JAVA opening file streams q

ok my question is how to:
1. open file stream
save something (system)
ensure it gets written onto a disk
close open files!
thanks

http://java.sun.com/docs/books/tutorial/essential/io/index.html

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Maximum simultaneous opened files in a java thread on linux 1.4.20

Hello,
It seems like a maximum of 1024 files can be opened by a processus on linux (in java, a thread is a linux processus).
Is it possible to change this value, or has it been set at the JVM compilation?
I created a nio server, and one thread is to manage thousands of connections. For the moment I can't pass 1010 connections.
As a fast test, I created the following source :
public class MaxOpenedFilesTest {
/** Creates a new instance of MaxOpenedFilesTest */
public MaxOpenedFilesTest() {
* @param args the command line arguments
public static void main(String[] args) {
File f = new File("/home/greg/a.out");
FileInputStream[] stream = new FileInputStream[2000];
try {
for (int i=0; i<stream.length; i++) {
stream[i] = new FileInputStream(f);
System.out.println(i+" files opened");
catch (Exception e) {
System.out.println("ERROR : "+e);
e.printStackTrace();
This test throws an IOException at 1019 files opened : Too many opened files...
I have tested a lot of things. I even recompiled the linux kernel. Changed the NR_OPEN, OPEN_MAX, __FD_SETSIZE, etc... Still don't work.
I havve set the global maximum file descriptor to 65536. It works. But for one thread, I can't have more than 1019 file descriptors (must be the 1024 initial limit defined by the kernel)...
Could somebody help.
It would be great.
Thank you.
Gr�goire.

Thank you for your answer.
I have already done all the described procedures in the link you provided.
In fact, I used this link :
file:///home/greg/1_NetNoLedge/LinuxTuning/linux.html
and this other one :
file:///home/greg/1_NetNoLedge/LinuxTuning/s1-custom-kernel-modularized.html
Still only 1024 files allowed to be opened for one process...
In your link, it is said :
You need to give processes the option of increasing their file descriptor limits:
In /etc/security/limits.conf add two lines:
* soft nofile 1024
* hard nofile 4096
Suggesting that it wouldn't even be necessary recompile the kernel to allow more opened file descriptors in a process... This really isn't clear for me.
Thank you.

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Java.io.IOException: Too many open files while deploying in soa 11g

hi all,
I am getting a strange error while deploying any composite .. it's a hello world kinda composite but while i am trying to deploy it i am getting "java.io.IOException: Too many open files" while deployment.. i have tried to deploy it in 2-3 ways but all of them resulted in the same error..bouncing the soa server might be an option but can someone give an insight as why it is happening and can it be resolved without restarting the server..
Thanks

yes..so this problem is with unix only ..coz i previously worked in Windows ..never got this problem..

"java.io.IOException: Too many open files" in LinuX

Hi Developers,
* I am continiously running and processing more than 2000 XML files by using SAX and DOM.....
* My process is as follows,
- Converting the XML file as Document object by DOM....
- And that DOM will be used while creating log file report, that log file will be created after executing all XML files..
* After processing approx 1000 files, it throws *"java.io.IOException: Too many open files" in LinuX system* ....
* I have googled more and more in all sites including sun forum also, but they are telling only to increase the system config by ULIMIT in linux....If i increase that its executing well without exception........
* My question is, Is it possible to do it by JAVA code itself or any other VM arguments like -Xms512m and -Xmx512m.....
* Please let me know , if you have any idea.....
Thanks And Regards,
JavaImran

Doh! I forgot to post my little code sample...
package forums.crap;
import java.io.*;
import java.util.*;
public class TooManyFileHandles
private static final int HOW_MANY = 8*1024;
public static void main(String[] args) {
    List<PrintWriter> writers = new ArrayList<PrintWriter>(HOW_MANY);
    try {
      try {
        for (int i=1; i<=HOW_MANY; i++ ) {
          writers.add(new PrintWriter("file"+i+".txt"));
      } finally {
        for (PrintWriter w : writers) {
          if(w!=null)w.close();
    } catch (Exception e) {
      e.printStackTrace();
}... and the problem still isn't OOME ;-)
Cheers. Keith.

