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  • sapply and concurrency in R

    - by JSmaga
    Good afternoon, Somebody asked me a question today and neither did I know the answer nor could I find it in the documentation. This person simply asked me if the sapply function in R was making concurrent calls to the function you want to apply to the list, or if the computation is done sequantially. Does anybody know the answer? What about rapply (the recursive version of this function)? Thanks, Jeremie

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  • How do I password protect my printer in Windows 7?

    - by Dillie-O
    I have two young kids who have gotten rather computer saavy. They love playing their games, especially when it allows them to print out awards or coloring pages. Unfortunately this means that in the time it takes to refresh my cup of coffee, they can easily drop a 10 page document into the printer queue, and my printer ink runs out rather fast. How would I setup some kind of password protection on the printing, so that I would have to do some kind of final approval before they get their printouts?

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  • Synergy 1.5 crash (OSX 10.6.8)

    - by Oliver
    THANKS FOR TAKING THE TIME TO READ THIS I recently installed Synergy 1.5 r2278 (for Mac OSX 10.6.8) and was using it fine for most of the day, then it decided to stop working (the only thing I changed systemwise was the screensaver - and then after it started crashing disabled it - to see if it would resolve). When I start Synergy (on the Mac - Client) it says: after about 5 seconds (and successfully connecting to the Server) "synergyc quit unexpectedly" Here is the crash log (w/ binery info removed - too long for post requirements) Process: synergyc [1026] Path: /Applications/Synergy.app/Contents/MacOS/synergyc Identifier: synergy Version: ??? (???) Code Type: X86 (Native) Parent Process: Synergy [1023] Date/Time: 2014-05-28 15:36:17.746 +0930 OS Version: Mac OS X 10.6.8 (10K549) Report Version: 6 Interval Since Last Report: 2144189 sec Crashes Since Last Report: 23 Per-App Interval Since Last Report: 10242 sec Per-App Crashes Since Last Report: 9 Anonymous UUID: 86D5A57C-13D4-470E-AC72-48ACDDDE5EB0 Exception Type: EXC_CRASH (SIGABRT) Exception Codes: 0x0000000000000000, 0x0000000000000000 Crashed Thread: 5 Application Specific Information: abort() called Thread 0: Dispatch queue: com.apple.main-thread 0 libSystem.B.dylib 0x95cf3afa mach_msg_trap + 10 1 libSystem.B.dylib 0x95cf4267 mach_msg + 68 2 com.apple.CoreFoundation 0x95af02df __CFRunLoopRun + 2079 3 com.apple.CoreFoundation 0x95aef3c4 CFRunLoopRunSpecific + 452 4 com.apple.CoreFoundation 0x95aef1f1 CFRunLoopRunInMode + 97 5 com.apple.HIToolbox 0x93654e04 RunCurrentEventLoopInMode + 392 6 com.apple.HIToolbox 0x93654bb9 ReceiveNextEventCommon + 354 7 com.apple.HIToolbox 0x937dd137 ReceiveNextEvent + 83 8 synergyc 0x000356d0 COSXEventQueueBuffer::waitForEvent(double) + 48 9 synergyc 0x00010dd5 CEventQueue::getEvent(CEvent&, double) + 325 10 synergyc 0x00011fb0 CEventQueue::loop() + 272 11 synergyc 0x00044eb6 CClientApp::mainLoop() + 134 12 synergyc 0x0005c509 standardStartupStatic(int, char**) + 41 13 synergyc 0x000448a9 CClientApp::runInner(int, char**, ILogOutputter*, int (*)(int, char**)) + 137 14 synergyc 0x0005c4b0 CAppUtilUnix::run(int, char**) + 64 15 synergyc 0x000427df CApp::run(int, char**) + 63 16 synergyc 0x00006e65 main + 117 17 synergyc 0x00006dd9 start + 53 Thread 1: 0 libSystem.B.dylib 0x95d607da __sigwait + 10 1 libSystem.B.dylib 0x95d607b6 sigwait$UNIX2003 + 71 2 synergyc 0x00009583 CArchMultithreadPosix::threadSignalHandler(void*) + 67 3 libSystem.B.dylib 0x95d21259 _pthread_start + 345 4 libSystem.B.dylib 0x95d210de thread_start + 34 Thread 2: 0 libSystem.B.dylib 0x95d21aa2 __semwait_signal + 10 1 libSystem.B.dylib 0x95d2175e _pthread_cond_wait + 1191 2 libSystem.B.dylib 0x95d212b1 pthread_cond_timedwait$UNIX2003 + 72 3 synergyc 0x00009476 CArchMultithreadPosix::waitCondVar(CArchCondImpl*, CArchMutexImpl*, double) + 150 4 synergyc 0x0002b18f CCondVarBase::wait(double) const + 63 5 synergyc 0x0002ce68 CSocketMultiplexer::serviceThread(void*) + 136 6 synergyc 0x0002d698 TMethodJob<CSocketMultiplexer>::run() + 40 7 synergyc 0x0002b8f4 CThread::threadFunc(void*) + 132 8 synergyc 0x00008f30 CArchMultithreadPosix::doThreadFunc(CArchThreadImpl*) + 80 9 synergyc 0x0000902a CArchMultithreadPosix::threadFunc(void*) + 74 10 libSystem.B.dylib 0x95d21259 _pthread_start + 345 11 libSystem.B.dylib 0x95d210de thread_start + 34 Thread 3: Dispatch queue: com.apple.libdispatch-manager 0 libSystem.B.dylib 0x95d1a382 kevent + 10 1 libSystem.B.dylib 0x95d1aa9c _dispatch_mgr_invoke + 215 2 libSystem.B.dylib 0x95d19f59 _dispatch_queue_invoke + 163 3 libSystem.B.dylib 0x95d19cfe _dispatch_worker_thread2 + 240 4 libSystem.B.dylib 0x95d19781 _pthread_wqthread + 390 5 libSystem.B.dylib 0x95d195c6 start_wqthread + 30 Thread 4: 0 libSystem.B.dylib 0x95d19412 __workq_kernreturn + 10 1 libSystem.B.dylib 0x95d199a8 _pthread_wqthread + 941 2 libSystem.B.dylib 0x95d195c6 start_wqthread + 30 Thread 5 Crashed: 0 libSystem.B.dylib 0x95d610ee __semwait_signal_nocancel + 10 1 libSystem.B.dylib 0x95d60fd2 nanosleep$NOCANCEL$UNIX2003 + 166 2 libSystem.B.dylib 0x95ddbfb2 usleep$NOCANCEL$UNIX2003 + 61 3 libSystem.B.dylib 0x95dfd6f0 abort + 105 4 libSystem.B.dylib 0x95d79b1b _Unwind_Resume + 59 5 synergyc 0x00008fd1 CArchMultithreadPosix::doThreadFunc(CArchThreadImpl*) + 241 6 synergyc 0x0000902a CArchMultithreadPosix::threadFunc(void*) + 74 7 libSystem.B.dylib 0x95d21259 _pthread_start + 345 8 libSystem.B.dylib 0x95d210de thread_start + 34 Thread 5 crashed with X86 Thread State (32-bit): eax: 0x0000003c ebx: 0x95d60f39 ecx: 0xb0288a7c edx: 0x95d610ee edi: 0x00521950 esi: 0xb0288ad8 ebp: 0xb0288ab8 esp: 0xb0288a7c ss: 0x0000001f efl: 0x00000247 eip: 0x95d610ee cs: 0x00000007 ds: 0x0000001f es: 0x0000001f fs: 0x0000001f gs: 0x00000037 cr2: 0x002fe000 Model: MacBook2,1, BootROM MB21.00A5.B07, 2 processors, Intel Core 2 Duo, 2.16 GHz, 2 GB

