parallel port - Page 16

Unified Parallel C - examples and list of extensions

- by osgx

Hello Where can I find examples of code, written in "Unified Parallel C"? I also interested in normative documents about this language (standards, reference manuals, online-accessible books and courses). What extensions were added to C to get UPC? Is this dialect alive or dead?

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Send raw data to USB parallel port after upgrading to 11.10

- by zaphod

I have a laser cutter connected via a generic USB to parallel adapter. The laser cutter speaks HPGL, as it happens, but since this is a laser cutter and not a plotter, I usually want to generate the HPGL myself, since I care about the ordering, speed, and direction of cuts and so on. In previous versions of Ubuntu, I was able to print to the cutter by copying an HPGL file directly to the corresponding USB "lp" device. For example: cp foo.plt /dev/usblp1 Well, I just upgraded to Ubuntu 11.10 oneiric, and I can't find any "lp" devices in /dev anymore. D'oh! What's the preferred way to send raw data to a parallel port in Ubuntu? I've tried System Settings Printing + Add, hoping that I might be able to associate my device with some kind of "raw printer" driver and print to it with a command like lp -d LaserCutter foo.plt But my USB to parallel adapter doesn't seem to show up in the list. What I do see are my HP Color LaserJet, two USB-to-serial adapters, "Enter URI", and "Network Printer". Meanwhile, over in /dev, I do see /dev/ttyUSB0 and /dev/ttyUSB1 devices for the 2 USB-to-serial adapters. I don't see anything obvious corresponding to the HP printer (which was /dev/usblp0 prior to the upgrade), except for generic USB stuff. For example, sudo find /dev | grep lp produces no output. I do seem to be able to print to the HP printer just fine, though. The printer setup GUI gives it a device URI starting with "hp:" which isn't much help for the parallel adapter. The CUPS administrator's guide makes it sound like I might need to feed it a device URI of the form parallel:/dev/SOMETHING, but of course if I had a /dev/SOMETHING I'd probably just go on writing to it directly. Here's what dmesg says after I disconnect and reconnect the device from the USB port: [ 924.722906] usb 1-1.1.4: USB disconnect, device number 7 [ 959.993002] usb 1-1.1.4: new full speed USB device number 8 using ehci_hcd And here's how it shows up in lsusb -v: Bus 001 Device 008: ID 1a86:7584 QinHeng Electronics CH340S Device Descriptor: bLength 18 bDescriptorType 1 bcdUSB 1.10 bDeviceClass 0 (Defined at Interface level) bDeviceSubClass 0 bDeviceProtocol 0 bMaxPacketSize0 8 idVendor 0x1a86 QinHeng Electronics idProduct 0x7584 CH340S bcdDevice 2.52 iManufacturer 0 iProduct 2 USB2.0-Print iSerial 0 bNumConfigurations 1 Configuration Descriptor: bLength 9 bDescriptorType 2 wTotalLength 32 bNumInterfaces 1 bConfigurationValue 1 iConfiguration 0 bmAttributes 0x80 (Bus Powered) MaxPower 96mA Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 0 bAlternateSetting 0 bNumEndpoints 2 bInterfaceClass 7 Printer bInterfaceSubClass 1 Printer bInterfaceProtocol 2 Bidirectional iInterface 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x82 EP 2 IN bmAttributes 2 Transfer Type Bulk Synch Type None Usage Type Data wMaxPacketSize 0x0020 1x 32 bytes bInterval 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x02 EP 2 OUT bmAttributes 2 Transfer Type Bulk Synch Type None Usage Type Data wMaxPacketSize 0x0020 1x 32 bytes bInterval 0 Device Status: 0x0000 (Bus Powered)

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Send raw data to USB parallel port after upgrading to 11.10 oneiric

- by zaphod

I have a laser cutter connected via a generic USB to parallel adapter. The laser cutter speaks HPGL, as it happens, but since this is a laser cutter and not a plotter, I usually want to generate the HPGL myself, since I care about the ordering, speed, and direction of cuts and so on. In previous versions of Ubuntu, I was able to print to the cutter by copying an HPGL file directly to the corresponding USB "lp" device. For example: cp foo.plt /dev/usblp1 Well, I just upgraded to Ubuntu 11.10 oneiric, and I can't find any "lp" devices in /dev anymore. D'oh! What's the preferred way to send raw data to a parallel port in Ubuntu? I've tried System Settings Printing + Add, hoping that I might be able to associate my device with some kind of "raw printer" driver and print to it with a command like lp -d LaserCutter foo.plt But my USB to parallel adapter doesn't seem to show up in the list. What I do see are my HP Color LaserJet, two USB-to-serial adapters, "Enter URI", and "Network Printer". Meanwhile, over in /dev, I do see /dev/ttyUSB0 and /dev/ttyUSB1 devices for the 2 USB-to-serial adapters. I don't see anything obvious corresponding to the HP printer (which was /dev/usblp0 prior to the upgrade), except for generic USB stuff. For example, sudo find /dev | grep lp produces no output. I do seem to be able to print to the HP printer just fine, though. The printer setup GUI gives it a device URI starting with "hp:" which isn't much help for the parallel adapter. The CUPS administrator's guide makes it sound like I might need to feed it a device URI of the form parallel:/dev/SOMETHING, but of course if I had a /dev/SOMETHING I'd probably just go on writing to it directly. Here's what dmesg says after I disconnect and reconnect the device from the USB port: [ 924.722906] usb 1-1.1.4: USB disconnect, device number 7 [ 959.993002] usb 1-1.1.4: new full speed USB device number 8 using ehci_hcd And here's how it shows up in lsusb -v: Bus 001 Device 008: ID 1a86:7584 QinHeng Electronics CH340S Device Descriptor: bLength 18 bDescriptorType 1 bcdUSB 1.10 bDeviceClass 0 (Defined at Interface level) bDeviceSubClass 0 bDeviceProtocol 0 bMaxPacketSize0 8 idVendor 0x1a86 QinHeng Electronics idProduct 0x7584 CH340S bcdDevice 2.52 iManufacturer 0 iProduct 2 USB2.0-Print iSerial 0 bNumConfigurations 1 Configuration Descriptor: bLength 9 bDescriptorType 2 wTotalLength 32 bNumInterfaces 1 bConfigurationValue 1 iConfiguration 0 bmAttributes 0x80 (Bus Powered) MaxPower 96mA Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 0 bAlternateSetting 0 bNumEndpoints 2 bInterfaceClass 7 Printer bInterfaceSubClass 1 Printer bInterfaceProtocol 2 Bidirectional iInterface 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x82 EP 2 IN bmAttributes 2 Transfer Type Bulk Synch Type None Usage Type Data wMaxPacketSize 0x0020 1x 32 bytes bInterval 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x02 EP 2 OUT bmAttributes 2 Transfer Type Bulk Synch Type None Usage Type Data wMaxPacketSize 0x0020 1x 32 bytes bInterval 0 Device Status: 0x0000 (Bus Powered)

