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• Want to make RTS strategy game, good starting point...?

  - by NOLANDI

  everybody! I find this community because I did research about game developing topics. So I decide to register on this community and ask for your opinion. I am not begineer in computer stuffs, and I know logic of programming language. I have little knowlegde of C, C++, Started to learn C#...but I was always oriented about other areas of IT. Amateur for game making but not in IT general! I am interested to make RTS strategy video game, isometric camera view (like PC GAME COMMANDOS for example)...so I started to read many books about DirectX, XNA, OpenGL, C#, AI programming...so I want to know where is good starting point for making this game genre. I want to use C# for this project, not C++, since I always had trouble with it, because it is too complicated. I see good oportunity for learning C#, since it has more object-oriented concept, with much less code and easy readible code for writing. Beside of that I know that C++ is the more powerful language until today. So I want to use DirectX and C# for my project. But it will required more time for sure, to learn it. I have trouble with finding books for c# & DirectX (I found just one), but in every next book, it is programming in c++! I read many web sites and they mentioned Slim DX, and in generaly, other articles which I read tells that it is possible to make good game with combination c# and directX, but...I don't have enough information about all this stuffs, so I became confused! It is really hard to have wish to learn c++ from scratch, since I started c# and I like it really...I don't try OpenGL, but I am already familiar with DirectX (some beginning stuffs), and I think that it is good and interesting. So, I decide to choose between maybe Unity3d and XNA first. XNA...hm, it sound that it is not bad solution, but I heard that it is already overcome technology, and I think that it is better to wait with XNA, until I try to make something with DirectX and C#, at first. But I dont know it is possible to make strategy game in XNA?! Maybe I am wrong. I also, find Unity 3D game engine and I find that I could programming there in C#, but many all examples are written in Javascript (Digital tutors videos)...But I generaly have wish to learn it too, because it allows to export games to mobile phones, there a lot of documentations, it is free, etc... I want to find best way to learn C# and DirectX, and make this game, but I dont know if it's possible to combine?! But maybe is good to first try Unity and XNA, because I am beginner?! Thank you all! I am willing to hear your expirience.

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• How does a programmer without a degree gain experience? [on hold]

  - by user96872

  Having a few years of experience is a must for many programming jobs nowadays. If one does not have a college degree but would like to get some experience with programming (with some prior knowledge, say, in JavaScript, PHP and Python), what are some ways to gain the experience that employers seek? I know about personal projects, but how about team experience and everything that goes along with it? Would I need to volunteer somewhere?

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• OpenCL 1.1 backward compatible, enhanced performance

  <b>Linux Magazine: </b>"The Khronos Group today announced OpenCL 1.1, a backwards compatible update that boosts performance in the parallel programming standard. OpenCL is a free programming standard designed from the ground up to optimize coding in muliticore processors."

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• Developing with the Google Wave APIs - For a grade!

  As a student at university, I always loved when I had the chance to use a Web API in my programming assignments. I think Web API programming is...

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• Throttling in OSB

  - by Knut Vatsendvik

  Technorati Tags: soa,integration,osb,throttling,overload protection A common problem with integration is the risk of overloading a particular web service. When the capacity of a web service is reached and it continues to accept connections, it will most likely start to deteriorate. Fortunately there are 2 techniques, with Oracle Service Bus, that you can apply for protecting this from happening. You can either limit the concurrent number of requests for a Business Service (outbound requests) or you can limit the number of threads processing the requests for a Proxy Service (inbound requests). Limiting the Concurrent Number of Requests Limiting the concurrent requests for a Business Service cannot be set at design time so you have to use the built-in Oracle Service Bus Administration Console to do it (/sbconsole). Follow these steps to enable it: In Change Center, click Create to start a new Session Select Project Explorer, and navigate to the Business Service you want to limit Select the Operational Settings tab of the View a Business Service page In this tab, under Throttling, select the Enable check box. By enabling throttling you Specify a value for Maximum Concurrency Specify a positive integer value for Throttling Queue to backlog messages that has exceeded the message concurrency limit Specify the maximum time in milliseconds for Message Expiration a message can spend in Throttling Queue Click Update Click Active in Change Center to active the new settings If you re-publish the service, it will not overwrite the settings. Only if the resource is renamed or moved, it will. Please note that a throttling queue is an in-memory queue. Messages that are placed in this queue are not recoverable when a server fails or when you restart a server. Limiting the Number of Threads A better approach, in my opinion, is to limit the number of threads that can work with request. Follow these steps to do it: Open the WebLogic Server Console (/console) In Change Center, click Create to start a new Session In the left pane expand Environment and select Work Managers In the Global Work Managers page, click New    Click the Work Manager radio button, then click Next Enter a Name for the new Work Manager, and click Next In the Available Targets list, select server instances or clusters on which you will deploy applications that reference the Work Manager Click Finish. The new Work Manager now appears in the Global Work Managers page. Select the new Work Manager Right next to the Maximum Threads Constraint drop-down box, click New   Click the Maximum Threads Constraint radio button, then click Next Enter a Name and a thread Count to be the maximum size to allocate for requests. Click Next  In the Available Targets list, select server instances or clusters on which you will deploy applications that reference the Work Manager Click Finish Click Save Click Active in Change Center to active your changes.  A restart may be necessary.   Puh! Almost there. Start a new session. Go to the Service Bus Console (/sbconsole) and find your consuming Proxy Service. Click the Edit button of the Transport Configuration tab. Click Next Set the Dispatch Policy to the new Work Manager Click Last Click Save Click Active in Change Center to active your changes. 