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  • Alternatives to "Raining Sockets"

    - by sanity
    I need to build a Java app with considerable IO requirements, supporting tens of thousands of concurrent TCP connections. I found a library called Raining Sockets which seems intended to make it easier to use Java's asynchronous NIO package, but the last update was 6 years ago. Are there other libraries, that are preferably still under active development, and with a public maven repository, that I should look at?

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  • Is there a way to set a handler function for when a set of events has happened in JavaScript?

    - by allyourcode
    eg I have two concurrent AJAX requests, and I need the result from both to compute a third result. I'm using the Prototype library, so it might look something like this: var r1 = new Ajax.Request(url1, ...); var r2 = new Ajax.Request(url2, ...); function on_both_requests_complete(resp1, resp2) { ... } One way would be to use polling, but I'm thinking there must be a better way.

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  • I want to read a big text file

    - by Rozer
    I want to read a big text file, what i decided to create four threads and read 25% of file by each one. and then join them. but its not more impressive. can any one tell me can i use concurrent programming for the same. as my file structure have some data as name contact compnay policyname policynumber uniqueno and I want to put all data in hashmap at last. thanks

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  • Organizing github repository for java 6 and 7

    - by Edmon
    I am wanting to create a gihub repository that offers benchmarking code that works for concurrent features available only in JDK 1.7 (Fork/Join) as well as for older ones found in JDK 1.6. Offering both options is important for what I need. Does anyone have a recommendation how should I structure the repository. I was planning on having a repo called and under it: jdk17 build src mycode ... jdk16 build src mycode Please suggest any alternatives, possibly use of Maven or other more practical approaches, if any.

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  • Server is sending SPAM but it's not an open relay

    - by alexandernst
    I have a problem with Dovecot + Postfix. My server is sending SPAM from the local user "dovecot", but my server is not configured as an open relay (mails can be sent without auth-ing only from localhost). Also, nobody except me, has SSH access to the server. How can I find what exactly is triggering all those SPAM mails? How can I get something like a backtrace that shows what exactly happened the moments before a SPAM email got in the queue of postfix? Regards

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  • Postfix sendmail bypass restrictions [on hold]

    - by EnEli
    I have setup a postfix/dovecot mail server and all thing work fine! BUT: I use virtual mailboxes and when you try to send a mail to a non existent mailbox via telnet postfix will punch you... But if you use sendmail, all restricitons are bypassed... This is bad becuase dovecot does not know what to do with this mail! It will stay in the queue for ever... How can I force sendmail to use normal smtp?

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  • how to open many tabs in chromium but unload/disable inactive/notCurrent ones, releasing memory and cpu?

