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• Longer execution through Java shell than console?

  - by czuk

  I have a script in Python which do some computations. When I run this script in console it takes about 7 minutes to complete but when I run it thought Java shell it takes three times longer. I use following code to execute the script in Java: this.p = Runtime.getRuntime().exec("script.py --batch", envp); this.input = new BufferedReader(new InputStreamReader(p.getInputStream())); this.output = new BufferedWriter(new OutputStreamWriter(p.getOutputStream())); this.error = new BufferedReader(new InputStreamReader(p.getErrorStream())); Do you have any suggestion why the Python script runs three time longer in Java than in a console? update The computation goes as follow: Java sends data to the Python. Python reads the data. Python generates a decision tree --- this is a long operation. Python sends a confirmation that the tree is ready. Java receives the confirmation. Later there is a series of communications between Java and Python but it takes only several second.

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• MySQL help, counting information on last records

  - by ee12csvt

  I need some advice I have two tables, one holds unique serial numbers of items (items) and the other holds status changes and other information for these items (details) The Tables are set up as follows Item itemID itemName itemDate details detID itemID modlvl status detDate All items have at least one record in the details table, but over time the status has changed or the modification level has changed (Both of these are identified by numbers which are held in other appropriate tables) and a new record is created each time the status/modlvl changes I want to display a table on my webpage using php that identifies the different mod levels of the items and shows a count of each of the current status of the items EDIT Hi Ronnis, This is an example of the data in the tables and what I want to achieve The current Mod Levels range from 1 to 3 Status representations are 1 In Use 2 In Store 3 Being repaired 4 In Transit 5 For Disposal 6 Disposed 7 Lost Item itemID OrigMod created 1000 1 2009-10-01 22:12:12 1001 1 2009-10-01 22:12:12 1002 1 2009-10-01 22:12:12 1003 1 2009-10-01 22:12:12 1004 1 2009-10-01 22:12:12 1005 1 2009-10-01 22:12:12 1006 1 2009-10-01 22:12:12 1007 1 2009-10-01 22:12:12 1008 1 2009-10-01 22:12:12 1009 1 2009-10-01 22:12:12 1010 1 2009-10-01 22:12:12 Details detID itemID modlvl detDate status 1 1000 1 2009-10-01 1 2 1001 1 2009-10-01 1 3 1002 1 2009-10-01 1 4 1003 1 2009-10-01 1 5 1004 1 2009-10-01 1 6 1005 1 2009-10-01 1 7 1006 1 2009-10-01 1 8 1007 1 2009-10-01 1 9 1008 1 2009-10-01 1 10 1009 1 2009-10-01 1 11 1010 1 2009-10-01 1 12 1001 1 2010-02-01 2 13 1001 1 2010-02-03 4 14 1001 1 2010-03-01 3 15 1000 1 2010-03-14 2 16 1001 2 2010-04-01 4 17 1006 1 2010-04-01 2 18 1001 2 2010-04-03 2 19 1006 1 2010-04-14 4 20 1006 1 2010-05-01 5 21 1002 1 2010-05-02 2 22 1003 1 2010-05-10 2 23 1010 1 2010-06-01 2 24 1006 1 2010-06-18 6 25 1010 1 2010-07-01 7 26 1007 1 2010-07-02 2 27 1007 1 2010-07-04 4 28 1003 1 2010-07-10 2 29 1007 1 2010-07-11 3 30 1007 2 2010-07-12 4 31 1007 2 2010-07-15 2 32 1001 2 2010-08-31 1 33 1001 2 2010-09-10 2 34 1001 2 2010-10-01 4 35 1008 1 2010-10-01 2 36 1001 2 2010-10-05 3 37 1008 1 2010-10-05 4 38 1008 1 2010-10-10 3 39 1001 3 2010-10-20 4 40 1001 3 2010-10-25 2 Using the tables above I want to get this result MoLvl Use Store Repd Transit Displ Dispd Lost Total 1 3 3 1 0 0 1 1 9 2 0 1 0 0 0 0 0 1 3 0 1 0 0 0 0 0 1 Total 3 5 1 0 0 1 1 11

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• Managing StringBuilder Resources

