Monday, 12 May 2008
|
| System.currentTimeMillis() on SMP systems Rodrick Brown 06:58:48 |
| | I'm stress testing my backend server and I wrote a small client application
that uses System.currentTimeMillis() on various operations the results dont
seem to be consistent with what I would expect my system is a 8 core Intel
x64 class machine running 64 Bit linux. I heard about issues with
System.currentTimeMillis() on SMP machines is this true? Is there a better
approach I should be taking?
--
[ Rodrick R. Brown ]
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| |  8 answers | Add comment |
Thursday, 8 May 2008
|
| [Messaging, JMS & JBossMQ] - How to configure the number of MDB instances for a queue to Rameshsr 14:52:19 |
| | I have an MDB listener (onMessage), meant for listening for messages from a particular queue. I want the messages in the queue to be processed serially in the order in which they arrived. This means, I can't have multiple instances of the MDB listensing on this queue. So, I want to restrict the number of MDB instances listening to this queue to 1. Is this configurable in JBoss and how do I do this?
View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3924995#3924995
Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&p=3924995
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| | 1 answer | Add comment |
|
| Hibernate and Multiple Session Factories Matt Johnston 09:35:40 |
| | My application is needing to connect to two seperate databases. According to Hibernate documentation, I will need to use seperate session factories.
Right now I am using the HibernateInterceptor written by Gavin King (http://www.hibernate.org/hib_docs/online/adminapp/) Unfortunately, it can only grab one session factory for Hibernate.
Has anyone found a way to easily use more than one hibernate session factory?
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| | 5 answers | Add comment |
|
| Question about broken pipe Michael Szalay 04:52:03 |
| |
Hi all
I've got a question about an exception message I often see in the log of my Jetty installation (see stack trace below). Its in a servlet reading a blob out of a database and writing the byte-stream back into the servlet output stream. It works fine, I've never heard any complaints from users. Does
anyone know if this message can be ignored?
Thanks for an answer
Regards
Michael
EOFException(java.net.SocketException: Broken pipe)
at org.mortbay.http.BufferedOutputStream.flush(BufferedOutputStream.java:196)
at org.mortbay.http.ChunkingOutputStream.flush(ChunkingOutputStream.java:69)
at org.mortbay.http.BufferedOutputStream.write(BufferedOutputStream.java:143)
at org.mortbay.http.HttpOutputStream.write(HttpOutputStream.java:438)
at org.mortbay.http.HttpOutputStream.write(HttpOutputStream.java:430)
at org.mortbay.jetty.servlet.ServletOut.write(ServletOut.java:35)
at ImageServlet.processRequest(Unknown Source)
at ImageServlet.doGet(Unknown Source)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:740)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:360)
at org.mortbay.jetty.servlet.WebApplicationHandler.dispatch(WebApplicationHandler.java:294)
at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:558)
at org.mortbay.http.HttpContext.handle(HttpContext.java:1723)
at org.mortbay.jetty.servlet.WebApplicationContext.handle(WebApplicationContext.java:507)
at org.mortbay.http.HttpContext.handle(HttpContext.java:1673)
at org.mortbay.http.HttpServer.service(HttpServer.java:863)
at org.mortbay.http.HttpConnection.service(HttpConnection.java:775)
at org.mortbay.http.HttpConnection.handleNext(HttpConnection.java:939)
at org.mortbay.http.HttpConnection.handle(HttpConnection.java:792)
at org.mortbay.http.SocketListener.handleConnection(SocketListener.java:201)
at org.mortbay.util.ThreadedServer.handle(ThreadedServer.java:289)
at org.mortbay.util.ThreadPool$PoolThread.run(ThreadPool.java:455)
getTargetException():
java.net.SocketException: Broken pipe
at java.net.SocketOutputStream.socketWrite0(Native Method)
at java.net.SocketOutputStream.socketWrite(SocketOutputStream.java:92)
at java.net.SocketOutputStream.write(SocketOutputStream.java:136)
at org.mortbay.http.NullableOutputStream.write(NullableOutputStream.java:119)
