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• Where does the compiler store methods for C++ classes?

  - by Mashmagar

  This is more a curiosity than anything else... Suppose I have a C++ class Kitty as follows: class Kitty { void Meow() { //Do stuff } } Does the compiler place the code for Meow() in every instance of Kitty? Obviously repeating the same code everywhere requires more memory. But on the other hand, branching to a relative location in nearby memory requires fewer assembly instructions than branching to an absolute location in memory on modern processors, so this is potentially faster. I suppose this is an implementation detail, so different compilers may perform differently. Keep in mind, I'm not considering static or virtual methods here.

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• A programming language for teaching data structures and algorithms with? [closed]

  - by Andreas Grech

  Possible Duplicate: Choice of programming language for learning data structures and algorithms Teachers have different opinions on what programming language they would choose to teach data structures and algorithms with. Some would prefer a lower level language such as C because it allows the student to learn more about what goes on beyond the abstractions in terms of memory allocation and deallocation and pointers and pointer arithmetic. On the other hand, others would say that they would prefer a higher level language like Java because it allows the student to learn more about the concepts of the structures and the algorithm design rather than 'waste time' and fiddle around with memory segmentation faults and all the blunders that come with languages where memory management is manual. What is your take on this issue? And also, please post any references you may know of that also discuss this argument.

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• C++ Singleton design pattern.

  - by Artem Barger

  Recently I've bumped into realization/implementation of Singleton design pattern for C++. It has looked in the following way (I have adopted it from real life example): // a lot of methods is omitted here class Singleton { public: static Singleton* getInstance( ); ~Singleton( ); private: Singleton( ); static Singleton* instance; }; From this declaration I can deduce that instance field is initiated on the heap, that means there is a memory allocation. That is completely unclear for me is when does exactly memory is going to be deallocated? Or there is a bug and memory leak? It seems like there is a problem in implementation. PS. And main question how to implement it in the right way?

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• STL deque accessing by index is O(1)?

  - by jasonline

  I've read that accessing elements by position index can be done in constant time in a STL deque. As far as I know, elements in a deque may be stored in several non-contiguous locations, eliminating safe access through pointer arithmetic. For example: abc-defghi-jkl-mnop The elements of the deque above consists of a single character. The set of characters in one group indicate it is allocated in contiguous memory (e.g. abc is in a single block of memory, defhi is located in another block of memory, etc.). Can anyone explain how accessing by position index can be done in constant time, especially if the element to be accessed is in the second block? Or does a deque have a pointer to the group of blocks? Update: Or is there any other common implementation for a deque?

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• "Access violation reading location" troubles retrieveing buffer from directx

  - by numerical25

  Below is my code... ID3D10Texture2D *pBackBuffer; hr = mpSwapChain->GetBuffer(0, __uuidof(ID3D10Texture2D), (LPVOID*) &pBackBuffer); and I get the following error chp1.exe': Unloaded 'C:\Windows\SysWOW64\oleaut32.dll' First-chance exception at 0x757ce124 in chp1.exe: Microsoft C++ exception: _com_error at memory location 0x0018eeb0.. First-chance exception at 0x757ce124 in chp1.exe: Microsoft C++ exception: _com_error at memory location 0x0018edd0.. First-chance exception at 0x757ce124 in chp1.exe: Microsoft C++ exception: _com_error at memory location 0x0018ef1c.. The thread 'Win32 Thread' (0xfc4) has exited with code 0 (0x0). 'chp1.exe': Unloaded 'C:\Windows\SysWOW64\D3D10Ref.DLL' First-chance exception at 0x00b71894 in chp1.exe: 0xC0000005: Access violation reading location 0x00000000. Unhandled ex ception at 0x00b71894 in chp1.exe: 0xC0000005: Access violation reading location 0x00000000. It appears that the error occurs in the last parameter. &pBackBuffer. I added this single line of code and the error occurs.

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• c++ programming for clusters and HPC

  - by Abruzzo Forte e Gentile

  HI All I need to write a scientific application in C++ doing a lot of computations and using a lot of memory. I have part of the job but due to high requirements in terms of resources I was thinking to start moving to OpenMPI. Before doing that I have a simple curiosity: If I understood the principle of OpenMPI is the developer that has the task of splitting the jobs over different nodes calling SEND and RECEIVE based on node available at that time. Do you know if it does exist some library or OS or whatever that has this capability letting my code reamain as it is now? Basically something that connects all computers and let share as one their memory and CPU? I am a bit confused because of the high material available on the topic. Should I look at cloud computing? or Distributed Shared Memory? Can you help me or address me a bit? Thanks

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• Session Timeout and page response time

  - by Johnny5

  Hi, I'm load testing an asp.net app. The load test is simulating 500 user doing searchs on the site and browsing the results. I'm observing that the more I reduce the session timeout limit (in web.config) the better the page response time. For exemple, with a timeout at 10 minutes, I got an average response time of 8.35 seconds. With a timout at 3 minutes, the average response time for the same page is 3,98 seconds. The session in stored "InProc". I supposed the memory used by the "no more used but still actives" sessions may be in cause. But, even if there is more memory used when the timeout is at 10, there is still plenty of memory available (about 2.7Gb). Any ideas?

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• Can I compile and execute C# expression without saving the assembly to disk?

  - by Sasha

  I can compile, get an instance and invoke a method of any C# type programmaticaly. There lots of info on that, including the StackOverflow (http://stackoverflow.com/questions/53844/how-can-i-evaluate-a-c-expression-dynamically). My problem is that I'm in the web environment and cannot save anything to /bin directory. I can compile "in-memory" as the above mentioned link suggests but then I won't be able to "unload" my custom assembly from the current AppDomain. After a while that will become a huge memory problem. Is it possible to open a new AppDomain, compile new assembly "in-memory", evaluate some expression or access some member of that assembly inside of that new AppDomain and kill that AppDomain safely when done, all that without saving anything to a hard drive? Thanks in advance for any links, suggestions, etc.

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• Access to bytes array of a Bitmap

  - by Deulis

  1- In Windows CE, I have a Bitmap object in C#. 2- I have a C function in an extern dll that expects as parameters the pointer to a bytes array that represents an image in RGB565 format, width and height. This function will draw on this array of bytes. So I need to pass the byte array pointer of the Bitmap object, but I can find a practical way to get this pointer. One way is convert this Bitmap into a bytes array using a memory stream or something else, but it will create a new bytes array, so I will keep in memory both object, the Bitmap and the bytes array, but I don’t want it because the few available memory, that’s why I need to access to the bytes array of the bitmap object, not create a new bytes array. Anyone can help me?

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• Is it possible to load a file full of binary data into GDB when GDB is debugging a core file?

  - by efunneko

  I am debugging a crash using GDB and a core file. A large portion of the memory space is mmapped into the process. That portion of the memory is not saved into the core file. I have a file that contains all the data in that mmapped memory. I would like to find a way to load the data from that file into GDB at a certain offset so that I can display datastructures within that address space. Is this possible? Note that I have tried the 'restore' command in GDB and it does not work when debugging a core file. Perhaps there are tools that allow a core file to have additional data appended to it?

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• static effect on python

  - by fatai

  how we can construct static effect on python instead of using class and global ? not like that one : global a a = [] #simple ex ; fonk ( a , b , d) x = 1 a.append ( x) EDIT: I want to create temporary memory , if I exit the function namely fonk , I want to save change as list on temporary memory . We can do that demand only put static keyword in front of data type but in python , we dont have static, so I want that effect in python . Therefore , how can I do ? As above code say "a" represents temporary memory

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• C++ Singleton design pattern

  - by Artem Barger

  Recently I've bumped into a realization/implementation of the Singleton design pattern for C++. It has looked like this (I have adopted it from the real life example): // a lot of methods are omitted here class Singleton { public: static Singleton* getInstance( ); ~Singleton( ); private: Singleton( ); static Singleton* instance; }; From this declaration I can deduce that the instance field is initiated on the heap. That means there is a memory allocation. What is completely unclear for me is when exactly the memory is going to be deallocated? Or is there a bug and memory leak? It seems like there is a problem in the implementation. My main question is, how do I implement it in the right way?