  - by Jim Fell

  My C# (.NET 2.0) application has a StringBuilder variable with a capacity of 2.5MB. Obviously, I do not want to copy such a large buffer to a larger buffer space every time it fills. By that point, there is so much data in the buffer anyways, removing the older data is a viable option. Can anyone see any obvious problems with how I'm doing this (i.e. am I introducing more performance problems than I'm solving), or does it look okay? tText_c = new StringBuilder(2500000, 2500000); private void AppendToText(string text) { if (tText_c.Length * 100 / tText_c.Capacity > 95) { tText_c.Remove(0, tText_c.Length / 2); } tText_c.Append(text); } EDIT: Additional information: In this application new data is received very rapidly (on the order of milliseconds) through a serial connection. I don't want to populate the multiline textbox with this new information so frequently because that kills the performance of the application, so I'm saving it to a StringBuilder. Every so often, the application copies the contents of the StringBuilder to the textbox and wipes out the StringBuilder contents.

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• Standard term for a thread I/O reorder buffer?

  - by Crashworks

  I have a case where many threads all concurrently generate data that is ultimately written to one long, serial file. I need to somehow serialize these writes so that the file gets written in the right order. ie, I have an input queue of 2048 jobs j0..jn, each of which produces a chunk of data oi. The jobs run in parallel on, say, eight threads, but the output blocks have to appear in the file in the same order as the corresponding input blocks — the output file has to be in the order o0o1o2... The solution to this is pretty self evident: I need some kind of buffer that accumulates and writes the output blocks in the correct order, similar to a CPU reorder buffer in Tomasulo's algorithm, or to the way that TCP reassembles out-of-order packets before passing them to the application layer. Before I go code it, I'd like to do a quick literature search to see if there are any papers that have solved this problem in a particularly clever or efficient way, since I have severe realtime and memory constraints. I can't seem to find any papers describing this though; a Scholar search on every permutation of [threads, concurrent, reorder buffer, reassembly, io, serialize] hasn't yielded anything useful. I feel like I must just not be searching the right terms. Is there a common academic name or keyword for this kind of pattern that I can search on?

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• Sharepoint fails to load a C++ dll on windows 2008

  - by Nathan

  I have a sharepoint DLL that does some licensing things and as part of the code it uses an external C++ DLL to get the serial number of the hardisk. When i run this application on windows server 2003 it works fine, but on 2008 the whole site (loaded on load) crashes and resets continually. This is not 2008 R2 and is the same in 64 or 32 bits. If i put a debugger.break before the dll execution then I see the code get to the point of the break then never come back into the dll again. I do get some debug assertion warnings from within the function, again only in 2008, but im not sure this is related. I created a console app that runs the c# dll, which in turn loads the c++ dll, and this works perfectly on 2008 (although does show the assertion errors, but I have suppressed these now). The assertion errors are not in my code but within ICtypes.c and not something I can debug. If i put a breakpoint in the DLL it is never hit and the compiler says : "step in: Stepping over non user code" if i try to debug into the DLL using VS. I have tried wrapping the code used to call the DLL in: SPSecurity.RunWithElevatedPrivileges(delegate() but this also does not help. I have the sourcecode for this DLL so that is not a problem. If i delete the DLL from the directory I get an error about a missing DLL, if i replace it back to no error or warning just a complete failure. If i replace this code with a hardcoded string the whole application works fine. Any advice would be much appreciated, I can't understand why it works as a console app yet not when run by sharepoint, this is with the same user account, on the same machine... This is the code used to call the DLL: [DllImport("idDll.dll", EntryPoint = "GetMachineId", SetLastError = true)] extern static string GetComponentId([MarshalAs(UnmanagedType.LPStr)]String s); public static string GetComponentId() { Debugger.Break(); if (_machine == string.Empty) { string temp = ""; id= ComponentId.GetComponentId(temp); } return id; }

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• What about parallelism across network using multiple PCs?