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Configure Postfix to send/relay emails Gmail (smtp.gmail.com) via port 587

- by tom smith

Hi. Using Centos 5.4, with Postfix. I can do a mail [email protected] subject: blah test . Cc: and the msg gets sent to gmail, but it resides in the spam folder, which is to be expected. My goal is to be able to generate email msgs, and to have them appear in the regular Inbox! As I understand Postfix/Gmail, it's possible to configure Postfix to send/relay mail via the authenticated/valid user using port 587, which would no longer have the mail be seen as spam. I've tried a number of parameters based on different sites/articles from the 'net, with no luck. Some of the articles, actually seem to conflict with other articles! I've also looked over the stacflow postings on this, but i'm still missing something... Also talked to a few people on IRC (Centos/Postfix) and still have questions.. So, i'm turning to Serverfault, once again! If there's someone who's managed to accomplish this, would you mind posting your main.cf, sasl-passwd, and any other conf files that you use to get this working! If I can review your config files, I can hopefully see where I've screwed up, and figure out how to correct the issue. Thanks for reading this, and any help/pointers you provide! ps, If there is a stackflow posting that speaks to this that I may have missed, feel free to point it out to me! -tom

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Port forwarding on D-Link DIR-615 super-slow, useless

- by Jaroslav Záruba

Hello I have replaced my old router with DIR-615 from D-Link, and now the port forwarding is so slow it makes the router practically useless for requests coming from outside of my network. Accessing the router itself (admin UI) from outside is without any issues, no delay whatsoever. But when I try to access a service residing on any of the computers in my network from outside the requests take minutes and minutes. (E.g. I can see source of my GWT-app main page, but loading additional CSS and JS files takes years.) If anyone could recommend any further diagnostics I should do to figure out what is happening it would be great. Few notes: happens with more services (web-app on Tomcat, viewing directory index via Apache) it does not make a difference whether the service is hosted on wired or wireless PC accessing the service on a localhost works fine, as does any 'inner' communication turning off firewall on target PC does not make difference either (makes sense) when I replace this router with the old one (both 192.168.1.1) everything works fine I see nothing suspicious in the router's log I believe I have the latest firmware (4.11) DIR-615 sucks, it already died once completely Regards Jarda Z.

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TCP: Address already in use exception - possible causes for client port? NO PORT EXHAUSTION

- by TomTom

Hello, stupid problem. I get those from a client connecting to a server. Sadly, the setup is complicated making debugging complex - and we run out of options. The environment: *Client/Server system, both running on the same machine. The client is actually a service doing some database manipulation at specific times. * The cnonection comes from C# going through OleDb to an EasySoft JDBC driver to a custom written JDBC server that then hosts logic in C++. Yeah, compelx - but the third party supplier decided to expose the extension mechanisms for their server through a JDBC interface. Not a lot can be done here ;) The Symptom: At (ir)regular intervals we get a "Address already in use: connect" told from the JDBC driver. They seem to come from one particular service we run. Now, I did read all the stuff about port exhaustion. This is why we have a little tool running now that counts ports and their states every minute. Last time this happened, we had an astonishing 370 ports in use, with the count rising to about 900 AFTER the error. We aleady patched the registry (it is a windows machine) to allow more than the 5000 client ports standard, but even then, we are far far from that limit to start with. Which is why I am asking here. Ayneone an ide what ELSE could cause this? It is a Windows 2003 Server machine, 64 bit. The only other thing I can see that may cause it (but this functionality is supposedly disabled) is Symantec Endpoint Protection that is installed on the server - and being capable of actinc as a firewall, it could possibly intercept network traffic. I dont want to open a can of worms by pointing to Symantec prematurely (if pointing to Symantec can ever be seen as such). So, anyone an idea what else may be the cause? Thanks

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Thin server : `start_tcp_server': no acceptor (port is in use or requires root privileges) (RuntimeError)

