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  • Global name not defined

    - by anteater7171
    I wrote a CPU monitoring program in Python. For some reason sometimes the the program will run without any problem. Then other times the program won't even start because of the following error. Traceback (most recent call last): File "", line 244, in run_nodebug File "C:\Python26\CPUR1.7.pyw", line 601, in app = simpleapp_tk(None) File "C:\Python26\CPUR1.7.pyw", line 26, in init self.initialize() File "C:\Python26\CPUR1.7.pyw", line 107, in initialize self.F() File "C:\Python26\CPUR1.7.pyw", line 517, in F S2 = TL.entryVariableS.get() NameError: global name 'TL' is not defined I can't seem to find the problem, maybe someone more experienced may assist me? Here is a snippet of the part giving me trouble: (The second to last line in the snippet is what's giving me trouble) def E(self): if self.selectedM.get() =='Options...': Setup global TL TL = Tkinter.Toplevel(self) menu = Tkinter.Menu(TL) TL.config(menu=menu) filemenu = Tkinter.Menu(menu) menu.add_cascade(label="| Menu |", menu=filemenu) filemenu.add_command(label="Instruction Manual...", command=self.helpmenu) filemenu.add_command(label="About...", command=self.aboutmenu) filemenu.add_separator() filemenu.add_command(label="Exit Options", command=TL.destroy) filemenu.add_command(label="Exit", command=self.destroy) helpmenu = Tkinter.Menu(menu) menu.add_cascade(label="| Help |", menu=helpmenu) helpmenu.add_command(label="Instruction Manual...", command=self.helpmenu) helpmenu.add_separator() helpmenu.add_command(label="Quick Help...", command=self.helpmenu) Title TL.label5 = Tkinter.Label(TL,text="CPU Usage: Options",anchor="center",fg="black",bg="lightgreen",relief="ridge",borderwidth=5,font=('Arial', 18, 'bold')) TL.label5.pack(padx=15,ipadx=5) X Y scale TL.separator = Tkinter.Frame(TL,height=7, bd=1, relief='ridge', bg='grey95') TL.separator.pack(pady=5,padx=5) # TL.sclX = Tkinter.Scale(TL.separator, from_=0, to=1500, orient='horizontal', resolution=1, command=self.A) TL.sclX.grid(column=1,row=0,ipadx=27, sticky='w') TL.label1 = Tkinter.Label(TL.separator,text="X",anchor="s",fg="black",bg="grey95",font=('Arial', 8 ,'bold')) TL.label1.grid(column=0,row=0, pady=1, sticky='S') TL.sclY = Tkinter.Scale(TL.separator, from_=0, to=1500, resolution=1, command=self.A) TL.sclY.grid(column=2,row=1,rowspan=2,sticky='e', padx=4) TL.label3 = Tkinter.Label(TL.separator,text="Y",fg="black",bg="grey95",font=('Arial', 8 ,'bold')) TL.label3.grid(column=2,row=0, padx=10, sticky='e') TL.entryVariable2 = Tkinter.StringVar() TL.entry2 = Tkinter.Entry(TL.separator,textvariable=TL.entryVariable2, fg="grey15",bg="grey90",relief="sunken",insertbackground="black",borderwidth=5,font=('Arial', 10)) TL.entry2.grid(column=1,row=1,ipadx=20, pady=10,sticky='EW') TL.entry2.bind("<Return>", self.B) TL.label2 = Tkinter.Label(TL.separator,text="X:",fg="black",bg="grey95",font=('Arial', 8 ,'bold')) TL.label2.grid(column=0,row=1, ipadx=4, sticky='W') TL.entryVariable1 = Tkinter.StringVar() TL.entry1 = Tkinter.Entry(TL.separator,textvariable=TL.entryVariable1, fg="grey15",bg="grey90",relief="sunken",insertbackground="black",borderwidth=5,font=('Arial', 10)) TL.entry1.grid(column=1,row=2,sticky='EW') TL.entry1.bind("<Return>", self.B) TL.label4 = Tkinter.Label(TL.separator,text="Y:", anchor="center",fg="black",bg="grey95",font=('Arial', 8 ,'bold')) TL.label4.grid(column=0,row=2, ipadx=4, sticky='W') TL.label7 = Tkinter.Label(TL.separator,text="Text Colour:",fg="black",bg="grey95",font=('Arial', 8 ,'bold'),justify='left') TL.label7.grid(column=1,row=3, sticky='W',padx=10,ipady=10,ipadx=30) TL.selectedP = Tkinter.StringVar() TL.opt1 = Tkinter.OptionMenu(TL.separator, TL.selectedP,'Normal', 'White','Black', 'Blue', 'Steel Blue','Green','Light Green','Yellow','Orange' ,'Red',command=self.G) TL.opt1.config(fg="black",bg="grey90",activebackground="grey90",activeforeground="black", anchor="center",relief="raised",direction='right',font=('Arial', 10)) TL.opt1.grid(column=1,row=4,sticky='EW',padx=20,ipadx=20) TL.selectedP.set('Normal') TL.sclS = Tkinter.Scale(TL.separator, from_=10, to=2000, orient='horizontal', resolution=10, command=self.H) TL.sclS.grid(column=1,row=5,ipadx=27, sticky='w') TL.sclS.set(600) TL.entryVariableS = Tkinter.StringVar() TL.entryS = Tkinter.Entry(TL.separator,textvariable=TL.entryVariableS, fg="grey15",bg="grey90",relief="sunken",insertbackground="black",borderwidth=5,font=('Arial', 10)) TL.entryS.grid(column=1,row=6,ipadx=20, pady=10,sticky='EW') TL.entryS.bind("<Return>", self.I) TL.entryVariableS.set(600) # TL.resizable(False,False) TL.title('Options') geomPatt = re.compile(r"(\d+)?x?(\d+)?([+-])(\d+)([+-])(\d+)") s = self.wm_geometry() m = geomPatt.search(s) X = m.group(4) Y = m.group(6) TL.sclY.set(Y) TL.sclX.set(X) if self.selectedM.get() == 'Exit': self.destroy() def F (self): G = round(psutil.cpu_percent(), 1) G1 = str(G) + '%' self.labelVariable.set(G1) if G < 5: self.imageLabel.configure(image=self.image0) if G >= 5: self.imageLabel.configure(image=self.image5) if G >= 10: self.imageLabel.configure(image=self.image10) if G >= 15: self.imageLabel.configure(image=self.image15) if G >= 20: self.imageLabel.configure(image=self.image20) if G >= 25: self.imageLabel.configure(image=self.image25) if G >= 30: self.imageLabel.configure(image=self.image30) if G >= 35: self.imageLabel.configure(image=self.image35) if G >= 40: self.imageLabel.configure(image=self.image40) if G >= 45: self.imageLabel.configure(image=self.image45) if G >= 50: self.imageLabel.configure(image=self.image50) if G >= 55: self.imageLabel.configure(image=self.image55) if G >= 60: self.imageLabel.configure(image=self.image60) if G >= 65: self.imageLabel.configure(image=self.image65) if G >= 70: self.imageLabel.configure(image=self.image70) if G >= 75: self.imageLabel.configure(image=self.image75) if G >= 80: self.imageLabel.configure(image=self.image80) if G >= 85: self.imageLabel.configure(image=self.image85) if G >= 90: self.imageLabel.configure(image=self.image90) if 100> G >= 95: self.imageLabel.configure(image=self.image95) if G == 100: self.imageLabel.configure(image=self.image100) S2 = TL.entryVariableS.get() self.after(int(S2), self.F)

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  • Java web-app debugging not possible due to direct undeploy on debug