  - by MainMa

  Parallel computing is used more and more, and new framework features and shortcuts make it easier to use (for example Parallel extensions which are directly available in .NET 4). Now what about the parallelism across network? I mean, an abstraction of everything related to communications, creation of processes on remote machines, etc. Something like, in C#: NetworkParallel.ForEach(myEnumerable, () => { // Computing and/or access to web ressource or local network database here }); I understand that it is very different from the multi-core parallelism. The two most obvious differences would probably be: The fact that such parallel task will be limited to computing, without being able for example to use files stored locally (but why not a database?), or even to use local variables, because it would be rather two distinct applications than two threads of the same application, The very specific implementation, requiring not just a separate thread (which is quite easy), but spanning a process on different machines, then communicating with them over local network. Despite those differences, such parallelism is quite possible, even without speaking about distributed architecture. Do you think it will be implemented in a few years? Do you agree that it enables developers to easily develop extremely powerfull stuff with much less pain? Example: Think about a business application which extracts data from the database, transforms it, and displays statistics. Let's say this application takes ten seconds to load data, twenty seconds to transform data and ten seconds to build charts on a single machine in a company, using all the CPU, whereas ten other machines are used at 5% of CPU most of the time. In a such case, every action may be done in parallel, resulting in probably six to ten seconds for overall process instead of forty.

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• threading and getting COM port of attached phone

  - by I__

  i have the following code: using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; using System.Threading; namespace WindowsFormsApplication1 { public partial class Form1 : Form { public Form1() { InitializeComponent(); } public class ThreadWork { public static void DoWork() { } } private void Form1_Load(object sender, EventArgs e) { ThreadStart myThreadDelegate = new ThreadStart(ThreadWork.DoWork); Thread myThread = new Thread(myThreadDelegate); myThread.Start(); // Begin communications serialPort1.Open(); serialPort1.Write("AT+CMGF=1\r\n"); //Thread.Sleep(500); serialPort1.Write("AT+CNMI=2,2\r\n"); //Thread.Sleep(500); serialPort1.Write("AT+CSCA=\"+4790002100\"\r\n"); //Thread.Sleep(500); } private void serialPort1_DataReceived_1(object sender, System.IO.Ports.SerialDataReceivedEventArgs e) { string response = serialPort1.ReadLine(); this.BeginInvoke(new MethodInvoker(() => textBox1.AppendText(response + "\r\n"))); } } } what i am trying to do is send AT COMMANDS to my phone which is attached to the computer through USB how do i know how to configure the properties of the serial port? (like which COM is the phone on [it's attached through USB], what about baudrate and databits?) when i run the program nothing really happens, i would like to send AT COMMANDS to my phone and the textbox is there to receive the response from my phone this is my first time using threads. am i using them correctly? what is the purpose of it in the current example? is it to just have a delay between send a response? what am i doing wrong?

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• c# threading and getting COM port of attached phone

  - by I__

  i have the following code: using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; using System.Threading; namespace WindowsFormsApplication1 { public partial class Form1 : Form { public Form1() { InitializeComponent(); } public class ThreadWork { public static void DoWork() { } } private void Form1_Load(object sender, EventArgs e) { ThreadStart myThreadDelegate = new ThreadStart(ThreadWork.DoWork); Thread myThread = new Thread(myThreadDelegate); myThread.Start(); // Begin communications serialPort1.Open(); serialPort1.Write("AT+CMGF=1\r\n"); //Thread.Sleep(500); serialPort1.Write("AT+CNMI=2,2\r\n"); //Thread.Sleep(500); serialPort1.Write("AT+CSCA=\"+4790002100\"\r\n"); //Thread.Sleep(500); } private void serialPort1_DataReceived_1(object sender, System.IO.Ports.SerialDataReceivedEventArgs e) { string response = serialPort1.ReadLine(); this.BeginInvoke(new MethodInvoker(() => textBox1.AppendText(response + "\r\n"))); } } } what i am trying to do is send AT COMMANDS to my phone which is attached to the computer through USB how do i know how to configure the properties of the serial port? (like which COM is the phone on [it's attached through USB], what about baudrate and databits?) when i run the program nothing really happens, i would like to send AT COMMANDS to my phone and the textbox is there to receive the response from my phone this is my first time using threads. am i using them correctly? what is the purpose of it in the current example? is it to just have a delay between send a response? what am i doing wrong?

