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  • gprof and execl() - is it possible?

    - by Chris
    Background: I have a game (an old-school-esque MUD) which I've been attempting to profile with gprof. The documentation of gprof (on Linux 2.6) states that The profiled program must call "exit"(2) or return normally for the profiling information to be saved in the gmon.out file. Now, if I kill the server with the shutdown command, the application "returns normally" (i.e., main() returns) and I get a gmon.out to analyze. However, it's far more common to reboot the server. The reboot command does the following: Writes usernames and socket FD numbers to disc. Makes a call to execl(). The new process looks for the stored data, picks up the FDs, and moves on. I see the following error on the command line, as the whole process fails: Profiling timer expired ./program Question: Is it possible to get a gmon.out file from the execl()-calling process? Perhaps some environmental parameter to execl(), or else perhaps a different, gprof-friendly, system call to achieve the same effect (beginning a new process while preserving file descriptors)?

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  • reading a random access file

    - by user1067332
    The file I create has text in it, but when i try to read it, the output is null. here is the file the creates the text file, it creates the file and puts it in the right postion import java.util.*; import java.io.*; public class CreateCustomerFile { public static void main(String[] args) throws IOException { int pos; RandomAccessFile it = new RandomAccessFile("CustomerFile.txt", "rw"); Scanner input = new Scanner(System.in); int id; String name; int zip; final int RECORDSIZE = 100; final int NUMRECORDS = 1000; final int STOP = 99; try { for(int x = 0; x < NUMRECORDS; ++x) { it.writeInt(0); it.writeUTF(""); it.writeInt(0); } } catch(IOException e) { System.out.println("Error: " + e.getMessage()); } finally { it.close(); } it = new RandomAccessFile("CustomerFile.txt","rw"); try { System.out.print("Enter ID number" + " or " + STOP + " to quit "); id = input.nextInt(); while(id != STOP) { input.nextLine(); System.out.print("Enter last name"); name = input.nextLine(); System.out.print("Enter zipcode "); zip = input.nextInt(); pos = id - 1; it.seek(pos * RECORDSIZE); it.writeInt(id); it.writeUTF(name); it.writeInt(zip); System.out.print("Enter ID number" + " or " + STOP + " to quit "); id = input.nextInt(); } } catch(IOException e) { System.out.println("Error: " + e.getMessage()); } finally { it.close(); } } } Here is the file to read, the pos is correct but ouput always goes to the error: null. import javax.swing.*; import java.io.*; public class CustomerItemOrder { public static void main(String[] args) throws IOException { int pos; RandomAccessFile it = new RandomAccessFile("CustomerFile.txt","rw"); String inputString; int id, zip; String name; final int RECORDSIZE = 100; final int STOP = 99; inputString = JOptionPane.showInputDialog(null, "Enter id or "+ STOP + " to quit"); id = Integer.parseInt(inputString); try { while(id != STOP) { pos = id -1 ; it.seek(pos * RECORDSIZE ); id = it.readInt(); name = it.readLine(); zip = it.readInt(); JOptionPane.showMessageDialog(null, "ID:" + id + " last name is " + name + " and zipcode is " + zip); inputString = JOptionPane.showInputDialog(null, "Enter id or " + STOP + " to quit"); id = Integer.parseInt(inputString); } } catch(IOException e) { System.out.println("Error: " + e.getMessage()); } finally { it.close(); } } }

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  • Overhead of serving pages - JSPs vs. PHP vs. ASPXs vs. C

    - by John Shedletsky
    I am interested in writing my own internet ad server. I want to serve billions of impressions with as little hardware possible. Which server-side technologies are best suited for this task? I am asking about the relative overhead of serving my ad pages as either pages rendered by PHP, or Java, or .net, or coding Http responses directly in C and writing some multi-socket IO monster to serve requests (I assume this one wins, but if my assumption is wrong, that would actually be most interesting). Obviously all the most efficient optimizations are done at the algorithm level, but I figure there has got to be some speed differences at the end of the day that makes one method of serving ads better than another. How much overhead does something like apache or IIS introduce? There's got to be a ton of extra junk in there I don't need. At some point I guess this is more a question of which platform/language combo is best suited - please excuse the in-adroitly posed question, hopefully you understand what I am trying to get at.