    - by Aquarius Power
    So I have 50 tabs opened on chromium, but that is using too much memory and some of the CPU. How can I have all those concurrent researches I am doing opened but not clog my machine? I think there should have a way that only the active tab is loaded in memory and running, and all the others should stay closed/unloaded from memory, until I want to look at them... Any extension can do something like that?

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  • Maintaining many socket connections with a single thread

    - by John
    Many tutorials on socket communication I see seem to use 1 thread per socket. But on a server used for online gaming, you might have 10k concurrent users - 10k threads isn't probably a wonderful idea. I came across a tool (SmartFox) which claims to use a single thread for monitoring all socket connections, potentially thousands of them. This app happens to be in Java, but I figure C++ or C# could do the same... how would you achieve this?

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  • Java Multi threading - Avoid duplicate request processing

    - by seawaves
    I have following multi threaded environment scenario - Requests are coming to a method and I want to avoid the duplicate processing of concurrent requests coming. As multiple similar requests might be waiting for being processed in blocked state. I used hashtable to keep track of processed request, but it will create memory leaks, so how should keep track of processed request and avoid the same requests to be processed which may be in blocking state.

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  • How to achieve a specific fraction(say 80%) of the cpus and balanced over them

    - by swellfr
    Hi, I was wondering if it would be possible to run app not at 100% of the cpu but at a specific amount of the cpus. I see different usage of this , we can better balance concurrent application ( we may want to have balance app 50% to have fair apps/agent/... ) i was also wondering if the power consumption would not be better if the cpus doesnt run at full throttle but at some lower level( say 80% ) What are your thoughts Thx examples are welcomed :)

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  • ODI 12c - Parallel Table Load

    - by David Allan
    In this post we will look at the ODI 12c capability of parallel table load from the aspect of the mapping developer and the knowledge module developer - two quite different viewpoints. This is about parallel table loading which isn't to be confused with loading multiple targets per se. It supports the ability for ODI mappings to be executed concurrently especially if there is an overlap of the datastores that they access, so any temporary resources created may be uniquely constructed by ODI. Temporary objects can be anything basically - common examples are staging tables, indexes, views, directories - anything in the ETL to help the data integration flow do its job. In ODI 11g users found a few workarounds (such as changing the technology prefixes - see here) to build unique temporary names but it was more of a challenge in error cases. ODI 12c mappings by default operate exactly as they did in ODI 11g with respect to these temporary names (this is also true for upgraded interfaces and scenarios) but can be configured to support the uniqueness capabilities. We will look at this feature from two aspects; that of a mapping developer and that of a developer (of procedures or KMs). 1. Firstly as a Mapping Developer..... 1.1 Control when uniqueness is enabled A new property is available to set unique name generation on/off. When unique names have been enabled for a mapping, all temporary names used by the collection and integration objects will be generated using unique names. This property is presented as a check-box in the Property Inspector for a deployment specification. 1.2 Handle cleanup after successful execution Provided that all temporary objects that are created have a corresponding drop statement then all of the temporary objects should be removed during a successful execution. This should be the case with the KMs developed by Oracle. 1.3 Handle cleanup after unsuccessful execution If an execution failed in ODI 11g then temporary tables would have been left around and cleaned up in the subsequent run. In ODI 12c, KM tasks can now have a cleanup-type task which is executed even after a failure in the main tasks. These cleanup tasks will be executed even on failure if the property 'Remove Temporary Objects on Error' is set. If the agent was to crash and not be able to execute this task, then there is an ODI tool (OdiRemoveTemporaryObjects here) you can invoke to cleanup the tables - it supports date ranges and the like. That's all there is to it from the aspect of the mapping developer it's much, much simpler and straightforward. You can now execute the same mapping concurrently or execute many mappings using the same resource concurrently without worrying about conflict.  