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• Using sizeof with a dynamically allocated array

  - by robUK

  Hello, gcc 4.4.1 c89 I have the following code snippet: #include <stdlib.h> #include <stdio.h> char *buffer = malloc(10240); /* Check for memory error */ if(!buffer) { fprintf(stderr, "Memory error\n"); return 1; } printf("sizeof(buffer) [ %d ]\n", sizeof(buffer)); However, the sizeof(buffer) always prints 4. I know that a char* is only 4 bytes. However, I have allocated the memory for 10kb. So shouldn't the size be 10240? I am wondering am I thinking right here? Many thanks for any suggestions,

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• How is the implicit segment register of a near pointer determined?

  - by Daniel Trebbien

  In section 4.3 of Intel 64® and IA-32 Architectures Software Developer's Manual. Volume 1: Basic Architecture, it says: A near pointer is a 32-bit offset ... within a segment. Near pointers are used for all memory references in a flat memory model or for references in a segmented model where the identity of the segment being accessed is implied. This leads me to wondering: how is the implied segment register determined? I know that (%eip) and displaced (%eip) (e.g. -4(%eip)) addresses use %cs by default, and that (%esp) and displaced (%esp) addresses use %ss, but what about (%eax), (%edx), (%edi), (%ebp) etc., and can the implicit segment register depend also on the instruction that the memory address operand appears in?

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• Secure way to run other people code (sandbox) on my server?

  - by amikazmi

  I want to make a web service that run other people code locally... Naturally, I want to limit their code access to certain "sandbox" directory, and that they wont be able to connect to other parts of my server (DB, main webserver, etc) Whats the best way to do it? Run VMware/Virtualbox: (+) I guess it's as secure as it gets.. even if someone manage to "hack".. they only hack the guest machine (+) can limit the cpu & memory the process uses (+) easy to setup.. just create the VM (-) harder to "connect" the sandbox directory from the host to the guest (-) wasting extra memory and cpu for managing the VM Run underprivileged user: (+) doesnt waste extra resources (+) sandbox directory is just a plain directory (?) cant limit cpu and memory? (?) dont know if it's secure enough... Any other way? Server running Fedora Core 8, the "other" codes written in Java & C++

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• Can I play any Buffer only once at a given time?

  - by mystify

  From the OpenAL documentation: The basic OpenAL objects are a Listener, a Source, and a Buffer. There can be a large number of Buffers, which contain audio data. Each buffer can be attached to one or more Sources My problem is, that I have one sound file which I need to play multiple times per second, at the same time. The sound is 2 seconds long. So it will overlap. Would I need multiple filled buffers for this (= multiple times that sound in memory)? If I would attach one Buffer to multiple Sources, would I be able to play the sound 10 times, overlapping itself, with just one copy in memory? Or would I still have to deal with 10 copies of that sound in memory?

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• Why hashCode() returns the same value for a object in all consecutive executions?

  - by Vijay Shanker

  Hi, I am trying some code around object equality in java. As I have read somewhere hashCode() is a number which is generated by applying the hash function. Hash Function can be different for each object but can also be same. At the object level, it returns the memory address of the object. Now, I have sample program, which I run 10 times, consecutively. Every time i run the program I get the same value as hash code. If hashCode() function returns the memory location for the object, how come the java(JVM) store the object at same memory address in the consecutive runs? Can you please give me some insight and your view over this issue?

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• DirectX works for 64-bit but not 32-bit