    - by Hendrik
    When i try to debug my webapp it starts up the tomcat server and the application, but shuts down the debugger shortly before the app gets usable. I see the debugging toolbar for a second before it vanishes again, though the app keeps running. Tomcat-log: Listening for transport dt_socket at address: 11555 23.03.2010 01:24:35 org.apache.catalina.core.AprLifecycleListener init INFO: The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: .:/Library/Java/Extensions:/System/Library/Java/Extensions:/usr/lib/java 23.03.2010 01:24:35 org.apache.coyote.http11.Http11Protocol init INFO: Initializing Coyote HTTP/1.1 on http-8084 23.03.2010 01:24:35 org.apache.catalina.startup.Catalina load INFO: Initialization processed in 847 ms 23.03.2010 01:24:35 org.apache.catalina.core.StandardService start INFO: Starting service Catalina 23.03.2010 01:24:35 org.apache.catalina.core.StandardEngine start INFO: Starting Servlet Engine: Apache Tomcat/6.0.20 log4j:WARN No appenders could be found for logger (org.springframework.web.context.ContextLoader). log4j:WARN Please initialize the log4j system properly. 23.03.2010 01:24:41 org.apache.coyote.http11.Http11Protocol start INFO: Starting Coyote HTTP/1.1 on http-8084 23.03.2010 01:24:41 org.apache.jk.common.ChannelSocket init INFO: JK: ajp13 listening on /0.0.0.0:8009 23.03.2010 01:24:41 org.apache.jk.server.JkMain start INFO: Jk running ID=0 time=0/78 config=null 23.03.2010 01:24:41 org.apache.catalina.startup.Catalina start INFO: Server startup in 5855 ms 23.03.2010 01:24:42 org.apache.catalina.startup.HostConfig checkResources INFO: Undeploying context [] 23.03.2010 01:24:45 org.apache.catalina.core.StandardContext start INFO: Container org.apache.catalina.core.ContainerBase.[Catalina].[localhost].[/] has already been started Debugging log: Attached JPDA debugger to localhost:11555 Checking data source definitions for missing JDBC drivers... Deploying JDBC driver to /Applications/NetBeans/apache-tomcat-6.0.20/lib/mysql-connector-java-5.1.6-bin.jar Stopping Tomcat process... Waiting for Tomcat... Tomcat server stopped. Starting Tomcat process... Waiting for Tomcat... Tomcat server started. Undeploying ... OK - Undeployed application at context path / In-place deployment at /path/to/project/dir/build/web deploy?config=file%3A%2Fvar%2Ffolders%2FZP%2FZPbqxGrbHFaUlXzAfgWV1%2B%2B%2B%2BTQ%2F-Tmp-%2Fcontext734173871283203218.xml&path=/ OK - Deployed application at context path / start?path=/ Start is in progress... OK - Started application at context path / debug-display-browser: Browsing: http://localhost:8084/ connect-client-debugger: BUILD SUCCESSFUL (total time: 18 seconds) System is Netbeans 6.8 on MacOS 10.6.2. Thank you very much, guys!

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  • Difficulty getting Saxon into XQuery mode instead of XSLT

    - by Rosarch
    I'm having difficulty getting XQuery to work. I downloaded Saxon-HE 9.2. It seems to only want to work with XSLT. When I type: java -jar saxon9he.jar I get back usage information for XSLT. When I use the command syntax for XQuery, it doesn't recognize the parameters (like -q), and gives XSLT usage information. Here are some command line interactions: >java -jar saxon9he.jar No source file name Saxon-HE 9.2.0.6J from Saxonica Usage: see http://www.saxonica.com/documentation/using-xsl/commandline.html Options: -a Use xml-stylesheet PI, not -xsl argument -c:filename Use compiled stylesheet from file -config:filename Use configuration file -cr:classname Use collection URI resolver class -dtd:on|off Validate using DTD -expand:on|off Expand defaults defined in schema/DTD -explain[:filename] Display compiled expression tree -ext:on|off Allow|Disallow external Java functions -im:modename Initial mode -ief:class;class;... List of integrated extension functions -it:template Initial template -l:on|off Line numbering for source document -m:classname Use message receiver class -now:dateTime Set currentDateTime -o:filename Output file or directory -opt:0..10 Set optimization level (0=none, 10=max) -or:classname Use OutputURIResolver class -outval:recover|fatal Handling of validation errors on result document -p:on|off Recognize URI query parameters -r:classname Use URIResolver class -repeat:N Repeat N times for performance measurement -s:filename Initial source document -sa Use schema-aware processing -strip:all|none|ignorable Strip whitespace text nodes -t Display version and timing information -T[:classname] Use TraceListener class -TJ Trace calls to external Java functions -tree:tiny|linked Select tree model -traceout:file|#null Destination for fn:trace() output -u Names are URLs not filenames -val:strict|lax Validate using schema -versionmsg:on|off Warn when using XSLT 1.0 stylesheet -warnings:silent|recover|fatal Handling of recoverable errors -x:classname Use specified SAX parser for source file -xi:on|off Expand XInclude on all documents -xmlversion:1.0|1.1 Version of XML to be handled -xsd:file;file.. Additional schema documents to be loaded -xsdversion:1.0|1.1 Version of XML Schema to be used -xsiloc:on|off Take note of xsi:schemaLocation -xsl:filename Stylesheet file -y:classname Use specified SAX parser for stylesheet --feature:value Set configuration feature (see FeatureKeys) -? Display this message param=value Set stylesheet string parameter +param=filename Set stylesheet document parameter ?param=expression Set stylesheet parameter using XPath !option=value Set serialization option >java -jar saxon9he.jar -q:"..\w3xQueryTut.xq" Unknown option -q:..\w3xQueryTut.xq Saxon-HE 9.2.0.6J from Saxonica Usage: see http://www.saxonica.com/documentation/using-xsl/commandline.html Options: -a Use xml-stylesheet PI, not -xsl argument // etc... >java net.sf.saxon.Query -q:"..\w3xQueryTut.xq" Exception in thread "main" java.lang.NoClassDefFoundError: net/sf/saxon/Query Caused by: java.lang.ClassNotFoundException: net.sf.saxon.Query // etc... Could not find the main class: net.sf.saxon.Query. Program will exit. I'm probably making some stupid mistake. Do you know what it could be?

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  • Some questions about writing on ASP.NET response stream

    - by vtortola
    Hi, I'm making tests with ASP.NET HttpHandler for download a file writting directly on the response stream, and I'm not pretty sure about the way I'm doing it. This is a example method, in the future the file could be stored in a BLOB in the database: public void GetFile(HttpResponse response) { String fileName = "example.iso"; response.ClearHeaders(); response.ClearContent(); response.ContentType = "application/octet-stream"; response.AppendHeader("Content-Disposition", "attachment; filename=" + fileName); using (FileStream fs = new FileStream(Path.Combine(HttpContext.Current.Server.MapPath("~/App_Data"), fileName), FileMode.Open)) { Byte[] buffer = new Byte[4096]; Int32 readed = 0; while ((readed = fs.Read(buffer, 0, buffer.Length)) > 0) { response.OutputStream.Write(buffer, 0, readed); response.Flush(); } } } But, I'm not sure if this is correct or there is a better way to do it. My questions are: When I open the url with the browser, appears the "Save File" dialog... but it seems like the server has started already to push data into the stream before I click "Save", is that normal? If I remove the line"response.Flush()", when I open the url with the browser, ... I see how the web server is pushing data but the "Save File" dialog doesn't come up, (or at least not in a reasonable time fashion) why? When I open the url with a WebRequest object, I see that the HttpResponse.ContentLength is "-1", although I can read the stream and get the file. What is the meaning of -1? When is HttpResponse.ContentLength going to show the length of the response? For example, I have a method that retrieves a big xml compresed with deflate as a binary stream, but in that case... when I access it with a WebRequest, in the HttpResponse I can actually see the ContentLength with the length of the stream, why? What is the optimal length for the Byte[] array that I use as buffer for optimal performance in a web server? I've read that is between 4K and 8K... but which factors should I consider to make the correct decision. Does this method bloat the IIS or client memory usage? or is it actually buffering the transference correctly? Sorry for so many questions, I'm pretty new in web development :P Cheers.

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  • Asynchronous readback from opengl front buffer using multiple PBO's

    - by KillianDS
    I am developing an application that needs to read back the whole frame from the front buffer of an openGL application. I can hijack the application's opengl library and insert my code on swapbuffers. At the moment I am successfully using a simple but excruciating slow glReadPixels command without PBO's. Now I read about using multiple PBO's to speed things up. While I think I've found enough resources to actually program that (isn't that hard), I have some operational questions left. I would do something like this: create a series (e.g. 3) of PBO's use glReadPixels in my swapBuffers override to read data from front buffer to a PBO (should be fast and non-blocking, right?) Create a seperate thread to call glMapBufferARB, once per PBO after a glReadPixels, because this will block until the pixels are in client memory. Process the data from step 3. Now my main concern is of course in steps 2 and 3. I read about glReadPixels used on PBO's being non-blocking, will this be an issue if I issue new opengl commands after that very fast? Will those opengl commands block? Or will they continue (my guess), and if so, I guess only swapbuffers can be a problem, will this one stall or will glReadPixels from front buffer be many times faster than swapping (about each 15-30ms) or, worst case scenario, will swapbuffers be executed while glReadPixels is still reading data to the PBO? My current guess is this logic will do something like this: copy FRONT_BUFFER - generic place in VRAM, copy VRAM-RAM. But I have no idea which of those 2 is the real bottleneck and more, what the influence on the normal opengl command stream is. Then in step 3. Is it wise to do this asynchronously in a thread separated from normal opengl logic? At the moment I think not, It seems you have to restore buffer operations to normal after doing this and I can't install synchronization objects in the original code to temporarily block those. So I think my best option is to define a certain swapbuffer delay before reading them out, so e.g. calling glReadPixels on PBO i%3 and glMapBufferARB on PBO (i+2)%3 in the same thread, resulting in a delay of 2 frames. Also, when I call glMapBufferARB to use data in client memory, will this be the bottleneck or will glReadPixels (asynchronously) be the bottleneck? And finally, if you have some better ideas to speed up frame readback from GPU in opengl, please tell me, because this is a painful bottleneck in my current system. I hope my question is clear enough, I know the answer will probably also be somewhere on the internet but I mostly came up with results that used PBO's to keep buffers in video memory and do processing there. I really need to read back the front buffer to RAM and I do not find any clear explanations about performance in that case (which I need, I cannot rely on "it's faster", I need to explain why it's faster). Thank you