Java.util.zip.ZipException: Too many open files on Linux

Hi,
We have web application running on Caucho's resin server on jdk 1.5.0_11 and Red hat Linux. We are noticing that java process is running out of file handles within 24-30 hours. We have file limit of 5000 which it consumes in 24 hours throwing 'java.util.zip.ZipException: Too many open files'.
I have made sure all sorts of file handles are closed from application point of view. Here is the snapshot of lsof (list of file handles) from java process. The following list keeps growing until it runs out of limit. Do you have tips/suggestions on how to mitigate this problem (considering we dont want to increase ulimit for this process)? Also, can you make out any thing more from the description of file handles like, are they unclosed POP3 connections or URL connection to external sites?
java 7156 resin 120u IPv4 34930051 UDP localhost.localdomain:59693
java 7156 resin 121u IPv4 34927823 UDP localhost.localdomain:59663
java 7156 resin 122u IPv4 34931861 UDP localhost.localdomain:59739
java 7156 resin 123u IPv4 34932023 UDP localhost.localdomain:59745
java 7156 resin 124u IPv4 34930054 UDP localhost.localdomain:59700
java 7156 resin 125u IPv4 34927826 UDP localhost.localdomain:59665
java 7156 resin 126u IPv4 34927829 UDP localhost.localdomain:59666
java 7156 resin 127u IPv4 34930057 UDP localhost.localdomain:59703
java 7156 resin 128u IPv4 34930713 UDP localhost.localdomain:59727
java 7156 resin 129u IPv4 34930716 UDP localhost.localdomain:59730
java 7156 resin 130u IPv4 34932238 UDP localhost.localdomain:59789
java 7156 resin 131u IPv4 34932026 UDP localhost.localdomain:59749
java 7156 resin 132u IPv4 34932221 UDP localhost.localdomain:59770
java 7156 resin 133u IPv4 34932224 UDP localhost.localdomain:59775
java 7156 resin 134u IPv4 34932029 UDP localhost.localdomain:59753
java 7156 resin 135u IPv4 34932032 UDP localhost.localdomain:59754
java 7156 resin 138u IPv4 34932035 UDP localhost.localdomain:59760
java 7156 resin 139u IPv4 34932038 UDP localhost.localdomain:59763
java 7156 resin 140u IPv4 34932227 UDP localhost.localdomain:59780
java 7156 resin 141u IPv4 34932230 UDP localhost.localdomain:59781
java 7156 resin 144u IPv4 34932234 UDP localhost.localdomain:59786
java 7156 resin 146u IPv4 34932241 UDP localhost.localdomain:59792
java 7156 resin 147u IPv4 34932247 UDP localhost.localdomain:59802

Finally we resolved this issue. It was oracle driver which had some compatibility issue, we upgraded our Oracle client driver to newer version, and this fixed the problem. Base line, there was nothing wrong with application code, code was doing good resource clean up, but oracle driver was leaking handles per every connection.

Java Code file 1 meg... Can't open it

Hi All,
I've just started using SJSE and have run into a couple of issues. First problem is that I can't open my java source file. Second issue is I can't get the ide to run my applet. It just displays a small box and that's it. Everything worked great in V7. Below is the output with respect to the opening of the source file.
java.lang.NullPointerException
     at org.netbeans.modules.javanavigation.actions.OpenAction.selectElementInPane(OpenAction.java:187)
     at org.netbeans.modules.javanavigation.actions.OpenAction.access$000(OpenAction.java:56)
[catch] at org.netbeans.modules.javanavigation.actions.OpenAction$1.run(OpenAction.java:129)
     at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
     at java.awt.EventQueue.dispatchEvent(EventQueue.java:461)
     at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:242)
     at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:163)
     at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:157)
     at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:149)
     at java.awt.EventDispatchThread.run(EventDispatchThread.java:110)

Yes it only happens with large files. I have set the following in the jstudio.conf file.
netbeans_default_options="-J-Xms512m -J-Xmx512m -J-XX:PermSize=128m -J-XX:MaxPermSize=256m -J-Dnetbeans.logger.console=true -J-ea -J-Dsun.java2d.pmoffscreen=false -J-Dcom.sun.im.service.xmpp.session.keepaliveinterval=30 -J-Dcom.sun.aas.installRoot=\"K:\Program Files\Sun\jstudio_ent8\AppServ8.1UR2\""
Also, when building my sources I get another 'bug report' message.
An exception has occurred in the compiler (1.5.0_04). Please file a bug at the Java Developer Connection (http://java.sun.com/webapps/bugreport) after checking the Bug Parade for duplicates. Include your program and the following diagnostic in your report. Thank you.
com.sun.tools.javac.code.Symbol$CompletionFailure: file javax\servlet\ServletContext.class not found

Java side batch commands? I.e.: open FILE

Is there a way to add commands for a batch file into a java code?
Like...
If i was going to make a code to open a text file, in a ms-dos/batch file i would put
open FILENAMESo is there a way i can make it use the batch to open a file, but without clicking the batch to do it.
For example;
Im going to have my own game, people will have the open in the batch file of the game client, so they can just edit so it dosn't do it, but the client will be obfuscated and closed source, so they wont be able to edit that'
Thanks for any help.