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  • Porting Windows C++ to Standard (Linux) C++ - WSAGetLastError()

    - by Donal Rafferty
    I am currently porting some Windows mobile C++ code to standard C++. So I am trying to find alternatives for windows specific functions. I have had very little luck in finding a standard C++ function that can help me replace the WSAGetLastError() windows specific function. WSAGetLastError() returns error numbers for errors that occur with sockets in windows. So I was wondering if anyone was aware of a way to replace this function in standard c++? A way to get different error numbers for different outcomes of connecting/dissconection a socket would be sufficent.

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  • Backing Up User Data when data is not in use. Should I be concerned?

    - by jberryman
    This may be a dumb question. I would like to use duplicity to make backups to Amazon S3 of directories, each of which contains a different user's data. Each directory could be written to at any time. So I have two questions: Should I be concerned that a scheduled backup of a directory might occur in the middle of data being written to files in the directory, resulting in a corrupted backup? And if that is a valid concern, how would I go about temporarily delaying an operation while IO was happening, to try to minimize that effect. Thanks for the advice

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  • Boost ASIO read X bytes synchroniously into a vector

    - by xeross
    Hey, I've been attempting to write a client/server app with boost now, so far it sends and receives but I can't seem to just read X bytes into a vector. If I use the following code vector<uint8_t> buf; for (;;) { buf.resize(4); boost::system::error_code error; size_t len = socket.read_some(boost::asio::buffer(buf), error); if (error == boost::asio::error::eof) break; // Connection closed cleanly by peer. else if (error) throw boost::system::system_error(error); // Some other error. } And the packet is bigger then 4 bytes then it seems it keeps writing into those 4 bytes until the entire packet has been received, however I want it to fetch 4 bytes, then allow me to parse them, and then get the rest of the packet. Can anyone provide me with a working example, or at least a pointer on how to make it work properly ? Regards, Xeross

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  • how to pass one variable value frm one class to the oder

    - by Arunabha
    i hav two packages one is com.firstBooks.series.db.parser which hav a java file XMLParser.java,i hav another package com.firstBooks.series79 which hav a class called AppMain.NW i want to send the value of a variable called _xmlFileName frm AppMain class to the xmlFile variable in XMLParser class,i am posting the codes for both the class,kindly help me. package com.firstBooks.series.db.parser; import java.io.IOException; import java.io.InputStream; import java.util.Vector; import net.rim.device.api.xml.parsers.DocumentBuilder; import net.rim.device.api.xml.parsers.DocumentBuilderFactory; import net.rim.device.api.xml.parsers.ParserConfigurationException; import org.w3c.dom.Document; import org.w3c.dom.Element; import org.w3c.dom.NodeList; import org.xml.sax.SAXException; import com.firstBooks.series.db.Question; public class XMLParser { private Document document; public static Vector questionList; public static String xmlFile; public XMLParser() { questionList = new Vector(); } public void parseXMl() throws SAXException, IOException, ParserConfigurationException { // Build a document based on the XML file. DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance(); DocumentBuilder builder = factory.newDocumentBuilder(); InputStream inputStream = getClass().getResourceAsStream(xmlFile); document = builder.parse(inputStream); } public void parseDocument() { Element element = document.getDocumentElement(); NodeList nl = element.getElementsByTagName("question"); if (nl != null && nl.getLength() > 0) { for (int i = 0; i < nl.getLength(); i++) { Element ele = (Element) nl.item(i); Question question = getQuestions(ele); questionList.addElement(question); } } } private Question getQuestions(Element element) { String title = getTextValue(element, "title"); String choice1 = getTextValue(element, "choice1"); String choice2 = getTextValue(element, "choice2"); String choice3 = getTextValue(element, "choice3"); String choice4 = getTextValue(element, "choice4"); String answer = getTextValue(element, "answer"); String rationale = getTextValue(element, "rationale"); Question Questions = new Question(title, choice1, choice2, choice3, choice4, answer, rationale); return Questions; } private String getTextValue(Element ele, String tagName) { String textVal = null; NodeList nl = ele.getElementsByTagName(tagName); if (nl != null && nl.getLength() > 0) { Element el = (Element) nl.item(0); textVal = el.getFirstChild().getNodeValue(); } return textVal; } } Nw the code for AppMain class //#preprocess package com.firstBooks.series79; import net.rim.device.api.ui.UiApplication; import com.firstBooks.series.ui.screens.HomeScreen; public class AppMain extends UiApplication { public static String _xmlFileName; public static boolean _Lite; public static int _totalNumofQuestions; public static void initialize(){ //#ifndef FULL /* //#endif _xmlFileName = "/res/Series79_FULL.xml"; _totalNumofQuestions = 50; _Lite = false; //#ifndef FULL */ //#endif //#ifndef LITE /* //#endif _xmlFileName = "/res/Series79_LITE.xml"; _totalNumofQuestions = 10; _Lite = true; //#ifndef LITE */ //#endif } private AppMain() { initialize(); pushScreen(new HomeScreen()); } public static void main(String args[]) { new AppMain().enterEventDispatcher(); } }