2. Secondly as a Procedure or KM Developer..... In the ODI Operator the executed code shows the actual name that is generated - you can also see the runtime code prior to execution (introduced in 11.1.1.7), for example below in the code type I selected 'Pre-executed Code' this lets you see the code about to be processed and you can also see the executed code (which is the default view). References to the collection (C$) and integration (I$) names will be automatically made unique by using the odiRef APIs - these objects will have unique names whenever concurrency has been enabled for a particular mapping deployment specification. It's also possible to use name uniqueness functions in procedures and your own KMs. 2.1 New uniqueness tags  You can also make your own temporary objects have unique names by explicitly including either %UNIQUE_STEP_TAG or %UNIQUE_SESSION_TAG in the name passed to calls to the odiRef APIs. Such names would always include the unique tag regardless of the concurrency setting. To illustrate, let's look at the getObjectName() method. At <% expansion time, this API will append %UNIQUE_STEP_TAG to the object name for collection and integration tables. The name parameter passed to this API may contain  %UNIQUE_STEP_TAG or %UNIQUE_SESSION_TAG. This API always generates to the <? version of getObjectName() At execution time this API will replace the unique tag macros with a string that is unique to the current execution scope. The returned name will conform to the name-length restriction for the target technology, and its pattern for the unique tag. Any necessary truncation will be performed against the initial name for the object and any other fixed text that may have been specified. Examples are:- <?=odiRef.getObjectName("L", "%COL_PRFEMP%UNIQUE_STEP_TAG", "D")?> SCOTT.C$_EABH7QI1BR1EQI3M76PG9SIMBQQ <?=odiRef.getObjectName("L", "EMP%UNIQUE_STEP_TAG_AE", "D")?> SCOTT.EMPAO96Q2JEKO0FTHQP77TMSAIOSR_ Methods which have this kind of support include getFrom, getTableName, getTable, getObjectShortName and getTemporaryIndex. There are APIs for retrieving this tag info also, the getInfo API has been extended with the following properties (the UNIQUE* properties can also be used in ODI procedures); UNIQUE_STEP_TAG - Returns the unique value for the current step scope, e.g. 5rvmd8hOIy7OU2o1FhsF61 Note that this will be a different value for each loop-iteration when the step is in a loop. UNIQUE_SESSION_TAG - Returns the unique value for the current session scope, e.g. 6N38vXLrgjwUwT5MseHHY9 IS_CONCURRENT - Returns info about the current mapping, will return 0 or 1 (only in % phase) GUID_SRC_SET - Returns the UUID for the current source set/execution unit (only in % phase) The getPop API has been extended with the IS_CONCURRENT property which returns info about an mapping, will return 0 or 1.  2.2 Additional APIs Some new APIs are provided including getFormattedName which will allow KM developers to construct a name from fixed-text or ODI symbols that can be optionally truncate to a max length and use a specific encoding for the unique tag. It has syntax getFormattedName(String pName[, String pTechnologyCode]) This API is available at both the % and the ? phase.  The format string can contain the ODI prefixes that are available for getObjectName(), e.g. %INT_PRF, %COL_PRF, %ERR_PRF, %IDX_PRF alongwith %UNIQUE_STEP_TAG or %UNIQUE_SESSION_TAG. The latter tags will be expanded into a unique string according to the specified technology. Calls to this API within the same execution context are guaranteed to return the same unique name provided that the same parameters are passed to the call. e.g. <%=odiRef.getFormattedName("%COL_PRFMY_TABLE%UNIQUE_STEP_TAG_AE", "ORACLE")%> <?=odiRef.getFormattedName("%COL_PRFMY_TABLE%UNIQUE_STEP_TAG_AE", "ORACLE")?> C$_MY_TAB7wDiBe80vBog1auacS1xB_AE <?=odiRef.getFormattedName("%COL_PRFMY_TABLE%UNIQUE_STEP_TAG.log", "FILE")?> C2_MY_TAB7wDiBe80vBog1auacS1xB.log 2.3 Name length generation  As part of name generation, the length of the generated name will be compared with the maximum length for the target technology and truncation may need to be applied. When a unique tag is included in the generated string it is important that uniqueness is not compromised by truncation of the unique tag. When a unique tag is NOT part of the generated name, the name will be truncated by removing characters from the end - this is the existing 11g algorithm. When a unique tag is included, the algorithm will first truncate the <postfix> and if necessary  the <prefix>. It is recommended that users will ensure there is sufficient uniqueness in the <prefix> section to ensure uniqueness of the final resultant name. SUMMARY To summarize, ODI 12c make it much simpler to utilize mappings in concurrent cases and provides APIs for helping developing any procedures or custom knowledge modules in such a way they can be used in highly concurrent, parallel scenarios. 