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• problem linking vba modules in MS Access 2007

  - by Ted

  I am upgrading a database system from Access 2000 db to Access 2007, which communicates with several chemistry measuring devices(pH meter, scale, etc) via an RS 232 serial port. The first db consists of several modules containing vba code that enables the communications with the ports, as well as supports the code behind the forms in the second db. The user, or lab tech, navigates through the forms in the second db to interact with the lab devices, and also to generate the reports which display the info. from the devices. The reports are also part of the second db. The code works in Access 2000, but once I convert it to 2007, the code in the second db cannot find the function calls in the first db that dictate the progression from screen to screen. I have tried importing the modules into the second db, and I have tried linking them, but it still doesn't work. The error message is #438: "Object doesn't support this property or method." Any suggestions would be greatly appreciated. Here is the code for the first function that is not being called correctly: Description: ' This routine is used to return to the calling form and close the active form. ' ' Input: ' strFormCalled --- the active form ' strCallingForm --- the form that called the active form ' blnUnhideOrOpen --- whether to open or just unhide form Public Sub basReturnToCallingForm(ByVal strFormCalled As String, ByVal _ strCallingForm As Variant, Optional blnUnhideOrOpen As Boolean = True) On Error GoTo err_basReturnToCaliingForm If Not basIsBlankString(strCallingForm) And blnUnhideOrOpen Then DoCmd.OpenForm strCallingForm, acNormal Else Call basUnHideForm(strCallingForm) End If Call basCloseForm(strFormCalled) exit_basReturnToCaliingForm: Exit Sub err_basReturnToCaliingForm: Err.Raise Err.Number, "basReturnToCaliingForm", Err.Description End Sub I will post the second function shortly, but I have to go to a meeting... The second funtion that isn't 'working' is a cmdStartClick that is supposed to be called when a user initializes a pump. However, within that function, it's also sticking on a line that is supposed to progress to the next form in the db. The other thing is that the code works in Access 2002, but not in Access 2007...

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• How can I take advantage of IObservable/IObserver to get rid of my "god object"?

  - by Will

  In a system I'm currently working on, I have many components which are defined as interfaces and base classes. Each part of the system has some specific points where they interact with other parts of the system. For example, the data readying component readies some data which eventually needs to go to the data processing portion, the communications component needs to query different components for their status for relaying to the outside, etc. Currently, I glue these parts of the system together using a "god object", or an object with intimate knowledge of different parts of the system. It registers with events over here and shuttles the results to methods over there, creates a callback method here and returns the result of that method over there, and passes many requests through a multi-threaded queue for processing because it "knows" certain actions have to run on STA threads, etc. While its convenient, it concerns me that this one type knows so much about how everybody else in the system is designed. I'd much prefer a more generic hub that can be given instances which can expose events or methods or callbacks or that can consume these. I've been seeing more about the IObservable/IObserver features of the reactive framework and that are being rolled into .NET 4.0 (I believe). Can I leverage this pattern to help replace my "god object"? How should I go about doing this? Are there any resources for using this pattern for this specific purpose?

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• Arduino variable going blank after first pass.

  - by user541597

  I have an arduino sketch that takes a timet and when that timet is equal to the current time it sets the new timet to timet + 2. For example: char* convert(char* x, String y){ int hour; int minute; sscanf(x, "%d:%d", &hour, &minute); char buf[6]; if (y == "6"){ if (hour > 17){ hour = (hour+6)%24; snprintf(buf, 10, "%d:%d", hour, minute ); }else if (hour < 18){ //hour = hour + 6; minute = (minute + 2); snprintf(buf, 10, "%d:%d", hour, minute); } } if (y == "12"){ if (hour > 11){ hour = (hour+12)%24; snprintf(buf, 10, "%d:%d", hour, minute ); } else if (hour < 12){ hour = hour + 12; snprintf(buf, 10, "%d:%d", hour, minute); } } if (y == "24"){ hour = (hour+24)%24; snprintf(buf, 10, "%d:%d", hour, minute ); } return buf; } sketch starts for example at 1:00am timet is set to 1:02, at system time 1:02 timet == system time my loops looks like this: if (timet == currenttime){ timet = convert(timet) } From this now when ever I check the value of timet it should equal 1:04, however I am getting the correct value at the first run after the execution of convert however everytime after that my timet value is blank. I tried changing the code instead of using the if loop I only run the convert function when I send for example t through the serial monitor, this works fine and outputs the correct timet after the execution of the convert function, So I figured the problem is in the if loop... Any ideas?