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• Problem with AssetManager while loading a Model type

  - by user1204548

  Today I've tried the AssetManager for the first time with .g3db files and I'm having some problems. Exception in thread "LWJGL Application" com.badlogic.gdx.utils.GdxRuntimeException: com.badlogic.gdx.utils.GdxRuntimeException: Couldn't load dependencies of asset: data/data at com.badlogic.gdx.assets.AssetManager.handleTaskError(AssetManager.java:508) at com.badlogic.gdx.assets.AssetManager.update(AssetManager.java:342) at com.lostchg.martagdx3d.MartaGame.render(MartaGame.java:78) at com.badlogic.gdx.Game.render(Game.java:46) at com.badlogic.gdx.backends.lwjgl.LwjglApplication.mainLoop(LwjglApplication.java:207) at com.badlogic.gdx.backends.lwjgl.LwjglApplication$1.run(LwjglApplication.java:114) Caused by: com.badlogic.gdx.utils.GdxRuntimeException: Couldn't load dependencies of asset: data/data at com.badlogic.gdx.assets.AssetLoadingTask.handleAsyncLoader(AssetLoadingTask.java:119) at com.badlogic.gdx.assets.AssetLoadingTask.update(AssetLoadingTask.java:89) at com.badlogic.gdx.assets.AssetManager.updateTask(AssetManager.java:445) at com.badlogic.gdx.assets.AssetManager.update(AssetManager.java:340) ... 4 more Caused by: com.badlogic.gdx.utils.GdxRuntimeException: com.badlogic.gdx.utils.GdxRuntimeException: Couldn't load file: data/data at com.badlogic.gdx.utils.async.AsyncResult.get(AsyncResult.java:31) at com.badlogic.gdx.assets.AssetLoadingTask.handleAsyncLoader(AssetLoadingTask.java:117) ... 7 more Caused by: com.badlogic.gdx.utils.GdxRuntimeException: Couldn't load file: data/data at com.badlogic.gdx.graphics.Pixmap.<init>(Pixmap.java:140) at com.badlogic.gdx.assets.loaders.TextureLoader.loadAsync(TextureLoader.java:72) at com.badlogic.gdx.assets.loaders.TextureLoader.loadAsync(TextureLoader.java:41) at com.badlogic.gdx.assets.AssetLoadingTask.call(AssetLoadingTask.java:69) at com.badlogic.gdx.assets.AssetLoadingTask.call(AssetLoadingTask.java:34) at com.badlogic.gdx.utils.async.AsyncExecutor$2.call(AsyncExecutor.java:49) at java.util.concurrent.FutureTask.run(Unknown Source) at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) at java.lang.Thread.run(Unknown Source) Caused by: com.badlogic.gdx.utils.GdxRuntimeException: File not found: data\data (Internal) at com.badlogic.gdx.files.FileHandle.read(FileHandle.java:132) at com.badlogic.gdx.files.FileHandle.length(FileHandle.java:586) at com.badlogic.gdx.files.FileHandle.readBytes(FileHandle.java:220) at com.badlogic.gdx.graphics.Pixmap.<init>(Pixmap.java:137) ... 9 more Why it tries to load that unexisting file? It seems that the AssetManager manages to load my .g3db file at first, because earlier the java console threw some errors related to the textures associated to the 3D scene having to be a power of 2. Relevant code: public void show() { ... assets = new AssetManager(); assets.load("data/levelprueba2.g3db", Model.class); loading = true; ... } private void doneLoading() { Model model = assets.get("data/levelprueba2.g3db", Model.class); for (int i = 0; i < model.nodes.size; i++) { String id = model.nodes.get(i).id; ModelInstance instance = new ModelInstance(model, id); Node node = instance.getNode(id); instance.transform.set(node.globalTransform); node.translation.set(0,0,0); node.scale.set(1,1,1); node.rotation.idt(); instance.calculateTransforms(); instances.add(instance); } loading = false; } public void render(float delta) { super.render(delta); if (loading && assets.update()) doneLoading(); ... } The error points to the line with the assets.update() method. Please, help! Sorry for my bad English and my amateurish doubts.

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• World Record Siebel PSPP Benchmark on SPARC T4 Servers

  - by Brian

  Oracle's SPARC T4 servers set a new World Record for Oracle's Siebel Platform Sizing and Performance Program (PSPP) benchmark suite. The result used Oracle's Siebel Customer Relationship Management (CRM) Industry Applications Release 8.1.1.4 and Oracle Database 11g Release 2 running Oracle Solaris on three SPARC T4-2 and two SPARC T4-1 servers. The SPARC T4 servers running the Siebel PSPP 8.1.1.4 workload which includes Siebel Call Center and Order Management System demonstrates impressive throughput performance of the SPARC T4 processor by achieving 29,000 users. This is the first Siebel PSPP 8.1.1.4 benchmark supporting 29,000 concurrent users with a rate of 239,748 Business Transactions/hour. The benchmark demonstrates vertical and horizontal scalability of Siebel CRM Release 8.1.1.4 on SPARC T4 servers. Performance Landscape Systems Txn/hr Users Call Center Order Management Response Times (sec) 1 x SPARC T4-1 (1 x SPARC T4 2.85 GHz) – Web 3 x SPARC T4-2 (2 x SPARC T4 2.85 GHz) – App/Gateway 1 x SPARC T4-1 (1 x SPARC T4 2.85 GHz) – DB 239,748 29,000 0.165 0.925 Oracle: Call Center + Order Management Transactions: 197,128 + 42,620 Users: 20300 + 8700 Configuration Summary Web Server Configuration: 1 x SPARC T4-1 server 1 x SPARC T4 processor, 2.85 GHz 128 GB memory Oracle Solaris 10 8/11 iPlanet Web Server 7 Application Server Configuration: 3 x SPARC T4-2 servers, each with 2 x SPARC T4 processor, 2.85 GHz 256 GB memory 3 x 300 GB SAS internal disks Oracle Solaris 10 8/11 Siebel CRM 8.1.1.5 SIA Database Server Configuration: 1 x SPARC T4-1 server 1 x SPARC T4 processor, 2.85 GHz 128 GB memory Oracle Solaris 11 11/11 Oracle Database 11g Release 2 (11.2.0.2) Storage Configuration: 1 x Sun Storage F5100 Flash Array 80 x 24 GB flash modules Benchmark Description Siebel 8.1 PSPP benchmark includes Call Center and Order Management: Siebel Financial Services Call Center – Provides the most complete solution for sales and service, allowing customer service and telesales representatives to provide superior customer support, improve customer loyalty, and increase revenues through cross-selling and up-selling. High-level description of the use cases tested: Incoming Call Creates Opportunity, Quote and Order and Incoming Call Creates Service Request . Three complex business transactions are executed simultaneously for specific number of concurrent users. The ratios of these 3 scenarios were 30%, 40%, 30% respectively, which together were totaling 70% of all transactions simulated in this benchmark. Between each user operation and the next one, the think time averaged approximately 10, 13, and 35 seconds respectively. Siebel Order Management – Oracle's Siebel Order Management allows employees such as salespeople and call center agents to create and manage quotes and orders through their entire life cycle. Siebel Order Management can be tightly integrated with back-office applications allowing users to perform tasks such as checking credit, confirming availability, and monitoring the fulfillment process. High-level description of the use cases tested: Order & Order Items Creation and Order Updates. Two complex Order Management transactions were executed simultaneously for specific number of concurrent users concurrently with aforementioned three Call Center scenarios above. The ratio of these 2 scenarios was 50% each, which together were totaling 30% of all transactions simulated in this benchmark. Between each user operation and the next one, the think time averaged approximately 20 and 67 seconds respectively. Key Points and Best Practices No processor cores or cache were activated or deactivated on the SPARC T-Series systems to achieve special benchmark effects. See Also Siebel White Papers SPARC T4-1 Server oracle.com OTN SPARC T4-2 Server oracle.com OTN Siebel CRM oracle.com OTN Oracle Solaris oracle.com OTN Oracle Database 11g Release 2 Enterprise Edition oracle.com OTN Disclosure Statement Copyright 2012, Oracle and/or its affiliates. All rights reserved. Oracle and Java are registered trademarks of Oracle and/or its affiliates. Other names may be trademarks of their respective owners. Results as of 30 September 2012.