  - by dtbarne

  I'm trying to play a game (Civilization 5) which was previously working but no longer. I believe I've narrowed it down to a DirectX issue because I get an error running dxdiag.exe in 32 bit mode. My goal (at least I believe) is to get Direct3D Acceleration "Enabled" in dxdiag (as it is in 64 bit dxdiag). A very similar issue is here: http://answers.microsoft.com/en-us/windows/forum/windows_7-gaming/direct3d-acceleration-is-not-available-in-windows/4c345e6e-dc68-e011-8dfc-68b599b31bf5?page=1 The proposed answer, which looks very promising, doesn't seem to work for me. Like other users in that thread, HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Direct3D\Drivers does not have a SoftwareOnly key to change. I even tried manually adding it as a string and dword, to no avail. I have a NVIDIA GeForce GT 525M, and before you ask, yes I've tried updating (also uninstalling, reinstalling) my drivers. I've also tried doing the same with DirectX (and Civilization 5 for that matter). Been debugging for some 4+ hours now after a full day of work and I've run out of ideas. I'm hoping somebody knows the solution here! :) Here's what I see when I open dxdiag: DxDiag has detected that there mgiht have been a problem accessing Direct3D the last time this program was used. Would you like to bypass Direct3D this time? No - Crash Yes - Works, but in Display tab: DirectDraw Acceleration: Disabled Direct3D Acceleration: Not Available AGP Texture Acceleration: Not Available If I click "Run 64-bit DxDiag", all three are "Enabled". I should also note that I've tried the following steps as Microsoft suggests, but I'm not able to do so as the "Change Settings" button is disabled. Some programs run very slowly—or not at all—unless Microsoft DirectDraw or Direct3D hardware acceleration is turned on. To determine this, click the Display tab, and then under DirectX Features, check to see whether DirectDraw, Direct3D, and AGP Texture Acceleration appear as Enabled. If not, try turning on hardware acceleration. Click to open Screen Resolution. Click Advanced settings. Click the Troubleshoot tab, and then click Change settings. If you're prompted for an administrator password or confirmation, type the password or provide confirmation. Move the Hardware Acceleration slider to Full. Full dxdiag dump: ------------------ System Information ------------------ Time of this report: 11/8/2012, 23:13:24 Machine name: DTBARNE Operating System: Windows 7 Professional 64-bit (6.1, Build 7601) Service Pack 1 (7601.win7sp1_gdr.120830-0333) Language: English (Regional Setting: English) System Manufacturer: Dell Inc. System Model: Dell System XPS L502X BIOS: Default System BIOS Processor: Intel(R) Core(TM) i5-2450M CPU @ 2.50GHz (4 CPUs), ~2.5GHz Memory: 8192MB RAM Available OS Memory: 8086MB RAM Page File: 2466MB used, 13704MB available Windows Dir: C:\Windows DirectX Version: DirectX 11 DX Setup Parameters: Not found User DPI Setting: Using System DPI System DPI Setting: 96 DPI (100 percent) DWM DPI Scaling: Disabled DxDiag Version: 6.01.7601.17514 32bit Unicode DxDiag Previously: Crashed in Direct3D (stage 2). Re-running DxDiag with "dontskip" command line parameter or choosing not to bypass information gathering when prompted might result in DxDiag successfully obtaining this information ------------ DxDiag Notes ------------ Display Tab 1: No problems found. Sound Tab 1: No problems found. Sound Tab 2: No problems found. Input Tab: No problems found. -------------------- DirectX Debug Levels -------------------- Direct3D: 0/4 (retail) DirectDraw: 0/4 (retail) DirectInput: 0/5 (retail) DirectMusic: 0/5 (retail) DirectPlay: 0/9 (retail) DirectSound: 0/5 (retail) DirectShow: 0/6 (retail) --------------- Display Devices --------------- Card name: Intel(R) HD Graphics 3000 Manufacturer: Chip type: DAC type: Device Key: Enum\PCI\VEN_8086&DEV_0126&SUBSYS_04B61028&REV_09 Display Memory: Dedicated Memory: n/a Shared Memory: n/a Current Mode: 1920 x 1080 (32 bit) (60Hz) Monitor Name: Generic PnP Monitor Monitor Model: Monitor Id: Native Mode: Output Type: Driver Name: Driver File Version: () Driver Version: DDI Version: Driver Model: WDDM 1.1 Driver Attributes: Final Retail Driver Date/Size: , 0 bytes WHQL Logo'd: n/a WHQL Date Stamp: n/a Device Identifier: Vendor ID: Device ID: SubSys ID: Revision ID: Driver Strong Name: oem11.inf:IntelGfx.NTamd64.6.0:iSNBM0:8.15.10.2696:pci\ven_8086&dev_0126&subsys_04b61028 Rank Of Driver: 00E60001 Video Accel: Deinterlace Caps: n/a D3D9 Overlay: DXVA-HD: DDraw Status: Disabled D3D Status: Not Available AGP Status: Not Available ------------- Sound Devices ------------- Description: Speakers (High Definition Audio Device) Default Sound Playback: Yes Default Voice Playback: Yes Hardware ID: HDAUDIO\FUNC_01&VEN_10EC&DEV_0665&SUBSYS_102804B6&REV_1000 Manufacturer ID: 1 Product ID: 65535 Type: WDM Driver Name: HdAudio.sys Driver Version: 6.01.7601.17514 (English) Driver Attributes: Final Retail WHQL Logo'd: Yes Date and Size: 11/20/2010 22:23:47, 350208 bytes Other Files: Driver Provider: Microsoft HW Accel Level: Basic Cap Flags: 0xF1F Min/Max Sample Rate: 100, 200000 Static/Strm HW Mix Bufs: 1, 0 Static/Strm HW 3D Bufs: 0, 0 HW Memory: 0 Voice Management: No EAX(tm) 2.0 Listen/Src: No, No I3DL2(tm) Listen/Src: No, No Sensaura(tm) ZoomFX(tm): No Description: Digital Audio (S/PDIF) (High Definition Audio Device) Default Sound Playback: No Default Voice Playback: No Hardware ID: HDAUDIO\FUNC_01&VEN_10EC&DEV_0665&SUBSYS_102804B6&REV_1000 Manufacturer ID: 1 Product ID: 65535 Type: WDM Driver Name: HdAudio.sys Driver Version: 6.01.7601.17514 (English) Driver Attributes: Final Retail WHQL Logo'd: Yes Date and Size: 11/20/2010 22:23:47, 350208 bytes Other Files: Driver Provider: Microsoft HW Accel Level: Basic Cap Flags: 0xF1F Min/Max Sample Rate: 100, 200000 Static/Strm HW Mix Bufs: 1, 0 Static/Strm HW 3D Bufs: 0, 0 HW Memory: 0 Voice Management: No EAX(tm) 2.0 Listen/Src: No, No I3DL2(tm) Listen/Src: No, No Sensaura(tm) ZoomFX(tm): No --------------------- Sound Capture Devices --------------------- Description: Microphone (High Definition Audio Device) Default Sound Capture: Yes Default Voice Capture: Yes Driver Name: HdAudio.sys Driver Version: 6.01.7601.17514 (English) Driver Attributes: Final Retail Date and Size: 11/20/2010 22:23:47, 350208 bytes Cap Flags: 0x1 Format Flags: 0xFFFFF ------------------- DirectInput Devices ------------------- Device Name: Mouse Attached: 1 Controller ID: n/a Vendor/Product ID: n/a FF Driver: n/a Device Name: Keyboard Attached: 1 Controller ID: n/a Vendor/Product ID: n/a FF Driver: n/a Poll w/ Interrupt: No ----------- USB Devices ----------- + USB Root Hub | Vendor/Product ID: 0x8086, 0x1C26 | Matching Device ID: usb\root_hub20 | Service: usbhub | +-+ Generic USB Hub | | Vendor/Product ID: 0x8087, 0x0024 | | Location: Port_#0001.Hub_#0002 | | Matching Device ID: usb\class_09 | | Service: usbhub ---------------- Gameport Devices ---------------- ------------ PS/2 Devices ------------ + Standard PS/2 Keyboard | Matching Device ID: *pnp0303 | Service: i8042prt | + Terminal Server Keyboard Driver | Matching Device ID: root\rdp_kbd | Upper Filters: kbdclass | Service: TermDD | + Synaptics PS/2 Port TouchPad | Matching Device ID: *dll04b6 | Upper Filters: SynTP | Service: i8042prt | + Terminal Server Mouse Driver | Matching Device ID: root\rdp_mou | Upper Filters: mouclass | Service: TermDD ------------------------ Disk & DVD/CD-ROM Drives ------------------------ Drive: C: Free Space: 26.2 GB Total Space: 122.0 GB File System: NTFS Model: M4-CT128M4SSD2 ATA Device Drive: D: Model: Optiarc DVDRWBD BC-5540H ATA Device Driver: c:\windows\system32\drivers\cdrom.sys, 6.01.7601.17514 (English), , 0 bytes -------------- System Devices -------------- Name: High Definition Audio Controller Device ID: PCI\VEN_8086&DEV_1C20&SUBSYS_04B61028&REV_05\3&11583659&0&D8 Driver: n/a Name: PCI standard host CPU bridge Device ID: PCI\VEN_8086&DEV_0104&SUBSYS_04B61028&REV_09\3&11583659&0&00 Driver: n/a Name: PCI standard PCI-to-PCI bridge Device ID: PCI\VEN_8086&DEV_1C1A&SUBSYS_04B61028&REV_B5\3&11583659&0&E5 Driver: n/a Name: PCI standard PCI-to-PCI bridge Device ID: PCI\VEN_8086&DEV_0101&SUBSYS_20108086&REV_09\3&11583659&0&08 Driver: n/a Name: PCI standard PCI-to-PCI bridge Device ID: PCI\VEN_8086&DEV_1C18&SUBSYS_04B61028&REV_B5\3&11583659&0&E4 Driver: n/a Name: Intel(R) Centrino(R) Advanced-N 6230 Device ID: PCI\VEN_8086&DEV_0091&SUBSYS_52218086&REV_34\4&2634DE8D&0&00E1 Driver: n/a Name: PCI standard ISA bridge Device ID: PCI\VEN_8086&DEV_1C4B&SUBSYS_04B61028&REV_05\3&11583659&0&F8 Driver: n/a Name: PCI standard PCI-to-PCI bridge Device ID: PCI\VEN_8086&DEV_1C16&SUBSYS_04B61028&REV_B5\3&11583659&0&E3 Driver: n/a Name: Realtek PCIe GBE Family Controller Device ID: PCI\VEN_10EC&DEV_8168&SUBSYS_04B61028&REV_06\4&109EAB2F&0&00E5 Driver: n/a Name: Intel(R) Management Engine Interface Device ID: PCI\VEN_8086&DEV_1C3A&SUBSYS_04B61028&REV_04\3&11583659&0&B0 Driver: n/a Name: PCI standard PCI-to-PCI bridge Device ID: PCI\VEN_8086&DEV_1C12&SUBSYS_04B61028&REV_B5\3&11583659&0&E1 Driver: n/a Name: NVIDIA GeForce GT 525M Device ID: PCI\VEN_10DE&DEV_0DF5&SUBSYS_04B61028&REV_A1\4&4DCA75F&0&0008 Driver: n/a Name: Standard Enhanced PCI to USB Host Controller Device ID: PCI\VEN_8086&DEV_1C2D&SUBSYS_04B61028&REV_05\3&11583659&0&D0 Driver: n/a Name: PCI standard PCI-to-PCI bridge Device ID: PCI\VEN_8086&DEV_1C10&SUBSYS_04B61028&REV_B5\3&11583659&0&E0 Driver: n/a Name: Standard Enhanced PCI to USB Host Controller Device ID: PCI\VEN_8086&DEV_1C26&SUBSYS_04B61028&REV_05\3&11583659&0&E8 Driver: n/a Name: Standard AHCI 1.0 Serial ATA Controller Device ID: PCI\VEN_8086&DEV_1C03&SUBSYS_04B61028&REV_05\3&11583659&0&FA Driver: n/a Name: SM Bus Controller Device ID: PCI\VEN_8086&DEV_1C22&SUBSYS_04B61028&REV_05\3&11583659&0&FB Driver: n/a Name: Intel(R) HD Graphics 3000 Device ID: PCI\VEN_8086&DEV_0126&SUBSYS_04B61028&REV_09\3&11583659&0&10 Driver: n/a Name: Renesas Electronics USB 3.0 Host Controller Device ID: PCI\VEN_1033&DEV_0194&SUBSYS_04B61028&REV_04\4&3494AC3A&0&00E3 Driver: n/a ------------------ DirectShow Filters ------------------ DirectShow Filters: WMAudio Decoder DMO,0x00800800,1,1,WMADMOD.DLL,6.01.7601.17514 WMAPro over S/PDIF DMO,0x00600800,1,1,WMADMOD.DLL,6.01.7601.17514 WMSpeech Decoder DMO,0x00600800,1,1,WMSPDMOD.DLL,6.01.7601.17514 MP3 Decoder DMO,0x00600800,1,1,mp3dmod.dll,6.01.7600.16385 Mpeg4s Decoder DMO,0x00800001,1,1,mp4sdecd.dll,6.01.7600.16385 WMV Screen decoder DMO,0x00600800,1,1,wmvsdecd.dll,6.01.7601.17514 WMVideo Decoder DMO,0x00800001,1,1,wmvdecod.dll,6.01.7601.17514 Mpeg43 Decoder DMO,0x00800001,1,1,mp43decd.dll,6.01.7600.16385 Mpeg4 Decoder DMO,0x00800001,1,1,mpg4decd.dll,6.01.7600.16385 DV Muxer,0x00400000,0,0,qdv.dll,6.06.7601.17514 Color Space Converter,0x00400001,1,1,quartz.dll,6.06.7601.17713 WM ASF Reader,0x00400000,0,0,qasf.dll,12.00.7601.17514 Screen Capture filter,0x00200000,0,1,wmpsrcwp.dll,12.00.7601.17514 AVI Splitter,0x00600000,1,1,quartz.dll,6.06.7601.17713 VGA 16 Color Ditherer,0x00400000,1,1,quartz.dll,6.06.7601.17713 SBE2MediaTypeProfile,0x00200000,0,0,sbe.dll,6.06.7601.17528 Microsoft DTV-DVD Video Decoder,0x005fffff,2,4,msmpeg2vdec.dll,6.01.7140.0000 AC3 Parser Filter,0x00600000,1,1,mpg2splt.ax,6.06.7601.17528 StreamBufferSink,0x00200000,0,0,sbe.dll,6.06.7601.17528 MJPEG Decompressor,0x00600000,1,1,quartz.dll,6.06.7601.17713 MPEG-I Stream Splitter,0x00600000,1,2,quartz.dll,6.06.7601.17713 SAMI (CC) Parser,0x00400000,1,1,quartz.dll,6.06.7601.17713 VBI Codec,0x00600000,1,4,VBICodec.ax,6.06.7601.17514 MPEG-2 Splitter,0x005fffff,1,0,mpg2splt.ax,6.06.7601.17528 Closed Captions Analysis Filter,0x00200000,2,5,cca.dll,6.06.7601.17514 SBE2FileScan,0x00200000,0,0,sbe.dll,6.06.7601.17528 Microsoft MPEG-2 Video Encoder,0x00200000,1,1,msmpeg2enc.dll,6.01.7601.17514 Internal Script Command Renderer,0x00800001,1,0,quartz.dll,6.06.7601.17713 MPEG Audio Decoder,0x03680001,1,1,quartz.dll,6.06.7601.17713 DV Splitter,0x00600000,1,2,qdv.dll,6.06.7601.17514 Video Mixing Renderer 9,0x00200000,1,0,quartz.dll,6.06.7601.17713 Microsoft MPEG-2 Encoder,0x00200000,2,1,msmpeg2enc.dll,6.01.7601.17514 ACM Wrapper,0x00600000,1,1,quartz.dll,6.06.7601.17713 Video Renderer,0x00800001,1,0,quartz.dll,6.06.7601.17713 MPEG-2 Video Stream Analyzer,0x00200000,0,0,sbe.dll,6.06.7601.17528 Line 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SampleGrabber,0x00200000,1,1,qedit.dll,6.06.7601.17514 Null Renderer,0x00200000,1,0,qedit.dll,6.06.7601.17514 MPEG-2 Sections and Tables,0x005fffff,1,0,Mpeg2Data.ax,6.06.7601.17514 Microsoft AC3 Encoder,0x00200000,1,1,msac3enc.dll,6.01.7601.17514 StreamBufferSource,0x00200000,0,0,sbe.dll,6.06.7601.17528 Smart Tee,0x00200000,1,2,qcap.dll,6.06.7601.17514 Overlay Mixer,0x00200000,0,0,qdvd.dll,6.06.7601.17835 AVI Decompressor,0x00600000,1,1,quartz.dll,6.06.7601.17713 AVI/WAV File Source,0x00400000,0,2,quartz.dll,6.06.7601.17713 Wave Parser,0x00400000,1,1,quartz.dll,6.06.7601.17713 MIDI Parser,0x00400000,1,1,quartz.dll,6.06.7601.17713 Multi-file Parser,0x00400000,1,1,quartz.dll,6.06.7601.17713 File stream renderer,0x00400000,1,1,quartz.dll,6.06.7601.17713 Microsoft DTV-DVD Audio Decoder,0x005fffff,1,1,msmpeg2adec.dll,6.01.7140.0000 StreamBufferSink2,0x00200000,0,0,sbe.dll,6.06.7601.17528 AVI Mux,0x00200000,1,0,qcap.dll,6.06.7601.17514 Line 21 Decoder 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IYUV codec,0x00200000,1,1,qcap.dll,6.06.7601.17514 Microsoft RLE,0x00200000,1,1,qcap.dll,6.06.7601.17514 Microsoft Video 1,0x00200000,1,1,qcap.dll,6.06.7601.17514 Audio Compressors: WM Speech Encoder DMO,0x00600800,1,1,WMSPDMOE.DLL,6.01.7600.16385 WMAudio Encoder DMO,0x00600800,1,1,WMADMOE.DLL,6.01.7600.16385 IMA ADPCM,0x00200000,1,1,quartz.dll,6.06.7601.17713 PCM,0x00200000,1,1,quartz.dll,6.06.7601.17713 Microsoft ADPCM,0x00200000,1,1,quartz.dll,6.06.7601.17713 GSM 6.10,0x00200000,1,1,quartz.dll,6.06.7601.17713 CCITT A-Law,0x00200000,1,1,quartz.dll,6.06.7601.17713 CCITT u-Law,0x00200000,1,1,quartz.dll,6.06.7601.17713 MPEG Layer-3,0x00200000,1,1,quartz.dll,6.06.7601.17713 Audio Capture Sources: Microphone (High Definition Aud,0x00200000,0,0,qcap.dll,6.06.7601.17514 PBDA CP Filters: PBDA DTFilter,0x00600000,1,1,CPFilters.dll,6.06.7601.17528 PBDA ETFilter,0x00200000,0,0,CPFilters.dll,6.06.7601.17528 PBDA PTFilter,0x00200000,0,0,CPFilters.dll,6.06.7601.17528 Midi Renderers: Default MidiOut Device,0x00800000,1,0,quartz.dll,6.06.7601.17713 Microsoft GS Wavetable Synth,0x00200000,1,0,quartz.dll,6.06.7601.17713 WDM Streaming Capture Devices: HD Audio Microphone 2,0x00200000,1,1,ksproxy.ax,6.01.7601.17514 Integrated Webcam,0x00200000,1,2,ksproxy.ax,6.01.7601.17514 WDM Streaming Rendering Devices: HD Audio Headphone/Speakers,0x00200000,1,1,ksproxy.ax,6.01.7601.17514 HD Audio SPDIF out,0x00200000,1,1,ksproxy.ax,6.01.7601.17514 BDA Network Providers: Microsoft ATSC Network Provider,0x00200000,0,1,MSDvbNP.ax,6.06.7601.17514 Microsoft DVBC Network Provider,0x00200000,0,1,MSDvbNP.ax,6.06.7601.17514 Microsoft DVBS Network Provider,0x00200000,0,1,MSDvbNP.ax,6.06.7601.17514 Microsoft DVBT Network Provider,0x00200000,0,1,MSDvbNP.ax,6.06.7601.17514 Microsoft Network Provider,0x00200000,0,1,MSNP.ax,6.06.7601.17514 Video Capture Sources: Integrated Webcam,0x00200000,1,2,ksproxy.ax,6.01.7601.17514 Multi-Instance Capable VBI Codecs: VBI 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Speakers (High Definition Audio Device),0x00200000,1,0,quartz.dll,6.06.7601.17713 --------------- EVR Power Information --------------- Current Setting: {651288E5-A7ED-4076-A96B-6CC62D848FE1} (Balanced) Quality Flags: 2576 Enabled: Force throttling Allow half deinterlace Allow scaling Decode Power Usage: 100 Balanced Flags: 1424 Enabled: Force throttling Allow batching Force half deinterlace Force scaling Decode Power Usage: 50 PowerFlags: 1424 Enabled: Force throttling Allow batching Force half deinterlace Force scaling Decode Power Usage: 0