Ok, this is a simple batch file;
@echo off
echo this is a simple batch file
*open file.txt*
*del file2.txt*
pauseI want to execute those bits in **'s* in a java file, so someone can't just right click the batch file and edit them out.
I hope you understand me now.

Hello Sorry for the inconvenience, but I have a problem in Java I can not open files, audio chat, which type of jnlp after the last update of the Java 2012-004 Please help me in solving this problem.

Hello Sorry for the inconvenience, but I have a problem in Java I can not open files, audio chat, which type of jnlp after the last update of the Java 2012-004
Please help me in solving this problem.

Make sure Java is enable in your browser's security settings.
Open Java Preferences (in Utilities folder)
Make sure Web-start applications are enabled.
Drag Java 32-bit to the top of the list.
jnlp isn't an audio file format. It's just a java web-start program (Java Network Launching Protocol).

Java applet runs inside html page when opened with http, but no longer with "Open File" menu, why?

Using the "Open File" menu, file:///Users/234866H/Documents/atom/atomic1.html fails to open the java applet atomic1.class inside atomic.html. However, http://atom.curtin.edu.au/igor/atom/atomic1.html works just fine.
I suspect the problem arose following the recent java upgrade. It is also there on Safari.
Testing Java at http://www.java.com/en/download/testjava.jsp yields:
"Your Java is working. Your Java configuration is as follows: Vendor: Apple Inc. Version: Java SE 6 Update 51 Operating System: Mac OS X 10.6.8 Java Architecture: 64-bit"
However, this is an http test, and not an "Open File" test.
Any help would be appreciated.

Hello, I don't know about this specifically but this is what I would try.
Instead of the string "\u7834\u70C2\u7269\u7A0B\u5E8F\u5458..."
Set the encoding type in the String constructor first...
ie:
new String( "\u7834\u70C2\u7269\u7A0B\u5E8F\u5458...","GB18030");
Here is a little class I whipped up to show the CharSets that are available to you..
public class ShowAllCharSets
ShowAllCharSets()
Map myMap = Charset.availableCharsets();
Iterator iterator = myMap.keySet().iterator();
   while (iterator.hasNext())
      System.out.println("Char set name = "+((String)it.next()));
public static void main(String args[])
   new ShowAllCharSets();
}Then use the preset charset String with the specific encoding already set for your menu items.
GB18030 I picked arbitrarily because it is Chinese and you may have to try another.
Good Luck!
(T)

Getting java.io.FileNotFoundException: Too many open files

I have search for different strings in a file again and again. I am using following code:
try
               fileReaderObject = new BufferedReader(new FileReader(fileObject));
               String inputLine;
               while ((inputLine = fileReaderObject.readLine()) != null)
                    if (zipCode.equalsIgnoreCase(inputLine.split("\t")[0]))
                         s = inputLine;
                         fileReaderObject.close();
                         return s;
               fileReaderObject.close();
          catch (Exception e)
               Utils.writeMessage(e.toString());
               e.printStackTrace();
          }But getting java.io.FileNotFoundException:file/emp_info (Too many open files)
1. Whats the main reason of this exception and how can it be removed.
2. Is there any way to move the pointer to the start of the file. I tried reset() but its seems to have some problem.
-vc

A hint: your fileReaderObject is not closed if an exception occurs.
Lacking desctructors, the Java-ish way is to close in a finally clause.