at org.mortbay.util.ByteBufferOutputStream.writeTo(ByteBufferOutputStream.java:160)
at org.mortbay.http.BufferedOutputStream.flush(BufferedOutputStream.java:192)
at org.mortbay.http.ChunkingOutputStream.flush(ChunkingOutputStream.java:69)
at org.mortbay.http.BufferedOutputStream.write(BufferedOutputStream.java:143)
at org.mortbay.http.HttpOutputStream.write(HttpOutputStream.java:438)
at org.mortbay.http.HttpOutputStream.write(HttpOutputStream.java:430)
at org.mortbay.jetty.servlet.ServletOut.write(ServletOut.java:35)
at ImageServlet.processRequest(Unknown Source)
at ImageServlet.doGet(Unknown Source)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:740)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:360)
at org.mortbay.jetty.servlet.WebApplicationHandler.dispatch(WebApplicationHandler.java:294)
at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:558)
at org.mortbay.http.HttpContext.handle(HttpContext.java:1723)
at org.mortbay.jetty.servlet.WebApplicationContext.handle(WebApplicationContext.java:507)
at org.mortbay.http.HttpContext.handle(HttpContext.java:1673)
at org.mortbay.http.HttpServer.service(HttpServer.java:863)
at org.mortbay.http.HttpConnection.service(HttpConnection.java:775)
at org.mortbay.http.HttpConnection.handleNext(HttpConnection.java:939)
at org.mortbay.http.HttpConnection.handle(HttpConnection.java:792)
at org.mortbay.http.SocketListener.handleConnection(SocketListener.java:201)
at org.mortbay.util.ThreadedServer.handle(ThreadedServer.java:289)
at org.mortbay.util.ThreadPool$PoolThread.run(ThreadPool.java:455)
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| | 7 answers | Add comment |
Wednesday, 7 May 2008
|
| javacvs client: PServerConnection not connecting. Vadiraj Deshpande 14:08:00 |
| | Hi ,
I wrote a method to connect to a CVS server like below. When I run this
code, I got the following exception:
======================================================================================
org.netbeans.lib.cvsclient.connection.AuthenticationException:
Authentication failed. Response from server was: "cvs [pserve".
at
org.netbeans.lib.cvsclient.connection.PServerConnection.openConnection(
PServerConnection.java:238)
======================================================================================
I checked the cvs protocol<http://www.delorie.com/gnu/docs/cvs/cvsclient_3.html>
I do not see why the connection returns : "cvs [pserve".
obviously something wrong going on with the connection code..
Can somebody help me here? All the input data are proper and CVSRoot object
has the right values.
The code follows:
======================================================================================
private static PServerConnection getPServerCVSConnection(CVSRoot cvsRoot)
throws
AuthenticationException, CommandAbortedException {
System.out.println("Got cvsroot as : " + cvsRoot.toString());//DEBUG
System.out.println("hostname: " + cvsRoot.getHostName());//DEBUG
System.out.println("Password : " +
getEncodedCVSPassword(cvsRoot));//DEBUG
System.out.println("username : " + cvsRoot.getUserName());//DEBUG
System.out.println("repository: " + cvsRoot.getRepository());//DEBUG
//cvsRoot.setPassword(getEncodedCVSPassword(cvsRoot));
PServerConnection c = new PServerConnection(cvsRoot);
c.setUserName(cvsRoot.getUserName());
c.setEncodedPassword(getEncodedCVSPassword(cvsRoot));
c.setHostName(cvsRoot.getHostName());
// c.setPort(cvsRoot.getPort());
System.out.println("CVS port from cvsroot " + cvsRoot.getPort
());//DEBUG
c.setRepository(cvsRoot.getRepository());
c.open(); // Here the exception is thrown.
return c;
}
|
| | 2 answer | Add comment |
Friday, 25 April 2008
|
| Permission denied Guest 21:34:01 |
| | Today moved to anthill v1.6.3 because the workspace is now removed before the build and not "after" (1.5.3).
However all the files are extracted with read only permissions which causes the following error when it tries to update the version file ...
13:42:03:307 [Thread - AnthillBuildDaemon] ERROR com.urbancode.anthill.BuildManager - /hfx/home/develop/ssbuild/superstructure/ss1/ssab2/manifest/fooVersion.txt (Permission denied)
java.io.FileNotFoundException: /hfx/home/develop/ssbuild/superstructure/ss1/ssab2/manifest/fooVersion.txt (Permission denied)
Is there a solution?
