the document cache each time.
getXPathContext().getSourceTreeManager().reset();
- m_reportInPostExceptionFromThread = false;
+// m_reportInPostExceptionFromThread = false;
}
// ========= Transformer Interface Implementation ==========
@@ -574,8 +576,8 @@
}
else
{
- Thread t = new Thread(this);
- m_reportInPostExceptionFromThread = true;
+ Thread t = createTransformThread();
+// m_reportInPostExceptionFromThread = false;
t.start();
transformNode(doc);
}
@@ -2697,6 +2699,18 @@
////////////////////////
// Implement Runnable //
////////////////////////
+
+ /**
+ * Create a thread for the transform. This can be overridden by derived
+ * implementations to provide their own thread, for thread pooling and the
+ * like.
+ *
+ * @return thread suitable to use for the transformation.
+ */
+ public Thread createTransformThread()
+ {
+ return new Thread(this);
+ }
/**
* Get the exception thrown by the secondary thread (normally
@@ -2740,11 +2754,12 @@
*/
void postExceptionFromThread(Exception e)
{
- if(m_reportInPostExceptionFromThread)
- {
- // Consider re-throwing the exception if this flag is set.
- e.printStackTrace();
- }
+ // Commented out in response to problem reported by Nicola Brown <[EMAIL
PROTECTED]>
+// if(m_reportInPostExceptionFromThread)
+// {
+// // Consider re-throwing the exception if this flag is set.
+// e.printStackTrace();
+// }
if (m_inputContentHandler instanceof SourceTreeHandler)
{