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• How to fix “The requested service, ‘net.pipe://localhost/SecurityTokenServiceApplication/appsts.svc’ could not be activated.”

  - by ybbest

  Problem: When I try to publish a SharePoint2013 workflow, I received the error: The requested service, ‘net.pipe://localhost/SecurityTokenServiceApplication/appsts.svc’ could not be activated. After that, my workflow stopped working and every time I start a work I receive the following error message: System.ApplicationException: PreconditionFailed ---> System.ApplicationException: Error in the application. --- End of inner exception stack trace --- at System.Activities.Statements.Throw.Execute(CodeActivityContext context) at System.Activities.CodeActivity.InternalExecute(ActivityInstance instance, ActivityExecutor executor, BookmarkManager bookmarkManager) at System.Activities.Runtime.ActivityExecutor.ExecuteActivityWorkItem.ExecuteBody(ActivityExecutor executor, BookmarkManager bookmarkManager, Location resultLocation) Analysis: After analysis, I found the error by visiting the http://localhost:32843/SecurityTokenServiceApplication/securitytoken.svc and the error I got on the message is                                                                                                                                              Solution: The solution is basically getting more memory to the server. For development environment, you can restart your noderunner.exe or some other services to release some memories. To verify you have enough memory    you can browse to http://localhost:32843/SecurityTokenServiceApplication/securitytoken.svc , it should return the information below. Then you can republish your workflow and it will work like a charm.

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• Linux-Containers — Part 1: Overview

  - by Lenz Grimmer

  "Containers" by Jean-Pierre Martineau (CC BY-NC-SA 2.0). Linux Containers (LXC) provide a means to isolate individual services or applications as well as of a complete Linux operating system from other services running on the same host. To accomplish this, each container gets its own directory structure, network devices, IP addresses and process table. The processes running in other containers or the host system are not visible from inside a container. Additionally, Linux Containers allow for fine granular control of resources like RAM, CPU or disk I/O. Generally speaking, Linux Containers use a completely different approach than "classicial" virtualization technologies like KVM or Xen (on which Oracle VM Server for x86 is based on). An application running inside a container will be executed directly on the operating system kernel of the host system, shielded from all other running processes in a sandbox-like environment. This allows a very direct and fair distribution of CPU and I/O-resources. Linux containers can offer the best possible performance and several possibilities for managing and sharing the resources available. Similar to Containers (or Zones) on Oracle Solaris or FreeBSD jails, the same kernel version runs on the host as well as in the containers; it is not possible to run different Linux kernel versions or other operating systems like Microsoft Windows or Oracle Solaris for x86 inside a container. However, it is possible to run different Linux distribution versions (e.g. Fedora Linux in a container on top of an Oracle Linux host), provided it supports the version of the Linux kernel that runs on the host. This approach has one caveat, though - if any of the containers causes a kernel crash, it will bring down all other containers (and the host system) as well. For example, Oracle's Unbreakable Enterprise Kernel Release 2 (2.6.39) is supported for both Oracle Linux 5 and 6. This makes it possible to run Oracle Linux 5 and 6 container instances on top of an Oracle Linux 6 system. Since Linux Containers are fully implemented on the OS level (the Linux kernel), they can be easily combined with other virtualization technologies. It's certainly possible to set up Linux containers within a virtualized Linux instance that runs inside Oracle VM Server for Oracle VM Virtualbox. Some use cases for Linux Containers include: Consolidation of multiple separate Linux systems on one server: instances of Linux systems that are not performance-critical or only see sporadic use (e.g. a fax or print server or intranet services) do not necessarily need a dedicated server for their operations. These can easily be consolidated to run inside containers on a single server, to preserve energy and rack space. Running multiple instances of an application in parallel, e.g. for different users or customers. Each user receives his "own" application instance, with a defined level of service/performance. This prevents that one user's application could hog the entire system and ensures, that each user only has access to his own data set. It also helps to save main memory — if multiple instances of a same process are running, the Linux kernel can share memory pages that are identical and unchanged across all application instances. This also applies to shared libraries that applications may use, they are generally held in memory once and mapped to multiple processes. Quickly creating sandbox environments for development and testing purposes: containers that have been created and configured once can be archived as templates and can be duplicated (cloned) instantly on demand. After finishing the activity, the clone can safely be discarded. This allows to provide repeatable software builds and test environments, because the system will always be reset to its initial state for each run. Linux Containers also boot significantly faster than "classic" virtual machines, which can save a lot of time when running frequent build or test runs on applications. Safe execution of an individual application: if an application running inside a container has been compromised because of a security vulnerability, the host system and other containers remain unaffected. The potential damage can be minimized, analyzed and resolved directly from the host system. Note: Linux Containers on Oracle Linux 6 with the Unbreakable Enterprise Kernel Release 2 (2.6.39) are still marked as Technology Preview - their use is only recommended for testing and evaluation purposes. The Open-Source project "Linux Containers" (LXC) is driving the development of the technology behind this, which is based on the "Control Groups" (CGroups) and "Name Spaces" functionality of the Linux kernel. Oracle is actively involved in the Linux Containers development and contributes patches to the upstream LXC code base. Control Groups provide means to manage and monitor the allocation of resources for individual processes or process groups. Among other things, you can restrict the maximum amount of memory, CPU cycles as well as the disk and network throughput (in MB/s or IOP/s) that are available for an application. Name Spaces help to isolate process groups from each other, e.g. the visibility of other running processes or the exclusive access to a network device. It's also possible to restrict a process group's access and visibility of the entire file system hierarchy (similar to a classic "chroot" environment). CGroups and Name Spaces provide the foundation on which Linux containers are based on, but they can actually be used independently as well. A more detailed description of how Linux Containers can be created and managed on Oracle Linux will be explained in the second part of this article. Additional links related to Linux Containers: OTN Article: The Role of Oracle Solaris Zones and Linux Containers in a Virtualization Strategy Linux Containers on Wikipedia - Lenz Grimmer Follow me on: Personal Blog | Facebook | Twitter | Linux Blog |

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• Heaps of Trouble?