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  • Intercommunication between Java Chat Servers

    - by Pravingate
    I have a application in which I am using socket programming , having this(image) scenario. Where number of clients will try to connect Broadcast server. Now here I am managing load through LVS(Load balancer). so as a example shown in image, suppose 200 clients will wish to login for broadcast they will be distributed as 100 users on server 1 and another 100 users on server 2.clients will get connected to servers using TCP connection. Now I am maintaining user information on server side in arraylist which will be stored in heap memory,Now the problem is if client wish to broadcast to all logged in users, but that particular client is logged in server 1. and so client will not be able to broadcast another 100 users from server 2. Because both ther servers are unaware about each others state. please suggest to solve this scenario by whatever means you want.

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  • Strange "cache" effect between client and server

    - by mark
    I use a Socket-based connection between Client and server with ObjectOutputStream. The objects serialized and exchanged have this structure: public class RichiestaSalvataggioArticolo implements Serializable { private ArticoloDati articolo; public RichiestaSalvataggioArticolo(ArticoloDati articolo) { this.articolo = articolo; } @Override public void ricevi(GestoreRichieste gestore) throws Exception { gestore.interpreta(this); } public ArticoloDati getArticolo() { return articolo; } } the issue is that when I try to exchange messages between C/S with incapsulated content very similar (ArticoloDati whom differ only in 2 fields out of 10), the Client sends an ArticoloDati, but the Server receives the previous one. Does the ObjectOutputStream implement some kind of cache or memory between the calls, that fails to recognize that my 2 objects are different because they are very similar?

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  • what happens when I don't manage to call `recv` fast enough?

    - by amn
    Hi all, I want to account for a possible scenario where clients of my TCP/IP stream socket service send data to my service faster than it manages to move the data to its buffers (I am talking about application buffers, naturally) with recv and work with it. So basically, what happens in such scenarios? Obviously, some sort of service beneath my service which is a user application, has to receive incoming stream and store it somewhere until I issue 'recv', right? Most certainly the operating system. I don't want to re-open old questions, but I can't seem to find an answer to this seemingly obvious one?

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  • How do I start a cloud9 service

    - by Lord Loh.
    Cloud9 is a free IDE available from https://github.com/ajaxorg/cloud9/ under GPLv3. I would like to use this to set up a service like https://c9.io/. The Cloud9 documentations do not mention anything about it. The Cloud9 documentation assume a sing user on localhost or bind to another address without one hard set username and hard set password. How do I run cloud9 IDE on my computer allowing multiple users? Are there any documentations? This is the closest to what I found - https://github.com/avgp/cloud9hub (for multiple workspaces)

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  • Opening up TCP Sockets in j2ee Webapplication

    - by Gvenez
    Hello, We have to communicate with a C++ component from a J2ee web application and my proposal involved using JMS server to communicate with the C++ component which is located on other machine. However the developer of the C++ component wants me to open up TCP/IP sockets from the webapplication and communicate over XML. My view is that socket programming in web application is error prone and will not scale well since there is a limited amount of sockets that can be opened up. Please let me have your architecture/design preference on using JMS vs TCP/IP sockets. Thank you

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  • Windows service only gets called when Visual Studio is attached to process

    - by 64th
    I've created a simple windows service in C# using Visual Studio 2010. It uses a TcpListener and socket to listen for messages on a given port. This worked absolutely perfectly when my laptop had Windows Vista on it. However, since upgrading to Windows 7 and re-installing my service it only responds if I'm attached to the process and debugging in Visual Studio 2010 - at which time it behaves as expected. I've tried running the service under my (administrator) credentials and setting the exe to run as administrator. I've also checked "Allow service to interact with desktop" when it was running under the Local System account. I'm testing using both a test console app and an Adobe Air application - both with the same results. Are there some specific permissions that I need to allow the service to be called?