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• AWS S3 status code 403 SignatureDoesNotMatch - Check your key and signing method

  - by Matt

  i have checked a rechecked my keys and they are correct but i keep the below Exception whenever i try to upload, can anyone shed some light on this problem? 11-01 09:21:26.331: W/System.err(13934): AmazonS3Exception: Status Code: 403, AWS Service: Amazon S3, AWS Request ID: B97CC81E13D81XXX, AWS Error Code: SignatureDoesNotMatch, AWS Error Message: The request signature we calculated does not match the signature you provided. Check your key and signing method., S3 Extended Request ID: PPieuQpqElIizNBQPc42JwC4WnBkUciCKRT5S4HSftBraeacN8y0lKfsVP9LXXXX 11-01 09:21:26.331: W/System.err(13934): at com.amazonaws.http.AmazonHttpClient.handleErrorResponse(AmazonHttpClient.java:659) 11-01 09:21:26.331: W/System.err(13934): at com.amazonaws.http.AmazonHttpClient.executeHelper(AmazonHttpClient.java:330) 11-01 09:21:26.331: W/System.err(13934): at com.amazonaws.http.AmazonHttpClient.execute(AmazonHttpClient.java:182) 11-01 09:21:26.331: W/System.err(13934): at com.amazonaws.services.s3.AmazonS3Client.invoke(AmazonS3Client.java:3038) 11-01 09:21:26.331: W/System.err(13934): at com.amazonaws.services.s3.AmazonS3Client.putObject(AmazonS3Client.java:1218) 11-01 09:21:26.331: W/System.err(13934): at com.apprssd.capsule.S3UploaderActivity$S3PutObjectTask.doInBackground(S3UploaderActivity.java:165) 11-01 09:21:26.331: W/System.err(13934): at com.apprssd.capsule.S3UploaderActivity$S3PutObjectTask.doInBackground(S3UploaderActivity.java:1) 11-01 09:21:26.331: W/System.err(13934): at android.os.AsyncTask$2.call(AsyncTask.java:287) 11-01 09:21:26.331: W/System.err(13934): at java.util.concurrent.FutureTask.run(FutureTask.java:234) 11-01 09:21:26.341: W/System.err(13934): at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230) 11-01 09:21:26.341: W/System.err(13934): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080) 11-01 09:21:26.341: W/System.err(13934): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573) 11-01 09:21:26.341: W/System.err(13934): at java.lang.Thread.run(Thread.java:841) It happens during the below. PutObjectRequest por = new PutObjectRequest( Constants.getDataBucket(), selectedZip.toString(), selectedZip); s3Client.putObject(por);

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• Weblogic 10.3.0 : Loosing a stateless session bean in the bean pool

  - by KlasE

  Hi, We have a strange situation where we loose a Stateless SessionBean in a Bean Pool in Weblogic 10.3.0 Since we only have one bean in the pool, this effectively hangs all incoming calls. We do not want more than one instance in the pool because of application restrictions. In the Weblogic admin console, we can see that there are 1 instance in the bean pool, 0 beans in use and 1 waiting incoming request. The question is, what can have caused the system to not send the request to the one obviously free bean instance? This happens after several hours and over 100000 incoming requests, and the same scenario worked fine in the old weblogic 8 environment. We get the following stacktrace: "[ACTIVE] ExecuteThread: '5' for queue: 'weblogic.kernel.Default (self-tuning)'" waiting for lock java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject@b0d484 TIMED_WAITING sun.misc.Unsafe.park(Native Method) java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:198) java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2054) weblogic.ejb.container.pool.StatelessSessionPool.waitForBean(StatelessSessionPool.java:269) weblogic.ejb.container.pool.StatelessSessionPool.getBean(StatelessSessionPool.java:111) weblogic.ejb.container.manager.StatelessManager.preInvoke(StatelessManager.java:148) weblogic.ejb.container.internal.BaseRemoteObject.preInvoke(BaseRemoteObject.java:227) weblogic.ejb.container.internal.StatelessRemoteObject.preInvoke(StatelessRemoteObject.java:52) com.mycompany.beans.MessageLogFacace_n73y0z_EOImpl.isMyStuffValid(MessageLogFacace_n73y0z_EOImpl.java:261) com.mycompany.beans.MessageLogFacace_n73y0z_EOImpl_WLSkel.invoke(Unknown Source) weblogic.rmi.internal.BasicServerRef.invoke(BasicServerRef.java:589) weblogic.rmi.cluster.ClusterableServerRef.invoke(ClusterableServerRef.java:230) weblogic.rmi.internal.BasicServerRef$1.run(BasicServerRef.java:477) weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java:363) weblogic.security.service.SecurityManager.runAs(Unknown Source) weblogic.rmi.internal.BasicServerRef.handleRequest(BasicServerRef.java:473) weblogic.rmi.internal.wls.WLSExecuteRequest.run(WLSExecuteRequest.java:118) weblogic.work.ExecuteThread.execute(ExecuteThread.java:201) weblogic.work.ExecuteThread.run(ExecuteThread.java:173) Any help would be very welcome. Regards Klas