  - by Paul White NZ

  If you’re not already a regular reader of Brad Schulz’s blog, you’re missing out on some great material.  In his latest entry, he is tasked with optimizing a query run against tables that have no indexes at all.  The problem is, predictably, that performance is not very good.  The catch is that we are not allowed to create any indexes (or even new statistics) as part of our optimization efforts. In this post, I’m going to look at the problem from a slightly different angle, and present an alternative solution to the one Brad found.  Inevitably, there’s going to be some overlap between our entries, and while you don’t necessarily need to read Brad’s post before this one, I do strongly recommend that you read it at some stage; he covers some important points that I won’t cover again here. The Example We’ll use data from the AdventureWorks database, copied to temporary unindexed tables.  A script to create these structures is shown below: CREATE TABLE #Custs ( CustomerID INTEGER NOT NULL, TerritoryID INTEGER NULL, CustomerType NCHAR(1) COLLATE SQL_Latin1_General_CP1_CI_AI NOT NULL, ); GO CREATE TABLE #Prods ( ProductMainID INTEGER NOT NULL, ProductSubID INTEGER NOT NULL, ProductSubSubID INTEGER NOT NULL, Name NVARCHAR(50) COLLATE SQL_Latin1_General_CP1_CI_AI NOT NULL, ); GO CREATE TABLE #OrdHeader ( SalesOrderID INTEGER NOT NULL, OrderDate DATETIME NOT NULL, SalesOrderNumber NVARCHAR(25) COLLATE SQL_Latin1_General_CP1_CI_AI NOT NULL, CustomerID INTEGER NOT NULL, ); GO CREATE TABLE #OrdDetail ( SalesOrderID INTEGER NOT NULL, OrderQty SMALLINT NOT NULL, LineTotal NUMERIC(38,6) NOT NULL, ProductMainID INTEGER NOT NULL, ProductSubID INTEGER NOT NULL, ProductSubSubID INTEGER NOT NULL, ); GO INSERT #Custs ( CustomerID, TerritoryID, CustomerType ) SELECT C.CustomerID, C.TerritoryID, C.CustomerType FROM AdventureWorks.Sales.Customer C WITH (TABLOCK); GO INSERT #Prods ( ProductMainID, ProductSubID, ProductSubSubID, Name ) SELECT P.ProductID, P.ProductID, P.ProductID, P.Name FROM AdventureWorks.Production.Product P WITH (TABLOCK); GO INSERT #OrdHeader ( SalesOrderID, OrderDate, SalesOrderNumber, CustomerID ) SELECT H.SalesOrderID, H.OrderDate, H.SalesOrderNumber, H.CustomerID FROM AdventureWorks.Sales.SalesOrderHeader H WITH (TABLOCK); GO INSERT #OrdDetail ( SalesOrderID, OrderQty, LineTotal, ProductMainID, ProductSubID, ProductSubSubID ) SELECT D.SalesOrderID, D.OrderQty, D.LineTotal, D.ProductID, D.ProductID, D.ProductID FROM AdventureWorks.Sales.SalesOrderDetail D WITH (TABLOCK); The query itself is a simple join of the four tables: SELECT P.ProductMainID AS PID, P.Name, D.OrderQty, H.SalesOrderNumber, H.OrderDate, C.TerritoryID FROM #Prods P JOIN #OrdDetail D ON P.ProductMainID = D.ProductMainID AND P.ProductSubID = D.ProductSubID AND P.ProductSubSubID = D.ProductSubSubID JOIN #OrdHeader H ON D.SalesOrderID = H.SalesOrderID JOIN #Custs C ON H.CustomerID = C.CustomerID ORDER BY P.ProductMainID ASC OPTION (RECOMPILE, MAXDOP 1); Remember that these tables have no indexes at all, and only the single-column sampled statistics SQL Server automatically creates (assuming default settings).  The estimated query plan produced for the test query looks like this (click to enlarge): The Problem The problem here is one of cardinality estimation – the number of rows SQL Server expects to find at each step of the plan.  The lack of indexes and useful statistical information means that SQL Server does not have the information it needs to make a good estimate.  Every join in the plan shown above estimates that it will produce just a single row as output.  Brad covers the factors that lead to the low estimates in his post. In reality, the join between the #Prods and #OrdDetail tables will produce 121,317 rows.  It should not surprise you that this has rather dire consequences for the remainder of the query plan.  In particular, it makes a nonsense of the optimizer’s decision to use Nested Loops to join to the two remaining tables.  Instead of scanning the #OrdHeader and #Custs tables once (as it expected), it has to perform 121,317 full scans of each.  The query takes somewhere in the region of twenty minutes to run to completion on my development machine. A Solution At this point, you may be thinking the same thing I was: if we really are stuck with no indexes, the best we can do is to use hash joins everywhere. We can force the exclusive use of hash joins in several ways, the two most common being join and query hints.  A join hint means writing the query using the INNER HASH JOIN syntax; using a query hint involves adding OPTION (HASH JOIN) at the bottom of the query.  The difference is that using join hints also forces the order of the join, whereas the query hint gives the optimizer freedom to reorder the joins at its discretion. Adding the OPTION (HASH JOIN) hint results in this estimated plan: That produces the correct output in around seven seconds, which is quite an improvement!  As a purely practical matter, and given the rigid rules of the environment we find ourselves in, we might leave things there.  (We can improve the hashing solution a bit – I’ll come back to that later on). Faster Nested Loops It might surprise you to hear that we can beat the performance of the hash join solution shown above using nested loops joins exclusively, and without breaking the rules we have been set. The key to this part is to realize that a condition like (A = B) can be expressed as (A <= B) AND (A >= B).  Armed with this tremendous new insight, we can rewrite the join predicates like so: SELECT P.ProductMainID AS PID, P.Name, D.OrderQty, H.SalesOrderNumber, H.OrderDate, C.TerritoryID FROM #OrdDetail D JOIN #OrdHeader H ON D.SalesOrderID >= H.SalesOrderID AND D.SalesOrderID <= H.SalesOrderID JOIN #Custs C ON H.CustomerID >= C.CustomerID AND H.CustomerID <= C.CustomerID JOIN #Prods P ON P.ProductMainID >= D.ProductMainID AND P.ProductMainID <= D.ProductMainID AND P.ProductSubID = D.ProductSubID AND P.ProductSubSubID = D.ProductSubSubID ORDER BY D.ProductMainID OPTION (RECOMPILE, LOOP JOIN, MAXDOP 1, FORCE ORDER); I’ve also added LOOP JOIN and FORCE ORDER query hints to ensure that only nested loops joins are used, and that the tables are joined in the order they appear.  The new estimated execution plan is: This new query runs in under 2 seconds. Why Is It Faster? The main reason for the improvement is the appearance of the eager Index Spools, which are also known as index-on-the-fly spools.  If you read my Inside The Optimiser series you might be interested to know that the rule responsible is called JoinToIndexOnTheFly. An eager index spool consumes all rows from the table it sits above, and builds a index suitable for the join to seek on.  Taking the index spool above the #Custs table as an example, it reads all the CustomerID and TerritoryID values with a single scan of the table, and builds an index keyed on CustomerID.  The term ‘eager’ means that the spool consumes all of its input rows when it starts up.  The index is built in a work table in tempdb, has no associated statistics, and only exists until the query finishes executing. The result is that each unindexed table is only scanned once, and just for the columns necessary to build the temporary index.  From that point on, every execution of the inner side of the join is answered by a seek on the temporary index – not the base table. A second optimization is that the sort on ProductMainID (required by the ORDER BY clause) is performed early, on just the rows coming from the #OrdDetail table.  The optimizer has a good estimate for the number of rows it needs to sort at that stage – it is just the cardinality of the table itself.  The accuracy of the estimate there is important because it helps determine the memory grant given to the sort operation.  Nested loops join preserves the order of rows on its outer input, so sorting early is safe.  (Hash joins do not preserve order in this way, of course). The extra lazy spool on the #Prods branch is a further optimization that avoids executing the seek on the temporary index if the value being joined (the ‘outer reference’) hasn’t changed from the last row received on the outer input.  It takes advantage of the fact that rows are still sorted on ProductMainID, so if duplicates exist, they will arrive at the join operator one after the other. The optimizer is quite conservative about introducing index spools into a plan, because creating and dropping a temporary index is a relatively expensive operation.  It’s presence in a plan is often an indication that a useful index is missing. I want to stress that I rewrote the query in this way primarily as an educational exercise – I can’t imagine having to do something so horrible to a production system. Improving the Hash Join I promised I would return to the solution that uses hash joins.  You might be puzzled that SQL Server can create three new indexes (and perform all those nested loops iterations) faster than it can perform three hash joins.  The answer, again, is down to the poor information available to the optimizer.  Let’s look at the hash join plan again: Two of the hash joins have single-row estimates on their build inputs.  SQL Server fixes the amount of memory available for the hash table based on this cardinality estimate, so at run time the hash join very quickly runs out of memory. This results in the join spilling hash buckets to disk, and any rows from the probe input that hash to the spilled buckets also get written to disk.  The join process then continues, and may again run out of memory.  This is a recursive process, which may eventually result in SQL Server resorting to a bailout join algorithm, which is guaranteed to complete eventually, but may be very slow.  The data sizes in the example tables are not large enough to force a hash bailout, but it does result in multiple levels of hash recursion.  You can see this for yourself by tracing the Hash Warning event using the Profiler tool. The final sort in the plan also suffers from a similar problem: it receives very little memory and has to perform multiple sort passes, saving intermediate runs to disk (the Sort Warnings Profiler event can be used to confirm this).  Notice also that because hash joins don’t preserve sort order, the sort cannot be pushed down the plan toward the #OrdDetail table, as in the nested loops plan. Ok, so now we understand the problems, what can we do to fix it?  We can address the hash spilling by forcing a different order for the joins: SELECT P.ProductMainID AS PID, P.Name, D.OrderQty, H.SalesOrderNumber, H.OrderDate, C.TerritoryID FROM #Prods P JOIN #Custs C JOIN #OrdHeader H ON H.CustomerID = C.CustomerID JOIN #OrdDetail D ON D.SalesOrderID = H.SalesOrderID ON P.ProductMainID = D.ProductMainID AND P.ProductSubID = D.ProductSubID AND P.ProductSubSubID = D.ProductSubSubID ORDER BY D.ProductMainID OPTION (MAXDOP 1, HASH JOIN, FORCE ORDER); With this plan, each of the inputs to the hash joins has a good estimate, and no hash recursion occurs.  The final sort still suffers from the one-row estimate problem, and we get a single-pass sort warning as it writes rows to disk.  Even so, the query runs to completion in three or four seconds.  That’s around half the time of the previous hashing solution, but still not as fast as the nested loops trickery. Final Thoughts SQL Server’s optimizer makes cost-based decisions, so it is vital to provide it with accurate information.  We can’t really blame the performance problems highlighted here on anything other than the decision to use completely unindexed tables, and not to allow the creation of additional statistics. I should probably stress that the nested loops solution shown above is not one I would normally contemplate in the real world.  It’s there primarily for its educational and entertainment value.  I might perhaps use it to demonstrate to the sceptical that SQL Server itself is crying out for an index. Be sure to read Brad’s original post for more details.  My grateful thanks to him for granting permission to reuse some of his material. Paul White Email: [email protected] Twitter: @PaulWhiteNZ

