Thread Blocking..help

Hi All,
I'm finding it hard to understand the concept of Threads blocking, for example, when u have a UI u'll want to run your main work in a different thread than in the event dispatcher thread as that will speed things up with the GUI.
now let's say we have the following code:
//Thread to prevent blocking and return control to GUI
Runnable r = new Runnable() {
public void run() {
try
ThreadThatDoesAlotOfWork.start();
} catch (Exception e)
e.printStackTrace();
if I'll run it within a another thread within the GUI, howcome it doesn't block till all work is done?
could u provide some code for blocking/non blocking threads..
can u direct me maybe to helpfull docs somewhere..
Thanks for the help and hope I'm being clear with my question..

That article is about synchronisation access to variables by mutiple threads.
I'm talking about using Threads for speeding things up...
Thanks for the reply anyway..

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Thread blocking on java.nio.charset.CoderResult

Hello all,
I have a multi-threaded app which does some fairly intestive string operations (basically extracts text from documents for indexing a search system).
I am seeing a massive bottleneck around the java.nio.charset.CoderResult class. When profiling, I see a whole stack of threads blocking on (waiting for) a monitor on this java.nio.charset.CoderResult class. Seems to be a result of string encoding/decoding (I am often encoding strings as UTF-8).
Anyone know why the JVM would want my threads to sync on this class? It's creating a huge performance issue for my app. Approximately 15% of ALL the processing time is spent waiting for this class.
Help!

I would guess that you're using some of the static methods in the CoderResult class. The static methods CoderResult.unmappableCache(), CoderResult.malformedForLength() and CoderResult.malformedCache all use a static inner class called Cache. Its get() method is synchronized on Cache.class. Since the Cache inner-class is static, any part of your multi-threaded application that goes through the Cache.get() method is going to be waiting for the lock on Cache.class.
Could you create a CoderResult instance for each thread? That would mean that there would be a different static Cache class for each thread, reducing the number of threads competing for the Cache.class lock.
I'd have to see some of your code to give a better answer.
Brian

Thread blocked in printStackTrace

I find one of my thread blocked in printStackTrace after perform an overload test. But it doesn't wait any java lock. So I don't know what happened.
Part of dumped thread stack looked like this:
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Can u pstack the process at this moment? The stacks of all the threads are probably too large to be shown here.
Show the thread #575. i.e. nid = 0x23f, convert to decimal = 575, maybe its stuck in the native portion.
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hi
i am using weblogic 10 and jdk1.5.
My application is deployed in ear format, with 2 wars, and 20 ejbs.
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The call is like this in a servlet....
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reqDisp.forward(req, res);
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"ExecuteThread: '12' for queue: 'default'" daemon prio=6 tid=0x2b8edad0 nid=0xc1
0 in Object.wait() [0x2da1e000..0x2da1fb64]
at java.lang.Object.wait(Native Method)
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at javelin.client.ClientUtilsImpl.build(ClientUtilsImpl.java:838)
at weblogic.servlet.jsp.JavelinxJSPStub.compilePage(JavelinxJSPStub.java:248)
at weblogic.servlet.jsp.JspStub.prepareServlet(JspStub.java:200)
at weblogic.servlet.jsp.JspStub.prepareServlet(JspStub.java:164)
at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:235)
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at weblogic.servlet.internal.ServletStubImpl.onAddToMapException(ServletStubImpl.java:391)
at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:309)
at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:175)
at weblogic.servlet.internal.RequestDispatcherImpl.invokeServlet(RequestDispatcherImpl.java:503)
at weblogic.servlet.internal.RequestDispatcherImpl.forward(RequestDispatcherImpl.java:245)
at LCDisplayController.handleProcessing(Unknown Source)
at DisplayControllerServlet.doPost(Unknown Source)
at DisplayControllerServlet.doGet(Unknown Source) at javax.servlet.http.HttpServlet.service(HttpServlet.java:707)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
at weblogic.servlet.internal.StubSecurityHelper$ServletServiceAction.run(StubSecurityHelper.java:226)
at weblogic.servlet.internal.StubSecurityHelper.invokeServlet(StubSecurityHelper.java:124)
at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:283)
at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:175)
at weblogic.servlet.internal.RequestDispatcherImpl.invokeServlet(RequestDispatcherImpl.java:503)
at weblogic.servlet.internal.RequestDispatcherImpl.forward(RequestDispatcherImpl.java:245)
at com.orbitech.workflow.servlet.WFAppListController.openWorkitem(WFAppListController.java:793)
at com.orbitech.workflow.servlet.WFAppListController.processRequest(WFAppListController.java:102)
at com.orbitech.workflow.servlet.WFAppController.doProcessRequest(WFAppController.java:97)
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i think the there is thread blocking and the jsp is not getting compiled or smthing....
i am unable to understnd the exception....
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We are using jBPM and Hibernate in our application which runs fine on other java application servers. On Weblogic we were getting an error:
org.hibernate.HibernateException: Errors in named queries: GraphSession...........
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<container-descriptor>
<prefer-web-inf-classes>true</prefer-web-inf-classes>
</container-descriptor>
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Error 500--Internal Server Error
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^---------------------------------------^
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^---------------------------------------^
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TS1363 my ipod classic is visible in windows but not in itunes, this happens on 2 different computers where my iphone and ipod touch work fine which leads me to think something is up with the ipod itself and i cant find any threads to help