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• Passing an object as parameter from Andriod to web service using ksoap

  - by user3718626

  I have an object called User which implements KvmSerializable. Would like to pass this object to the webservice. PropertyInfo pi = new PropertyInfo(); pi.setName("obj"); pi.setValue(user); pi.setType(user.getClass()); request.addProperty(pi); SoapSerializationEnvelope envelope = new SoapSerializationEnvelope(SoapEnvelope.VER11); envelope.setOutputSoapObject(request); envelope.addMapping(NAMESPACE, "User",User.class); HttpTransportSE androidHttpTransport = new HttpTransportSE(URL); I get the following error.... SoapFault - faultcode: 'soapenv:Server' faultstring: 'Unknow type {http://users.com}User' faultactor: 'null' detail: org.kxml2.kdom.Node@53263024 at org.ksoap2.serialization.SoapSerializationEnvelope.parseBody(SoapSerializationEnvelope.java:141) at org.ksoap2.SoapEnvelope.parse(SoapEnvelope.java:140) at org.ksoap2.transport.Transport.parseResponse(Transport.java:118) at org.ksoap2.transport.HttpTransportSE.call(HttpTransportSE.java:272) at org.ksoap2.transport.HttpTransportSE.call(HttpTransportSE.java:118) at org.ksoap2.transport.HttpTransportSE.call(HttpTransportSE.java:113) at com.compete.WebServiceCallTask.getQuestion(WebServiceCallTask.java:114) at com.compete.WebServiceCallTask.doInBackground(WebServiceCallTask.java:53) at com.compete.WebServiceCallTask.doInBackground(WebServiceCallTask.java:1) at android.os.AsyncTask$2.call(AsyncTask.java:287) at java.util.concurrent.FutureTask.run(FutureTask.java:234) at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573) at java.lang.Thread.run(Thread.java:856) Appreciate if any one can point me to an sample code or can direct me what is the issue. Thanks.

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• What is optimal hardware configuration for heavy load LAMP application

  - by Piotr Kochanski

  I need to run Linux-Apache-PHP-MySQL application (Moodle e-learning platform) for a large number of concurrent users - I am aiming 5000 users. By concurrent I mean that 5000 people should be able to work with the application at the same time. "Work" means not only do database reads but writes as well. The application is not very typical, since it is doing a lot of inserts/updates on the database, so caching techniques are not helping to much. We are using InnoDB storage engine. In addition application is not written with performance in mind. For instance one Apache thread usually occupies about 30-50 MB of RAM. I would be greatful for information what hardware is needed to build scalable configuration that is able to handle this kind of load. We are using right now two HP DLG 380 with two 4 core processors which are able to handle much lower load (typically 300-500 concurrent users). Is it reasonable to invest in this kind of boxes and build cluster using them or is it better to go with some more high-end hardware? I am particularly curious how many and how powerful servers are needed (number of processors/cores, size of RAM) what network equipment should be used (what kind of switches, network cards) any other hardware, like particular disc storage solutions, etc, that are needed Another thing is how to put together everything, that is what is the most optimal architecture. Clustering with MySQL is rather hard (people are complaining about MySQL Cluster, even here on Stackoverflow).

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• g-wan - reproducing the performance claims

  - by user2603628

  Using gwan_linux64-bit.tar.bz2 under Ubuntu 12.04 LTS unpacking and running gwan then pointing wrk at it (using a null file null.html) wrk --timeout 10 -t 2 -c 100 -d20s http://127.0.0.1:8080/null.html Running 20s test @ http://127.0.0.1:8080/null.html 2 threads and 100 connections Thread Stats Avg Stdev Max +/- Stdev Latency 11.65s 5.10s 13.89s 83.91% Req/Sec 3.33k 3.65k 12.33k 75.19% 125067 requests in 20.01s, 32.08MB read Socket errors: connect 0, read 37, write 0, timeout 49 Requests/sec: 6251.46 Transfer/sec: 1.60MB .. very poor performance, in fact there seems to be some kind of huge latency issue. During the test gwan is 200% busy and wrk is 67% busy. Pointing at nginx, wrk is 200% busy and nginx is 45% busy: wrk --timeout 10 -t 2 -c 100 -d20s http://127.0.0.1/null.html Thread Stats Avg Stdev Max +/- Stdev Latency 371.81us 134.05us 24.04ms 91.26% Req/Sec 72.75k 7.38k 109.22k 68.21% 2740883 requests in 20.00s, 540.95MB read Requests/sec: 137046.70 Transfer/sec: 27.05MB Pointing weighttpd at nginx gives even faster results: /usr/local/bin/weighttp -k -n 2000000 -c 500 -t 3 http://127.0.0.1/null.html weighttp - a lightweight and simple webserver benchmarking tool starting benchmark... spawning thread #1: 167 concurrent requests, 666667 total requests spawning thread #2: 167 concurrent requests, 666667 total requests spawning thread #3: 166 concurrent requests, 666666 total requests progress: 9% done progress: 19% done progress: 29% done progress: 39% done progress: 49% done progress: 59% done progress: 69% done progress: 79% done progress: 89% done progress: 99% done finished in 7 sec, 13 millisec and 293 microsec, 285172 req/s, 57633 kbyte/s requests: 2000000 total, 2000000 started, 2000000 done, 2000000 succeeded, 0 failed, 0 errored status codes: 2000000 2xx, 0 3xx, 0 4xx, 0 5xx traffic: 413901205 bytes total, 413901205 bytes http, 0 bytes data The server is a virtual 8 core dedicated server (bare metal), under KVM Where do I start looking to identify the problem gwan is having on this platform ? I have tested lighttpd, nginx and node.js on this same OS, and the results are all as one would expect. The server has been tuned in the usual way with expanded ephemeral ports, increased ulimits, adjusted time wait recycling etc.