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• Invoking different methods on threads

  - by Kraken

  I have a main process main. It creates 10 threads (say) and then what i want to do is the following: while(required){ Thread t= new Thread(new ClassImplementingRunnable()); t.start(); counter++; } Now i have the list of these threads, and for each thread i want to do a set of process, same for all, hence i put that implementation in the run method of ClassImplementingRunnable. Now after the threads have done their execution, i wan to wait for all of them to stop, and then evoke them again, but this time i want to do them serially not in parallel. for this I join each thread, to wait for them to finish execution but after that i am not sure how to evoke them again and run that piece of code serially. Can i do something like for(each thread){ t.reevoke(); //how can i do that. t.doThis(); // Also where does `dothis()` go, given that my ClassImplementingRunnable is an inner class. } Also, i want to use the same thread, i.e. i want the to continue from where they left off, but in a serial manner. I am not sure how to go about the last piece of pseudo code. Kindly help. Working with with java.

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• Protocol specification in XML

  - by Mathijs

  Is there a way to specify a packet-based protocol in XML, so (de)serialization can happen automatically? The context is as follows. I have a device that communicates through a serial port. It sends and receives a byte stream consisting of 'packets'. A packet is a collection of elementary data types and (sometimes) other packets. Some elements of packets are conditional; their inclusion depends on earlier elements. I have a C# application that communicates with this device. Naturally, I don't want to work on a byte-level throughout my application; I want to separate the protocol from my application code. Therefore I need to translate the byte stream to structures (classes). Currently I have implemented the protocol in C# by defining a class for each packet. These classes define the order and type of elements for each packet. Making class members conditional is difficult, so protocol information ends up in functions. I imagine XML that looks like this (note that my experience designing XML is limited): <packet> <field name="Author" type="int32" /> <field name="Nickname" type="bytes" size="4"> <condition type="range"> <field>Author</field> <min>3</min> <max>6</min> </condition> </field> </packet> .NET has something called a 'binary serializer', but I don't think that's what I'm looking for. Is there a way to separate protocol and code, even if packets 'include' other packets and have conditional elements?

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• Loading more than 10 images on iPhone??

  - by SeniorLee

  I'm trying to add more than 10 pictures on ScrollView. NSUInteger i; for (i = 1; i <= numberOfImage; i++) { NSString *imageName = [NSString stringWithFormat:@"d%dimage%d.png", imageSection, i]; UIImage *image = [UIImage imageNamed:imageName]; UIImageView *imageView = [[UIImageView alloc] initWithImage:image]; // setup each frame to a default height and width, it will be properly placed when we call "updateScrollList" CGRect rect = imageView.frame; rect.size.height = kScrollObjHeight; rect.size.width = kScrollObjWidth; imageView.frame = rect; imageView.tag = i; // tag our images for later use when we place them in serial fashion [scrollView addSubview:imageView]; [imageView release]; } This code is from Apple example and it works fine. But if the variable 'i' is bigger than 10, 'UIImage *image' is empty. The imageName seems to correct. But I don't know why it does not load image. Does anybody sees the problem?? And one more thing. If I do like that, does iOS controls memory automatically? I mean it's kind of wasting memory if all (more than 10) images are loaded on memory even they are not displayed. I've heard that iOS loads images only displayed on screen and free images those are not displayed. Is that right? Thanks for reading.

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• Navigating sorted XML data (XSLT)

  - by Andrew Parisi

  I have an XML file with company data in it, for 30 companies across 8 industries, on a portfolio page. The user has the option to sort this data by Industry, and this XML file will be added to constantly. This sorting is done in my XSL file using <xsl:choose>. Example: <xsl:when test="(invest[@investid='con'])"> <xsl:for-each select="$invest-port/portfolio/company[@industry='Communications']"> <xsl:sort select="name" /> <div class="invest-port-thumb"> <a> <xsl:attribute name="href"> <xsl:value-of select="link" /> </xsl:attribute> </a> </div> </xsl:for-each> </xsl:when> When navigating to an individual company's page, there are "previous" and "next" buttons at the bottom of the window. My issue is that I need these to dynamically link to the previous and next elements from within the XML data that has been sorted. Is this possible? Or is there an easier way to do this? (such as place each company in industry-divided XML files instead of one) Any insight would be greatly appreciated!