Simon
Simon Richardson> Technology> Tel: 020 7574 8838> E Mail: simonrichardson2-bUHX2rxDcLHQT0dZR+AlfA@public.gmane.org> HBOS Treasury Services plc> 33 Old Broad Street> London> EC2N 1HZ>
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| | 17 answers | Add comment |
Thursday, 24 April 2008
|
| jboss-head-jdks Build Failed Guest 12:52:58 |
| | View results here ->
http://cruisecontrol.jboss.com/cc/buildresults/jboss-head-jdks?log=log20041029043622 [http://cruisecontrol.jboss.com/cc/buildresults/jboss-head-jdks?log=log20041029043622]
BUILD FAILED
Ant Error Message: /home/cruisecontrol/work/scripts/build-jboss-head.xml:66:
The following error occurred while executing this line:
/home/cruisecontrol/work/scripts/build-jboss-head.xml:34: Exit code: 1
See compile_jdk15.log in Build Artifacts for details.
JAVA_HOME=/opt/jdk1.5.0/
Date of build: 10/29/2004 04:36:22
Time to build: 16 minutes 44 seconds
Last changed: 10/29/2004 03:58:39
Last log entry: Fixed TX removal: local transactions are now removed
correctly
Unit Tests: (0) Total Errors and Failures: (0)
Modifications since last build: (8)
1.11
modified
belaban
cache/src/main/org/jboss/cache/interceptors/ReplicationInterceptor.java
Fixed TX removal: local transactions are now removed correctly
1.8
modified
belaban
cache/src/main/org/jboss/cache/interceptors/TransactionInterceptor.java
Fixed TX removal: local transactions are now removed correctly
1.5
modified
belaban
cache/src/main/org/jboss/cache/interceptors/CacheLoaderInterceptor.java
Fixed TX removal: local transactions are now removed correctly
1.11
modified
belaban
testsuite/src/main/org/jboss/test/cache/test/local/TxUnitTestCase.java
no message
1.3
modified
recampbell
tools/etc/cruisecontrol/TODO
move jdk& testsuite to toplevel projects
1.1
added
recampbell
tools/etc/cruisecontrol/scripts/cc-config-head-jdks.xml
move jdk& testsuite to toplevel projects
1.1
added
recampbell
tools/etc/cruisecontrol/scripts/cc-config-head-testsuite.xml
move jdk& testsuite to toplevel projects
1.3
modified
recampbell
tools/etc/cruisecontrol/scripts/cc-config.xml
move jdk& testsuite to toplevel projects
|
| | 4 answer | Add comment |
|
| [ jboss-Bugs-626484 ] Incorrect libraries classpath? Guest 11:57:34 |
| | Bugs item #626484, was opened at 2002-10-21 20:58
You can respond by visiting:
https://sourceforge.net/tracker/?func=detail&atid=376685&aid=626484&group_id=22866
Category: Build System
Group: CVS HEAD
Status: Open
Resolution: None
Priority: 5
Submitted By: ycswyw (ycswyw)
Assigned to: Jason Dillon (user57)
Summary: Incorrect libraries classpath?
Initial Comment:
In CVS of jboss4.0.0alpha, thirdparty libraries are
structured as "${project.thirdparty}/vendor/product",
but in
"jboss-all/tools/etc/buildfragments/libraries.ent" are
referenced as "${project.thirdparty}/vendor-product".
The attached file is a replacement of "libraries.ent",
to fix the problem.
----------------------------------------------------------------------
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| | 1 answer | Add comment |
|
| How does thirdparty/libraries.ent get created? Bill Burke 11:25:13 |
| |
--
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Chief Architect
JBoss Inc.
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| | 2 answer | Add comment |
Tuesday, 22 April 2008
|
| Internationalization and Java Strings Avinash Lakshman 20:36:13 |
| | Hi
I have been reading up a bit on Internationalization and how the Collation API's help out with searching and sorting of Strings etc. But if I had a need to store a String to file and this String could have weird characters in them how should I be storing them. Should I convert it to a byte[] and store them, use the writeUTF() method on one of the OutputStream classes or should I be doing something special? The requirement is I store them and later retrieve them for various comparisons against strings that would have weird characters in them. For eg. I would store a string "Can " and later retrieve it to compare it with some string that gets passed in via some method call. What is the best way of doing this? If I store them using writeUTF() and later read them using readUTF() would the special characters be stripped out?
Thanks
Avinash
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| | 2 answer | Add comment |
|
| Roles Rick LaBanca 15:14:12 |
| | A general question about roles and where things go in jboss.
I realize j2ee has the roles of the developer, assembler, deployer. Too big
for some, but I see the point for large companies.