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• What does a Software Developer actually do?

  - by chobo2

  Hi I am graduating from my Computer Science degree in a few weeks from now!! I started to look for my first job. For the last couple years I gotten really into web programming(Asp.net). My first choice would be to get a junior asp.net MVC developer but I don't any companies in my area use MVC yet or if they do they are not hiring. So my second choice would be a junior asp.net Webforms developer. My other choices after that would be forms applications, mobile applications using .Net and C#. As you can see I am looking for something with .Net. I spent the last couple years doing .Net projects for school, on my free time and love the Language and it would pain me right now to switch to something like php. So now I found a posting in my area for an Entry Software Developer. I like the fact that they are using .net and that it is entry job(I never worked in this industry and never had more then like a tutoring job so I want to for like intermediate jobs). Posting Are you looking for an exciting challenge within a dynamic, people-oriented culture where you can launch your technical career? Company Name Inc. is a technology consulting company, located in Canada, that designs, develops, and delivers real-time interactive applications accessed via the Internet as well as back-end tools to support these applications. Company Name provides a combination of out-of-the-box and customized solutions to an expanding list of partners and customers. POSITION SUMMARY As a member of our team, the successful candidate will be responsible for helping us increase the quality and stability of our software systems by working jointly and directly with both the Software Development teams and the QA Team. The primary mission of this role will be to substantially enhance our test automation suite. The incumbent will design and program automated tests (unit, integration, system, stress and load) in Visual Studio using C# and will develop sound processes that help us identify and resolve defects as early as possible. The successful incumbent will help us improve and enhance system functionality, reliability, performance and scalability. This role is specifically designed for an eager, bright, new graduate who is looking for a stepping stone into a software engineering role. We promote from within and invite new graduates to apply for this important position - which may lead to new opportunities. We also offer a generous professional development plan to help you on your way. You will be a key part of a team of experts that is responsible for improving the quality of our software by: • Designing, writing, and executing test plans and programmatic tests in Visual Studio using C# and NUnit for functional testing of our code, new features, regression, and performance test procedures. • Working with the engineers to design and build the stress and load testing framework which emulates tens and even hundreds of thousands of concurrent users via a distributed network interfacing with our Load Testing Lab. • Interfacing with both the Development Team and the QA Team to ensure risks are identified and managed. • Mentoring and leading the QA Team in programmatic test automation technologies and tools. MUST HAVE SKILLS / QUALIFICATIONS: • Diploma or higher Degree in Computer Science, or equivalent formal training. • Fundamental C# programming skills. • Knowledge of Internet technologies and Microsoft Windows platforms. • Knowledge of PC hardware. • Excellent communication skills (both oral and written). • Self-starter who takes initiative, requires minimal supervision, can handle multiple simultaneous tasks. • Detail-oriented, able to concentrate, and work quickly. • Proven diagnostic, analytical, and problem solving skills. NICE TO HAVE SKILLS: • Exposure to Visual Studio Team System or Visual Studio Test Edition. • Exposure in C# using NUnit. • Exposure to NUnit, HTTPUnit, and other automation tool suites. • Exposure to Performance/Stress/Load Testing. • Good understanding of relational databases (MS SQL Server). • Familiar with video and online multi-player games. As part of our team you will have the opportunity to work with a supportive team of experts, drive your own success, and ride the wave as we continually expand our team of experts. If you are interested in this opportunity, please send your resume to [email protected] with “Entry Level Software Developer” in the subject line. So that is the posting. To me it sounds like it is QA job. I don't have anything against QA jobs but alot of them seems to be your just clicking buttons and running scripts. Is this what a typical software developer does? Like I am so on the fence to apply for this job. On one side I am not sure how much programming I would be doing. Like I want to be at least half the time programming otherwise my skills will never improve since I will never be programming in teams and stuff. At the same time I have no experience in the industry so on the other side I am thinking just go for it and then maybe a year later try to get a full programming job(provided that I got the job). Yet if I am not programming in that job then that experience will not help me for the next job I find as I will be back a square one.

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• How can i assign a two dimensional array into other temporary two dimensional array.....?? in C Programming..

  - by AGeek

  Hi I am trying to store the contents of two dimensional array into a temporary array.... How is it possible... I don't want looping over here, as it would add an extra overhead.. Any pointer notation would be good. struct bucket { int nStrings; char strings[MAXSTRINGS][MAXWORDLENGTH]; }; void func() { char **tArray; int tLenArray = 0; for(i=0; i<TOTBUCKETS-1; i++) { if(buck[i].nStrings != 0) { tArray = buck[i].strings; tLenArray = buck[i].nStrings; } } } The error here i am getting is:- [others@centos htdocs]$ gcc lexorder.c lexorder.c: In function âlexSortingâ: lexorder.c:40: warning: assignment from incompatible pointer type Please let me know if this needs some more explanaition...

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• JMeter Stress testing

  - by mcondiff

  MAMP server hosting a Joomla instance. I'd like to hear the community's thoughts on the best way to stress test the server and find it's breaking point on concurrent users etc. Currently I have setup a test plan which I have going to the home page, grabbing the index.php, css, js and all images and have run tests on 1 to 100 users and a varying number of loops. What I'd like to know is how do I determine at what number of concurrent requests or looping requests is a good way to gauge if my server can handle the proposed increase in traffic? What is a good KB/sec, Throughput, Average, Max, Min via the Aggregate Report and at what number of threads/loops etc? I have googled and have not found immediate answers to these questions and thought to come here. More or less I have just used this http://jakarta.apache.org/jmeter/usermanual/jmeter_proxy_step_by_step.pdf to guide me and then I have been winging it in terms of Thread and Loop numbers. Any light shed on these subject would be much appreciated.