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  • SQL SERVER – LCK_M_XXX – Wait Type – Day 15 of 28

    - by pinaldave
    Locking is a mechanism used by the SQL Server Database Engine to synchronize access by multiple users to the same piece of data, at the same time. In simpler words, it maintains the integrity of data by protecting (or preventing) access to the database object. From Book On-Line: LCK_M_BU Occurs when a task is waiting to acquire a Bulk Update (BU) lock. LCK_M_IS Occurs when a task is waiting to acquire an Intent Shared (IS) lock. LCK_M_IU Occurs when a task is waiting to acquire an Intent Update (IU) lock. LCK_M_IX Occurs when a task is waiting to acquire an Intent Exclusive (IX) lock. LCK_M_S Occurs when a task is waiting to acquire a Shared lock. LCK_M_SCH_M Occurs when a task is waiting to acquire a Schema Modify lock. LCK_M_SCH_S Occurs when a task is waiting to acquire a Schema Share lock. LCK_M_SIU Occurs when a task is waiting to acquire a Shared With Intent Update lock. LCK_M_SIX Occurs when a task is waiting to acquire a Shared With Intent Exclusive lock. LCK_M_U Occurs when a task is waiting to acquire an Update lock. LCK_M_UIX Occurs when a task is waiting to acquire an Update With Intent Exclusive lock. LCK_M_X Occurs when a task is waiting to acquire an Exclusive lock. LCK_M_XXX Explanation: I think the explanation of this wait type is the simplest. When any task is waiting to acquire lock on any resource, this particular wait type occurs. The common reason for the task to be waiting to put lock on the resource is that the resource is already locked and some other operations may be going on within it. This wait also indicates that resources are not available or are occupied at the moment due to some reasons. There is a good chance that the waiting queries start to time out if this wait type is very high. Client application may degrade the performance as well. You can use various methods to find blocking queries: EXEC sp_who2 SQL SERVER – Quickest Way to Identify Blocking Query and Resolution – Dirty Solution DMV – sys.dm_tran_locks DMV – sys.dm_os_waiting_tasks Reducing LCK_M_XXX wait: Check the Explicit Transactions. If transactions are very long, this wait type can start building up because of other waiting transactions. Keep the transactions small. Serialization Isolation can build up this wait type. If that is an acceptable isolation for your business, this wait type may be natural. The default isolation of SQL Server is ‘Read Committed’. One of my clients has changed their isolation to “Read Uncommitted”. I strongly discourage the use of this because this will probably lead to having lots of dirty data in the database. Identify blocking queries mentioned using various methods described above, and then optimize them. Partition can be one of the options to consider because this will allow transactions to execute concurrently on different partitions. If there are runaway queries, use timeout. (Please discuss this solution with your database architect first as timeout can work against you). Check if there is no memory and IO-related issue using the following counters: Checking Memory Related Perfmon Counters SQLServer: Memory Manager\Memory Grants Pending (Consistent higher value than 0-2) SQLServer: Memory Manager\Memory Grants Outstanding (Consistent higher value, Benchmark) SQLServer: Buffer Manager\Buffer Hit Cache Ratio (Higher is better, greater than 90% for usually smooth running system) SQLServer: Buffer Manager\Page Life Expectancy (Consistent lower value than 300 seconds) Memory: Available Mbytes (Information only) Memory: Page Faults/sec (Benchmark only) Memory: Pages/sec (Benchmark only) Checking Disk Related Perfmon Counters Average Disk sec/Read (Consistent higher value than 4-8 millisecond is not good) Average Disk sec/Write (Consistent higher value than 4-8 millisecond is not good) Average Disk Read/Write Queue Length (Consistent higher value than benchmark is not good) Read all the post in the Wait Types and Queue series. Note: The information presented here is from my experience and there is no way that I claim it to be accurate. I suggest reading Book OnLine for further clarification. All the discussion of Wait Stats in this blog is generic and varies from system to system. It is recommended that you test this on a development server before implementing it to a production server. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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  • Email a very large list of WordPress subscribers = fail (every single time)