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• Option Trading: Getting the most out of the event session options

  - by extended_events

  You can control different aspects of how an event session behaves by setting the event session options as part of the CREATE EVENT SESSION DDL. The default settings for the event session options are designed to handle most of the common event collection situations so I generally recommend that you just use the defaults. Like everything in the real world though, there are going to be a handful of “special cases” that require something different. This post focuses on identifying the special cases and the correct use of the options to accommodate those cases. There is a reason it’s called Default The default session options specify a total event buffer size of 4 MB with a 30 second latency. Translating this into human terms; this means that our default behavior is that the system will start processing events from the event buffer when we reach about 1.3 MB of events or after 30 seconds, which ever comes first. Aside: What’s up with the 1.3 MB, I thought you said the buffer was 4 MB?The Extended Events engine takes the total buffer size specified by MAX_MEMORY (4MB by default) and divides it into 3 equally sized buffers. This is done so that a session can be publishing events to one buffer while other buffers are being processed. There are always at least three buffers; how to get more than three is covered later. Using this configuration, the Extended Events engine can “keep up” with most event sessions on standard workloads. Why is this? The fact is that most events are small, really small; on the order of a couple hundred bytes. Even when you start considering events that carry dynamically sized data (eg. binary, text, etc.) or adding actions that collect additional data, the total size of the event is still likely to be pretty small. This means that each buffer can likely hold thousands of events before it has to be processed. When the event buffers are finally processed there is an economy of scale achieved since most targets support bulk processing of the events so they are processed at the buffer level rather than the individual event level. When all this is working together it’s more likely that a full buffer will be processed and put back into the ready queue before the remaining buffers (remember, there are at least three) are full. I know what you’re going to say: “My server is exceptional! My workload is so massive it defies categorization!” OK, maybe you weren’t going to say that exactly, but you were probably thinking it. The point is that there are situations that won’t be covered by the Default, but that’s a good place to start and this post assumes you’ve started there so that you have something to look at in order to determine if you do have a special case that needs different settings. So let’s get to the special cases… What event just fired?! How about now?! Now?! If you believe the commercial adage from Heinz Ketchup (Heinz Slow Good Ketchup ad on You Tube), some things are worth the wait. This is not a belief held by most DBAs, particularly DBAs who are looking for an answer to a troubleshooting question fast. If you’re one of these anxious DBAs, or maybe just a Program Manager doing a demo, then 30 seconds might be longer than you’re comfortable waiting. If you find yourself in this situation then consider changing the MAX_DISPATCH_LATENCY option for your event session. This option will force the event buffers to be processed based on your time schedule. This option only makes sense for the asynchronous targets since those are the ones where we allow events to build up in the event buffer – if you’re using one of the synchronous targets this option isn’t relevant. Avoid forgotten events by increasing your memory Have you ever had one of those days where you keep forgetting things? That can happen in Extended Events too; we call it dropped events. In order to optimizes for server performance and help ensure that the Extended Events doesn’t block the server if to drop events that can’t be published to a buffer because the buffer is full. You can determine if events are being dropped from a session by querying the dm_xe_sessions DMV and looking at the dropped_event_count field. Aside: Should you care if you’re dropping events?Maybe not – think about why you’re collecting data in the first place and whether you’re really going to miss a few dropped events. For example, if you’re collecting query duration stats over thousands of executions of a query it won’t make a huge difference to miss a couple executions. Use your best judgment. If you find that your session is dropping events it means that the event buffer is not large enough to handle the volume of events that are being published. There are two ways to address this problem. First, you could collect fewer events – examine you session to see if you are over collecting. Do you need all the actions you’ve specified? Could you apply a predicate to be more specific about when you fire the event? Assuming the session is defined correctly, the next option is to change the MAX_MEMORY option to a larger number. Picking the right event buffer size might take some trial and error, but a good place to start is with the number of dropped events compared to the number you’ve collected. Aside: There are three different behaviors for dropping events that you specify using the EVENT_RETENTION_MODE option. The default is to allow single event loss and you should stick with this setting since it is the best choice for keeping the impact on server performance low.You’ll be tempted to use the setting to not lose any events (NO_EVENT_LOSS) – resist this urge since it can result in blocking on the server. If you’re worried that you’re losing events you should be increasing your event buffer memory as described in this section. Some events are too big to fail A less common reason for dropping an event is when an event is so large that it can’t fit into the event buffer. Even though most events are going to be small, you might find a condition that occasionally generates a very large event. You can determine if your session is dropping large events by looking at the dm_xe_sessions DMV once again, this time check the largest_event_dropped_size. If this value is larger than the size of your event buffer [remember, the size of your event buffer, by default, is max_memory / 3] then you need a large event buffer. To specify a large event buffer you set the MAX_EVENT_SIZE option to a value large enough to fit the largest event dropped based on data from the DMV. When you set this option the Extended Events engine will create two buffers of this size to accommodate these large events. As an added bonus (no extra charge) the large event buffer will also be used to store normal events in the cases where the normal event buffers are all full and waiting to be processed. (Note: This is just a side-effect, not the intended use. If you’re dropping many normal events then you should increase your normal event buffer size.) Partitioning: moving your events to a sub-division Earlier I alluded to the fact that you can configure your event session to use more than the standard three event buffers – this is called partitioning and is controlled by the MEMORY_PARTITION_MODE option. The result of setting this option is fairly easy to explain, but knowing when to use it is a bit more art than science. First the science… You can configure partitioning in three ways: None, Per NUMA Node & Per CPU. This specifies the location where sets of event buffers are created with fairly obvious implication. There are rules we follow for sub-dividing the total memory (specified by MAX_MEMORY) between all the event buffers that are specific to the mode used: None: 3 buffers (fixed)Node: 3 * number_of_nodesCPU: 2.5 * number_of_cpus Here are some examples of what this means for different Node/CPU counts: Configuration None Node CPU 2 CPUs, 1 Node 3 buffers 3 buffers 5 buffers 6 CPUs, 2 Node 3 buffers 6 buffers 15 buffers 40 CPUs, 5 Nodes 3 buffers 15 buffers 100 buffers   Aside: Buffer size on multi-processor computersAs the number of Nodes or CPUs increases, the size of the event buffer gets smaller because the total memory is sub-divided into more pieces. The defaults will hold up to this for a while since each buffer set is holding events only from the Node or CPU that it is associated with, but at some point the buffers will get too small and you’ll either see events being dropped or you’ll get an error when you create your session because you’re below the minimum buffer size. Increase the MAX_MEMORY setting to an appropriate number for the configuration. The most likely reason to start partitioning is going to be related to performance. If you notice that running an event session is impacting the performance of your server beyond a reasonably expected level [Yes, there is a reasonably expected level of work required to collect events.] then partitioning might be an answer. Before you partition you might want to check a few other things: Is your event retention set to NO_EVENT_LOSS and causing blocking? (I told you not to do this.) Consider changing your event loss mode or increasing memory. Are you over collecting and causing more work than necessary? Consider adding predicates to events or removing unnecessary events and actions from your session. Are you writing the file target to the same slow disk that you use for TempDB and your other high activity databases? <kidding> <not really> It’s always worth considering the end to end picture – if you’re writing events to a file you can be impacted by I/O, network; all the usual stuff. Assuming you’ve ruled out the obvious (and not so obvious) issues, there are performance conditions that will be addressed by partitioning. For example, it’s possible to have a successful event session (eg. no dropped events) but still see a performance impact because you have many CPUs all attempting to write to the same free buffer and having to wait in line to finish their work. This is a case where partitioning would relieve the contention between the different CPUs and likely reduce the performance impact cause by the event session. There is no DMV you can check to find these conditions – sorry – that’s where the art comes in. This is  largely a matter of experimentation. On the bright side you probably won’t need to to worry about this level of detail all that often. The performance impact of Extended Events is significantly lower than what you may be used to with SQL Trace. You will likely only care about the impact if you are trying to set up a long running event session that will be part of your everyday workload – sessions used for short term troubleshooting will likely fall into the “reasonably expected impact” category. Hey buddy – I think you forgot something OK, there are two options I didn’t cover: STARTUP_STATE & TRACK_CAUSALITY. If you want your event sessions to start automatically when the server starts, set the STARTUP_STATE option to ON. (Now there is only one option I didn’t cover.) I’m going to leave causality for another post since it’s not really related to session behavior, it’s more about event analysis. - Mike Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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• Extending ASP.NET Output Caching