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• JBoss Seam project can not be run/deployed

  - by user1494328

  I created sample application in Seam framework (Seam Web Project) and JBoss Server 7.1. When I try run application, console dislays: 23:29:35,419 ERROR [org.jboss.msc.service.fail] (MSC service thread 1-3) MSC00001: Failed to start service jboss.deployment.unit."secoundProject-ds.xml".PARSE: org.jboss.msc.service.StartException in service jboss.deployment.unit."secoundProject-ds.xml".PARSE: Failed to process phase PARSE of deployment "secoundProject-ds.xml" at org.jboss.as.server.deployment.DeploymentUnitPhaseService.start(DeploymentUnitPhaseService.java:119) [jboss-as-server-7.1.1.Final.jar:7.1.1.Final] at org.jboss.msc.service.ServiceControllerImpl$StartTask.startService(ServiceControllerImpl.java:1811) [jboss-msc-1.0.2.GA.jar:1.0.2.GA] at org.jboss.msc.service.ServiceControllerImpl$StartTask.run(ServiceControllerImpl.java:1746) [jboss-msc-1.0.2.GA.jar:1.0.2.GA] at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) [rt.jar:1.6.0_24] at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) [rt.jar:1.6.0_24] at java.lang.Thread.run(Thread.java:662) [rt.jar:1.6.0_24] Caused by: org.jboss.as.server.deployment.DeploymentUnitProcessingException: IJ010061: Unexpected element: local-tx-datasource at org.jboss.as.connector.deployers.processors.DsXmlDeploymentParsingProcessor.deploy(DsXmlDeploymentParsingProcessor.java:85) at org.jboss.as.server.deployment.DeploymentUnitPhaseService.start(DeploymentUnitPhaseService.java:113) [jboss-as-server-7.1.1.Final.jar:7.1.1.Final] ... 5 more Caused by: org.jboss.jca.common.metadata.ParserException: IJ010061: Unexpected element: local-tx-datasource at org.jboss.jca.common.metadata.ds.DsParser.parseDataSources(DsParser.java:183) at org.jboss.jca.common.metadata.ds.DsParser.parse(DsParser.java:119) at org.jboss.jca.common.metadata.ds.DsParser.parse(DsParser.java:82) at org.jboss.as.connector.deployers.processors.DsXmlDeploymentParsingProcessor.deploy(DsXmlDeploymentParsingProcessor.java:80) ... 6 more 23:29:35,452 INFO [org.jboss.as.server.deployment] (MSC service thread 1-4) JBAS015877: Stopped deployment secoundProject-ds.xml in 1ms 23:29:35,455 INFO [org.jboss.as.server] (DeploymentScanner-threads - 2) JBAS015863: Replacement of deployment "secoundProject-ds.xml" by deployment "secoundProject-ds.xml" was rolled back with failure message {"JBAS014671: Failed services" => {"jboss.deployment.unit.\"secoundProject-ds.xml\".PARSE" => "org.jboss.msc.service.StartException in service jboss.deployment.unit.\"secoundProject-ds.xml\".PARSE: Failed to process phase PARSE of deployment \"secoundProject-ds.xml\""}} 23:29:35,457 INFO [org.jboss.as.server.deployment] (MSC service thread 1-1) JBAS015876: Starting deployment of "secoundProject-ds.xml" 23:29:35,920 ERROR [org.jboss.msc.service.fail] (MSC service thread 1-1) MSC00001: Failed to start service jboss.deployment.unit."secoundProject-ds.xml".PARSE: org.jboss.msc.service.StartException in service jboss.deployment.unit."secoundProject-ds.xml".PARSE: Failed to process phase PARSE of deployment "secoundProject-ds.xml" at org.jboss.as.server.deployment.DeploymentUnitPhaseService.start(DeploymentUnitPhaseService.java:119) [jboss-as-server-7.1.1.Final.jar:7.1.1.Final] at org.jboss.msc.service.ServiceControllerImpl$StartTask.startService(ServiceControllerImpl.java:1811) [jboss-msc-1.0.2.GA.jar:1.0.2.GA] at org.jboss.msc.service.ServiceControllerImpl$StartTask.run(ServiceControllerImpl.java:1746) [jboss-msc-1.0.2.GA.jar:1.0.2.GA] at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) [rt.jar:1.6.0_24] at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) [rt.jar:1.6.0_24] at java.lang.Thread.run(Thread.java:662) [rt.jar:1.6.0_24] Caused by: org.jboss.as.server.deployment.DeploymentUnitProcessingException: IJ010061: Unexpected element: local-tx-datasource at org.jboss.as.connector.deployers.processors.DsXmlDeploymentParsingProcessor.deploy(DsXmlDeploymentParsingProcessor.java:85) at org.jboss.as.server.deployment.DeploymentUnitPhaseService.start(DeploymentUnitPhaseService.java:113) [jboss-as-server-7.1.1.Final.jar:7.1.1.Final] ... 5 more Caused by: org.jboss.jca.common.metadata.ParserException: IJ010061: Unexpected element: local-tx-datasource at org.jboss.jca.common.metadata.ds.DsParser.parseDataSources(DsParser.java:183) at org.jboss.jca.common.metadata.ds.DsParser.parse(DsParser.java:119) at org.jboss.jca.common.metadata.ds.DsParser.parse(DsParser.java:82) at org.jboss.as.connector.deployers.processors.DsXmlDeploymentParsingProcessor.deploy(DsXmlDeploymentParsingProcessor.java:80) ... 6 more 23:29:35,952 INFO [org.jboss.as.controller] (DeploymentScanner-threads - 2) JBAS014774: Service status report JBAS014777: Services which failed to start: service jboss.deployment.unit."secoundProject-ds.xml".PARSE: org.jboss.msc.service.StartException in service jboss.deployment.unit."secoundProject-ds.xml".PARSE: Failed to process phase PARSE of deployment "secoundProject-ds.xml" My secoundProject-ds.xml: <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE datasources PUBLIC "-//JBoss//DTD JBOSS JCA Config 1.5//EN" "http://www.jboss.org/j2ee/dtd/jboss-ds_1_5.dtd"> <datasources> <local-tx-datasource> <jndi-name>secoundProjectDatasource</jndi-name> <use-java-context>true</use-java-context> <connection-url>jdbc:mysql://localhost:3306/database</connection-url> <driver-class>com.mysql.jdbc.Driver</driver-class> <user-name>root</user-name> <password></password> </local-tx-datasource> </datasources> When I comment tags errors disappear, but application is disabled in browser (The requested resource (/secoundProject/) is not available.). What should I do to fix this problem?