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  • Finding minimum cut-sets between bounded subgraphs

    - by Tore
    If a game map is partitioned into subgraphs, how to minimize edges between subgraphs? I have a problem, Im trying to make A* searches through a grid based game like pacman or sokoban, but i need to find "enclosures". What do i mean by enclosures? subgraphs with as few cut edges as possible given a maximum size and minimum size for number of vertices for each subgraph that act as a soft constraints. Alternatively you could say i am looking to find bridges between subgraphs, but its generally the same problem. Given a game that looks like this, what i want to do is find enclosures so that i can properly find entrances to them and thus get a good heuristic for reaching vertices inside these enclosures. So what i want is to find these colored regions on any given map. My Motivation The reason for me bothering to do this and not just staying content with the performance of a simple manhattan distance heuristic is that an enclosure heuristic can give more optimal results and i would not have to actually do the A* to get some proper distance calculations and also for later adding competitive blocking of opponents within these enclosures when playing sokoban type games. Also the enclosure heuristic can be used for a minimax approach to finding goal vertices more properly. A possible solution to the problem is the Kernighan-Lin algorithm: function Kernighan-Lin(G(V,E)): determine a balanced initial partition of the nodes into sets A and B do A1 := A; B1 := B compute D values for all a in A1 and b in B1 for (i := 1 to |V|/2) find a[i] from A1 and b[i] from B1, such that g[i] = D[a[i]] + D[b[i]] - 2*c[a][b] is maximal move a[i] to B1 and b[i] to A1 remove a[i] and b[i] from further consideration in this pass update D values for the elements of A1 = A1 / a[i] and B1 = B1 / b[i] end for find k which maximizes g_max, the sum of g[1],...,g[k] if (g_max > 0) then Exchange a[1],a[2],...,a[k] with b[1],b[2],...,b[k] until (g_max <= 0) return G(V,E) My problem with this algorithm is its runtime at O(n^2 * lg(n)), i am thinking of limiting the nodes in A1 and B1 to the border of each subgraph to reduce the amount of work done. I also dont understand the c[a][b] cost in the algorithm, if a and b do not have an edge between them is the cost assumed to be 0 or infinity, or should i create an edge based on some heuristic. Do you know what c[a][b] is supposed to be when there is no edge between a and b? Do you think my problem is suitable to use a multi level problem? Why or why not? Do you have a good idea for how to reduce the work done with the kernighan-lin algorithm for my problem?

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  • UITableViewCells appear behind backgroundView

    - by Khanzor
    I am having a problem setting the background of UITableView to a UIImageView (see below for why I am doing this), once the view is set, it works fine, and scrolls with the UITableView, but it hides the elements of the Table View. I need to have a UIImageView as the background for a UITableView. I know this has been answered before, but the answers are to use: [UIColor colorWithPatternImage:[UIImage imageNamed:@"myImage.png"]]; Or something like (which I need to use): UIImageView *background = [MainWindow generateBackgroundWithFrame:tableView.bounds]; [tableView addSubview:background]; [tableView sendSubviewToBack:background]; The reason I need to use the latter is because of my generateBackgroundWithFrame method, which takes a large image, and draws a border around that image to the dimensions specified, and clips the remainder of the image: + (UIImageView *) generateBackgroundWithFrame: (CGRect)frame { UIImageView *background = [[[UIImageView alloc] initWithFrame:frame] autorelease]; background.image = [UIImage imageNamed:@"globalBackground.png"]; [background.layer setMasksToBounds:YES]; [background.layer setCornerRadius:10.0]; [background.layer setBorderColor:[[UIColor grayColor] CGColor]]; [background.layer setBorderWidth:3.0]; return background; } Please note: I understand that this might poorly effect performance, but I don't have the resources to go through and make those images for each potential screen in the app. Please do not answer this question with a mindless "you shouldn't do this" response. I am aware that it is possibly the wrong thing to do. How do I show my UITableView control elements? Is there something that I am doing wrong in my delegate? Here is a simplified version: - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { static NSString *CellIdentifier = @"Cell"; UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier]; if (cell == nil) { cell = [[[UITableViewCell alloc] initWithFrame:CGRectMake(20, 20, 261, 45) reuseIdentifier:CellIdentifier] autorelease]; cell.accessoryType = UITableViewCellAccessoryDetailDisclosureButton; UIImage *rowBackground; NSString *imageName = @"standAloneTVButton.png"; rowBackground = [UIImage imageNamed:imageName]; UITextView *textView = [[UITextView alloc] initWithFrame:CGRectMake(0, 5, 300, 200)]; textView.backgroundColor = [UIColor clearColor]; textView.textColor = [UIColor blackColor]; textView.font = [UIFont fontWithName:@"Helvetica" size:18.0f]; Purchase *purchase = [[PurchaseModel productsPurchased] objectAtIndex:indexPath.row]; textView.text = [purchase Title]; selectedTextView.text = textView.text; UIImageView *normalBackground = [[[UIImageView alloc] init] autorelease]; normalBackground.image = rowBackground; [normalBackground insertSubview:textView atIndex:0]; cell.backgroundView = normalBackground; [textView release]; } return cell; }

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  • Eclipselink read complex object model in an ordered way

    - by Raven
    Hi, I need to read a complex model in an ordered way with eclipselink. The order is mandantory because it is a huge database and I want to have an output of a small portion of the database in a jface tableview. Trying to reorder it in the loading/quering thread takes too long and ordering it in the LabelProvider blocks the UI thread too much time, so I thought if Eclipselink could be used that way, that the database will order it, it might give me the performance I need. Unfortunately the object model can not be changed :-( The model is something like: @SuppressWarnings("serial") @Entity public class Thing implements Serializable { @Id @GeneratedValue(strategy = GenerationType.TABLE) private int id; private String name; @OneToMany(cascade=CascadeType.ALL) @PrivateOwned private List<Property> properties = new ArrayList<Property>(); ... // getter and setter following here } public class Property implements Serializable { @Id @GeneratedValue(strategy = GenerationType.TABLE) private int id; @OneToOne private Item item; private String value; ... // getter and setter following here } public class Item implements Serializable { @Id @GeneratedValue(strategy = GenerationType.TABLE) private int id; private String name; .... // getter and setter following here } // Code end In the table view the y-axis is more or less created with the query Query q = em.createQuery("SELECT m FROM Thing m ORDER BY m.name ASC"); using the "name" attribute from the Thing objects as label. In the table view the x-axis is more or less created with the query Query q = em.createQuery("SELECT m FROM Item m ORDER BY m.name ASC"); using the "name" attribute from the Item objects as label. Each cell has the value Things.getProperties().get[x].getValue() Unfortunately the list "properties" is not ordered, so the combination of cell value and x-axis column number (x) is not necessarily correct. Therefore I need to order the list "properties" in the same way as I ordered the labeling of the x-axis. And exactly this is the thing I dont know how it is done. So querying for the Thing objects should return the list "properties" "ORDER BY name ASC" but of the "Item"s objects. My ideas are something like having a query with two JOINs. Joing Things with Property and with Item but somehow I was unable to get it to work yet. Thank you for your help and your ideas to solve this riddle.

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  • timeIntervalSinceDate Accuracy

    - by mmccomb
    I've been working on a game with an engine that updates 20 times per seconds. I've got to point now where I want to start getting some performance figures and tweak the rendering and logic updates. In order to do so I started to add some timing code to my game loop, implemented as follows... NSDate* startTime = [NSDate date]; // Game update logic here.... // Also timing of smaller internal events NSDate* endTime = [NSDate date]; [endTime timeIntervalSinceDate:startTime]; I noticed however that when I timed blocks within the outer timing logic that the time they took to execute did not sum up to match the overall time taken. So I wrote a small unit test to demonstrate the problem in which I time the overall time taken to complete the test and then 10 smaller events, here it is... - (void)testThatSumOfTimingsMatchesOverallTiming { NSDate* startOfOverallTime = [NSDate date]; // Variable to hold summation of smaller timing events in the upcoming loop... float sumOfIndividualTimes = 0.0; NSTimeInterval times[10] = {0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0}; for (int i = 0; i < 10; i++) { NSDate* startOfIndividualTime = [NSDate date]; // Kill some time... sleep(1); NSDate* endOfIndividualTime = [NSDate date]; times[i] = [endOfIndividualTime timeIntervalSinceDate:startOfIndividualTime]; sumOfIndividualTimes += times[i]; } NSDate* endOfOverallTime = [NSDate date]; NSTimeInterval overallTimeTaken = [endOfOverallTime timeIntervalSinceDate:startOfOverallTime]; NSLog(@"Sum of individual times: %fms", sumOfIndividualTimes); NSLog(@"Overall time: %fms", overallTimeTaken); STAssertFalse(TRUE, @""); } And here's the output... Sum of individual times: 10.001377ms Overall time: 10.016834ms Which illustrates my problem quite clearly. The overall time was 0.000012ms but the smaller events took only 0.000001ms. So what happened to the other 0.000011ms? Is there anything that looks particularly wrong with my code? Or is there an alternative timing mechanism I should use?