my ipod classic is visible in windows but not in itunes, this happens on 2 different computers where my iphone and ipod touch work fine which leads me to think something is up with the ipod itself and i cant find any threads to help.
any thoughts anyone??

Perhaps the reason you haven't had any replies is because there is no such thing as an 8GB iPod Classic.
I suggest that you begin by correctly identifying which iPod you have.
http://support.apple.com/kb/HT1353

Thread Problem - (Thread Blocking Problems?)

Hi Friends
In my program while using thread i found a problem in this code .
In this whlie running the 'msg' was printen only after all 5 inputs are given .
why i was not getting output after one input.why the thread out was waiting for remaining threads input.
my code is
import java.io.*;
class MyThread extends Thread
BufferedReader bin;
   MyThread()
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     start();
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      try
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      catch(IOException e)
         System.out.println(e);
public class Threads
     public static void main(String args[])
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}

Hi Friends
In my program while using thread i found a problem
em in this code .
In this whlie running the 'msg' was printen only
after all 5 inputs are given .
why i was not getting output after one input.why
hy the thread out was waiting for remaining threads
input.Probably because of how the scheduler was rotating among the threads while waiting for input and queueing up output.
When you call readLine, that thread blocks until a line is available. So it probably goes to the next thread's readLine, and so on. All threads are probably blocked waiting for input before you enter a single character.
Something inside the VM has to coordinate the interaction with the console, and between that and your threads, the out stuff just doesn't get a chance to display right away.
In general, you can't predict the order of execution of separate threads.

[svn:bz-trunk] 12951: Changed synchronized PropertyProxyRegistry#getRegistry method to non-synchronized to avoid threads blocking in message push .

Revision: 12951
Revision: 12951
Author:   [email protected]
Date:     2009-12-15 02:17:31 -0800 (Tue, 15 Dec 2009)
Log Message:
Changed synchronized PropertyProxyRegistry#getRegistry method to non-synchronized to avoid threads blocking in message push.
Checkintests: Pass with the usual 3-4 tests that time out with and without this change.
QA: Yes
Doc: No
Modified Paths:
    blazeds/trunk/modules/core/src/flex/messaging/io/PropertyProxyRegistry.java

Revision: 12951
Revision: 12951
Author:   [email protected]
Date:     2009-12-15 02:17:31 -0800 (Tue, 15 Dec 2009)
Log Message:
Changed synchronized PropertyProxyRegistry#getRegistry method to non-synchronized to avoid threads blocking in message push.
Checkintests: Pass with the usual 3-4 tests that time out with and without this change.
QA: Yes
Doc: No
Modified Paths:
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Thread Blocked Problem