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• java.lang.OutOfMemoryError on ec2 machine

  - by vinchan

  I have a java app on a large instance that will spawn up to 800 threads. I can run the application fine as user "root" but not as another user which I created. I get the deadly. java.lang.OutOfMemoryError: unable to create new native thread at java.lang.Thread.start0(Native Method) at java.lang.Thread.start(Thread.java:657) at java.util.concurrent.ThreadPoolExecutor.addWorker(ThreadPoolExecutor.java:943) at java.util.concurrent.ThreadPoolExecutor.execute(ThreadPoolExecutor.java:1325) nightmare. I have tried increasing the stack size already in limits.conf to no avail. Please, help me out. What is different here for the root and other user?

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• What would be better in my case - apache, nginx or lighttpd ?

  - by The Devil

  Hey everybody, I'm writing a php site that's expected to get about 200-300 concurrent users browsing it. When initializing the application will load about 30 php classes, some 10 maybe 15 images and a couple of css files. So my question is what else can I do (except optimizing my code and using apc/eaccelerator for php) to get as close as possible to those numbers of concurrent users ? Currently we haven't chosen a server for the site to be hosted on but most probably it'll be a VPS Dual core + 2 or maybe 4gb ram. Is it possible for such a server to handle that load ? Also how could I test it myself and be sure that it'll be able to handle it ? Thanks in advance, Me

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• how limit the number of open TCP streams from same IP to a local port?

  - by JMW

  Hi, i would like to limit the number of concurrent open TCP streams from the the same IP to the server's (local) port. Let's say 4 concurrent conncetions. How can this be done with ip tables? the closest thing, that i've found was: In Apache, is there a way to limit the number of new connections per second/hour/day? iptables -A INPUT -p tcp --dport 80 -i eth0 -m state --state NEW -m recent --set iptables -A INPUT -p tcp --dport 80 -i eth0 -m state --state NEW -m recent --update --seconds 86400 --hitcount 100 -j REJECT But this limitation just messures the number of new connections over the time. This might be good for controlling HTTP traffic. But this is not a good solution for me, since my TCP streams usually have a lifetime between 5 minutes and 2 hours. thanks a lot in advance for any reply :)

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• AB failed requests - What can I do about them?

  - by matthewsteiner

  So, in the past I've never had any problems with this app. All benchmarks had 100% success rate. Yesterday I set up nginx to server static content and pass on other requests to apache. Now, if I have 1 concurrent user (-c 1) then everything is fine. But it seems the more concurrent users I have, the more failed requests I get. Not a lot, but maybe about 10 or 15 out of 350. They're "length", whatever that means. Visiting the website with a browser, I don't have any problems at all. How can I find out the cause of these failed requests?

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• TCP and fair bandwidth sharing

  - by lxgr

  The congestion control algorithm(s) of TCP seem to distribute the available bandwidth fairly between individual TCP flows. Is there some way to enable (or more precisely, enforce) fair bandwidth sharing on a per-host instead of a per-flow basis on a router? There should not be an (easy) way for a user to gain a disproportional bandwidth share by using multiple concurrent TCP flows (the way some download managers and most P2P clients do). I'm currently running a DD-WRT router to share a residential DSL line, and currently it's possible to (inadvertently or maliciously) hog most of the bandwidth by using multiple concurrent connections, which affecty VoIP conversations badly. I've played with the QoS settings a bit, but I'm not sure how to enable fair bandwidth sharing on a per-IP basis (per-service is not an option, as most of the flows are HTTP).

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• Can't run my servlet from tomcat server even though the classes are in package

  - by Mido

  Hi there, i am trying to get my servlet to run, i have been searching for 2 days and trying every possible solution and no luck. The servet class is in the appropriate folder (i.e under the package name). I also added the jar files needed in my servlet into lib folder. the web.xml file maps the url and defines the servlet. So i did everything in the documentation and wt people said in here and still getting this error : type Exception report message description The server encountered an internal error () that prevented it from fulfilling this request. exception javax.servlet.ServletException: Error instantiating servlet class assign1a.RPCServlet org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:108) org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:558) org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:379) org.apache.coyote.http11.Http11AprProcessor.process(Http11AprProcessor.java:282) org.apache.coyote.http11.Http11AprProtocol$Http11ConnectionHandler.process(Http11AprProtocol.java:357) org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:1687) java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) java.lang.Thread.run(Thread.java:619) root cause java.lang.NoClassDefFoundError: assign1a/RPCServlet (wrong name: server/RPCServlet) java.lang.ClassLoader.defineClass1(Native Method) java.lang.ClassLoader.defineClassCond(ClassLoader.java:632) java.lang.ClassLoader.defineClass(ClassLoader.java:616) java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141) org.apache.catalina.loader.WebappClassLoader.findClassInternal(WebappClassLoader.java:2820) org.apache.catalina.loader.WebappClassLoader.findClass(WebappClassLoader.java:1143) org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1638) org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1516) org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:108) org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:558) org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:379) org.apache.coyote.http11.Http11AprProcessor.process(Http11AprProcessor.java:282) org.apache.coyote.http11.Http11AprProtocol$Http11ConnectionHandler.process(Http11AprProtocol.java:357) org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:1687) java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) java.lang.Thread.run(Thread.java:619) note The full stack trace of the root cause is available in the Apache Tomcat/7.0.5 logs. Also here is my servlet code : package assign1a; import java.io.IOException; import java.util.logging.Level; import java.util.logging.Logger; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import lib.jsonrpc.RPCService; public class RPCServlet extends HttpServlet { /** * */ private static final long serialVersionUID = -5274024331393844879L; private static final Logger log = Logger.getLogger(RPCServlet.class.getName()); protected RPCService service = new ServiceImpl(); public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException { response.setContentType("text/html"); response.getWriter().write("rpc service " + service.getServiceName() + " is running..."); } public void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException { try { service.dispatch(request, response); } catch (Throwable t) { log.log(Level.WARNING, t.getMessage(), t); } } } Please help me :) Thanks. EDIT: here are the contents of my web.xml file <web-app xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" version="3.0" metadata-complete="true"> <servlet> <servlet-name>jsonrpc</servlet-name> <servlet-class>assign1a.RPCServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>jsonrpc</servlet-name> <url-pattern>/rpc</url-pattern> </servlet-mapping> </web-app>

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• Why does this Java code not utilize all CPU cores?