- by Rubytastic

My thin webserver fails to start with an error message. I can hardly find any information or leads on how to fix this, anyone an idea? thx Thin web server (v1.5.0 codename Knife) Maximum connections set to 1024 Listening on 0.0.0.0:9292, CTRL+C to stop /srv/gamers/shared/bundle/ruby/1.9.1/gems/eventmachine-1.0.0/lib/eventmachine.rb:526:in start_tcp_server': no acceptor (port is in use or requires root privileges) (RuntimeError) from /srv/gamers/shared/bundle/ruby/1.9.1/gems/eventmachine-1.0.0/lib/eventmachine.rb:526:instart_server' from /srv/gamers/shared/bundle/ruby/1.9.1/gems/thin-1.5.0/lib/thin/backends/tcp_server.rb:16:in connect' from /srv/gamers/shared/bundle/ruby/1.9.1/gems/thin-1.5.0/lib/thin/backends/base.rb:55:inblock in start' from /srv/gamers/shared/bundle/ruby/1.9.1/gems/eventmachine-1.0.0/lib/eventmachine.rb:187:in call' from /srv/gamers/shared/bundle/ruby/1.9.1/gems/eventmachine-1.0.0/lib/eventmachine.rb:187:inrun_machine' from /srv/gamers/shared/bundle/ruby/1.9.1/gems/eventmachine-1.0.0/lib/eventmachine.rb:187:in run' from /srv/gamers/shared/bundle/ruby/1.9.1/gems/thin-1.5.0/lib/thin/backends/base.rb:63:instart' from /srv/gamers/shared/bundle/ruby/1.9.1/gems/thin-1.5.0/lib/thin/server.rb:159:in start' from /srv/gamers/shared/bundle/ruby/1.9.1/gems/rack-1.4.1/lib/rack/handler/thin.rb:13:inrun' from /srv/gamers/shared/bundle/ruby/1.9.1/gems/rack-1.4.1/lib/rack/server.rb:265:in start' from /srv/gamers/shared/bundle/ruby/1.9.1/gems/rack-1.4.1/lib/rack/server.rb:137:instart' from /srv/gamers/shared/bundle/ruby/1.9.1/gems/rack-1.4.1/bin/rackup:4:in <top (required)>' from /srv/gamers/shared/bundle/ruby/1.9.1/bin/rackup:19:inload' from /srv/gamers/shared/bundle/ruby/1.9.1/bin/rackup:19:in `'

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My Ruby on Rails application only works if the address contains the port

- by True Soft

I have a Ruby on Rails application that works ok on my notebook ( http://localhost:3000/ ) I uploaded it on my hosting server, created with CPanel X an application, the URL is http://example.com:12007/ created a rewrite from http://example.com/ to http://example.com:12007/, and started it. If I write in my browser http://example.com:12007/ or http://www.example.com:12007/ all the pages work as expected. But if I write http://example.com/ or http://www.example.com/ the first page is displayed, but without any css or images (just like it wouldn't find them). I can see all the text (even the text from my MySQL database), but with no format. And if I click on any link, I get a error page like this: Not Found The requested URL /some_controller was not found on this server. Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request. What should I do to make my website work without writing the port in the address bar? The content of my /public_html/.htaccess file is RewriteEngine on RewriteCond %{HTTP_HOST} ^example.com$ [OR] RewriteCond %{HTTP_HOST} ^www.example.com$ RewriteRule ^/?$ "http\:\/\/127\.0\.0\.1\:12007%{REQUEST_URI}" [P,QSA,L] which I guess was generated by CPanel Rewrites.

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Several web applications on a single port

- by Nevermind

We're developing an online browser-based game. The game itself is a plugin in the web page, that uses TCP connection to a game server, and also sends http requests to "content server" web application. This makes 3 servers total: the site itself, game server and content server. Site and content server are IIS web applications, game server is a custom application communicating over TCP with proprietary protocol. While the game is in beta stage, all these servers are physically hosted on a single machine, and distinguished by ports. For example, website is game.example.com:80, game server is game.example.com:34285 and content server is game.example.com:50000. This works OK most of the time, but some of our players have ports other than 80 closed. Is there any way to make all these application work through port 80, while still having them one one physical server? Maybe using different sub-domains? There's probably a way to make IIS forward requests to different web applications based on URL alone, but that doesn't help with game server. Edit Server is Windows Server 2008, IIS 7

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On checking is a port open on the firewall?

- by [email protected]

Hi, well sometimes DBAs and sysadmin need to check if a particular port is "open" on the corporate firewall --i.e. *Grid Control* Will the communication between OMS and a management agent work? --One solution well consist on deploying the piece of software in question, start it and just check if everything works fine, however i find more classy trying to get that information beforeThere are several tools for doing so --i.e. nmap *like Trinity on The Matrix*, but just found a nice piece of code for establishing a socket on a parameter passed port.After running the program doing a telnet from the client machine will be a walk in the park Normal 0 21 false false false MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman"; mso-ansi-language:#0400; mso-fareast-language:#0400; mso-bidi-language:#0400;} #include <stdio.h> #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> int main(int argc, char *argv[]) { int sockfd, newsockfd, portno, clilen; char buffer[256]; struct sockaddr_in serv_addr, cli_addr; int n; if (argc < 2) { fprintf(stderr,"ERROR: A port must be provided. Aborting ...\n"); return 1; } sockfd = socket(AF_INET, SOCK_STREAM, 0); if (sockfd < 0) { fprintf("ERROR: Unable to open socket. Aborting ...\n"); return 1; } portno = atoi(argv[1]); serv_addr.sin_family = AF_INET; serv_addr.sin_addr.s_addr = INADDR_ANY; serv_addr.sin_port = htons(portno); if (bind(sockfd, (struct sockaddr *) &serv_addr,sizeof(serv_addr)) < 0) { fprintf("ERROR: Unable to bind socket. Aborting ...\n"); return 1; } listen(sockfd,5); clilen = sizeof(cli_addr); newsockfd = accept(sockfd, (struct sockaddr *) &cli_addr,&clilen); if (newsockfd < 0) { fprintf("ERROR: Unable to accept connection. Aborting...\n"); return 1; } return 0; }Of course, you can still ask to the network guy if the port is open or notHope it helpsL