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  • HP to Cisco spanning tree root flapping

    - by Tim Brigham
    Per a recent question I recently configured both my HP (2x 2900) and Cisco (1x 3750) hardware to use MSTP for interoperability. I thought this was functional until I applied the change to the third device (HP switch 1 below) at which time the spanning tree root started flapping causing performance issues (5% packet loss) between my two HP switches. I'm not sure why. HP Switch 1 A4 connected to Cisco 1/0/1. HP Switch 2 B2 connected to Cisco 2/0/1. HP Switch 1 A2 connected to HP Switch 2 A1. I'd prefer the Cisco stack to act as the root. EDIT: There is one specific line - 'spanning-tree 1 path-cost 500000' in the HP switch 2 that I didn't add and was preexisting. I'm not sure if it could have the kind of impact that I'm describing. I'm more a security and monitoring guy then networking. EDIT 2: I'm starting to believe the problem lies in the fact that the value for my MST 0 instance on the Cisco is still at the default 32768. I worked up a diagram: This is based on every show command I could find for STP. I'll make this change after hours and see if it helps. Cisco 3750 Config: version 12.2 spanning-tree mode mst spanning-tree extend system-id spanning-tree mst configuration name mstp revision 1 instance 1 vlan 1, 40, 70, 100, 250 spanning-tree mst 1 priority 0 vlan internal allocation policy ascending interface TenGigabitEthernet1/1/1 switchport trunk encapsulation dot1q switchport mode trunk ! interface TenGigabitEthernet2/1/1 switchport trunk encapsulation dot1q switchport mode trunk ! interface Vlan1 no ip address ! interface Vlan100 ip address 192.168.100.253 255.255.255.0 ! Cisco 3750 show spanning tree: show spanning-tree MST0 Spanning tree enabled protocol mstp Root ID Priority 32768 Address 0004.ea84.5f80 Cost 200000 Port 53 (TenGigabitEthernet1/1/1) Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Bridge ID Priority 32768 (priority 32768 sys-id-ext 0) Address a44c.11a6.7c80 Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Interface Role Sts Cost Prio.Nbr Type ------------------- ---- --- --------- -------- -------------------------------- Te1/1/1 Root FWD 2000 128.53 P2p MST1 Spanning tree enabled protocol mstp Root ID Priority 1 Address a44c.11a6.7c80 This bridge is the root Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Bridge ID Priority 1 (priority 0 sys-id-ext 1) Address a44c.11a6.7c80 Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Interface Role Sts Cost Prio.Nbr Type ------------------- ---- --- --------- -------- -------------------------------- Te1/1/1 Desg FWD 2000 128.53 P2p Cisco 3750 show logging: %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan1, changed state to down %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan100, changed state to down %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan1, changed state to up %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan100, changed state to up %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan1, changed state to down %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan1, changed state to up HP Switch 1: ; J9049A Configuration Editor; Created on release #T.13.71 vlan 1 name "DEFAULT_VLAN" untagged 1-8,10,13-16,18-23,A1-A4 ip address 100.100.100.17 255.255.255.0 no untagged 9,11-12,17,24 exit vlan 100 name "192.168.100" untagged 9,11-12,17,24 tagged 1-8,10,13-16,18-23,A1-A4 no ip address exit vlan 21 name "Users_2" tagged 1,A1-A4 no ip address exit vlan 40 name "Cafe" tagged 1,4,7,A1-A4 no ip address exit vlan 250 name "Firewall" tagged 1,4,7,A1-A4 no ip address exit vlan 70 name "DMZ" tagged 1,4,7-8,13,A1-A4 no ip address exit spanning-tree spanning-tree config-name "mstp" spanning-tree config-revision 1 spanning-tree instance 1 vlan 1 40 70 100 250 password manager password operator HP Switch 1 show spanning tree: show spanning-tree Multiple Spanning Tree (MST) Information STP Enabled : Yes Force Version : MSTP-operation IST Mapped VLANs : 2-39,41-69,71-99,101-249,251-4094 Switch MAC Address : 0021f7-126580 Switch Priority : 32768 Max Age : 20 Max Hops : 20 Forward Delay : 15 Topology Change Count : 363,490 Time Since Last Change : 14 hours CST Root MAC Address : 0004ea-845f80 CST Root Priority : 32768 CST Root Path Cost : 200000 CST Root Port : 1 IST Regional Root MAC Address : 0021f7-126580 IST Regional Root Priority : 32768 IST Regional Root Path Cost : 0 IST Remaining Hops : 20 Root Guard Ports : TCN Guard Ports : BPDU Protected Ports : BPDU Filtered Ports : PVST Protected Ports : PVST Filtered Ports : | Prio | Designated Hello Port Type | Cost rity State | Bridge Time PtP Edge ----- --------- + --------- ---- ---------- + ------------- ---- --- ---- A1 | Auto 128 Disabled | A2 10GbE-CX4 | 2000 128 Forwarding | 0021f7-126580 2 Yes No A3 10GbE-CX4 | Auto 128 Disabled | A4 10GbE-SR | Auto 128 Disabled | HP Switch 1 Logging: I removed the date / time fields since they are inaccurate (no NTP configured on these switches) 00839 stp: MSTI 1 Root changed from 0:a44c11-a67c80 to 32768:0021f7-126580 00839 stp: MSTI 1 Root changed from 32768:0021f7-126580 to 0:a44c11-a67c80 00842 stp: MSTI 1 starved for an MSTI Msg Rx on port A4 from 0:a44c11-a67c80 00839 stp: MSTI 1 Root changed from 0:a44c11-a67c80 to 32768:0021f7-126580 00839 stp: MSTI 1 Root changed from 32768:0021f7-126580 to 0:a44c11-a67c80 00839 stp: MSTI 1 Root changed from 0:a44c11-a67c80 to ... HP Switch 2 Configuration: ; J9146A Configuration Editor; Created on release #W.14.49 vlan 1 name "DEFAULT_VLAN" untagged 1,3-17,21-24,A1-A2,B2 ip address 100.100.100.36 255.255.255.0 no untagged 2,18-20,B1 exit vlan 100 name "192.168.100" untagged 2,18-20 tagged 1,3-17,21-24,A1-A2,B1-B2 no ip address exit vlan 21 name "Users_2" tagged 1,A1-A2,B2 no ip address exit vlan 40 name "Cafe" tagged 1,13-14,16,A1-A2,B2 no ip address exit vlan 250 name "Firewall" tagged 1,13-14,16,A1-A2,B2 no ip address exit vlan 70 name "DMZ" tagged 1,13-14,16,A1-A2,B2 no ip address exit logging 192.168.100.18 spanning-tree spanning-tree 1 path-cost 500000 spanning-tree config-name "mstp" spanning-tree config-revision 1 spanning-tree instance 1 vlan 1 40 70 100 250 HP Switch 2 Spanning Tree: show spanning-tree Multiple Spanning Tree (MST) Information STP Enabled : Yes Force Version : MSTP-operation IST Mapped VLANs : 2-39,41-69,71-99,101-249,251-4094 Switch MAC Address : 0024a8-cd6000 Switch Priority : 32768 Max Age : 20 Max Hops : 20 Forward Delay : 15 Topology Change Count : 21,793 Time Since Last Change : 14 hours CST Root MAC Address : 0004ea-845f80 CST Root Priority : 32768 CST Root Path Cost : 200000 CST Root Port : A1 IST Regional Root MAC Address : 0021f7-126580 IST Regional Root Priority : 32768 IST Regional Root Path Cost : 2000 IST Remaining Hops : 19 Root Guard Ports : TCN Guard Ports : BPDU Protected Ports : BPDU Filtered Ports : PVST Protected Ports : PVST Filtered Ports : | Prio | Designated Hello Port Type | Cost rity State | Bridge Time PtP Edge ----- --------- + --------- ---- ---------- + ------------- ---- --- ---- A1 10GbE-CX4 | 2000 128 Forwarding | 0021f7-126580 2 Yes No A2 10GbE-CX4 | Auto 128 Disabled | B1 SFP+SR | 2000 128 Forwarding | 0024a8-cd6000 2 Yes No B2 | Auto 128 Disabled | HP Switch 2 Logging: I removed the date / time fields since they are inaccurate (no NTP configured on these switches) 00839 stp: CST Root changed from 32768:0021f7-126580 to 32768:0004ea-845f80 00839 stp: IST Root changed from 32768:0021f7-126580 to 32768:0024a8-cd6000 00839 stp: CST Root changed from 32768:0004ea-845f80 to 32768:0024a8-cd6000 00839 stp: CST Root changed from 32768:0024a8-cd6000 to 32768:0004ea-845f80 00839 stp: CST Root changed from 32768:0004ea-845f80 to 32768:0024a8-cd6000 00435 ports: port B1 is Blocked by STP 00839 stp: CST Root changed from 32768:0024a8-cd6000 to 32768:0021f7-126580 00839 stp: IST Root changed from 32768:0024a8-cd6000 to 32768:0021f7-126580 00839 stp: CST Root changed from 32768:0021f7-126580 to 32768:0004ea-845f80