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• Creating a network adapter - how hard is it?

  - by Vilx-

  I'm interested in building a little (commercial) device on top of Arduino. I want it to be able to interface with network. Network as in standard Ethernet, Cat5, RJ-45, etc. I know that there is an Ethernet Shield, but it costs even more than the Arduino itself, and it's pretty big. Naturally, I want my device to be as small and as cheap as possible. So I'm thinking about recreating an Ethernet module myself. The problem is - I haven't got any experience with Ethernet, nor do I have a good idea where to start looking. Thus I can't even say if my ideas are feasible. Ultimately I would like the device to have three ports - one for incoming signal, two for outgoing, so the device is essentially a little switch where it is plugged in itself as well. The switching capabilities need not be very fast - the volume of data will be low. 10Mbit is more than enough, can be even slower. If that is not possible, a single port for controlling the device itself will also do. Another possibility I'm considering is power line communications - sending information through power lines. That's another area I've no experience with. What hardware should I be looking at, and where can I find information about the necessary software? So - can anyone tell me if these ideas are feasible, and if yes - where should I start looking?

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• How to make ActiveRecord work with legacy partitioned/sharded databases/tables?

  - by Utensil

  thanks for your time first...after all the searching on google, github and here, and got more confused about the big words(partition/shard/fedorate),I figure that I have to describe the specific problem I met and ask around. My company's databases deals with massive users and orders, so we split databases and tables in various ways, some are described below: way database and table name shard by (maybe it's should be called partitioned by?) YZ.X db_YZ.tb_X order serial number last three digits YYYYMMDD. db_YYYYMMDD.tb date YYYYMM.DD db_YYYYMM.tb_ DD date too The basic concept is that databases and tables are seperated acording to a field(not nessissarily the primary key), and there are too many databases and too many tables, so that writing or magically generate one database.yml config for each database and one model for each table isn't possible or at least not the best solution. I looked into drnic's magic solutions, and datafabric, and even the source code of active record, maybe I could use ERB to generate database.yml and do database connection in around filter, and maybe I could use named_scope to dynamically decide the table name for find, but update/create opertions are bounded to "self.class.quoted_table_name" so that I couldn't easily get my problem solved. And even I could generate one model for each table, because its amount is up to 30 most. But this is just not DRY! What I need is a clean solution like the following DSL: class Order < ActiveRecord::Base shard_by :order_serialno do |key| [get_db_config_by(key), #because some or all of the databaes might share the same machine in a regular way or can be configed by a hash of regex, and it can also be a const get_db_name_by(key), get_tb_name_by(key), ] end end Can anybody enlight me? Any help would be greatly appreciated~~~~

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• Concurrent Threads in C# using BackgroundWorker

  - by Jim Fell

  My C# application is such that a background worker is being used to wait for the acknowledgement of some transmitted data. Here is some psuedo code demonstrating what I'm trying to do: UI_thread { TransmitData() { // load data for tx // fire off TX background worker } RxSerialData() { // if received data is ack, set ack received flag } } TX_thread { // transmit data // set ack wait timeout // fire off ACK background worker // wait for ACK background worker to complete // evaluate status of ACK background worker as completed, failed, etc. } ACK_thread { // wait for ack received flag to be set } What happens is that the ACK BackgroundWorker times out, and the acknowledgement is never received. I'm fairly certain that it is being transmitted by the remote device because that device has not changed at all, and the C# application is transmitting. I have changed the ack thread from this (when it was working)... for( i = 0; (i < waitTimeoutVar) && (!bAckRxd); i++ ) { System.Threading.Thread.Sleep(1); } ...to this... DateTime dtThen = DateTime.Now(); DateTime dtNow; TimeSpan stTime; do { dtNow = DateTime.Now(); stTime = dtNow - dtThen; } while ( (stTime.TotalMilliseconds < waitTimeoutVar) && (!bAckRxd) ); The latter generates a very acurate wait time, as compared to the former. However, I am wondering if removal of the Sleep function is interferring with the ability to receive serial data. Does C# only allow one thread to run at a time, that is, do I have to put threads to sleep at some time to allow other threads to run? Any thoughts or suggestions you may have would be appreciated. I am using Microsoft Visual C# 2008 Express Edition. Thanks.