  This ASP.NET tutorial shows how to customize ASP.NET 4's output caching functionality to save cached content to disk instead of memory.

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• Virtual Box - How to open a .VDI Virtual Machine

  - by [email protected]

   How to open a .VDI Virtual MachineSometimes someone share with us one Virtual machine with extension .VDI, after that we can wonder how and what with?Well the answer is... It is a VirtualBox - Virtual Machine. If you have not downloaded it you can do this easily just follow this post.http://listeningoracle.blogspot.com/2010/04/que-es-virtualbox.htmlor http://oracleoforacle.wordpress.com/2010/04/14/ques-es-virtualbox/Ok, Now with VirtualBox Installed open it and proceed with the following:1. Open the Virtual File Manager. 2. Click on Actions ? Add and select the .VDI file Click "Ok"3. Now we can register the new Virtual Machine - Click New, and Click Next4. Write down a Name for the virtual Machine a proceed to select a Operating System and Version. (In this case it is a Linux (Oracle Enterprise Linux or RedHat)Click Next5. Select the memory amount base for the Virtual Machine (Minimal 1280 for our case) - Click Next6. Select the Disk 11GR2_OEL5_32GB.vdi it was added in the virtual media manager in the step 2. Dont forget let selected Boot hard Disk (Primary Master) . Given it is the only disk assigned to the virtual machine.Click Next7. Click Finish8. This step is important. Once you have click on the settings Button.9. On General option click the advanced settings. Here you must change the default directory to save your Snapshots; my recommendation set it to the same directory where the .Vdi file is. Otherwise you can have the same Virtual Machine and its snapshots in different paths.10. Now Click on System, and proceed to assign the correct memory (If you did not before) Note: Enable "Enable IO APIC" if you are planning to assign more than one CPU to the Virtual Machine.Define the processors for the Virtual machine. If you processor is dual core choose 211. Select the video memory amount you want to assign to the Virtual Machine 12. Associated more storage disk to the Virtual machine, if you have more VDI files. (Not our case)The disk must be selected as IDE Primary Master. 13. Well you can verify the other options, but with these changes you will be able to start the VM.Note: Sometime the VM owner may share some instructions, if so follow his instructions.14. Finally Start the Virtual Machine (Click > Start)

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• SQL SERVER – PAGELATCH_DT, PAGELATCH_EX, PAGELATCH_KP, PAGELATCH_SH, PAGELATCH_UP – Wait Type – Day 12 of 28

  - by pinaldave

  This is another common wait type. However, I still frequently see people getting confused with PAGEIOLATCH_X and PAGELATCH_X wait types. Actually, there is a big difference between the two. PAGEIOLATCH is related to IO issues, while PAGELATCH is not related to IO issues but is oftentimes linked to a buffer issue. Before we delve deeper in this interesting topic, first let us understand what Latch is. Latches are internal SQL Server locks which can be described as very lightweight and short-term synchronization objects. Latches are not primarily to protect pages being read from disk into memory. It’s a synchronization object for any in-memory access to any portion of a log or data file.[Updated based on comment of Paul Randal] The difference between locks and latches is that locks seal all the involved resources throughout the duration of the transactions (and other processes will have no access to the object), whereas latches locks the resources during the time when the data is changed. This way, a latch is able to maintain the integrity of the data between storage engine and data cache. A latch is a short-living lock that is put on resources on buffer cache and in the physical disk when data is moved in either directions. As soon as the data is moved, the latch is released. Now, let us understand the wait stat type  related to latches. From Book On-Line: PAGELATCH_DT Occurs when a task is waiting on a latch for a buffer that is not in an I/O request. The latch request is in Destroy mode. PAGELATCH_EX Occurs when a task is waiting on a latch for a buffer that is not in an I/O request. The latch request is in Exclusive mode. PAGELATCH_KP Occurs when a task is waiting on a latch for a buffer that is not in an I/O request. The latch request is in Keep mode. PAGELATCH_SH Occurs when a task is waiting on a latch for a buffer that is not in an I/O request. The latch request is in Shared mode. PAGELATCH_UP Occurs when a task is waiting on a latch for a buffer that is not in an I/O request. The latch request is in Update mode. PAGELATCH_X Explanation: When there is a contention of access of the in-memory pages, this wait type shows up. It is quite possible that some of the pages in the memory are of very high demand. For the SQL Server to access them and put a latch on the pages, it will have to wait. This wait type is usually created at the same time. Additionally, it is commonly visible when the TempDB has higher contention as well. If there are indexes that are heavily used, contention can be created as well, leading to this wait type. Reducing PAGELATCH_X wait: The following counters are useful to understand the status of the PAGELATCH: Average Latch Wait Time (ms): The wait time for latch requests that have to wait. Latch Waits/sec: This is the number of latch requests that could not be granted immediately. Total Latch Wait Time (ms): This is the total latch wait time for latch requests in the last second. If there is TempDB contention, I suggest that you read the blog post of Robert Davis right away. He has written an excellent blog post regarding how to find out TempDB contention. The same blog post explains the terms in the allocation of GAM, SGAM and PFS. If there was a TempDB contention, Paul Randal explains the optimal settings for the TempDB in his misconceptions series. Trace Flag 1118 can be useful but use it very carefully. I totally understand that this blog post is not as clear as my other blog posts. I suggest if this wait stats is on one of your higher wait type. Do leave a comment or send me an email and I will get back to you with my solution for your situation. May the looking at all other wait stats and types together become effective as this wait type can help suggest proper bottleneck in your system. 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 discussions of Wait Stats in this blog are generic and vary 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 Scripts, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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