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  • 16 millisecond quantization when sending/receivingtcp packets

    - by MKZ
    Hi, I have a C++ application running on windows xp 32 system sending and receiving short tcp/ip packets. Measuring (accurately) the arrival time I see a quantization of the arrival time to 16 millisecond time units. (Meaning all packets arriving are at (16 )xN milliseconds separated from each other) To avoid packet aggregation I tried to disable the NAGLE algorithm by setting the IPPROTO_TCP option to TCP_NODELAY in the socket variables but it did not help I suspect that the problem is related to the windows schedular which also have a 16 millisecond clock.. Any idea of a solution to this problem ? Thanks

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  • Send files between python+django and C#

    - by SuitUp
    Hi, i would like to know, what is the best way to send files between python and C# and vice versa. I have my own protocol which work on socket level, and i can send string and numbers in both ways. Loops works too. With this i can send pretty much anything, like package of users id, if it is simple data. But soon i will start sending whole files, maybe xml or executables. Simple server with files is no an option because i want sending files from client too. I was thinking about serialization but i don't know it is the best solution, but if it is i will love some tips from stackoverflow community. EDIT: I added django to question and chose using http.

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  • MySQL, PHP, and Apache errors while connecting to DB

    - by cypherdelton
    I'm having two errors when I test the "mysql_connect()" function in php. I just installed PHP and MySQL from scratch. These errors may be related, so I will post them both here: Warning: mysql_connect() [function.mysql-connect]: Headers and client library minor version mismatch. Headers:50158 Library:50518 in /usr/local/apache2/htdocs/index.php on line 6 Warning: mysql_connect() [function.mysql-connect]: Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2) in /usr/local/apache2/htdocs/index.php on line 6 Many websites say to start the mysql server if you are getting error #2. Whenever I execute the command mysqld start --user=mysql I get the error "mysqld: Too many arguments (first extra is 'start'); Adding the "&" to the end of the command makes no difference (I don't know if it is supposed to). Thanks, Cypher Delton

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  • Writing directory: permission denied even though dir seems to be chmodded correctly

    - by Aron Rotteveel
    I am having some trouble creating files in directory on my Ubuntu machine: I added myself to the www-data group in order for me to easily edit stuff in my /var/www dir on my development machine. stat /var/www shows the following: File: ‘/var/www’ Size: 4096 Blocks: 8 IO Block: 4096 map Device: 808h/2056d Inode: 142853 Links: 3 Access: (0775/drwxrwxr-x) Uid: ( 33/www-data) Gid: ( 33/www-data) Access: 2010-12-30 16:03:18.563998000 +0100 Modify: 2010-12-30 16:02:52.663998000 +0100 Change: 2010-12-30 16:03:13.111998001 +0100 Still, it is impossible for me to create anything below /var/www (the only way for it to work is to chmod it to 777. What am I missing?

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  • Total network data sent/received of a non-daemon Linux process?

    - by leden
    I'm looking for a simple and effective way of measuring total bytes received/sent from a single process upon its termination. Basically, I am looking for a tool which has the interface similar to "time" and "/usr/bin/time", e.g. measure-net-data <prog_to_run> <prog_args> Received (b): XYZ Sent (b): ABC I know that there are many tools for bandwidth/network monitoring, but as far I can tell all of them are performing the measurements it real-time, which is inappropriate not only because of overhead but also because of the inconvenience - I would need to stop the program, capture the output of the tool and then kill it. I have seen that newer versions of Linux 2.6.20+ provide /proc/<pid>/io/ which contain the information I'm looking for; however, everything under /proc/<pid> when the process terminates, so I'm again back to the same problem as with any network monitoring tool.