Right now, unless 3.2 changed, the directories mash together apps and server
configs it seems. The deploy directory is the thing for me, and partially
lib. My apps go in there, but the web server, and cmp files also do.
I suppose I could make an extra appdeploy/ directory and just put apps in
there. I consider the current deploy directory really a system level area as
shipped. Just wondering what everyone else does.
Rick
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| | 8 answers | Add comment |
Monday, 21 April 2008
|
| Makefile. Charlie Wyse 07:45:18 |
| |
Hello. I'm trying to install php with apache on solaris 8 sparc. I
followed the directions and the compile and installation of php goes fine
but when I do the make for apache it goes into the src/modules/php4/ and
says "make: *** No targets. Stop." I went in that directory and checked all
the permissions and made sure everything was fine. There is a MAkefile and
Makefile.tmpl and a Makefile.libdir. However even when I type make in that
directory it gives me the same message. There are also 5
mod_php4.(c,exp,h,lo,o) files and a libmodphp4.a and libmodphp4.module file
in that directory aswell. Is there something I'm doing wrong?
|
| | 8 answers | Add comment |
Saturday, 19 April 2008
|
| Question on checking JNIEnv validity Don Rhummy 02:16:17 |
| | I am building some C++ classes that will be used by
other people. These classes work with JNI and can be
used in multiple threads (C++ created, not in Java). I
know this means that each thread created needs to get
a valid JNIEnv from the JavaVM.
The problem is that AttachCurrentThread is, I'm
guessing, quite an expensive call. So I want to "know"
when to call it. However, I can't seem to find a
function to tell me if the JNIEnv is valid or not. For
example a function such as EnvIsValid(JavaVM* vm,
JNIEnv* env). Is there a way to tell if the current
JNIEnv is valid without having to reload it?
Thanks!
Don
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| | Add comment |
Friday, 18 April 2008
|
| Consulting Hayley Greenberg 22:58:18 |
| | Hello,
Our company is looking for help in generating
printable reports that include charts and tables.
Do you know of anyone offering this service and
expertise?
Thank you,
Hayley Greenberg
LINX Test Systems, Inc.
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| | 1 answer | Add comment |
Thursday, 17 April 2008
|
| Java NIO: calling selector.select() before socketChannel.write() Sergey Marakhov 03:28:35 |
| | Hi all.
I'm looking at ways to simplify our current implementation of socket communications between an agent and multiple clients. There is a client connection object created per connected client, client connection is passed through an "incomingSelector" and each client connection opens its own outgoing selector. So, question 1: do I need to create separate outgoing selectors, or is using a single selector for both in and out operations is the way to go?
Next, before each invocation of socketChannel.write(...) method, we do outgoingSelector.select(). Is it necessary to do select() before write operations?
Our knowledge of NIO is rather limited, hence all this questions.
Much appreciated...
Thank you,
Sergey Marakhov
Phone: (613) 9811 8083
Quest Software
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| | 6 answers | Add comment |
|
| Re: Targeting WideScreen vs "Standard" Stephen Denne 01:12:24 |
| | Ken Gentle wrote
2) What are you personally using for your development/work computer? Widescreen or Standard? At what resolutions?
At work:
Laptop with 15" LCD 4x3 1400x1050, plus 19" LCD 4x3 1024x1280 (currently rotated 90deg as an experiment - not recommended as it usually requires turning cleartype off, and more severely limits your tolerable viewing angle)
Desktop with 19" LCD 4x3 1280x1024
Using synergy to get the effect of three monitors, (and multiple cores with very strong processor affinity!)
At home:
Laptop with 12" widescreen 1280x800
One thing I do with both widescreen displays, and multiple 4x3 displays is place the WinXP taskbar at the side of the screen.
I personally prefer more smaller monitors over one larger one, so that maximising application windows is a really quick and easy way of arranging multiple windows.
Regards,
Stephen Denne.
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| | Add comment |
Wednesday, 16 April 2008
|
| UI: Targeting WideScreen vs "Standard" Ken Gentle 19:00:42 |
| | Hello again...
This is really a two part question:
1) Have you adjusted your UI development to target wider but apparently
shorter screens? (Widescreen is 16:9 or 1.78:1; Standard is 4:3 or 1.33:1)
a) Have you attempted to provide a UI targeted to either, making
adjustments on the fly?
2) What are you personally using for your development/work computer?
Widescreen or Standard? At what resolutions? Any makes/models recommended
or recommended to avoid?