  - by ReneS

  The attached simple Java code should load all available cpu core when starting it with the right parameters. So for instance, you start it with java VMTest 8 int 0 and it will start 8 threads that do nothing else than looping and adding 2 to an integer. Something that runs in registers and not even allocates new memory. The problem we are facing now is, that we do not get a 24 core machine loaded (AMD 2 sockets with 12 cores each), when running this simple program (with 24 threads of course). Similar things happen with 2 programs each 12 threads or smaller machines. So our suspicion is that the JVM (Sun JDK 6u20 on Linux x64) does not scale well. Did anyone see similar things or has the ability to run it and report whether or not it runs well on his/her machine (= 8 cores only please)? Ideas? I tried that on Amazon EC2 with 8 cores too, but the virtual machine seems to run different from a real box, so the loading behaves totally strange. package com.test; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; import java.util.concurrent.Future; import java.util.concurrent.TimeUnit; public class VMTest { public class IntTask implements Runnable { @Override public void run() { int i = 0; while (true) { i = i + 2; } } } public class StringTask implements Runnable { @Override public void run() { int i = 0; String s; while (true) { i++; s = "s" + Integer.valueOf(i); } } } public class ArrayTask implements Runnable { private final int size; public ArrayTask(int size) { this.size = size; } @Override public void run() { int i = 0; String[] s; while (true) { i++; s = new String[size]; } } } public void doIt(String[] args) throws InterruptedException { final String command = args[1].trim(); ExecutorService executor = Executors.newFixedThreadPool(Integer.valueOf(args[0])); for (int i = 0; i < Integer.valueOf(args[0]); i++) { Runnable runnable = null; if (command.equalsIgnoreCase("int")) { runnable = new IntTask(); } else if (command.equalsIgnoreCase("string")) { runnable = new StringTask(); } Future<?> submit = executor.submit(runnable); } executor.awaitTermination(1, TimeUnit.HOURS); } public static void main(String[] args) throws InterruptedException { if (args.length < 3) { System.err.println("Usage: VMTest threadCount taskDef size"); System.err.println("threadCount: Number 1..n"); System.err.println("taskDef: int string array"); System.err.println("size: size of memory allocation for array, "); System.exit(-1); } new VMTest().doIt(args); } }

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• Parallelism in .NET – Introduction

  - by Reed

  Parallel programming is something that every professional developer should understand, but is rarely discussed or taught in detail in a formal manner.  Software users are no longer content with applications that lock up the user interface regularly, or take large amounts of time to process data unnecessarily.  Modern development requires the use of parallelism.  There is no longer any excuses for us as developers. Learning to write parallel software is challenging.  It requires more than reading that one chapter on parallelism in our programming language book of choice… Today’s systems are no longer getting faster with each generation; in many cases, newer computers are actually slower than previous generation systems.  Modern hardware is shifting towards conservation of power, with processing scalability coming from having multiple computer cores, not faster and faster CPUs.  Our CPU frequencies no longer double on a regular basis, but Moore’s Law is still holding strong.  Now, however, instead of scaling transistors in order to make processors faster, hardware manufacturers are scaling the transistors in order to add more discrete hardware processing threads to the system. This changes how we should think about software.  In order to take advantage of modern systems, we need to redesign and rewrite our algorithms to work in parallel.  As with any design domain, it helps tremendously to have a common language, as well as a common set of patterns and tools. For .NET developers, this is an exciting time for parallel programming.  Version 4 of the .NET Framework is adding the Task Parallel Library.  This has been back-ported to .NET 3.5sp1 as part of the Reactive Extensions for .NET, and is available for use today in both .NET 3.5 and .NET 4.0 beta. In order to fully utilize the Task Parallel Library and parallelism, both in .NET 4 and previous versions, we need to understand the proper terminology.  For this series, I will provide an introduction to some of the basic concepts in parallelism, and relate them to the tools available in .NET.

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• The C++ Standard Template Library as a BDB Database (part 1)

  - by Gregory Burd

  If you've used C++ you undoubtedly have used the Standard Template Libraries. Designed for in-memory management of data and collections of data this is a core aspect of all C++ programs. Berkeley DB is a database library with a variety of APIs designed to ease development, one of those APIs extends and makes use of the STL for persistent, transactional data storage. dbstl is an STL standard compatible API for Berkeley DB. You can make use of Berkeley DB via this API as if you are using C++ STL classes, and still make full use of Berkeley DB features. Being an STL library backed by a database, there are some important and useful features that dbstl can provide, while the C++ STL library can't. The following are a few typical use cases to use the dbstl extensions to the C++ STL for data storage. When data exceeds available physical memory.Berkeley DB dbstl can vastly improve performance when managing a dataset which is larger than available memory. Performance suffers when the data can't reside in memory because the OS is forced to use virtual memory and swap pages of memory to disk. Switching to BDB's dbstl improves performance while allowing you to keep using STL containers. When you need concurrent access to C++ STL containers.Few existing C++ STL implementations support concurrent access (create/read/update/delete) within a container, at best you'll find support for accessing different containers of the same type concurrently. With the Berkeley DB dbstl implementation you can concurrently access your data from multiple threads or processes with confidence in the outcome. When your objects are your database.You want to have object persistence in your application, and store objects in a database, and use the objects across different runs of your application without having to translate them to/from SQL. The dbstl is capable of storing complicated objects, even those not located on a continous chunk of memory space, directly to disk without any unnecessary overhead. These are a few reasons why you should consider using Berkeley DB's C++ STL support for your embedded database application. In the next few blog posts I'll show you a few examples of this approach, it's easy to use and easy to learn.

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