Getting java.io.IOException: Too many open files+ClassNotFoundException

Dear All
We have a web application deployed on Rational Application Developer 6.0 (Operating System is Windows 2000 professional) our users are randomly getting java.io.IOException: Too many open files+ClassNotFoundException when they click on some servlet or jsp link, but they are getting this error randomly for example when they click some link they may get these exceptions but refreshing page or clicking once again on same link executes servlet successfully.If anyone could help on this topic we will be grateful
Thanks

I think this these two exceptions are occuring in differrent environment
java.io.IOException is occuring under heavy load to web server its stack trace is as follows:
JSPG0225E: An error occurred at line: 2 in the statically included file: /SessionCheck.jsp
JSPG0093E: Generated servlet error from file: /Admin/AdminInsuranceCertificates.jsp
E:\WebSphere_6\AppServer\profiles\AUSECert\temp\centraNode04\server1\AUSECert\Vero.war\Admin\_AdminInsuranceCertificates.java:259: cannot access com.bplus.natmar.LoginDetails
bad class file: E:\WebSphere_6\AppServer\java\jre\lib\core.jar(java/io/Writer.class)
unable to access file: E:\WebSphere_6\AppServer\profiles\AUSECert\installedApps\centraNode04Cell\AUSECert.ear\Vero.war\WEB-INF\classes\com\bplus\natmar\LoginDetails.class (Too many open files)
Please remove or make sure it appears in the correct subdirectory of the classpath.
(source unavailable)
1 error
]: com.ibm.ws.jsp.JspCoreException: JSPG0049E: /Admin/AdminInsuranceCertificates.jsp failed to compile :
this error always occurs in reference to logindetails class this clas is used to make a session check on different roles in our project for e.g., user having end user role should not be able to log in as a user having admin role
we have included a sessioncheck.jsp in our every jsp page in this jsp we have simply used logindetails class as useBean and called its getresource() method
above stacktrace is from our live application server
while testing same project on our local system we are not getting too many open files exception but we are getting following ClassNotFoundException
[11/30/05 17:11:42:797 EST] 0000004a SystemOut O SELECT count(*) as NoofRecs FROM resourcerolebindings WHERE ResourceName = 'mainEdit.jsp' and IsEndUser=1
[11/30/05 17:12:50:891 EST] 000001eb SystemOut O SELECT count(*) as NoofRecs FROM resourcerolebindings WHERE ResourceName = 'InsuranceCertificates.jsp' and IsEndUser=1
[11/30/05 17:17:40:828 EST] 0000008d SystemOut O AppURL is: http://www.VeroECert.com/Vero/indexU.jsp
[11/30/05 17:17:58:141 EST] 0000008b SystemOut O SELECT count(*) as NoofRecs FROM resourcerolebindings WHERE ResourceName = 'InsuranceCertificates.jsp' and IsEndUser=1
[11/30/05 17:20:41:703 EST] 00000034 ServletWrappe E SRVE0026E: [Servlet Error]-[com.servlet.UserHelpServlet]: java.lang.ClassNotFoundException: com.servlet.UserHelpServlet
     at com.ibm.ws.classloader.CompoundClassLoader.findClass(CompoundClassLoader.java(Compiled Code))
     at com.ibm.ws.classloader.CompoundClassLoader.loadClass(CompoundClassLoader.java(Compiled Code))
     at java.lang.ClassLoader.loadClass(ClassLoader.java(Compiled Code))
     at java.beans.Beans.instantiate(Beans.java:202)
     at java.beans.Beans.instantiate(Beans.java:63)
     at com.ibm.ws.webcontainer.servlet.ServletWrapper$3.run(ServletWrapper.java:1384)
     at com.ibm.ws.security.util.AccessController.doPrivileged(AccessController.java(Compiled Code))
     at com.ibm.ws.webcontainer.servlet.ServletWrapper.loadServlet(ServletWrapper.java(Compiled Code))
     at com.ibm.ws.webcontainer.servlet.ServletWrapper.initialize(ServletWrapper.java:1312)
     at com.ibm.wsspi.webcontainer.extension.WebExtensionProcessor.createServletWrapper(WebExtensionProcessor.java:84)
     at com.ibm.ws.webcontainer.extension.InvokerExtensionProcessor.handleRequest(InvokerExtensionProcessor.java:238)
     at com.ibm.ws.webcontainer.webapp.WebApp.handleRequest(WebApp.java:2841)
     at com.ibm.ws.webcontainer.webapp.WebGroup.handleRequest(WebGroup.java:220)
     at com.ibm.ws.webcontainer.VirtualHost.handleRequest(VirtualHost.java:204)
     at com.ibm.ws.webcontainer.WebContainer.handleRequest(WebContainer.java(Compiled Code))
     at com.ibm.ws.webcontainer.channel.WCChannelLink.ready(WCChannelLink.java(Compiled Code))
     at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleDiscrimination(HttpInboundLink.java(Compiled Code))
     at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleNewInformation(HttpInboundLink.java(Compiled Code))
     at com.ibm.ws.http.channel.inbound.impl.HttpICLReadCallback.complete(HttpICLReadCallback.java(Compiled Code))
     at com.ibm.ws.tcp.channel.impl.WorkQueueManager.requestComplete(WorkQueueManager.java(Compiled Code))
     at com.ibm.ws.tcp.channel.impl.WorkQueueManager.attemptIO(WorkQueueManager.java(Compiled Code))
     at com.ibm.ws.tcp.channel.impl.WorkQueueManager.workerRun(WorkQueueManager.java(Compiled Code))
     at com.ibm.ws.tcp.channel.impl.WorkQueueManager$Worker.run(WorkQueueManager.java(Compiled Code))
     at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java(Compiled Code))
this error is occuring on concurrent clicks suppose three users click on same button then it is possible that one user gets correct output while other users experience this exception
Also one more point we are not using web.xml for calling servlets we are directly calling it giving its full path.
Thanks