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  • Parallel.For System.OutOfMemoryException

    - by Martin Neal
    We have a fairly simple program that's used for creating backups. I'm attempting to parallelize it but am getting an OutofMemoryException within an AggregateExcption. Some of the source folders are quite large, and the program doesn't crash for about 40 minutes after it starts. I don't know where to start looking so the below code is a near exact dump of all code the code sans directory structure and Exception logging code. Any advise as to where to start looking? using System; using System.Diagnostics; using System.IO; using System.Threading.Tasks; namespace SelfBackup { class Program { static readonly string[] saSrc = { "\\src\\dir1\\", //... "\\src\\dirN\\", //this folder is over 6 GB }; static readonly string[] saDest = { "\\dest\\dir1\\", //... "\\dest\\dirN\\", }; static void Main(string[] args) { Parallel.For(0, saDest.Length, i => { try { if (Directory.Exists(sDest)) { //Delete directory first so old stuff gets cleaned up Directory.Delete(sDest, true); } //recursive function clsCopyDirectory.copyDirectory(saSrc[i], sDest); } catch (Exception e) { //standard error logging CL.EmailError(); } }); } } /////////////////////////////////////// using System.IO; using System.Threading.Tasks; namespace SelfBackup { static class clsCopyDirectory { static public void copyDirectory(string Src, string Dst) { Directory.CreateDirectory(Dst); /* Copy all the files in the folder If and when .NET 4.0 is installed, change Directory.GetFiles to Directory.Enumerate files for slightly better performance.*/ Parallel.ForEach<string>(Directory.GetFiles(Src), file => { /* An exception thrown here may be arbitrarily deep into this recursive function there's also a good chance that if one copy fails here, so too will other files in the same directory, so we don't want to spam out hundreds of error e-mails but we don't want to abort all together. Instead, the best solution is probably to throw back up to the original caller of copy directory an move on to the next Src/Dst pair by not catching any possible exception here.*/ File.Copy(file, //src Path.Combine(Dst, Path.GetFileName(file)), //dest true);//bool overwrite }); //Call this function again for every directory in the folder. Parallel.ForEach(Directory.GetDirectories(Src), dir => { copyDirectory(dir, Path.Combine(Dst, Path.GetFileName(dir))); }); } }

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  • SQL Server to PostgreSQL - Migration and design concerns

    - by youwhut
    Currently migrating from SQL Server to PostgreSQL and attempting to improve a couple of key areas on the way: I have an Articles table: CREATE TABLE [dbo].[Articles]( [server_ref] [int] NOT NULL, [article_ref] [int] NOT NULL, [article_title] [varchar](400) NOT NULL, [category_ref] [int] NOT NULL, [size] [bigint] NOT NULL ) Data (comma delimited text files) is dumped on the import server by ~500 (out of ~1000) servers on a daily basis. Importing: Indexes are disabled on the Articles table. For each dumped text file Data is BULK copied to a temporary table. Temporary table is updated. Old data for the server is dropped from the Articles table. Temporary table data is copied to Articles table. Temporary table dropped. Once this process is complete for all servers the indexes are built and the new database is copied to a web server. I am reasonably happy with this process but there is always room for improvement as I strive for a real-time (haha!) system. Is what I am doing correct? The Articles table contains ~500 million records and is expected to grow. Searching across this table is okay but could be better. i.e. SELECT * FROM Articles WHERE server_ref=33 AND article_title LIKE '%criteria%' has been satisfactory but I want to improve the speed of searching. Obviously the "LIKE" is my problem here. Suggestions? SELECT * FROM Articles WHERE article_title LIKE '%criteria%' is horrendous. Partitioning is a feature of SQL Server Enterprise but $$$ which is one of the many exciting prospects of PostgreSQL. What performance hit will be incurred for the import process (drop data, insert data) and building indexes? Will the database grow by a huge amount? The database currently stands at 200 GB and will grow. Copying this across the network is not ideal but it works. I am putting thought into changing the hardware structure of the system. The thought process of having an import server and a web server is so that the import server can do the dirty work (WITHOUT indexes) while the web server (WITH indexes) can present reports. Maybe reducing the system down to one server would work to skip the copying across the network stage. This one server would have two versions of the database: one with the indexes for delivering reports and the other without for importing new data. The databases would swap daily. Thoughts? This is a fantastic system, and believe it or not there is some method to my madness by giving it a big shake up. UPDATE: I am not looking for help with relational databases, but hoping to bounce ideas around with data warehouse experts.

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  • Need help manipulating WAV (RIFF) Files at a byte level

    - by Eric
    I'm writing an an application in C# that will record audio files (*.wav) and automatically tag and name them. Wave files are RIFF files (like AVI) which can contain meta data chunks in addition to the waveform data chunks. So now I'm trying to figure out how to read and write the RIFF meta data to and from recorded wave files. I'm using NAudio for recording the files, and asked on their forums as well on SO for way to read and write RIFF tags. While I received a number of good answers, none of the solutions allowed for reading and writing RIFF chunks as easily as I would like. But more importantly I have very little experience dealing with files at a byte level, and think this could be a good opportunity to learn. So now I want to try writing my own class(es) that can read in a RIFF file and allow meta data to be read, and written from the file. I've used streams in C#, but always with the entire stream at once. So now I'm little lost that I have to consider a file byte by byte. Specifically how would I go about removing or inserting bytes to and from the middle of a file? I've tried reading a file through a FileStream into a byte array (byte[]) as shown in the code below. System.IO.FileStream waveFileStream = System.IO.File.OpenRead(@"C:\sound.wav"); byte[] waveBytes = new byte[waveFileStream.Length]; waveFileStream.Read(waveBytes, 0, waveBytes.Length); And I could see through the Visual Studio debugger that the first four byte are the RIFF header of the file. But arrays are a pain to deal with when performing actions that change their size like inserting or removing values. So I was thinking I could then to the byte[] into a List like this. List<byte> list = waveBytes.ToList<byte>(); Which would make any manipulation of the file byte by byte a whole lot easier, but I'm worried I might be missing something like a class in the System.IO name-space that would make all this even easier. Am I on the right track, or is there a better way to do this? I should also mention that I'm not hugely concerned with performance, and would prefer not to deal with pointers or unsafe code blocks like this guy. If it helps at all here is a good article on the RIFF/WAV file format.

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  • Problems related to showing MessageBox from non-GUI threads

    - by Hans Løken
    I'm working on a heavily data-bound Win.Forms application where I've found some strange behavior. The app has separate I/O threads receiving updates through asynchronous web-requests which it then sends to the main/GUI thread for processing and updating of application-wide data-stores (which in turn may be data-bound to various GUI-elements, etc.). The server at the other end of the web-requests requires periodic requests or the session times out. I've gone through several attempted solutions of dealing with thread-issues etc. and I've observed the following behavior: If I use Control.Invoke for sending updates from I/O-thread(s) to main-thread and this update causes a MessageBox to be shown the main form's message pump stops until the user clicks the ok-button. This also blocks the I/O-thread from continuing eventually leading to timeouts on the server. If I use Control.BeginInvoke for sending updates from I/O-thread(s) to main-thread the main form's message pump does not stop, but if the processing of an update leads to a messagebox being shown, the processing of the rest of that update is halted until the user clicks ok. Since the I/O-threads keep running and the message pump keeps processing messages several BeginInvoke's for updates may be called before the one with the message box is finished. This leads to out-of-sequence updates which is unacceptable. I/O-threads add updates to a blocking queue (very similar to http://stackoverflow.com/questions/530211/creating-a-blocking-queuet-in-net/530228#530228). GUI-thread uses a Forms.Timer that periodically applies all updates in the blocking queue. This solution solves both the problem of blocking I/O threads and sequentiality of updates i.e. next update will be never be started until previous is finished. However, there is a small performance cost as well as introducing a latency in showing updates that is unacceptable in the long run. I would like update-processing in the main-thread to be event-driven rather than polling. So to my question. How should I do this to: avoid blocking the I/O-threads guarantee that updates are finished in-sequence keep the main message pump running while showing a message box as a result of an update.

