Force DLLs to tun in the same thread (expect the UI Thread)
Hi,
I want that three different DLLs run in the same thread but this thread must not be the "UI Thread". I there a way to force them to do so?
Best regards
Solved!
Go to Solution.
Jarrod S. wrote:
Do the DLL calls really have to execute in the same thread? Or is it just required that they not execute at the same time? In the latter case, you could consider using a semaphore to protect your DLL calls, or perhaps putting all the DLL calls into a single subVI with a case structure to decide which call to make. This second option might become more complicated if all the calls have different sets of inputs or outputs.
Using another Execution System other than the UI Thread won't work, because those Execution Systems each get 4-8 threads to run with.
Ho about...
Putting all of the calls into an Action Engine configured to run in "other1" (for example) and then use "threadconfig" to configure that for only one thread.
Write a wrapper for each call to the AE and ....
Done?
Ben
Ben Rayner
I am currently active on.. MainStream Preppers
Rayner's Ridge is under construction
Similar Messages
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How is it possible to make sure that LV uses the same thread for several threadsafe DLL calls?
Hello,
i have a thread safe DLL and most functions are called from serveral threads from the LV apllication without problems.
In case of an error i have to call an error handler function in this DLL (like WinAPI: GetLastError()) from the same thread which has called the function that failed before.
I can't use the user interface execution because some functions need a long execution time and i don't want to balk the user interface.
All other executions than the user interface execution have more than one thread and in most cases the DLL function calls were executed from different threads - so the error handling doesn't work...
Any idea?
Thanks for your help!Hmmm....
How about wrapping all of your dll calls in a single VI (or an Action Engine ) and make sure the VI's thread is NOT set for "Same as caller".
"Threadconfig.vi" (sp?) will also let you dictate the number of threads associated with an execution system. Set your target thread for "1".
Not sure on the above.
Please correct me if this is wrong!
Ben
Message Edited by Ben on 07-19-2007 08:26 AM
Ben Rayner
I am currently active on.. MainStream Preppers
Rayner's Ridge is under construction -
How can I use the same thread to display time in both JPanel & status bar
Hi everyone!
I'd like to ask for some assistance regarding the use of threads. I currently have an application that displays the current time, date & day on three separate JLabels on a JPanel by means of a thread class that I created and it's working fine.
I wonder how would I be able to use the same thread in displaying the current time, date & day in the status bar of my JFrame. I'd like to be able to display the date & time in the JPanel and JFrame synchronously. I am developing my application in Netbeans 4.1 so I was able to add a status bar in just a few clicks and codes.
I hope somebody would be able to help me on this one. A simple sample code would be greatly appreciated.
Thanks in advance!As you're using Swing, using threads directly just for this kind of purpose would be silly. You might as well use javax.swing.Timer, which has done a lot of the work for you already.
You would do it something like this...
ActionListener timerUpdater = new ActionListener() {
public void actionPerformed(ActionEvent evt) {
// DateFormat would be better, but this is an example.
String timeString = new Date().toString();
statusBar.setText(timeString);
someOtherLabel.setText(timeString);
new Timer(1000, timerUpdater).start();That code will update the time once a second. If you aren't going to display seconds, you might as well increase the delay.
The advantage of using a timer over using an explicit thread, is that multiple Swing timers will share a single thread. This way you don't blow out your thread count. :-) -
Multiple threads but they are using the same thread ID
I'm a newbie in Java programming. I have the following codes, please take a look and tell me what wrong with my codes: server side written in Java, client side written in C. Please help me out, thanks for your time.
Here is my problem: why my server program assigns the same thread ID for both threads???
.Server side: start server program
.Client side: set auto startup in /etc/rc.local file in a different machine, so whenever this machine boots up, the client program will start automatically.
==> here is the result with 2 clients, why they always come up the same thread ID ????????
Waiting for client ...
Server thread 1024 running
Waiting for client ...
Server thread 1024 running
But if I do like this, they all work fine:
.Server side: start server program
.Client side: telnet or ssh to each machine, start the client program
==> here is the result:
Waiting for client ...