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Using TPL and PLINQ to raise performance of feed aggregator

- by DigiMortal

In this posting I will show you how to use Task Parallel Library (TPL) and PLINQ features to boost performance of simple RSS-feed aggregator. I will use here only very basic .NET classes that almost every developer starts from when learning parallel programming. Of course, we will also measure how every optimization affects performance of feed aggregator. Feed aggregator Our feed aggregator works as follows: Load list of blogs Download RSS-feed Parse feed XML Add new posts to database Our feed aggregator is run by task scheduler after every 15 minutes by example. We will start our journey with serial implementation of feed aggregator. Second step is to use task parallelism and parallelize feeds downloading and parsing. And our last step is to use data parallelism to parallelize database operations. We will use Stopwatch class to measure how much time it takes for aggregator to download and insert all posts from all registered blogs. After every run we empty posts table in database. Serial aggregation Before doing parallel stuff let’s take a look at serial implementation of feed aggregator. All tasks happen one after other. internal class FeedClient { private readonly INewsService _newsService; private const int FeedItemContentMaxLength = 255; public FeedClient() { ObjectFactory.Initialize(container => { container.PullConfigurationFromAppConfig = true; }); _newsService = ObjectFactory.GetInstance<INewsService>(); } public void Execute() { var blogs = _newsService.ListPublishedBlogs(); for (var index = 0; index <blogs.Count; index++) { ImportFeed(blogs[index]); } } private void ImportFeed(BlogDto blog) { if(blog == null) return; if (string.IsNullOrEmpty(blog.RssUrl)) return; var uri = new Uri(blog.RssUrl); SyndicationContentFormat feedFormat; feedFormat = SyndicationDiscoveryUtility.SyndicationContentFormatGet(uri); if (feedFormat == SyndicationContentFormat.Rss) ImportRssFeed(blog); if (feedFormat == SyndicationContentFormat.Atom) ImportAtomFeed(blog); } private void ImportRssFeed(BlogDto blog) { var uri = new Uri(blog.RssUrl); var feed = RssFeed.Create(uri); foreach (var item in feed.Channel.Items) { SaveRssFeedItem(item, blog.Id, blog.CreatedById); } } private void ImportAtomFeed(BlogDto blog) { var uri = new Uri(blog.RssUrl); var feed = AtomFeed.Create(uri); foreach (var item in feed.Entries) { SaveAtomFeedEntry(item, blog.Id, blog.CreatedById); } } } Serial implementation of feed aggregator downloads and inserts all posts with 25.46 seconds. Task parallelism Task parallelism means that separate tasks are run in parallel. You can find out more about task parallelism from MSDN page Task Parallelism (Task Parallel Library) and Wikipedia page Task parallelism. Although finding parts of code that can run safely in parallel without synchronization issues is not easy task we are lucky this time. Feeds import and parsing is perfect candidate for parallel tasks. We can safely parallelize feeds import because importing tasks doesn’t share any resources and therefore they don’t also need any synchronization. After getting the list of blogs we iterate through the collection and start new TPL task for each blog feed aggregation. internal class FeedClient { private readonly INewsService _newsService; private const int FeedItemContentMaxLength = 255; public FeedClient() { ObjectFactory.Initialize(container => { container.PullConfigurationFromAppConfig = true; }); _newsService = ObjectFactory.GetInstance<INewsService>(); } public void Execute() { var blogs = _newsService.ListPublishedBlogs(); var tasks = new Task[blogs.Count]; for (var index = 0; index <blogs.Count; index++) { tasks[index] = new Task(ImportFeed, blogs[index]); tasks[index].Start(); } Task.WaitAll(tasks); } private void ImportFeed(object blogObject) { if(blogObject == null) return; var blog = (BlogDto)blogObject; if (string.IsNullOrEmpty(blog.RssUrl)) return; var uri = new Uri(blog.RssUrl); SyndicationContentFormat feedFormat; feedFormat = SyndicationDiscoveryUtility.SyndicationContentFormatGet(uri); if (feedFormat == SyndicationContentFormat.Rss) ImportRssFeed(blog); if (feedFormat == SyndicationContentFormat.Atom) ImportAtomFeed(blog); } private void ImportRssFeed(BlogDto blog) { var uri = new Uri(blog.RssUrl); var feed = RssFeed.Create(uri); foreach (var item in feed.Channel.Items) { SaveRssFeedItem(item, blog.Id, blog.CreatedById); } } private void ImportAtomFeed(BlogDto blog) { var uri = new Uri(blog.RssUrl); var feed = AtomFeed.Create(uri); foreach (var item in feed.Entries) { SaveAtomFeedEntry(item, blog.Id, blog.CreatedById); } } } You should notice first signs of the power of TPL. We made only minor changes to our code to parallelize blog feeds aggregating. On my machine this modification gives some performance boost – time is now 17.57 seconds. Data parallelism There is one more way how to parallelize activities. Previous section introduced task or operation based parallelism, this section introduces data based parallelism. By MSDN page Data Parallelism (Task Parallel Library) data parallelism refers to scenario in which the same operation is performed concurrently on elements in a source collection or array. In our code we have independent collections we can process in parallel – imported feed entries. As checking for feed entry existence and inserting it if it is missing from database doesn’t affect other entries the imported feed entries collection is ideal candidate for parallelization. internal class FeedClient { private readonly INewsService _newsService; private const int FeedItemContentMaxLength = 255; public FeedClient() { ObjectFactory.Initialize(container => { container.PullConfigurationFromAppConfig = true; }); _newsService = ObjectFactory.GetInstance<INewsService>(); } public void Execute() { var blogs = _newsService.ListPublishedBlogs(); var tasks = new Task[blogs.Count]; for (var index = 0; index <blogs.Count; index++) { tasks[index] = new Task(ImportFeed, blogs[index]); tasks[index].Start(); } Task.WaitAll(tasks); } private void ImportFeed(object blogObject) { if(blogObject == null) return; var blog = (BlogDto)blogObject; if (string.IsNullOrEmpty(blog.RssUrl)) return; var uri = new Uri(blog.RssUrl); SyndicationContentFormat feedFormat; feedFormat = SyndicationDiscoveryUtility.SyndicationContentFormatGet(uri); if (feedFormat == SyndicationContentFormat.Rss) ImportRssFeed(blog); if (feedFormat == SyndicationContentFormat.Atom) ImportAtomFeed(blog); } private void ImportRssFeed(BlogDto blog) { var uri = new Uri(blog.RssUrl); var feed = RssFeed.Create(uri); feed.Channel.Items.AsParallel().ForAll(a => { SaveRssFeedItem(a, blog.Id, blog.CreatedById); }); } private void ImportAtomFeed(BlogDto blog) { var uri = new Uri(blog.RssUrl); var feed = AtomFeed.Create(uri); feed.Entries.AsParallel().ForAll(a => { SaveAtomFeedEntry(a, blog.Id, blog.CreatedById); }); } } We did small change again and as the result we parallelized checking and saving of feed items. This change was data centric as we applied same operation to all elements in collection. On my machine I got better performance again. Time is now 11.22 seconds. Results Let’s visualize our measurement results (numbers are given in seconds). As we can see then with task parallelism feed aggregation takes about 25% less time than in original case. When adding data parallelism to task parallelism our aggregation takes about 2.3 times less time than in original case. More about TPL and PLINQ Adding parallelism to your application can be very challenging task. You have to carefully find out parts of your code where you can safely go to parallel processing and even then you have to measure the effects of parallel processing to find out if parallel code performs better. If you are not careful then troubles you will face later are worse than ones you have seen before (imagine error that occurs by average only once per 10000 code runs). Parallel programming is something that is hard to ignore. Effective programs are able to use multiple cores of processors. Using TPL you can also set degree of parallelism so your application doesn’t use all computing cores and leaves one or more of them free for host system and other processes. And there are many more things in TPL that make it easier for you to start and go on with parallel programming. In next major version all .NET languages will have built-in support for parallel programming. There will be also new language constructs that support parallel programming. Currently you can download Visual Studio Async to get some idea about what is coming. Conclusion Parallel programming is very challenging but good tools offered by Visual Studio and .NET Framework make it way easier for us. In this posting we started with feed aggregator that imports feed items on serial mode. With two steps we parallelized feed importing and entries inserting gaining 2.3 times raise in performance. Although this number is specific to my test environment it shows clearly that parallel programming may raise the performance of your application significantly.