    - by Greg-J
    I have tried using a number of plugins to email my 40,000 registered users on my WordPress-powered site, to no avail. I have tried Subscribe2 (seems to send some, but I have no idea how many) as well as a few Newsletter plugins. I either run out of memory trying to add 40K entries to the mail queue, or I error out trying to add 40K emails in the BCC of the email being sent. Is there anyone out there with a large subscriber-base that has found a successful solution? If so, please share.

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  • Cloud Based Load Testing Using TF Service &amp; VS 2013

    - by Tarun Arora [Microsoft MVP]
    Originally posted on: http://geekswithblogs.net/TarunArora/archive/2013/06/30/cloud-based-load-testing-using-tf-service-amp-vs-2013.aspx One of the new features announced as part of the Visual Studio 2013 Ultimate Preview is ‘Cloud Based Load Testing’. In this blog post I’ll walk you through, What is Cloud Based Load Testing? How have I been using this feature? – Success story! Where can you find more resources on this feature? What is Cloud Based Load Testing? It goes without saying that performance testing your application not only gives you the confidence that the application will work under heavy levels of stress but also gives you the ability to test how scalable the architecture of your application is. It is important to know how much is too much for your application! Working with various clients in the industry I have realized that the biggest barriers in Load Testing & Performance Testing adoption are, High infrastructure and administration cost that comes with this phase of testing Time taken to procure & set up the test infrastructure Finding use for this infrastructure investment after completion of testing Is cloud the answer? 100% Visual Studio Compatible Scalable and Realistic Start testing in < 2 minutes Intuitive Pay only for what you need Use existing on premise tests on cloud There are a lot of vendors out there offering Cloud Based Load Testing, to name a few, Load Storm Soasta Blaze Meter Blitz And others… The question you may want to ask is, why should you go with Microsoft’s Cloud based Load Test offering. If you are a Microsoft shop or already have investments in Microsoft technologies, you’ll see great benefit in the natural integration this offers with existing Microsoft products such as Visual Studio and Windows Azure. For example, your existing Web tests authored in Visual Studio 2010 or Visual Studio 2012 will run on the cloud without requiring any modifications what so ever. Microsoft’s cloud test rig also supports API based testing, for example, if you are building a WPF application which consumes WCF services, you can write unit tests to invoke the WCF service, these tests can be run on the cloud test rig and loaded with ‘N’ concurrent users for performance testing. If you have your assets already hosted in the Azure and possibly in the same data centre as the Cloud test rig, your Azure app will not incur a usage cost because of the generated traffic since the traffic is coming from the same data centre. The licensing or pricing information on Microsoft’s cloud based Load test service is yet to be announced, but I would expect this to be priced attractively to match the market competition.   The only additional configuration required for running load tests on Microsoft Cloud based Load Tests service is to select the Test run location as Run tests using Visual Studio Team Foundation Service, How have I been using Microsoft’s Cloud based Load Test Service? I have been part of the Microsoft Cloud Based Load Test Service advisory council for the last 7 months. This gave the opportunity to see the product shape up from concept to working solution. I was also the first person outside of Microsoft to try this offering out. This gave me the opportunity to test real world application at various clients using the Microsoft Load Test Service and provide real world feedback to the Microsoft product team. One of the most recent systems I tested using the Load Test Service has been an insurance quote generation engine. This insurance quote generation engine is,   hosted in Windows Azure expected to get quote requests from across the globe expected to handle 5 Million quote requests in a day (not clear how this load will be distributed across the day) There was no way, I could simulate such kind of load from on premise without standing up additional hardware. But Microsoft’s Cloud based Load Test service allowed me to test my key performance testing scenarios, i.e. Simulate expected Load, Endurance Testing, Threshold Testing and Testing for Latency. Simulating expected load: approach to devising a load pattern My approach to devising a load test pattern has been to run the test scenario with 1 user to figure out the response time. Then work out how many users are required to reach the target load. So, for example, to invoke 1 quote from the quote engine software takes 0.5 seconds. Now if you do the math,   1 quote request by 1 user = 0.5 seconds   quotes generated by 1 user in 24 hour = 1 * (((2 * 60) * 60) * 24) = 172,800   quotes generated by 30 users in 24 hours = 172,800 * 30 =  5,184,000 This was a very simple example, if your application requires more concurrent users to test scenario’s such as caching, etc then you can devise your own load pattern, some examples of load test patterns can be found here.  Endurance Testing To test for endurance, I loaded the quote generation engine with an expected fixed user load and ran the test for very long duration such as over 48 hours and observed the affect of the long running test on the Azure infrastructure. Currently Microsoft Load Test service does not support metrics from the machine under test. I used Azure diagnostics to begin with, but later started using Cerebrata Azure Diagnostics Manager to capture the metrics of the machine under test. Threshold Testing To figure out how much user load the application could cope with before falling on its belly, I opted to step load the quote generation engine by incrementing user load with different variations of incremental user load per minute till the application crashed out and forced an IIS reset. Testing for Latency Currently the Microsoft Load Test service does not support generating geographically distributed load, I however, deployed the insurance quote generation engine in different Azure data centres and ran the same set of performance tests to measure for latency. Because I could compare load test results from different runs by exporting the results to excel (this feature is provided out of the box right from Visual Studio 2010) I could see the different in response times. More resources on Microsoft Cloud based Load Test Service A few important links to get you started, Download Visual Studio Ultimate 2013 Preview Getting started guide for load testing using Team Foundation Service Troubleshooting guide for FAQs and known issues Team Foundation Service forum for questions and support Detailed demo and presentation (link to Tech-Ed session recording) Detailed demo and presentation (link to Build session recording) There a few limits on the usage of Microsoft Cloud based Load Test service that you can read about here. If you have any feedback on Microsoft Cloud based Load Test service, feel free to share it with the product team via the Visual Studio User Voice forum. I hope you found this useful. Thank you for taking the time out and reading this blog post. If you enjoyed the post, remember to subscribe to http://feeds.feedburner.com/TarunArora. Stay tuned!