I bring up the first question because in several of my more recent gigs the
UI folks have seemed blissfully ignorant of the differences in the
displays. Depending on the "height" of the UI, what fits nicely on a 4:3
can extend past the bottom of a 16:9 causing scrolling or other user
annoyances.
The second is a more personal question - my 21" CRTs are reaching the end of
their useful lifetime and the opinions of folks who work similarly would be
appreciated. The reviews posted on most monitors assume game playing or
video -- I'm more interested in font sharpness, contrast and being able to
work behind it for hours.
I'm debating getting two 17 or 19 widescreens (almost impossible to find a
4:3 19 LCD, and they're more expensive than the 19" Widescreen) to replace
my 21" CRT - one for Eclipse/Idea/IDE and the other for
reference/browsers/etc.
How do you, Advanced Java person that you are, use/abuse your monitor(s)?
Thanks!
Ken
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| | 1 answer | Add comment |
|
| Out-of-Memory Handling in Long-Running / Server Applications Randall R Schulz 14:03:25 |
| | Hi,
My application has highly variable running times and memory demands
based on the problems submitted to it. Some hard-to-solve (or
insoluble) problems will run it out of memory.
When memory is exhausted in the inner loop of the program (the only
place it's going to happen), I catch the OutOfMemoryError, release the
storage, trigger a GC (forcing it would seem desirable, but I'm not
sure how to do that) and report the failure back up the call chain.
The vast majority of the RAM is used in the search tree, which is
linked only upwardly from the leaves and the leaves are all in a
priority queue, so relinquishing the priority queue is enough to make
all the objects in the tree unreferenceable.
This technique sometimes works and sometimes does not. I.e., when it
doesn't work the program gets another OOM very shortly after or during
the my OOM handling and dies.
Until recently, this application was mostly run from the command line so
this behavior was not such a big problem. Now it's being used much more
in its Web-App form (running in Tomcat 5.5, at the moment), this
inadequate handling is becoming a problem.
What techniques are available for handling OOM errors in situations
where simply dying on the spot is not an option?
Thanks.
Randall Schulz
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| | 59 answers | Add comment |
Tuesday, 15 April 2008
|
| Group Dynamics (WAS: Out-of-Memory Handling in Long-Running / Server Applications Peter Booth 21:31:09 |
| | This discussion has echoes of Amy Hoy's superbly perceptive blog posting
http://www.slash7.com/pages/vampires
Peter
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| | Add comment |
Monday, 14 April 2008
|
| Re: Non-Deterministic / Unpredictable Behavior (Again) [SOLVED] Randall R Schulz 00:16:59 |
| | On Thursday 10 April 2008 18:25, Randall R Schulz wrote:
Hi, Well, I've done the fine-tooth-comb routine and still have the problem of unrepeatable results. ...
Well, I finally found the problem.
The reason it escaped my attention was that I had an auxiliary class
used internally in a key indexing structure that (intentionally) used
identity equality semantics. Because I was using the default equals(),
I did not implement a hashCode() override.
Big mistake.
Oh, well, I cleaned up a lot of other stuff along the way.
Randall Schulz
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| | 6 answers | Add comment |
Sunday, 13 April 2008
|
| Jetty Sourceforge project list is empty?!? Ted Neward 03:01:47 |
| | I went to download the latest Jetty servlet container bits, and SourceForge
shows zero/nada/zip/zilch for released project files, and the download
history shows zero downloads over the last week. Is this a random cosmic
ray, or has anybody else here had problems downloading Jetty?
Ted Neward
Java, .NET, XML Services
Consulting, Teaching, Speaking, Writing
http://www.tedneward.com
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| | 3 answer | Add comment |
Friday, 11 April 2008
|
| Non-Deterministic / Unpredictable Behavior (Again) Randall R Schulz 17:53:25 |
| | Hi,
Well, I've done the fine-tooth-comb routine and still have the problem
of unrepeatable results.
Here's some more information:
- I use the "immutable after initialization" (IAI) pattern extensively.
- In going over my code, I noticed many places in equals() or hashCode()
implementations that were careful not to dereference null fields. In
the light of IAI, it seems this is just a bad idea (one wants to know
if equals() or hashCode() are being called before an instance is fully
initialized), so I removed those checks. Now if equals() or hashCode()
are invoked on incompletely constituted instances, they'll throw NPEs.
- All the classes in question are descendants of one of two abstract
classes. I added implementations of equals() and hashCode() in these
abstract classes, each (pair) of which throws a "subclass
responsibility" exception when invoked.