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Explaining Explain Plan Notes for Auto DOP

- by jean-pierre.dijcks

I've recently gotten some questions around "why do I not see a parallel plan" while Auto DOP is on (I think)...? It is probably worthwhile to quickly go over some of the ways to find out what Auto DOP was thinking. In general, there is no need to go tracing sessions and look under the hood. The thing to start with is to do an explain plan on your statement and to look at the parameter settings on the system. Parameter Settings to Look At First and foremost, make sure that parallel_degree_policy = AUTO. If you have that parameter set to LIMITED you will not have queuing and we will only do the auto magic if your objects are set to default parallel (so no degree specified). Next you want to look at the value of parallel_degree_limit. It is typically set to CPU, which in default settings equates to the Default DOP of the system. If you are testing Auto DOP itself and the impact it has on performance you may want to leave it at this CPU setting. If you are running concurrent statements you may want to give this some more thoughts. See here for more information. In general, do stick with either CPU or with a specific number. For now avoid the IO setting as I've seen some mixed results with that... In 11.2.0.2 you should also check that IO Calibrate has been run. Best to simply do a: SQL> select * from V$IO_CALIBRATION_STATUS; STATUS CALIBRATION_TIME ------------- ---------------------------------------------------------------- READY 04-JAN-11 10.04.13.104 AM You should see that your IO Calibrate is READY and therefore Auto DOP is ready. In any case, if you did not run the IO Calibrate step you will get the following note in the explain plan: Note ----- - automatic DOP: skipped because of IO calibrate statistics are missing One more note on calibrate_io, if you do not have asynchronous IO enabled you will see: ERROR at line 1: ORA-56708: Could not find any datafiles with asynchronous i/o capability ORA-06512: at "SYS.DBMS_RMIN", line 463 ORA-06512: at "SYS.DBMS_RESOURCE_MANAGER", line 1296 ORA-06512: at line 7 While this is changed in some fixes to the calibrate procedure, you should really consider switching asynchronous IO on for your data warehouse. Explain Plan Explanation To see the notes that are shown and explained here (and the above little snippet ) you can use a simple explain plan mechanism. There should be no need to add +parallel etc. explain plan for <statement> SELECT PLAN_TABLE_OUTPUT FROM TABLE(DBMS_XPLAN.DISPLAY()); Auto DOP The note structure displaying why Auto DOP did not work (with the exception noted above on IO Calibrate) is like this: Automatic degree of parallelism is disabled: <reason> These are the reason codes: Parameter - parallel_degree_policy = manual which will not allow Auto DOP to kick in Hint - One of the following hints are used NOPARALLEL, PARALLEL(1), PARALLEL(MANUAL) Outline - A SQL outline of an older version (before 11.2) is used SQL property restriction - The statement type does not allow for parallel processing Rule-based mode - Instead of the Cost Based Optimizer the system is using the RBO Recursive SQL statement - The statement type does not allow for parallel processing pq disabled/pdml disabled/pddl disabled - For some reason (alter session?) parallelism is disabled Limited mode but no parallel objects referenced - your parallel_degree_policy = LIMITED and no objects in the statement are decorated with the default PARALLEL degree. In most cases all objects have a specific degree in which case Auto DOP will honor that degree. Parallel Degree Limited When Auto DOP does it works you may see the cap you imposed with parallel_degree_limit showing up in the note section of the explain plan: Note ----- - automatic DOP: Computed Degree of Parallelism is 16 because of degree limit This is an obvious indication that your are being capped for this statement. There is one quite interesting one that happens when you are being capped at DOP = 1. First of you get a serial plan and the note changes slightly in that it does not indicate it is being capped (we hope to update the note at some point in time to be more specific). It right now looks like this: Note ----- - automatic DOP: Computed Degree of Parallelism is 1 Dynamic Sampling With 11.2.0.2 you will start seeing another interesting change in parallel plans, and since we are talking about the note section here, I figured we throw this in for good measure. If we deem the parallel (!) statement complex enough, we will enact dynamic sampling on your query. This happens as long as you did not change the default for dynamic sampling on the system. The note looks like this: Note ----- - dynamic sampling used for this statement (level=5)

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Software to create a virtual parallel port in Windows XP?

- by drknexus

I am writing a program that will eventually be used on a computer with a physical parallel port and will need to set certain pins high or low in order to signal to an external device. However, the development laptop I am using does not have any physical parallel ports and is too low powered to run a virtual machine. Is there any option available that will create a virtual parallel port within Windows XP? Ideally it would include a debug mode that would allow me to see what values have been pushed out on the parallel port.

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Parallel Computing Platform Developer Lab

- by Daniel Moth

This is an exciting announcement that I must share: "Microsoft Developer & Platform Evangelism, in collaboration with the Microsoft Parallel Computing Platform product team, is hosting a developer lab at the Platform Adoption Center on April 12-15, 2010. This event is for Microsoft Partners and Customers seeking to incorporate either .NET Framework 4 or Visual C++ 2010 parallelism features into their new or existing applications, and to gain expertise with new Visual Studio 2010 tools including the Parallel Tasks and Parallel Stacks debugger toolwindows, and the Concurrency Visualizer in the profiler. Opportunities for attendees include: Gain expert design assistance with your Parallel Computing Platform based solution. Develop a solution prototype in collaboration with Microsoft Software Engineers. Attend topical presentations and “chalk-talk” sessions. Your team will be assigned private, secure offices for confidential collaboration activities. The event has limited capacity, thus enrollment is based on an application process. Please download and complete the application form then return it to the event management team per instructions included within the form. Applications will be evaluated based upon the technical solution scenario along with indicated project readiness timelines. Microsoft event management team members may contact you directly for additional clarification and discussion of your project scenario during the nomination process." Comments about this post welcome at the original blog.

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Unity: parallel vectors and cross product, how to compare vectors

- by Heisenbug

I read this post explaining a method to understand if the angle between 2 given vectors and the normal to the plane described by them, is clockwise or anticlockwise: public static AngleDir GetAngleDirection(Vector3 beginDir, Vector3 endDir, Vector3 upDir) { Vector3 cross = Vector3.Cross(beginDir, endDir); float dot = Vector3.Dot(cross, upDir); if (dot > 0.0f) return AngleDir.CLOCK; else if (dot < 0.0f) return AngleDir.ANTICLOCK; return AngleDir.PARALLEL; } After having used it a little bit, I think it's wrong. If I supply the same vector as input (beginDir equal to endDir), the cross product is zero, but the dot product is a little bit more than zero. I think that to fix that I can simply check if the cross product is zero, means that the 2 vectors are parallel, but my code doesn't work. I tried the following solution: Vector3 cross = Vector3.Cross(beginDir, endDir); if (cross == Vector.zero) return AngleDir.PARALLEL; And it doesn't work because comparison between Vector.zero and cross is always different from zero (even if cross is actually [0.0f, 0.0f, 0.0f]). I tried also this: Vector3 cross = Vector3.Cross(beginDir, endDir); if (cross.magnitude == 0.0f) return AngleDir.PARALLEL; it also fails because magnitude is slightly more than zero. So my question is: given 2 Vector3 in Unity, how to compare them? I need the elegant equivalent version of this: if (beginDir.x == endDir.x && beginDir.y == endDir.y && beginDir.z == endDir.z) return true;

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Python: Socket set source port number

- by beratch

Hi all, I'd like to send a specific UDP broadcast packet.. unfortunatly i need to send the udp packet from a very specific port for all packet I send. Let say I broadcast via UDP "BLABLAH", the server will only answer if my incoming packet source port was 1444, if not the packet is discarded. My broadcast socket setup look like this : s = socket(AF_INET,SOCK_DGRAM) s.setsockopt(SOL_SOCKET, SO_BROADCAST, 1) How can i do that (set the source port) in python ? Thanks!