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• perl multithreading issue for autoincrement

  - by user3446683

  I'm writing a multi threaded perl script and storing the output in a csv file. I'm trying to insert a field called sl.no. in the csv file for each row entered but as I'm using threads, the sl. no. overlaps in most. Below is an idea of my code snippet. for ( my $count = 1 ; $count <= 10 ; $count++ ) { my $t = threads->new( \&sub1, $count ); push( @threads, $t ); } foreach (@threads) { my $num = $_->join; } sub sub1 { my $num = shift; my $start = '...'; #distributing data based on an internal logic my $end = '...'; #distributing data based on an internal logic my $next; for ( my $x = $start ; $x <= $end ; $x++ ) { my $count = $x + 1; #part of code from which I get @data which has name and age my $j = 0; if ( $x != 0 ) { $count = $next; } foreach (@data) { #j is required here for some extra code flock( OUTPUT, LOCK_EX ); print OUTPUT $count . "," . $name . "," . $age . "\n"; flock( OUTPUT, LOCK_UN ); $j++; $count++; } $next = $count; } return $num; } I need the count to be incremented which is the serial number for the rows that would be inserted in the csv file. Any help would be appreciated.

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• Windows: Does something temporarily grab the com ports on startup?

  - by Tim

  I have a WPF/C# app that is launched as part of the "Startup" group on a Windows Embedded Standard machine. One of the first things the app does (in its static App() method) is create a new SerialPort object for COM1. COM1 is a hardwired serial port, not a USB virtual port or anything like that. My problem is that every so often (maybe 1 out of 12) on startup, I get an exception: System.UnauthorizedAccessException: Access to the port 'COM1' is denied. There are no other applications using this port. Also, when I relaunch the app following this error, it grabs the port just fine. It's as if the com port isn't ready/set up for my app sometimes. I'm clueless on this one! Any insight is appreciated! UPDATE: I added a call to SerialPort.GetPortNames() and printout all available ports before attempting to open the port. In the failure case COM1 is indeed THERE! So, it's not that the port isn't ready. It looks like something in Windows is actually grabbing the port temporarily and blocking me.

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• How can multiple variables be passed to a function cleanly in C?

  - by aquanar

  I am working on an embedded system that has different output capabilities (digital out, serial, analog, etc). I am trying to figure out a clean way to pass many of the variables that will control those functions. I don't need to pass ALL of them too often, but I was hoping to have a function that would read the input data (in this case from a TCP network), and then parse the data (IE, the 3rd byte contains the states of 8 of the digital outputs (according to which bit in that byte is high or low)), and put that into a variable where I can then use elsewhere in the program. I wanted that function to be separate from the main() function, but to do so would require passing pointers to some 20 or so variables that it would be writing to. I know I could make the variables global, but I am trying to make it easier to debug by making it obvious when a function is allowed to edit that variable, by passing it to the function. My best idea was a struct, and just pass a pointer to it, but wasn't sure if there was a more efficient way, especially since there is only really 1 function that would need to access all of them at once, while most others only require parts of the information that will be stored in this bunch of state variables. So anyway, is there a clean way to send many variables between functions at once that need to be edited?

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• What are provenly scalable data persistence solutions for consumer profiles?

  - by Hubbard

  Consumer profiles with analytical scores [ConsumerID, 1..n demographical variables, 1...n analytical scores e.g. "likely to churn" "likely to buy an item 100$ in worth" etc.] have to be possible to query fast if they are to be used in customizing web-sites, consumer communications etc. Well. If you have: Large number of consumers Large profiles with a huge set of variables (as profiles describing human behaviour are likely to be..) ...you are in trouble. If you really have a physical relational database to which you target a query and then a physical disk starts to rotate someplace to give you an individual profile or a set of profiles, the profile user (a web site customizing a page, a recommendation engine making a recommendation..) has died of boredom before getting any observable results. There is the possibility of having the profiles in memory, which would of course increase the performance hugely. What are the most proven solutions for a fast-response, scalable consumer profile storage? Is there a shootout of these someplace?

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• Is a web-server (e.g servlets) a good solution for an IM server?