Server thread 1024 running
Waiting for client ...
Server thread 1025 running
server.java file:
import java.io.*;
import java.net.*;
import java.awt.*;
import java.util.Hashtable;
import java.util.Enumeration;
import java.util.regex.Pattern;
import java.util.Date;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.text.*;
public class Server extends Frame implements Runnable
private ServerThread clients[] = new ServerThread[50];
private ServerSocket server = null;
private Thread thread = null;
private int clientCount = 0;
//some variables over here
public Server(int port)
//GUI stuffs here
//network stuff
try
System.out.println("Binding to port " + port + ", please wait ...");
server = new ServerSocket(port);
System.out.println("Server started: " + server);
start();
catch(IOException ioe)
System.out.println("Can not bind to port " + port + ": " + ioe.getMessage());
public boolean action(Event e, Object arg)
//do something
return true;
public synchronized void handle(int ID, String input)
//do something
public synchronized void remove(int ID)
int pos = findClient(ID);
if (pos >= 0)
//remove a client
ServerThread toTerminate = clients[pos];
System.out.println("Removing client thread " + ID + " at " + pos);
if (pos < clientCount-1)
for (int i = pos+1; i < clientCount; i++)
clients[i-1] = clients;
clientCount--;
try
{ toTerminate.close(); }
catch(IOException ioe)
{ System.out.println("Error closing thread: " + ioe); }
toTerminate.stop();
private void addThread(Socket socket)
if (clientCount < clients.length)
clients[clientCount] = new ServerThread(this, socket);
try
clients[clientCount].open();
clients[clientCount].start();
clientCount++;
catch(IOException ioe)
System.out.println("Error opening thread: " + ioe);
else
System.out.println("Client refused: maximum " + clients.length + " reached.");
public void run()
while (thread != null)
try
{ System.out.println("Waiting for a client ...");
addThread(server.accept());
catch(IOException ioe)
System.out.println("Server accept error: " + ioe); stop();
public void start()
if(thread == null)
thread = new Thread(this);
thread.start();
public void stop()
if(thread != null)
thread.stop();
thread = null;
private int findClient(int ID)
for (int i = 0; i < clientCount; i++)
if (clients[i].getID() == ID)
return i;
return -1;
public static void main(String args[])
Frame server = new Server(1500);
server.setSize(650,400);
server.setLocation(100,100);
server.setVisible(true);
ServerThread.java file
import java.net.*;
import java.io.*;
import java.lang.*;
public class ServerThread extends Thread
private Server server = null;
private Socket socket = null;
private int ID = -1;
InputStreamReader objInStreamReader = null;
BufferedReader objInBuffer = null;
PrintWriter objOutStream = null;
public ServerThread(Server server, Socket socket)
super();
server = _server;
socket = _socket;
ID = socket.getPort();
public void send(String msg)
objOutStream.write(msg);
objOutStream.flush();
public int getID()
return ID;
public void run()
System.out.println("Server thread " + ID + " running");
while(true)
try{
server.handle(ID,objInBuffer.readLine());
catch(IOException ioe)
System.out.println(ID + "Error reading: " + ioe.getMessage());
//remove a thread ID
server.remove(ID);
stop();
public void open() throws IOException
//---Set up streams---
objInStreamReader = new InputStreamReader(socket.getInputStream());
objInBuffer = new BufferedReader(objInStreamReader);
objOutStream = new PrintWriter(socket.getOutputStream(), true);
public void close() throws IOException
if(socket != null) socket.close();
if(objInStreamReader != null) objInStreamReader.close();
if(objOutStream !=null) objOutStream.close();
if(objInBuffer !=null) objInBuffer.close();
And client.c file
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h> /* close */
#include <time.h>
#define SERVER_PORT 1500
#define MAX_MSG 100
//global variables
long lines = 0;
int sd = 0;
char command[100];
time_t t1,t2;
double timetest = 0.00;
int main (int argc, char *argv[])
int rc, i = 0, j = 0;
struct sockaddr_in localAddr, servAddr;
struct hostent *h;
char buf[100];
FILE *fp;
h = gethostbyname(argv[1]);
if(h==NULL) {
printf("unknown host '%s'\n",argv[1]);
exit(1);
servAddr.sin_family = h->h_addrtype;
memcpy((char *) &servAddr.sin_addr.s_addr, h->h_addr_list[0], h->h_length);
servAddr.sin_port = htons(SERVER_PORT);
/* create socket */
sd = socket(AF_INET, SOCK_STREAM, 0);
if(sd<0) {
perror("cannot open socket ");
exit(1);
/* bind any port number */