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C# Monte Carlo Incremental Risk Calculation optimisation, random numbers, parallel execution

- by m3ntat

My current task is to optimise a Monte Carlo Simulation that calculates Capital Adequacy figures by region for a set of Obligors. It is running about 10 x too slow for where it will need to be in production and number or daily runs required. Additionally the granularity of the result figures will need to be improved down to desk possibly book level at some stage, the code I've been given is basically a prototype which is used by business units in a semi production capacity. The application is currently single threaded so I'll need to make it multi-threaded, may look at System.Threading.ThreadPool or the Microsoft Parallel Extensions library but I'm constrained to .NET 2 on the server at this bank so I may have to consider this guy's port, http://www.codeproject.com/KB/cs/aforge_parallel.aspx. I am trying my best to get them to upgrade to .NET 3.5 SP1 but it's a major exercise in an organisation of this size and might not be possible in my contract time frames. I've profiled the application using the trial of dotTrace (http://www.jetbrains.com/profiler). What other good profilers exist? Free ones? A lot of the execution time is spent generating uniform random numbers and then translating this to a normally distributed random number. They are using a C# Mersenne twister implementation. I am not sure where they got it or if it's the best way to go about this (or best implementation) to generate the uniform random numbers. Then this is translated to a normally distributed version for use in the calculation (I haven't delved into the translation code yet). Also what is the experience using the following? http://quantlib.org http://www.qlnet.org (C# port of quantlib) or http://www.boost.org Any alternatives you know of? I'm a C# developer so would prefer C#, but a wrapper to C++ shouldn't be a problem, should it? Maybe even faster leveraging the C++ implementations. I am thinking some of these libraries will have the fastest method to directly generate normally distributed random numbers, without the translation step. Also they may have some other functions that will be helpful in the subsequent calculations. Also the computer this is on is a quad core Opteron 275, 8 GB memory but Windows Server 2003 Enterprise 32 bit. Should I advise them to upgrade to a 64 bit OS? Any links to articles supporting this decision would really be appreciated. Anyway, any advice and help you may have is really appreciated.

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Programmatically talking to a Serial Port in OS X or Linux

- by deadprogrammer

I have a Prolite LED sign that I like to set up to show scrolling search queries from a apache logs and other fun statistics. The problem is, my G5 does not have a serial port, so I have to use a usb to serial dongle. It shows up as /dev/cu.usbserial and /dev/tty.usbserial . When i do this everything seems to be hunky-dory: stty -f /dev/cu.usbserial speed 9600 baud; lflags: -icanon -isig -iexten -echo iflags: -icrnl -ixon -ixany -imaxbel -brkint oflags: -opost -onlcr -oxtabs cflags: cs8 -parenb Everything also works when I use the serial port tool to talk to it. If I run this piece of code while the above mentioned serial port tool, everthing also works. But as soon as I disconnect the tool the connection gets lost. #!/usr/bin/python import serial ser = serial.Serial('/dev/cu.usbserial', 9600, timeout=10) ser.write("<ID01><PA> \r\n") read_chars = ser.read(20) print read_chars ser.close() So the question is, what magicks do I need to perform to start talking to the serial port without the serial port tool? Is that a permissions problem? Also, what's the difference between /dev/cu.usbserial and /dev/tty.usbserial?

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Parallel EntityFramework

- by mehanik

Is it possible to make some work in parallel with entity framework for following example? using (var dbContext = new DB()) { var res = (from c in dbContext.Customers orderby c.Name select new { c.Id, c.Name, c.Role } ).ToDictionary(c => c.Id, c => new Dictionary<string, object> { { "Name",c.Name }, { "Role", c.Role } }); } For exampe what will be changed if I add AsParrallel? using (var dbContext = new DB()) { var res = (from c in dbContext.Customers orderby c.Name select new { c.Id, c.Name, c.Role } ).AsParallel().ToDictionary(c => c.Id, c => new Dictionary<string, object> { { "Name",c.Name }, { "Role", c.Role } }); }

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Issues writing to serial port on MAC OSX using unistd.h in c