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  • Validate a string in a table in SQL Server - CLR function or T-SQL (Question updated)

    - by Ashish Gupta
    I need to check If a column value (string) in SQL server table starts with a small letter and can only contain '_', '-', numbers and alphabets. I know I can use a SQL server CLR function for that. However, I am trying to implement that validation using a scalar UDF and could make very little here...I can use 'NOT LIKE', but I am not sure how to make sure I validate the string irrespective of the order of characters or in other words write a pattern in SQL for this. Am I better off using a SQL CLR function? Any help will be appreciated.. Thanks in advance Thank you everyone for their comments. This morning, I chose to go CLR function way. For the purpose of what I was trying to achieve, I created one CLR function which does the validation of an input string and have that called from a SQL UDF and It works well. Just to measure the performance of t-SQL UDF using SQL CLR function vs t- SQL UDF, I created a SQL CLR function which will just check if the input string contains only small letters, it should return true else false and have that called from a UDF (IsLowerCaseCLR). After that I also created a regular t-SQL UDF(IsLowerCaseTSQL) which does the same thing using the 'NOT LIKE'. Then I created a table (Person) with columns Name(varchar) and IsValid(bit) columns and populate that with names to test. Data :- 1000 records with 'Ashish' as value for Name column 1000 records with 'ashish' as value for Name column then I ran the following :- UPDATE Person Set IsValid=1 WHERE dbo.IsLowerCaseTSQL (Name) Above updated 1000 records (with Isvalid=1) and took less than a second. I deleted all the data in the table and repopulated the same with same data. Then updated the same table using Sql CLR UDF (with Isvalid=1) and this took 3 seconds! If update happens for 5000 records, regular UDF takes 0 seconds compared to CLR UDF which takes 16 seconds! I am very less knowledgeable on t-SQL regular expression or I could have tested my actual more complex validation criteria. But I just wanted to know, even I could have written that, would that have been faster than the SQL CLR function considering the example above. Are we using SQL CLR because we can implement we can implement lot richer logic which would have been difficult otherwise If we write in regular SQL. Sorry for this long post. I just want to know from the experts. Please feel free to ask if you could not understand anything here. Thank you again for your time.

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  • Is this asking too much of a browser?

    - by Matt Ball
    I'm embedding a large array in <script> tags in my HTML, like this (nothing surprising): <script> var largeArray = [/* lots of stuff in here */]; </script> In this particular example, the array has 210,000 elements. That's well below the theoretical maximum of 231 - by 4 orders of magnitude. Here's the fun part: if I save JS source for the array to a file, that file is 44 megabytes (46,573,399 bytes, to be exact). If you want to see for yourself, you can download it from my Dropbox. (All the data in there is canned, so much of it is repeated. This will not be the case in production.) Now, I'm really not concerned about serving that much data. My server gzips its responses, so it really doesn't take all that long to get the data over the wire. However, there is a really nasty tendency for the page, once loaded, to crash the browser. I'm not testing at all in IE (this is an internal tool). My primary targets are Chrome 8 and Firefox 3.6. In Firefox, I can see a reasonably useful error in the console: Error: script stack space quota is exhausted In Chrome, I simply get the sad-tab page: Cut to the chase, already Is this really too much data for our modern, "high-performance" browsers to handle? Is there anything I can do* to gracefully handle this much data? Incidentally, I was able to get this to work (read: not crash the tab) on-and-off in Chrome. I really thought that Chrome, at least, was made of tougher stuff, but apparently I was wrong... Edit 1 @Crayon: I wasn't looking to justify why I'd like to dump this much data into the browser at once. Short version: either I solve this one (admittedly not-that-easy) problem, or I have to solve a whole slew of other problems. I'm opting for the simpler approach for now. @various: right now, I'm not especially looking for ways to actually reduce the number of elements in the array. I know I could implement Ajax paging or what-have-you, but that introduces its own set of problems for me in other regards. @Phrogz: each element looks something like this: {dateTime:new Date(1296176400000), terminalId:'terminal999', 'General___BuildVersion':'10.05a_V110119_Beta', 'SSM___ExtId':26680, 'MD_CDMA_NETLOADER_NO_BCAST___Valid':'false', 'MD_CDMA_NETLOADER_NO_BCAST___PngAttempt':0} @Will: but I have a computer with a 4-core processor, 6 gigabytes of RAM, over half a terabyte of disk space ...and I'm not even asking for the browser to do this quickly - I'm just asking for it to work at all! ? *other than the obvious: sending less data to the browser

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  • C++ vs Matlab vs Python as a main language for Computer Vision Research

    - by Hough
    Hi all, Firstly, sorry for a somewhat long question but I think that many people are in the same situation as me and hopefully they can also gain some benefit from this. I'll be starting my PhD very soon which involves the fields of computer vision, pattern recognition and machine learning. Currently, I'm using opencv (2.1) C++ interface and I especially like its powerful Mat class and the overloaded operations available for matrix and image operations and seamless transformations. I've also tried (and implemented many small vision projects) using opencv python interface (new bindings; opencv 2.1) and I really enjoy python's ability to integrate opencv, numpy, scipy and matplotlib. But recently, I went back to opencv C++ interface because I felt that the official python new bindings were not stable enough and no overloaded operations are available for matrices and images, not to mention the lack of machine learning modules and slow speeds in certain operations. I've also used Matlab extensively in the past and although I've used mex files and other means to speed up the program, I just felt that Matlab's performance was inadequate for real-time vision tasks, be it for fast prototyping or not. When the project becomes larger and larger, many tasks have to be re-written in C and compiled into Mex files increasingly and Matlab becomes nothing more than a glue language. Here comes the sub-questions: For carrying out research in these fields (machine learning, vision, pattern recognition), what is your main or ideal programming language for rapid prototyping of ideas and testing algorithms contained in papers? For computer vision research work, can you list down the pros and cons of using the following languages? C++ (with opencv + gsl + svmlib + other libraries) vs Matlab (with all its toolboxes) vs python (with the imcomplete opencv bindings + numpy + scipy + matplotlib). Are there computer vision PhD/postgrad students here who are using only C++ (with all its availabe libraries including opencv) without even needing to resort to Matlab or python? In other words, given the current existing computer vision or machine learning libraries, is C++ alone sufficient for fast prototyping of ideas? If you're currently using Java or C# for your research, can you list down the reasons why they should be used and how they compare to other languages in terms of available libraries? What is the de facto vision/machine learning programming language and its associated libraries used in your research group? Thanks in advance. Edit: As suggested, I've opened the question to both academic and non-academic computer vision/machine learning/pattern recognition researchers and groups.

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  • Asynchronous subprocess on Windows

    - by Stigma
    First of all, the overall problem I am solving is a bit more complicated than I am showing here, so please do not tell me 'use threads with blocking' as it would not solve my actual situation without a fair, FAIR bit of rewriting and refactoring. I have several applications which are not mine to modify, which take data from stdin and poop it out on stdout after doing their magic. My task is to chain several of these programs. Problem is, sometimes they choke, and as such I need to track their progress which is outputted on STDERR. pA = subprocess.Popen(CommandA, shell=False, stdout=subprocess.PIPE, stderr=subprocess.PIPE) # ... some more processes make up the chain, but that is irrelevant to the problem pB = subprocess.Popen(CommandB, shell=False, stdout=subprocess.PIPE, stderr=subprocess.PIPE, stdin=pA.stdout ) Now, reading directly through pA.stdout.readline() and pB.stdout.readline(), or the plain read() functions, is a blocking matter. Since different applications output in different paces and different formats, blocking is not an option. (And as I wrote above, threading is not an option unless at a last, last resort.) pA.communicate() is deadlock safe, but since I need the information live, that is not an option either. Thus google brought me to this asynchronous subprocess snippet on ActiveState. All good at first, until I implement it. Comparing the cmd.exe output of pA.exe | pB.exe, ignoring the fact both output to the same window making for a mess, I see very instantaneous updates. However, I implement the same thing using the above snippet and the read_some() function declared there, and it takes over 10 seconds to notify updates of a single pipe. But when it does, it has updates leading all the way upto 40% progress, for example. Thus I do some more research, and see numerous subjects concerning PeekNamedPipe, anonymous handles, and returning 0 bytes available even though there is information available in the pipe. As the subject has proven quite a bit beyond my expertise to fix or code around, I come to Stack Overflow to look for guidance. :) My platform is W7 64-bit with Python 2.6, the applications are 32-bit in case it matters, and compatibility with Unix is not a concern. I can even deal with a full ctypes or pywin32 solution that subverts subprocess entirely if it is the only solution, as long as I can read from every stderr pipe asynchronously with immediate performance and no deadlocks. :)

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  • jquery data selector

    - by Tauren
    I need to select elements based on values stored in an element's .data() object. At a minimum, I'd like to select top-level data properties using selectors, perhaps like this: $('a').data("category","music"); $('a:data(category=music)'); Or perhaps the selector would be in regular attribute selector format: $('a[category=music]'); Or in attribute format, but with a specifier to indicate it is in .data(): $('a[:category=music]'); I've found James Padolsey's implementation to look simple, yet good. The selector formats above mirror methods shown on that page. There is also this Sizzle patch. For some reason, I recall reading a while back that jQuery 1.4 would include support for selectors on values in the jquery .data() object. However, now that I'm looking for it, I can't find it. Maybe it was just a feature request that I saw. Is there support for this and I'm just not seeing it? Ideally, I'd like to support sub-properties in data() using dot notation. Like this: $('a').data("user",{name: {first:"Tom",last:"Smith"},username: "tomsmith"}); $('a[:user.name.first=Tom]'); I also would like to support multiple data selectors, where only elements with ALL specified data selectors are found. The regular jquery multiple selector does an OR operation. For instance, $('a.big, a.small') selects a tags with either class big or small). I'm looking for an AND, perhaps like this: $('a').data("artist",{id: 3281, name: "Madonna"}); $('a').data("category","music"); $('a[:category=music && :artist.name=Madonna]'); Lastly, it would be great if comparison operators and regex features were available on data selectors. So $(a[:artist.id>5000]) would be possible. I realize I could probably do much of this using filter(), but it would be nice to have a simple selector format. What solutions are available to do this? Is Jame's Padolsey's the best solution at this time? My concern is primarily in regards to performance, but also in the extra features like sub-property dot-notation and multiple data selectors. Are there other implementations that support these things or are better in some way?