I Have a multithread application which:
- access to database
- write files
- read files
- execute external process using exec
What considerations should I take in order to avoid Threads Blocking? When Thread blocking occurs how can I know what is the cause?
Thanks!
T

http://www.ibm.com/developerworks/library/j-thread.html
- Saish

Using Thread in Helper Class Used By MDB

Using Thread in Helper Class Used By MDB
I am writting one Message driven bean (MDB) which will be deployed on
weblogic 6.1.
In MDB.onMessage I create instance of helper class.
call it's method HelperClass.doSomething(s1,s2)
in doSomething I start new thread
checks if thread is alive
when thread is dead return flag
run method of helper class does following
1. opens socket connection to some server
2. writes some data to it
3. read some data from it
4. depending on response set flag
I want to know whether this approach is corect.
Specially when weblogic recommends not to use threads (or be extreamly
careful about thread handling) .
Following is code..
MessageDrivenBeanClass{
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          String s1 = "s1";
          String s2 = "s2";
          HelperClass helper = new HelperClass();
          boolean flg = helper.doSomething(s1,s2);
HelperClass implements Runnable {
     String s1;
     String s2;
     boolean flg = false;
     public void HelperClass(){}
     public boolean doSomething(String s1, String s2){
          this.s1 = s1;
          this.s2 = s2;
          Thread t1 = new Thread(this);
          t1.start();
          while(true)
          if(!t1.isAlive())
               break;
          return flg;
     public void run(){
          // do actual processing
          if(something)
               flg = true;
          else
               flg = false;

What is the purpose of creating an extra thread in this scenario (if your
code is going to wait until thread terminates anyway) ?
Also, creating new threads can be expensive, so it is always better to use
thread pool and not to create new thread every time.
And,
Thread t1 = new Thread(this);
t1.start();
while(true)
if(!t1.isAlive())
break;
is going to waste ALOT of CPU time. t1.join() will work much better.
sk <[email protected]> wrote:
Using Thread in Helper Class Used By MDB
I am writting one Message driven bean (MDB) which will be deployed on
weblogic 6.1.
In MDB.onMessage I create instance of helper class.
call it's method HelperClass.doSomething(s1,s2)
in doSomething I start new thread
checks if thread is alive
when thread is dead return flag
run method of helper class does following
1. opens socket connection to some server
2. writes some data to it
3. read some data from it
4. depending on response set flag
I want to know whether this approach is corect.
Specially when weblogic recommends not to use threads (or be extreamly
careful about thread handling) .
Following is code..
MessageDrivenBeanClass{
     puboic void onMessage(Message msg){
          String s1 = "s1";
          String s2 = "s2";
          HelperClass helper = new HelperClass();
          boolean flg = helper.doSomething(s1,s2);
HelperClass implements Runnable {
     String s1;
     String s2;
     boolean flg = false;
     public void HelperClass(){}
     public boolean doSomething(String s1, String s2){
          this.s1 = s1;
          this.s2 = s2;
          Thread t1 = new Thread(this);
          t1.start();
          while(true)
          if(!t1.isAlive())
               break;
          return flg;
     public void run(){
          // do actual processing
          if(something)
               flg = true;
          else
               flg = false;

Why happens when threads block on I/O?

I want to know what are the reasons for threads blocking on I/O.Do they block to allow the I/O operation or do they block(enter in waiting state) to allow other threads to continue operation while I/O opeation ?
If a particular thread is blocked for I/O do other threads get a chance by the Thread Scheduler ?
If this question has been asked and answered somewhere ,kindly let me know so that i can follow that thread.
Thanks for your consideration.

>
Which thread is that which is "suspended"? The thread which is blocked waiting for the I/O will, um, wait for the I/O. That means it doesn't do anything else. It just waits. That's all. Is that not obvious?
The "suspended" one is the one which is blocked waiting for the I/O.My question is when say the I/O is complete or the stream closes,won't the thread start executing again if given a chance by the scheduler ?
Of course that doesn't affect any other threads. And what do you mean by "related to this thread"? There's no such concept. Each thread operates independently, except when they interact by holding locks or waiting for locks.
"Related to this thread" means thread that share some common resources or say locks.Here i meant any other thread than the one which is blocked for I/O.
Seems to me your mental model of threads is far too complicated. You need to get rid of all those imaginary concepts you're trying to insert there.That is what i am trying to simplify !!!!