- by Schuyler

I am trying to write to a bluetooth device on MAC OSX using the unistd.h Linux functions in c. I am connecting fine and writing the first few bytes with success. When I try to write other commands to it (there are bytes added to the write buffer every 15ms), I don't see any results even though the write() function returns 1 (write success). If you start a write and it doesn't finish by the time you try to start another write (since it is non-blocking), could that possibly screw up the initial write? (If so, is there any way to check if a write has completed?) That is the only thing I can think of since the writes are occurring fairly frequently and the first two are successfully sent. qwbyte() simply adds a byte to the output array and increments its length The open port function: BAMid = -1; struct termios options; struct termios originalTTYAttrs; // Open the serial port read/write, nonblocking, with no controlling terminal, and don't wait for a connection. BAMid = open(strPath, O_RDWR | O_NOCTTY | O_NONBLOCK); if (BAMid == -1) { printf("Error opening serial port %s - %s(%d).\n", strPath, strerror(errno), errno); goto error; } // Issue TIOCEXCL ioctl to prevent additional opens except by root-owned processes. if (ioctl(BAMid, TIOCEXCL) == -1) { printf("Error setting TIOCEXCL on %s - %s(%d).\n", strPath, strerror(errno), errno); goto error; } // Get the current options and save them so we can restore the default settings later. if (tcgetattr(BAMid, &originalTTYAttrs) == -1) { printf("Error getting tty attributes %s - %s(%d).\n", strPath, strerror(errno), errno); goto error; } // The serial port attributes such as timeouts and baud rate are set by modifying the termios // structure and then calling tcsetattr() to cause the changes to take effect. Note that the // changes will not become effective without the tcsetattr() call. options = originalTTYAttrs; // Set raw input (non-canonical) mode, with reads blocking until either a single character // has been received or a one second timeout expires. [should be moot since we are leaving it as nonblocking] cfmakeraw(&options); options.c_cc[VMIN] = 1; options.c_cc[VTIME] = 10; cfsetspeed(&options, B57600); // Set 57600 baud options.c_cflag |= CS8; // Use 8 bit words // Cause the new options to take effect immediately. if (tcsetattr(BAMid, TCSANOW, &options) == -1) { printf("Error setting tty attributes %s - %s(%d).\n", strPath, strerror(errno), errno); goto error; } //flush old transmissions if (tcflush(BAMid,TCIOFLUSH) == -1) { printf("Error flushing BAM serial port - %s(%d).\n", strerror(errno), errno); } oBufLength = 0; // Ask it to start if (! qwbyte(CmdStart) ) { goto error; } if (! qwbyte(CmdFull) ) { goto error; } //this transmit works txbytes(); printf("success opening port!"); return -1; // Failure path error: if (BAMid != -1) { close(BAMid); } printf("returning an error--%d",errno); return errno; } The write function (txbytes): int i, bufSize, numBytes; if(oBufLength != 0) { //if the output array isn't empty //duplicating the output array and its size so it can //be overwritten while this write is occuring printf("about to transmit: "); for(i = 0; i < oBufLength; i++) { printf(" %u",oBuf[i]); tempBuf[i] = oBuf[i]; } printf("\n"); bufSize = oBufLength; oBufLength = 0; numBytes = write(BAMid, &tempBuf, bufSize); printf("bytes written = %d\n",numBytes); if (numBytes == -1) { printf("Error writing to port - %s(%d).\n", strerror(errno), errno); } return (numBytes 0); } else { return 0; }

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How to send a reply message to sender machine via serial port using c#

- by karthik

I am using the below code to receive the message via serial port which is working fine. Now i need to send back a acknowledgment message to the sender machine. How can send the message ? private void MonitorSP_DataReceived(object sender, SerialDataReceivedEventArgs e) { try { System.IO.Ports.SerialPort SP = (System.IO.Ports.SerialPort)sender; //Get the ports available in system string[] theSerialPortNames = System.IO.Ports.SerialPort.GetPortNames(); string strAvlPortNames = ""; foreach (string s in theSerialPortNames) { strAvlPortNames += s.ToString() + ", "; } //Read an contruct the message Thread.Sleep(1000); string msg = SP.ReadExisting(); string ConstructedMsg = "Port's Found : " + strAvlPortNames + "\n" + "Port Used : " + SP.PortName + "\n" + "Message Received : " + msg; if (InvokeRequired) { richTextBox1.Invoke(new MethodInvoker(delegate { richTextBox1.Text = ConstructedMsg; })); //Send acknowlegement to sender port SP.Write(SP.PortName); return; } } catch (Exception ex) { MessageBox.Show(ex.StackTrace.ToString()); } }

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serial port in C

- by user222820

I have written a program in C to send a byte to serial port (com). I have used BIOSCOM to send data but I guess that it doesn't open the port. Please tell how I can open and close a com port in C. My code is here: #define COM1 1; bioscom (1 , 65 , COM1); Please help me...

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What parallel programming model do you recommend today to take advantage of the manycore processors

- by Doctor J

If you were writing a new application from scratch today, and wanted it to scale to all the cores you could throw at it tomorrow, what parallel programming model/system/language/library would you choose? Why? I am particularly interested in answers along these axes: Programmer productivity / ease of use (can mortals successfully use it?) Target application domain (what problems is it (not) good at?) Concurrency style (does it support tasks, pipelines, data parallelism, messages...?) Maintainability / future-proofing (will anybody still be using it in 20 years?) Performance (how does it scale on what kinds of hardware?) I am being deliberately vauge on the nature of the application in anticipation of getting good general answers useful for a variety of applications.

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timing of reads from serial port on windows

- by Marcin K

I'm trying to implement a protocol over serial port on a windows(xp) machine. The problem is that message synchronization in the protocol is done via a gap in the messages, i.e., x millisecond gap between sent bytes signifies a new message. Now, I don't know if it is even possible to accurately detect this gap. I'm using win32/serport.h api to read in one of the many threads of our server. Data from the serial port gets buffered, so if there is enough (and there will be enough) latency in our software, I will get multiple messages from the port buffer in one sequence of reads. Is there a way of reading from the serial port, so that I would detect gaps in when particular bytes were received?

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C# check if a COM (Serial) port is already open

- by TK

Is there an easy way of programmatically checking if a serial COM port is already open/being used? Normally I would use: try { // open port } catch (Exception ex) { // handle the exception } However, I would like to programatically check so I can attempt to use another COM port or some such.

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