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  • Send files between python and C#

    - by SuitUp
    Hi, i would like to know, what is the best way to send files between python and C# and vice versa. I have my own protocol which work on socket level, and i can send string and numbers in both ways. Loops works too. With this i can send pretty much anything, like package of users id, if it is simple data. But soon i will start sending whole files, maybe xml or executables. Simple server with files is no an option because i want sending files from client too. I was thinking about serialization but i don't know it is the best solution, but if it is i will love some tips from stackoverflow community.

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  • Is pthread_spin_trylock safe inside of sigsegv handler of multithreaded application?

    - by TWMouton
    I am trying to implement a handler that on SIGSEGV will collect some information such as process-id, thread-id and a backtrace and write this information to a file/pipe/socket. The problem lies in that there is the (probably pretty high) possibility that if one thread experienced a SIGSEGV that the others will shortly follow. If two threads happen to make it to the bit of code where they're writing their report out at the same time then they'll interleave their writing (to the same file). I know that I should only be using async-signal-safe functions as detailed in signal(7) I also have seen at least two cases here and video linked in top answer here where others have used pthread_spin_trylock to get around this problem. Is this a safe way to prevent the above problem?

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  • Java ThreadPool for multiple identical tasks

    - by tdimmig
    I have 1 thread who sole job is to grab DatagramPackets off of a socket and stick them in a buffer. Another thread works out of that buffer, processing the DatagramPackets. I'd like to have a pool of threads working out of that buffer. I had thought to use a fixed thread pool to do this. To do so, do I need to create the pool, then submit enough runnables for execution to fill it up? I had hoped for a way to say "this is the thread/runnable that I want you to execute, this is how many I want running, GO!". Is there such a method of doing this? Is something other than a fixed thread pool better suited?

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  • Protect foreach loop when empty list

    - by SteB
    Using Powershell v2.0 I want to delete any files older than X days: $backups = Get-ChildItem -Path $Backuppath | Where-Object {($_.lastwritetime -lt (Get-Date).addDays(-$DaysKeep)) -and (-not $_.PSIsContainer) -and ($_.Name -like "backup*")} foreach ($file in $backups) { Remove-Item $file.FullName; } However, when $backups is empty I get: Remove-Item : Cannot bind argument to parameter 'Path' because it is null. I've tried: Protecting the foreach with if (!$backups) Protecting the Remove-Item with if (Test-Path $file -PathType Leaf) Protecting the Remove-Item with if ([IO.File]::Exists($file.FullName) -ne $true) None of these seem to work, what if the recommended way of preventing a foreach loop from being entered if the list is empty?

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  • Running Java Server Application 24/7 (NOT on local machine) ...?

    - by Steven
    I am currently experimenting with Java Socket Programming and succeeded in creating a simple application that allows me to send data back and forth between a client and a server. I don't want to power my laptop (on which the server application runs) 24/7. Therefore, of course, no computer (that runs my client application) will be able to communicate with my selfmade server application as long as my laptop is turned off. Now I'd like to know: (1) Is it possible to run the server application on a remote (physical) server, so that I don't need my laptop for that purpose? (2) If yes, do you have any suggestions where I could rent such a remote server? As I said, I'm just curious about how all that stuff works. I don't really something expensive.

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  • Check SSD stability before returning it as broken?

    - by data_jepp
    I have the Transcend SSD 720 256GB 2,5" 7mm disk. And randomly I get disk IO in utorrent and large files copying to external will fail. I have removed it from my laptop since I need max stability. I use my laptop on exams. How can I really bench/make-it-sweat whilst connected to my desktop? I want to re-create some of the fails as I need proof if I am to return it. Firmware is updated. BIOS on laptop is updated. I could just completely nul the disk and then check for bad sectors, but is there anything else I could use for testing? Edit: It has 7 bad sector replacement operations. What does it mean?

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  • Callback Timer function in C++

    - by user3596609
    I am trying to implement a callback timer function in C++ which should do a callback after a timeout. I am listening on a socket and then waiting for messages on it. so if I have something like getMessages() and I want to pass the timer function in it as an argument. So how can it be implemented that after the receive of a message, the timer is started and the callback happens if there is a timeout before the next messages arrives. I am new to callback functions. Any help is greatly appreciated. Thanks!

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