  - by John

  I'm looking at a new app, broadly speaking an IM application with a strong client-server model - all communications go through a server so they can be logged centrally. The server will be Java in some form, clients could at this point be anything from a .NET Desktop app to Flex/Silverlight, to a simple web-interface using JS/AJAX. I had anticipated doing the server using standard J2EE so I get a thread-safe, multi-user server for 'free'... to make things simple let's say using Servlets (but in practice SpringMVC would be likely). This all seemed very neat but I'm concerned if the stateless nature of Servlets is the best approach. If my memory of servlets (been a year or two) is right, each time a client sent a HTTP request, typically a new message entered by the user, the servlet could not assume it had the user/chat in memory and might have to get it from the DB... regardless it has to look it up. Then it either has to use some PUSH system to inform other members of the chat, or cache that there are new messages, for other clients who poll the server using AJAX or similar - and when they poll it again has to lookup the chat, including new messages, and send the new data. I'm wondering if a better system would be the server is running core Java, and implements a socket-based communication with clients. This allows much more immediate data transfer and is more flexible if say the IM client included some game you could play. But then you're writing a custom server and sockets don't sound very friendly to a browser-based client on current browsers. Am I missing some big piece of the puzzle here, it kind of feels like I am? Perhaps a better way to ask the question would simply be "if the client was browser-based using HTML/JS and had to run on IE7+,FF2+ (i.e no HTML5), how would you implement the server?" edit: if you are going to suggest using XMPP, I have been trying to get my head around this in another question, so please consider if that's a more appropriate place to discuss this specifically.

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• Combine MD5 hashes of multiple files

  - by user685869

  I have 7 files that I'm generating MD5 hashes for. The hashes are used to ensure that a remote copy of the data store is identical to the local copy. Unfortunately, the link between these two copies of the data is mind numbingly slow. Changes to the data are very rare but I have a requirement that the data be synchronized at all times (or as soon as possible). Rather than passing 7 different MD5 hashes across my (extremely slow) communications link, I'd like to generate the hash for each file and then combine these hashes into a single hash which I can then transfer and then re-calculate/use for comparison on the remote side. If the "combined hash" differs, then I'd start sending the 7 individual hashes to determine exactly which file(s) have been changed. For example, here are the MD5 hashes for the 7 files as of last week: 0709d609d69385255c496436eb50402c 709465a74411bd596595c7b9b158ae6a 4ab657320ef33e3d5eb498e4c13d41b7 3b49c6ab199994fd776bb63761414e72 0fc28c5a010fc3c06c0c930c88e31a15 c4ecd214662cac5aae0e53f6f252bf0e 8b086431e43148a2c2d943ba30d31cc6 I'd like to combine these hashes together such that I get a single unique value (perhaps another MD5 hash?) that I can then send to the remote system. On the remote system, I'd then perform the same calculation to determine if the data as a whole has been changed. If it has, then I'd start sending the individual hashes, etc. The most important factor is that my "combined hash" be short enough so that it uses less bandwidth than just sending all 7 hashes in the first place. I thought of writing the 7 MD5 hashes to a file and then hashing that file but is there a better way?

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• Common Properties: Consolidating Loan, Purchase, Inventory and Sale tables into one Transaction tabl

  - by Frank Computer

  Pawnshop Application: I have separate tables for Loan, Purchase, Inventory & Sales transactions. Each tables rows are joined to their respective customer rows by: customer.pk [serial] = loan.fk [integer]; = purchase.fk [integer]; = inventory.fk [integer]; = sale.fk [integer]; Since there are so many common properties within the four tables, I consolidated the four tables into one table called "transaction", where a column: transaction.trx_type char(1) {L=Loan, P=Purchase, I=Inventory, S=Sale} Scenario: A customer initially pawns merchandise, makes a couple of interest payments, then decides he wants to sell the merchandise to the pawnshop, who then places merchandise in Inventory and eventually sells it to another customer. I designed a generic transaction table where for example: transaction.main_amount DECIMAL(7,2) in a loan transaction holds the pawn amount, in a purchase holds the purchase price, in inventory and sale holds sale price. This is clearly a denormalized design, but has made programming alot easier and improved performance. Any type of transaction can now be performed from within one screen, without the need to change to different tables.

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