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  • Forensic Analysis of the OOM-Killer

    - by Oddthinking
    Ubuntu's Out-Of-Memory Killer wreaked havoc on my server, quietly assassinating my applications, sendmail, apache and others. I've managed to learn what the OOM Killer is, and about its "badness" rules. While my machine is small, my applications are even smaller, and typically only half of my physical memory is in use, let alone swap-space, so I was surprised. I am trying to work out the culprit, but I don't know how to read the OOM-Killer logs. Can anyone please point me to a tutorial on how to read the data in the logs (what are ve, free and gen?), or help me parse these logs? Apr 20 20:03:27 EL135 kernel: kill_signal(13516.0): selecting to kill, queued 0, seq 1, exc 2326 0 goal 2326 0... Apr 20 20:03:27 EL135 kernel: kill_signal(13516.0): task ebb0c6f0, thg d33a1b00, sig 1 Apr 20 20:03:27 EL135 kernel: kill_signal(13516.0): selected 1, signalled 1, queued 1, seq 1, exc 2326 0 red 61795 745 Apr 20 20:03:27 EL135 kernel: kill_signal(13516.0): selecting to kill, queued 0, seq 2, exc 122 0 goal 383 0... Apr 20 20:03:27 EL135 kernel: kill_signal(13516.0): task ebb0c6f0, thg d33a1b00, sig 1 Apr 20 20:03:27 EL135 kernel: kill_signal(13516.0): selected 1, signalled 1, queued 1, seq 2, exc 383 0 red 61795 745 Apr 20 20:03:27 EL135 kernel: kill_signal(13516.0): task ebb0c6f0, thg d33a1b00, sig 2 Apr 20 20:03:27 EL135 kernel: OOM killed process watchdog (pid=14490, ve=13516) exited, free=43104 gen=24501. Apr 20 20:03:27 EL135 kernel: OOM killed process tail (pid=4457, ve=13516) exited, free=43104 gen=24502. Apr 20 20:03:27 EL135 kernel: OOM killed process ntpd (pid=10816, ve=13516) exited, free=43104 gen=24503. Apr 20 20:03:27 EL135 kernel: OOM killed process tail (pid=27401, ve=13516) exited, free=43104 gen=24504. Apr 20 20:03:27 EL135 kernel: OOM killed process tail (pid=29009, ve=13516) exited, free=43104 gen=24505. Apr 20 20:03:27 EL135 kernel: OOM killed process apache2 (pid=10557, ve=13516) exited, free=49552 gen=24506. Apr 20 20:03:27 EL135 kernel: OOM killed process apache2 (pid=24983, ve=13516) exited, free=53117 gen=24507. Apr 20 20:03:27 EL135 kernel: OOM killed process apache2 (pid=29129, ve=13516) exited, free=68493 gen=24508. Apr 20 20:03:27 EL135 kernel: OOM killed process sendmail-mta (pid=941, ve=13516) exited, free=68803 gen=24509. Apr 20 20:03:27 EL135 kernel: OOM killed process tail (pid=12418, ve=13516) exited, free=69330 gen=24510. Apr 20 20:03:27 EL135 kernel: OOM killed process python (pid=22953, ve=13516) exited, free=72275 gen=24511. Apr 20 20:03:27 EL135 kernel: OOM killed process apache2 (pid=6624, ve=13516) exited, free=76398 gen=24512. Apr 20 20:03:27 EL135 kernel: OOM killed process python (pid=23317, ve=13516) exited, free=94285 gen=24513. Apr 20 20:03:27 EL135 kernel: OOM killed process tail (pid=29030, ve=13516) exited, free=95339 gen=24514. Apr 20 20:03:28 EL135 kernel: OOM killed process apache2 (pid=20583, ve=13516) exited, free=101663 gen=24515. Apr 20 20:03:28 EL135 kernel: OOM killed process logger (pid=12894, ve=13516) exited, free=101694 gen=24516. Apr 20 20:03:28 EL135 kernel: OOM killed process bash (pid=21119, ve=13516) exited, free=101849 gen=24517. Apr 20 20:03:28 EL135 kernel: OOM killed process atd (pid=991, ve=13516) exited, free=101880 gen=24518. Apr 20 20:03:28 EL135 kernel: OOM killed process apache2 (pid=14649, ve=13516) exited, free=102748 gen=24519. Apr 20 20:03:28 EL135 kernel: OOM killed process grep (pid=21375, ve=13516) exited, free=132167 gen=24520. Apr 20 20:03:57 EL135 kernel: kill_signal(13516.0): selecting to kill, queued 0, seq 4, exc 4215 0 goal 4826 0... Apr 20 20:03:57 EL135 kernel: kill_signal(13516.0): task ede29370, thg df98b880, sig 1 Apr 20 20:03:57 EL135 kernel: kill_signal(13516.0): selected 1, signalled 1, queued 1, seq 4, exc 4826 0 red 189481 331 Apr 20 20:03:57 EL135 kernel: kill_signal(13516.0): task ede29370, thg df98b880, sig 2 Apr 20 20:04:53 EL135 kernel: kill_signal(13516.0): selecting to kill, queued 0, seq 5, exc 3564 0 goal 3564 0... Apr 20 20:04:53 EL135 kernel: kill_signal(13516.0): task c6c90110, thg cdb1a100, sig 1 Apr 20 20:04:53 EL135 kernel: kill_signal(13516.0): selected 1, signalled 1, queued 1, seq 5, exc 3564 0 red 189481 331 Apr 20 20:04:53 EL135 kernel: kill_signal(13516.0): task c6c90110, thg cdb1a100, sig 2 Apr 20 20:07:14 EL135 kernel: kill_signal(13516.0): selecting to kill, queued 0, seq 6, exc 8071 0 goal 8071 0... Apr 20 20:07:14 EL135 kernel: kill_signal(13516.0): task d7294050, thg c03f42c0, sig 1 Apr 20 20:07:14 EL135 kernel: kill_signal(13516.0): selected 1, signalled 1, queued 1, seq 6, exc 8071 0 red 189481 331 Apr 20 20:07:14 EL135 kernel: kill_signal(13516.0): task d7294050, thg c03f42c0, sig 2 Watchdog is a watchdog task, that was idle; nothing in the logs to suggest it had done anything for days. Its job is to restart one of the applications if it dies, so a bit ironic that it is the first to get killed. Tail was monitoring a few logs files. Unlikely to be consuming memory madly. The apache web-server only serves pages to a little old lady who only uses it to get to church on Sundays a couple of developers who were in bed asleep, and hadn't visited a page on the site for a few weeks. The only traffic it might have had is from the port-scanners; all the content is password-protected and not linked from anywhere, so no spiders are interested. Python is running two separate custom applications. Nothing in the logs to suggest they weren't humming along as normal. One of them was a relatively recent implementation, which makes suspect #1. It doesn't have any data-structures of any significance, and normally uses only about 8% of the total physical RAW. It hasn't misbehaved since. The grep is suspect #2, and the one I want to be guilty, because it was a once-off command. The command (which piped the output of a grep -r to another grep) had been started at least 30 minutes earlier, and the fact it was still running is suspicious. However, I wouldn't have thought grep would ever use a significant amount of memory. It took a while for the OOM killer to get to it, which suggests it wasn't going mad, but the OOM killer stopped once it was killed, suggesting it may have been a memory-hog that finally satisfied the OOM killer's blood-lust.

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  • please explain NHibernate HiLo

    - by Ben
    I'm struggling to get my head round how the HiLo generator works in NHibernate. I've read the explanation here which made things a little clearer. My understanding is that each SessionFactory retrieves the high value from the database. This improves performance because we have access to IDs without hitting the database. The explanation from the above link also states: For instance, supposing you have a "high" sequence with a current value of 35, and the "low" number is in the range 0-1023. Then the client can increment the sequence to 36 (for other clients to be able to generate keys while it's using 35) and know that keys 35/0, 35/1, 35/2, 35/3... 35/1023 are all available. How does this work in a web application as don't I only have one SessionFactory and therefore one hi value. Does this mean that in a disconnected application you can end up with duplicate (low) ids in your entity table? In my tests I used these settings: <id name="Id" unsaved-value="0"> <generator class="hilo"/> </id> I ran a test to save 100 objects. The IDs in my table went from 32768 - 32868. The next hi value was incremented to 2. Then I ran my test again and the Ids were in the range 65536 - 65636. First off, why start at 32768 and not 1, and secondly why the jump from 32868 to 65536? Now I know that my surrogate keys shouldn't have any meaning but we do use them in our application. Why can't I just have them increment nicely like a SQL Server identity field would. Finally can someone give me an explanation of how the max_lo parameter works? Is this the maximum number of low values (entity ids in my head) that can be created against the high value? This is one topic in NHibernate that I have struggled to find documentation for. I read the entire NHibernate in action book and it still doesn't go into how this works in any detail. Thanks Ben

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  • Fixed point math in c#?