Java.io.IOException: Too many open files

I am running web-service, by which i have to run .sh file on linux. My code is as follow,
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
public class DomRenewProcessN4Vrsgn
     Process process;
     String s;
     String step;
public String renewDomain(String ACTIVITY_ID,String DOMAIN_NAME,String DURATION,String EXPIRY_DATE)
          //readOutput(ITEM_ID,TLD);
          Runtime runtime;
               runtime = Runtime.getRuntime();
               String domRegisterCmd = "";
               domRegisterCmd = "sh /home/kesharil/DomainRenew/n4vrsgn/DomainRenew-n4vrsgn.sh"+ " " ACTIVITY_ID " " DOMAIN_NAME" "+DURATION+" "+EXPIRY_DATE;
               try
               runtime = Runtime.getRuntime();
               step=runtime.toString();
               process =runtime.exec(domRegisterCmd);// + " " ITEM_ID " "+TLD);
               step=step+process;
               BufferedReader reader = new BufferedReader(
               new InputStreamReader(process.getInputStream()));
               step=step+reader.toString();
               s = reader.readLine();
               step=step+s.toString();
               try
                    process.waitFor();
               catch (InterruptedException e)
                    return e.getMessage()+1;
               catch (IOException ex)
                    return ex.getMessage()+step;
          process.destroy();
          int k=process.exitValue();
          String x=String.valueOf(k);
          return x;
After every 5-6 days, I am getting same error, "java.io.IOException: Too many open files"

hi,
domRegisterCmd = "sh /home/kesharil/DomainRenew/n4vrsgn/DomainRenew-n4vrsgn.sh{code}
you are opening the above file and not closing,,
so that each and every file still in existence, one the memory full, then you are getting this error..
please to confirm on this..

How to close a open file at OS level using Java program

I want to find a way to close a file connection at operating system (Windows 2000) level so that another program can overwrite the file. Here is the background information:
I need to schedule a job to automatically update certain files. But, when someone is accessing the file, the update will fail until I manually close the file connection at file server ( I have the system administrator privilege). I want to write a Java program that can automatically close the open file like I do manually at file server. This program can be placed on the file server in order to the job.
Does anyone know if there is any way in Java that can do the job?
Thanks

It's up to the application that opened the files to close them. There are utilities you can use to list/kill process on the machine..but you have to ask yourself WHY is this happening in the first place? It's more correct to fix the REAL problem - having your apps shut down properly - than to write a utility to close files.
That said...java alone cannot do this. You would either have to use JNI to get native access to the system or use System.Runtime to call an executable that does the job for you.

Opening a java jar file through a labview program

Hello,
I need to open a java jar file in labview........this jar file is a GUI with multiple frames and has buttons on each frame help navigate through between frames....i just require the program to open it and close it based on some signals so then i won't have to do it manually

LabVIEW doesn't have any control over what happens in a system exec, as you give the control to the system. You can, however, check the process list through .NET commands and kill the process (You should be able to stop it through "taskkill /F /im java.exe"). Not the prettiest solution, but should work.
/Y
LabVIEW 8.2 - 2014
"Only dead fish swim downstream" - "My life for Kudos!" - "Dumb people repeat old mistakes - smart ones create new ones."
G# - Free award winning reference based OOP for LV

JAVA opening file streams q

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