Itouch 4th gen won't turn on or sync to comp, no thread has helped so far

Hey there, no other thread has helped so far, no combination of holding power and home buttons has worked. Computer does not recognize it, it will not charge, completely black screen. Was not dropped or had anything spilled on it. Please assist!

Ah yeah I guess I have no choice but to go into an Apple store, calling Apple support didn't help.

Oracle Forms - need to update multi-record block - Help needed asap

Hi,
We are using Oracle apps release 11i - Oracle forms 6i.
I have a field "project_start_date" in project_block in a custom form. There is another multi-record block called role_block in the same custom form and it has a field named start_date. Requirement is when ever I make change in the project_start_date in project_block, that should reflect in role_block.start_date. I tried different means and could update only the very first record of the multi-record block - role_block. I need to update all the records in the role_block with the same project_start_date. Used looping and several other methods. But could not achieve. Any help is really appreciated.
Thanks
Akil

Hi;
For your issue i suggest close your thread here as changing thread status to answered and move it to Forum Home » Application Development in PL/SQL » Forms which you can get more quick response
Regard
Helios

Client threads block forever in SSLSocketImpl.startHandshake

Hi --
We have an application which has 4 threads polling a webservice over HTTPS every 1-2 minutes. We don't control the server platform or webservice framework.
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JVM thread dumps suggests that the polling threads are blocked inside SSLSocketImpl.startHandshake; each one always has the same stacktrace within the JSSE & Axis libraries:
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     at org.apache.axis.transport.http.HTTPSender.invoke(HTTPSender.java:88)
     at org.apache.axis.strategies.InvocationStrategy.visit(InvocationStrategy.java:32)
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     at org.apache.axis.client.Call.invoke(Call.java:2378)
     at org.apache.axis.client.Call.invoke(Call.java:2301)
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...(our application stacktrace)...
Client: JDK1.4.1-b21, JBoss 3.2.7RC1, Axis 1.2RC2, Win2k Server SP4, no client certificates
Server: Apache 1.3.29 (Unix) mod_ssl 2.8.16 OpenSSL 0.9.6j, mod_jk to Tomcat.
There's at least one firewall between client and server.
This problem appears similar: <http://issues.apache.org/bugzilla/show_bug.cgi?id=31832> & I've emailed the author.
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Any help gratefully received.
Thanks
-- Richard Barnett

Thanks for the reply.
This case is different from that JMeter bug report as it's a SOAP request.
We're not explicitly setting a timeout, but Axis defaults to a 10 minute timeout on its requests. The source seems to indicate that this doesn't apply when creating SSL sockets (although it is used when creating regular sockets). No timeout occurs in any case.
-- Richard

Archiver Issue| Automatic replication process | Archiver thread blocking

Hi,
Recently, we are facing a strange issue with Archiver auto replication process. Sometime, archiver thread is blocking and auto replication is stalling. We observed this issue after we apply latest OUCM patches downloded from Oracle support site.
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Jonathan
http://redstonecontentsolutions.com
http://corecontentonly.com

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hi all, i really need to submit this assignment and im at the point of banging my head on my PC coz java is making me run nuts.
i the code is working fine except that i need to run threads for any number of commands entered at input in the order in which thy're entered. i've written all commands in seperate classes and extended thread in each of them. all classes are working on a file so im calling them in my main class below. The for loop at the bottom of code is really giving me trouble. im sure i have to use if statements to run threads for commands entered. how can i do it. somebody help ps.
import java.io.*;
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Thread t[] = new Thread[numberofCommands];
System.out.println("Threads created");
for (int i=0; i < numberofCommands; i++)
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Do you actually have a question?
You're catching exceptions silently. Never do that. The solution to your problems may be in that catch block.
Why are you sure that you need to use if statements?
Why do you have that array of Thread?
What are you trying to accomplish?

Thread Blocking..help

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