    - by x4000
    Hi there, I was wondering if anyone here knows of any good resources for fixed point math in c#? I've seen things like this (http://2ddev.72dpiarmy.com/viewtopic.php?id=156) and this (http://stackoverflow.com/questions/79677/whats-the-best-way-to-do-fixed-point-math), and a number of discussions about whether decimal is really fixed point or actually floating point (update: responders have confirmed that it's definitely floating point), but I haven't seen a solid C# library for things like calculating cosine and sine. My needs are simple -- I need the basic operators, plus cosine, sine, arctan2, PI... I think that's about it. Maybe sqrt. I'm programming a 2D RTS game, which I have largely working, but the unit movement when using floating-point math (doubles) has very small inaccuracies over time (10-30 minutes) across multiple machines, leading to desyncs. This is presently only between a 32 bit OS and a 64 bit OS, all the 32 bit machines seem to stay in sync without issue, which is what makes me think this is a floating point issue. I was aware from this as a possible issue from the outset, and so have limited my use of non-integer position math as much as possible, but for smooth diagonal movement at varying speeds I'm calculating the angle between points in radians, then getting the x and y components of movement with sin and cos. That's the main issue. I'm also doing some calculations for line segment intersections, line-circle intersections, circle-rect intersections, etc, that also probably need to move from floating-point to fixed-point to avoid cross-machine issues. If there's something open source in Java or VB or another comparable language, I could probably convert the code for my uses. The main priority for me is accuracy, although I'd like as little speed loss over present performance as possible. This whole fixed point math thing is very new to me, and I'm surprised by how little practical information on it there is on google -- most stuff seems to be either theory or dense C++ header files. Anything you could do to point me in the right direction is much appreciated; if I can get this working, I plan to open-source the math functions I put together so that there will be a resource for other C# programmers out there. UPDATE: I could definitely make a cosine/sine lookup table work for my purposes, but I don't think that would work for arctan2, since I'd need to generate a table with about 64,000x64,000 entries (yikes). If you know any programmatic explanations of efficient ways to calculate things like arctan2, that would be awesome. My math background is all right, but the advanced formulas and traditional math notation are very difficult for me to translate into code.

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  • Asp.net hosting equivalent of Dreamhost (pricing, features and support)

    - by Cherian
    Disclaimer: I have browsed http://stackoverflow.com/questions/tagged/asp.net+hosting and didn’t find anything quite similar in value to Dreamhost. One of the biggest impediments IMHO for developing web applications on asp.net is the cost of deployment. I am not talking about building sites like Stackoverflow.com or plentyoffish.com. This is about sites that are bigger than brochureware and smaller than ones that require dedicated servers. Let me give you an example. xmec.org is an asp.net site I maintain for my college alumni. On an average it’s slated to hit around 1000-1100 views per day. At present it’s hosted on godaddy. The service is so damn pathetic; I am using it only because of the lack of options. The site doesn’t scale (no, it’s not the code) and the web control panels are extremely slow. The money I pay doesn’t justify the service or the performance. Every deployment push is a visit to the infuriating web control panel to set the permissions and the root directories. Had I developed it in python, this would have been deployed on Dreamhost.com with $10/year hosting fees (they have offers running all throughout) 50 GB space 5 MySQL Databases Shell / FTP Users POP / SMTP Access Unlimited Domains hosting Unlimited Sub domains hosting Unlimited Domains Forwarded/Mirrored Custom DNS (These are the only ones I could think of. More at the feature page) With a dream host shell, I even have a svn checked-out version of wordpress for my blog. Now, that’s control! To my question: Is there any asp.net (preferably .net 3.5. Dreamhost keeps on updating versions every fortnight) hosting company providing remotely similar feature-sets and pricing like Dreamhost. My requirements are: Less than $15-25/ year Typical WISP minus PHP .net 3.5 SP1 Full Trust mode(I can live with medium trust, if not for the IL emitting libraries) Isolated Application Pool 5 – 10 MySQL db’s Unlimited domain hosting MsSql 2005 or 2008 FTP support At Least 5 GB space SMTP IIS 7 Log files Accessibility Moderately good control panel Scripting, shell support Nominal bandwidth Another case in point: Recently I’ve been contemplating building a tool-website to find duplicates and weird characters in my Google contacts and fix them. With asp.net, the best part is that I can do this with LINQ to XML in less than 100 lines of code. What’s bad is the hosting part. I don’t think I stand to make any money out of this and therefore can’t afford to host it on GoGrid or DiscountAsp.net. Godaddy is not an option either. If I do this in python, I can push to this my existing $10 Dreamhost account with another domain pointed. No extra cost. Svn exported with scripts (capability) to change the connection string! Looking at the problem holistically, I think I represent a large breed of programmers playing it cheap and experimenting different things on a regular basis, one of which will become the next twitter/digg.

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  • Good Secure Backups Developers at Home

    - by slashmais
    What is a good, secure, method to do backups, for programmers who do research & development at home and cannot afford to lose any work? Conditions: The backups must ALWAYS be within reasonably easy reach. Internet connection cannot be guaranteed to be always available. The solution must be either FREE or priced within reason, and subject to 2 above. Status Report This is for now only considering free options. The following open-source projects are suggested in the answers (here & elsewhere): BackupPC is a high-performance, enterprise-grade system for backing up Linux, WinXX and MacOSX PCs and laptops to a server's disk. Storebackup is a backup utility that stores files on other disks. mybackware: These scripts were developed to create SQL dump files for basic disaster recovery of small MySQL installations. Bacula is [...] to manage backup, recovery, and verification of computer data across a network of computers of different kinds. In technical terms, it is a network based backup program. AutoDL 2 and Sec-Bk: AutoDL 2 is a scalable transport independant automated file transfer system. It is suitable for uploading files from a staging server to every server on a production server farm [...] Sec-Bk is a set of simple utilities to securely back up files to a remote location, even a public storage location. rsnapshot is a filesystem snapshot utility for making backups of local and remote systems. rbme: Using rsync for backups [...] you get perpetual incremental backups that appear as full backups (for each day) and thus allow easy restore or further copying to tape etc. Duplicity backs directories by producing encrypted tar-format volumes and uploading them to a remote or local file server. [...] uses librsync, [for] incremental archives Other Possibilities: Using a Distributed Version Control System (DVCS) such as Git(/Easy Git), Bazaar, Mercurial answers the need to have the backup available locally. Use free online storage space as a remote backup, e.g.: compress your work/backup directory and mail it to your gmail account. Strategies See crazyscot's answer

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  • Multi-part question about multi-threading, locks and multi-core processors (multi ^ 3)

    - by MusiGenesis
    I have a program with two methods. The first method takes two arrays as parameters, and performs an operation in which values from one array are conditionally written into the other, like so: void Blend(int[] dest, int[] src, int offset) { for (int i = 0; i < src.Length; i++) { int rdr = dest[i + offset]; dest[i + offset] = src[i] > rdr? src[i] : rdr; } } The second method creates two separate sets of int arrays and iterates through them such that each array of one set is Blended with each array from the other set, like so: void CrossBlend() { int[][] set1 = new int[150][75000]; // we'll pretend this actually compiles int[][] set2 = new int[25][10000]; // we'll pretend this actually compiles for (int i1 = 0; i1 < set1.Length; i1++) { for (int i2 = 0; i2 < set2.Length; i2++) { Blend(set1[i1], set2[i2], 0); // or any offset, doesn't matter } } } First question: Since this apporoach is an obvious candidate for parallelization, is it intrinsically thread-safe? It seems like no, since I can conceive a scenario (unlikely, I think) where one thread's changes are lost because a different threads ~simultaneous operation. If no, would this: void Blend(int[] dest, int[] src, int offset) { lock (dest) { for (int i = 0; i < src.Length; i++) { int rdr = dest[i + offset]; dest[i + offset] = src[i] > rdr? src[i] : rdr; } } } be an effective fix? Second question: If so, what would be the likely performance cost of using locks like this? I assume that with something like this, if a thread attempts to lock a destination array that is currently locked by another thread, the first thread would block until the lock was released instead of continuing to process something. Also, how much time does it actually take to acquire a lock? Nanosecond scale, or worse than that? Would this be a major issue in something like this? Third question: How would I best approach this problem in a multi-threaded way that would take advantage of multi-core processors (and this is based on the potentially wrong assumption that a multi-threaded solution would not speed up this operation on a single core processor)? I'm guessing that I would want to have one thread running per core, but I don't know if that's true.

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