localAddr.sin_family = AF_INET;
localAddr.sin_addr.s_addr = htonl(INADDR_ANY);
localAddr.sin_port = htons(0);
rc = bind(sd, (struct sockaddr *) &localAddr, sizeof(localAddr));
if(rc<0) {
printf("%s: cannot bind port TCP %u\n",argv[1],SERVER_PORT);
perror("error ");
exit(1);
/* connect to server */
rc = connect(sd, (struct sockaddr *) &servAddr, sizeof(servAddr));
if(rc<0) {
perror("cannot connect ");
exit(1);
//send register message
rc = send(sd, "register\n", strlen("register\n"), 0);
//if can't send
if(rc < 0)
close(sd);
exit(1);
//wait here until get the flag from server
while(1)
buf[0] = '\0';
rc = recv(sd,buf,MAX_MSG-1,0);
if(rc < 0)
perror("receive error\n");
close(sd);
exit(1);
buf[rc] = '\0';
if(strcmp(buf,"autoplay")==0)
//do something here
else if(strcmp(buf,"exit")==0)
printf("exiting now ....\n");
close(sd);
exit(1);
return 0;Yes......I do so all the time.
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Can use the same thread safe variable in the different processes?
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Can use the same thread safe variable in the different processes? my application has a log file used to record some event, the log file will be accessed by the different process, is there any synchronous method to access the log file with CVI ?
DavidLimiting concurrent access to shared resources can be better obtained by using locks: once created, the lock can be get by one requester at a time by calling CmtGetLock, the other being blocked in the same call until the lock is free. If you do not want to lock a process you can use CmtTryToGtLock instead.
Don't forget to discard locks when you have finished using them or at program end.
Alternatively you can PostDeferredCall a unique function (executed in the main thread) to write the log passing the apprpriate data to it.
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I try to send in parallel several ldap search request to an iDS5.0 SP1 ldap server. The ldap client is java coded using LDAP SDK.
To emphasis my problem, I wrote a very simple ldap client:
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searchListener = _ld.search("ou=city0, ou=region0, ou=LoadTest, o=surpass.com",1,"(cn=*)",attrs,false,null, searchConstraints);
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ldapMessage=searchListener.getResponse();
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Without waiting for the resultCode message, I send a new ldap search:
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This search locks the java process. A timeout message is generated in the ldap server logs:
[27/Jan/2003:14:13:35 +0100] conn=60660 op=2 fd=48 closed error 11 (Resource temporarily unavailable) - B4
Is it a bug? Or is it mandatory, in a single thread process, to wait for the resultCode message before sending any other search request?
YannickThank's for answering
You'r right, there are many ways to overcome the problem in my very simple ldap client:
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- Use the search constraint BATCHSIZE=0
But my question is: is it possible to run several concurrent ldap requets in the same thread (like a pool of ldap search) and check their results in a asynchronous way?
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Does it runs in the same thread of the Proxy?
If NOT,
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Thank you,
regards
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How can I use the same thread pool implementation for different tasks?
Dear java programmers,
I have written a class which submits Callable tasks to a thread pool while illustrating the progress of the overall procedure in a JFrame with a progress bar and text area. I want to use this class for several applications in which the process and consequently the Callable object varies. I simplified my code and looks like this:
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int chainArrayLength = chainArray.length;
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My question is how can I replace Parser object with something changeable, so that I can set it accordingly whenever I call this method to conduct a different task?
thanks,
TomOK lets's start from the beginning with more details. I have that class called ProgressGUI which opens a small window with 2 buttons ("start" and "stop"), a progress bar and a text area. It also implements a thread pool to conducts the analysis of multiple files.