After all this, the unrepeatability of results remains.
I am completely baffled by this.
Are there _any_ ways a properly written, single-threaded program can
yield this kind of behavior?
Randall Schulz
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| RE: DWR problem WANG Chi 10:35:41 |
| | Hi all,
I installed appfuse 1.9.1 Spring MVC version. And when I input http://localhost:8080/appfuse/dwr in my browser, it displays an error page
javax.servlet.ServletException: Servlet.init() for servlet dwr-invoker threw exception
at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1071)
at org.apache.catalina.core.StandardWrapper.allocate(StandardWrapper.java:687)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:144)
at org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:104)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:520)
at org.apache.catalina.core.StandardContextValve.invokeInternal(StandardContextValve.java:198)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:152)
at org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:104)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:520)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:137)
at org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:104)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:118)
at org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:102)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:520)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:104)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:520)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:929)
at org.apache.coyote.tomcat5.CoyoteAdapter.service(CoyoteAdapter.java:160)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:799)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:705)
at org.apache.tomcat.util.net.TcpWorkerThread.runIt(PoolTcpEndpoint.java:577)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:683)
at java.lang.Thread.run(Unknown Source)
And the console shows the log
[appfuse] INFO [http-8081-Processor25] DWRServlet.info(51) | retrieved system configuration file: java.io.ByteArrayInputStream@695a6a
[appfuse] INFO [http-8081-Processor25] DefaultConfiguration.info(51) | Creator 'pageflow' not loaded due to ClassNotFoundException. This is only an problem if you wanted to use it. Cause: Beehive/Weblogic Creator not available.
[appfuse] INFO [http-8081-Processor25] DefaultConfiguration.info(51) | Creator 'script' not loaded due to NoClassDefFoundError. This is only an problem if you wanted to use it. Cause: org/apache/bsf/BSFException
could someone give me a clue, thank you very much
Best Regards,
Wang Chi
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| | 2 answer | Add comment |
Thursday, 10 April 2008
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| RtfWriter2 and fitspage() SMETS Katy 12:28:05 |
| | Is there a method to check if a table fits on the page for the RtfWriter2? I know this exists for the PdfWriter - but I don't know how to achieve the same result with the RtfWriter2 .. Can anyone help me?
(please put me in CC as I'm not subscribed to the mailinglist)
Many thanks in advance!
|
| | 12 answers | Add comment |
Monday, 7 April 2008
|
| Seeming Non-determinism in Java Programs Randall R Schulz 09:26:07 |
| | Hi,
I have a long-standing, oft vexatious problem in a large, complex Java
program and I would like to solicit feedback from advanced java-nauts.
The program involves heuristic search in a large, incrementally built
tree. As nodes are added to the tree, a heuristic figure-of-merit (FOM)
is computed and that FOM orders the priority queue from which
successive nodes are extracted, examined and expanded. The queue is
implemented using a heap, though alternatives such as Skip-Lists are
available as options (mostly implemented because of the issue I'm
writing about here).
The program makes extensive use of hashed sets. I've implemented an
option to allow different collection implementations to be used. E.g.,
one can choose Sun's HashSet, LinkedHashSet or Trove's hash set.
It's worth noting that it's often the case that there is relatively
little distinction between actual FOM values (they are very frequently
always small integers). While the priority queue may at any time hold
several thousand items, there may be only a relative handful of
distinct FOMs ordering that queue. Note, too, that the heap data
structure is not stable w.r.t. equal key (FOM) values.
Lastly, the problems, even when known to be solvable, are not always
solved within the user-specified resource limits (number of tree nodes
generated being the typical one).
So here is the symptom I seek to alleviate: The program's behavior on
some problems is highly variable. That is, I can invoke the same
problem repeatedly and get widely varying results. E.g., a given
problem may be solved in one case in under a thousand nodes, in another
in ten or twenty thousand and in others not at all (with a 100,000-node
limit).
This is perplexing to me. How can multiple independent (but identical)
invocations of the JVM produce highly varying executions?
My first question is this: What phenomenon / dynamics can cause this
sort of behavior? While I'm open to the possibility that it is a bug
(permit me to say a _subtle_ bug), I'm experienced enough to know the
proper implementation of equals() and hashCode(), e.g.
Has anyone else seen this sort of phenomenon? If so, how have you dealt
with it?
Thanks.
Randall Schulz
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