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  • Regression testing with Selenium GRID

    - by Ben Adderson
    A lot of software teams out there are tasked with supporting and maintaining systems that have grown organically over time, and the web team here at Red Gate is no exception. We're about to embark on our first significant refactoring endeavour for some time, and as such its clearly paramount that the code be tested thoroughly for regressions. Unfortunately we currently find ourselves with a codebase that isn't very testable - the three layers (database, business logic and UI) are currently tightly coupled. This leaves us with the unfortunate problem that, in order to confidently refactor the code, we need unit tests. But in order to write unit tests, we need to refactor the code :S To try and ease the initial pain of decoupling these layers, I've been looking into the idea of using UI automation to provide a sort of system-level regression test suite. The idea being that these tests can help us identify regressions whilst we work towards a more testable codebase, at which point the more traditional combination of unit and integration tests can take over. Ending up with a strong battery of UI tests is also a nice bonus :) Following on from my previous posts (here, here and here) I knew I wanted to use Selenium. I also figured that this would be a good excuse to put my xUnit [Browser] attribute to good use. Pretty quickly, I had a raft of tests that looked like the following (this particular example uses Reflector Pro). In a nut shell the test traverses our shopping cart and, for a particular combination of number of users and months of support, checks that the price calculations all come up with the correct values. [BrowserTheory] [Browser(Browsers.Firefox3_6, "http://www.red-gate.com")] public void Purchase1UserLicenceNoSupport(SeleniumProvider seleniumProvider) {     //Arrange     _browser = seleniumProvider.GetBrowser();     _browser.Open("http://www.red-gate.com/dynamic/shoppingCart/ProductOption.aspx?Product=ReflectorPro");                  //Act     _browser = ShoppingCartHelpers.TraverseShoppingCart(_browser, 1, 0, ".NET Reflector Pro");     //Assert     var priceResult = PriceHelpers.GetNewPurchasePrice(db, "ReflectorPro", 1, 0, Currencies.Euros);         Assert.Equal(priceResult.Price, _browser.GetText("ctl00_content_InvoiceShoppingItemRepeater_ctl01_Price"));     Assert.Equal(priceResult.Tax, _browser.GetText("ctl00_content_InvoiceShoppingItemRepeater_ctl02_Tax"));     Assert.Equal(priceResult.Total, _browser.GetText("ctl00_content_InvoiceShoppingItemRepeater_ctl02_Total")); } These tests are pretty concise, with much of the common code in the TraverseShoppingCart() and GetNewPurchasePrice() methods. The (inevitable) problem arose when it came to execute these tests en masse. Selenium is a very slick tool, but it can't mask the fact that UI automation is very slow. To give you an idea, the set of cases that covers all of our products, for all combinations of users and support, came to 372 tests (for now only considering purchases in dollars). In the world of automated integration tests, that's a very manageable number. For unit tests, it's a trifle. However for UI automation, those 372 tests were taking just over two hours to run. Two hours may not sound like a lot, but those cases only cover one of the three currencies we deal with, and only one of the many different ways our systems can be asked to calculate a price. It was already pretty clear at this point that in order for this approach to be viable, I was going to have to find a way to speed things up. Up to this point I had been using Selenium Remote Control to automate Firefox, as this was the approach I had used previously and it had worked well. Fortunately,  the guys at SeleniumHQ also maintain a tool for executing multiple Selenium RC tests in parallel: Selenium Grid. Selenium Grid uses a central 'hub' to handle allocation of Selenium tests to individual RCs. The Remote Controls simply register themselves with the hub when they start, and then wait to be assigned work. The (for me) really clever part is that, as far as the client driver library is concerned, the grid hub looks exactly the same as a vanilla remote control. To create a new browser session against Selenium RC, the following C# code suffices: new DefaultSelenium("localhost", 4444, "*firefox", "http://www.red-gate.com"); This assumes that the RC is running on the local machine, and is listening on port 4444 (the default). Assuming the hub is running on your local machine, then to create a browser session in Selenium Grid, via the hub rather than directly against the control, the code is exactly the same! Behind the scenes, the hub will take this request and hand it off to one of the registered RCs that provides the "*firefox" execution environment. It will then pass all communications back and forth between the test runner and the remote control transparently. This makes running existing RC tests on a Selenium Grid a piece of cake, as the developers intended. For a more detailed description of exactly how Selenium Grid works, see this page. Once I had a test environment capable of running multiple tests in parallel, I needed a test runner capable of doing the same. Unfortunately, this does not currently exist for xUnit (boo!). MbUnit on the other hand, has the concept of concurrent execution baked right into the framework. So after swapping out my assembly references, and fixing up the resulting mismatches in assertions, my example test now looks like this: [Test] public void Purchase1UserLicenceNoSupport() {    //Arrange    ISelenium browser = BrowserHelpers.GetBrowser();    var db = DbHelpers.GetWebsiteDBDataContext();    browser.Start();    browser.Open("http://www.red-gate.com/dynamic/shoppingCart/ProductOption.aspx?Product=ReflectorPro");                 //Act     browser = ShoppingCartHelpers.TraverseShoppingCart(browser, 1, 0, ".NET Reflector Pro");    var priceResult = PriceHelpers.GetNewPurchasePrice(db, "ReflectorPro", 1, 0, Currencies.Euros);    //Assert     Assert.AreEqual(priceResult.Price, browser.GetText("ctl00_content_InvoiceShoppingItemRepeater_ctl01_Price"));     Assert.AreEqual(priceResult.Tax, browser.GetText("ctl00_content_InvoiceShoppingItemRepeater_ctl02_Tax"));     Assert.AreEqual(priceResult.Total, browser.GetText("ctl00_content_InvoiceShoppingItemRepeater_ctl02_Total")); } This is pretty much the same as the xUnit version. The exceptions are that the attributes have changed,  the //Arrange phase now has to handle setting up the ISelenium object, as the attribute that previously did this has gone away, and the test now sets up its own database connection. Previously I was using a shared database connection, but this approach becomes more complicated when tests are being executed concurrently. To avoid complexity each test has its own connection, which it is responsible for closing. For the sake of readability, I snipped out the code that closes the browser session and the db connection at the end of the test. With all that done, there was only one more step required before the tests would execute concurrently. It is necessary to tell the test runner which tests are eligible to run in parallel, via the [Parallelizable] attribute. This can be done at the test, fixture or assembly level. Since I wanted to run all tests concurrently, I marked mine at the assembly level in the AssemblyInfo.cs using the following: [assembly: DegreeOfParallelism(3)] [assembly: Parallelizable(TestScope.All)] The second attribute marks all tests in the assembly as [Parallelizable], whilst the first tells the test runner how many concurrent threads to use when executing the tests. I set mine to three since I was using 3 RCs in separate VMs. With everything now in place, I fired up the Icarus* test runner that comes with MbUnit. Executing my 372 tests three at a time instead of one at a time reduced the running time from 2 hours 10 minutes, to 55 minutes, that's an improvement of about 58%! I'd like to have seen an improvement of 66%, but I can understand that either inefficiencies in the hub code, my test environment or the test runner code (or some combination of all three most likely) contributes to a slightly diminished improvement. That said, I'd love to hear about any experience you have in upping this efficiency. Ultimately though, it was a saving that was most definitely worth having. It makes regression testing via UI automation a far more plausible prospect. The other obvious point to make is that this approach scales far better than executing tests serially. So if ever we need to improve performance, we just register additional RC's with the hub, and up the DegreeOfParallelism. *This was just my personal preference for a GUI runner. The MbUnit/Gallio installer also provides a command line runner, a TestDriven.net runner, and a Resharper 4.5 runner. For now at least, Resharper 5 isn't supported.