My main GUI, which is much bigger that the latter, is in a class named GUI. There are 3 types of operations which implement the thread pool, each one encapsulated in a different class (SMAP, Dock, EP). The user can set the necessary parameters and when clicking on a button, opens the ProgressGUI window which depicts the progress of the respective operation at each time step.
The code I posted is taken from ProgressGui.class and at the moment, in order to conduct one of the supported operations, I replace "new Parser(chainArray)" with either "new SMAP(chainArray[i])", "new Dock(chainArray[i])", "new EP(chainArray[i])". It would be redundant to have exactly the same thread pool implementation (shown in my first post) written 3 different times, when the only thing that needs to be changed is "new Parser(chainArray[i])".
What I though at first was defining an abstract method named MainOperation and replace "new Parser(chainArray[i])" with:
new Callable() {
public void call() {
MainOperation();
});For instance when one wants to use SMAP.class, he would initialize MainOperation as:
public abstract String MainOperation(){
return new SMAP(chainArray));
That's the most reasonable explanation I can give, but apparently an abstract method cannot be called anywhere else in the abstract class (ProgressGUI.class in my case).
Firstly it should be Callable not Runnable.Can you explain why? You are just running a method and ignoring any result or exception. However, it makes little difference.ExecutorCompletionService takes Future objects as input, that's why it should be Callable and not Runnable. The returned value is a score (String).
Secondly how can I change that runMyNewMethod() on demand, can I do it by defining it as abstract?How do you want to determine which method to run?The user will click on the appropriate button and the GUI will initialize (perhaps implicitly) the body of the abstract method MainOperation accordingly. Don't worry about that, this is not the point.
Edited by: tevang2 on Dec 28, 2008 7:18 AM -
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Do you realize that you're talking to yourself?
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When I try to access iTunes or safari, I get the following message:The procedure entry point QTCF_CFHTTP message set header field value could not be located in the dynamic link library QTCF.dll I uninstalled and reinstalled.same result HELP!
Taken at face value, you're having trouble with a QuickTime program file there.
Let's try something relatively simple first. Restart the PC. Now head into your Uninstall a program control panel, select "QuickTime" and then click "Repair".
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I'd like to use and airport express to create a wirelss network (and so use the internet) AND stream music to my stereo with air tunes - at the same time. Is this possible? So far, I have been able to create a wireless network (and use the internet) OR use the airport express to play music. But whenever my internet works, itune can't find the base station - claiming it "can't be found on the network?"
Can you do both at once?
I'm connecting to an ethernet jack (I'm at a college). It's not a cable modem or DSL. Is this the problem?
Under "music" in the utility configuration. I've selected "Enable Air tunes at the base station." I can't select "Enable Airtunes over ethernet port." When i try to change the network options to allow me to select this "ethernet port" option, I have to tell it how to "distribute IP" addresses. i don't know how to do this, and everything I've tried destroys my internet connection.
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Not sure if any of you above have managed to solve your problem or not but after coming across this same problem myself today as I am currently 'sofa bound' I decided to make it my mission to find a way around it.
Initially I did think, having ready what seemed like a million questions and people with the same problem, that the only way was to buy OS X 10.5 ... HOWEVER, no. In among all these threads I found a jewel - Download I Tunes 9.2.1 which gets rid of the download itunes 10 advert and allows you to then buy from itunes again :-) I am now one very happy lady.
I apologise to all those that dont have older versions of OS X that maybe wont support even this upgrade but certainly for those like me with just 4yr old lap tops at least it means it not longer means buying a new one.
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My i pod touch 4th gen. is in recovery mode. I am trying to back it up using i tunes but the option for backup is not highlighted. I am at a loss as to what I should do. I do not want to lose all of my pictures. I tried holding down the on/off button with the home button but that does not work. Keeps the touch in the same recovery mode. Suggestions??
No. If the photos are in a backup you made already then you can get them back by restoring from backup.
If they are in your PhotoStream you can get them from your stream. See that topic of:
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