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  • Troubleshooting High-CPU Utilization for SQL Server

    - by Susantha Bathige
    The objective of this FAQ is to outline the basic steps in troubleshooting high CPU utilization on  a server hosting a SQL Server instance. The first and the most common step if you suspect high CPU utilization (or are alerted for it) is to login to the physical server and check the Windows Task Manager. The Performance tab will show the high utilization as shown below: Next, we need to determine which process is responsible for the high CPU consumption. The Processes tab of the Task Manager will show this information: Note that to see all processes you should select Show processes from all user. In this case, SQL Server (sqlserver.exe) is consuming 99% of the CPU (a normal benchmark for max CPU utilization is about 50-60%). Next we examine the scheduler data. Scheduler is a component of SQLOS which evenly distributes load amongst CPUs. The query below returns the important columns for CPU troubleshooting. Note – if your server is under severe stress and you are unable to login to SSMS, you can use another machine’s SSMS to login to the server through DAC – Dedicated Administrator Connection (see http://msdn.microsoft.com/en-us/library/ms189595.aspx for details on using DAC) SELECT scheduler_id ,cpu_id ,status ,runnable_tasks_count ,active_workers_count ,load_factor ,yield_count FROM sys.dm_os_schedulers WHERE scheduler_id See below for the BOL definitions for the above columns. scheduler_id – ID of the scheduler. All schedulers that are used to run regular queries have ID numbers less than 1048576. Those schedulers that have IDs greater than or equal to 1048576 are used internally by SQL Server, such as the dedicated administrator connection scheduler. cpu_id – ID of the CPU with which this scheduler is associated. status – Indicates the status of the scheduler. runnable_tasks_count – Number of workers, with tasks assigned to them that are waiting to be scheduled on the runnable queue. active_workers_count – Number of workers that are active. An active worker is never preemptive, must have an associated task, and is either running, runnable, or suspended. current_tasks_count - Number of current tasks that are associated with this scheduler. load_factor – Internal value that indicates the perceived load on this scheduler. yield_count – Internal value that is used to indicate progress on this scheduler.                                                                 Now to interpret the above data. There are four schedulers and each assigned to a different CPU. All the CPUs are ready to accept user queries as they all are ONLINE. There are 294 active tasks in the output as per the current_tasks_count column. This count indicates how many activities currently associated with the schedulers. When a  task is complete, this number is decremented. The 294 is quite a high figure and indicates all four schedulers are extremely busy. When a task is enqueued, the load_factor  value is incremented. This value is used to determine whether a new task should be put on this scheduler or another scheduler. The new task will be allocated to less loaded scheduler by SQLOS. The very high value of this column indicates all the schedulers have a high load. There are 268 runnable tasks which mean all these tasks are assigned a worker and waiting to be scheduled on the runnable queue.   The next step is  to identify which queries are demanding a lot of CPU time. The below query is useful for this purpose (note, in its current form,  it only shows the top 10 records). SELECT TOP 10 st.text  ,st.dbid  ,st.objectid  ,qs.total_worker_time  ,qs.last_worker_time  ,qp.query_plan FROM sys.dm_exec_query_stats qs CROSS APPLY sys.dm_exec_sql_text(qs.sql_handle) st CROSS APPLY sys.dm_exec_query_plan(qs.plan_handle) qp ORDER BY qs.total_worker_time DESC This query as total_worker_time as the measure of CPU load and is in descending order of the  total_worker_time to show the most expensive queries and their plans at the top:      Note the BOL definitions for the important columns: total_worker_time - Total amount of CPU time, in microseconds, that was consumed by executions of this plan since it was compiled. last_worker_time - CPU time, in microseconds, that was consumed the last time the plan was executed.   I re-ran the same query again after few seconds and was returned the below output. After few seconds the SP dbo.TestProc1 is shown in fourth place and once again the last_worker_time is the highest. This means the procedure TestProc1 consumes a CPU time continuously each time it executes.      In this case, the primary cause for high CPU utilization was a stored procedure. You can view the execution plan by clicking on query_plan column to investigate why this is causing a high CPU load. I have used SQL Server 2008 (SP1) to test all the queries used in this article.

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  • Cheatsheet: 2010 04.01 ~ 04.07

    - by gOODiDEA
    Web Web Performance Best Practices: How masters.com re-designed their site to boost performance – and what that re-design missed What’s wrong with extending the DOM John Resig on Advanced Javascript to Improve your Web App .NET Hammock for REST - a REST library for .NET Programming Windows Phone 7 Series by Charlez Petzold – Free EBook Testing the Lock-Free Queue Some Last-Minute New C# 4.0 Features - while (x --> 0) { Console.WriteLine("x = {0}", x); } Better Coding with Visual Studio 2010 Revisiting Asynchronous ASP.NET Pages Database Understanding RAID for SQL Server – Part 2 Cassandra Jump Start For The Windows Developer Cassandra Internals – Writing - Cassandra Write Operation Performance Explained Cassandra Internals – Reading - Cassandra Reads Performance Explained MongoDB Growing Up: Release 1.4 and Commercial Support by 10gen Why NoSQL Will Not Die How Many Hard Drives Do I Need to Support SQL Server? Other Presentation: CouchDB and Lucene MongoDB Cacti Graphs HBase vs Cassandra: why we moved How to use the DedicatedDumpFile registry value to overcome space limitations on the system drive when capturing a system memory dump

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