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• Capture subprocess output

  - by schneck

  Hi there, I learned that when executing commands in Python, I should use subprocess. What I'm trying to achieve is to encode a file via ffmpeg and observe the program output until the file is done. Ffmpeg logs the progress to stderr. If I try something like this: child = subprocess.Popen(command, shell=True, stderr=subprocess.PIPE) complete = False while not complete: stderr = child.communicate() # Get progress print "Progress here later" if child.poll() is not None: complete = True time.sleep(2) the programm does not continue after calling child.communicate() and waits for the command to complete. Is there any other way to follow the output?

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• What is w componet [duplicate]

  - by Tifa

  This question already has an answer here: What does the graphics card do with the fourth element of a vector as the final position? 3 answers What is the W component on graphics programming. I read a blog about opengl that says that w must be equal to either 0 or 1 here. But the book I am currently reading has put w component to more than 1 value. So im kinda confuse what does it really do. The book I am reading is OpenGL es a quick start guide.

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• WMI instrinsic events. Resources

  - by Nickolodeon

  Hi. I subscribe to usb inserted event like this select * FROM __INSTANCECREATIONEVENT WITHIN 3 WHERE TARGETINSTANCE ISA Win32_DiskDrive After inserting usb flash it blinks every 3 seconds. This is polling interval and intrinsic events work by polling object that's in query. Now, we know these types of events may be resource expensive. (Putting value greater then 3 sometimes chokes these events and client program doesn't get notified). Are there other ways to do that, so that usb doesn't get scanned all the time? May be there some extrinsic events available? Right now the only solution I see is to unsubscribe from event above once it trigerred and resubscribe to it in __INSTANCEDELETIONEVENT handler. Hm, althought deletionevent will also poll diskdrive controllers(

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• HTML anchor #bottom, only going half-way down page

  - by RewbieNewbie

  http://www.planet-tolkien.com/board/44/621/0/poll-suggestions It's due to the multiple "bottom of the page" anchor links on each post to the anchor name at the bottom of the page. I tried to solve this by using a unique id and name for the attributes: <a href="#bottom" id="4656" name="4656"> But this hasn't worked. Suggestions? P.S. Don't use the URL bar, yes that works. Visit the page and click on a link in a post that says "Bottom of the page". This is where it isn't working.

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• Suddenly Spotify doesn't work anymore

  - by user191781

  I've been using Spotify for 18 months without a problem. I use Ubuntu 12.04. Today Spotify stopped and doesn't start anymore. I only see a quick flash of the Spotify-startup-screen and thats it. I uninstalled using Synaptic and reinstalled using Synaptic. No solution. I uninstalled using Synaptic and reinstalled by terminal. No solution. I used Backup to set the system back two days. No solution. I see no error message and I ran out of options I know of.

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• How to edit files on the users file system from my web server?

  - by Abs

  Hello all, I am really looking for implementation advice as I have entered a new realm that I am not familiar with. At the simplest level, I would like to find a way that I can read/write to a users machine from my web server. For this to work, I think I will have to install some sort of "plugin" on the users machine which can receive (or poll?) the server for instructions. The above is the line of thought that I currently have, maybe using JAVA to do this. This needs to work on Linux, Mac and Windows OS. I am really looking for advice on the above, is it a good idea? Is there a better way of doing this? Is there something out there already that I can build on top of? I really appreciate all input and advice as this is something I have not done before. Thanks all

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• Why are so many questions closed? [migrated]

  - by Justin984

  I just joined this stackexchange, and I'm sure this question will get closed like so many others as being subjective or "not constructive". I did a quick count on the first few pages, and it looks like at least 10% of questions are closed. One page I saw had 22 out of 50 questions closed. What does closing so many questions solve? Apparently it does not reduce the number of "bad questions". Instead it just prevents people who would otherwise be interested in answering from doing so. Why can't the people who dislike all these questions just.. not answer?

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• WhatsApp - writing a clone (iphone, android, wp7)

  - by Martin

  I am trying to create a instant messaging app very much like whatsapp I suppose. My resources I have available to me are Server development in C# (REST Service, dedicated server app etc) And currently an android development platform using eclipse (iphone, wp7 to follow later). I have done some development in Android before but I don't have any idea where to start an application like this. My guess would be it would work with UDP / TCP or similar ? I currently have a shared server for an asp.net website but I presume this wouldn't be ideal, I could essential setup a web service on the server and get a client to publish his messages there but then this would mean that the receivers would have to POLL (PULL) every 5 minutes or so - so I guess this wouldn't be real time Do I need to use UDP here ? And I presume platforms like Iphone, Android and WP7 will not have any issues sending msgs by UDP - if that is how its done. I look forward to any help or guidance.

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• Secunia PSI 3.0 has just been released?

  - by TATWORTH

  I have been using Secunia 3.0 Beta for some time and recommend it to all PC users. It is free for personal use. I suggest you use to keep your PC software up to date. Here is the message they sent:We just wanted to let you know that Secunia has released the final versionof Secunia PSI 3.0, featuring a new and simplified interface, moreautomated updates, multiple languages (English, German, Spanish, Frenchand Danish), as well as a lot of other improvements that we hope you willlike. You can download the new version here (it is of course still available forfree):http://secunia.com/vulnerability_scanning/personal/And if you want a quick product tour see the PSI video on Youtube:https://www.youtube.com/watch?v=iUmaLmO0gx0&list=UU8EGaYoGIGlMAbfeJrS_0OQ&index=2&feature=plcp If interested you can also read the full press release here:http://secunia.com/company/blog_news/news/319/

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• IOUG Enterprise Manager SIG Webinar: WEBINAR: Performance Tuning your Database Cloud in Oracle Enterprise Manager 12c Cloud Control - 360 Degrees

  - by Patrick Rood

  October 25, 2013 EM 12c Sales Blast | IOUG Enterprise Manager SIG WEBINAR: Performance Tuning your Database Cloud in Oracle Enterprise Manager 12c Cloud Control - 360 Degrees Last year, the Independent Oracle User Group (IOUG) established a fast-growing Special Interest Group (SIG) devoted to Enterprise Manager, and has sponsored Quarterly Newsletters and Webinars about EM. To drive more interest in EM and the SIG, IOUG would like Oracle to invite customers to its latest techcast. Your customers will learn how to leverage Oracle Enterprise Manager 12c for tuning, trouble-shooting and monitoring their Oracle Database Cloud Ecosystem. The session covers lessons learned, tips/tricks, recommendations, best practices, "gotchas" and a whole lot more on how to effectively use Oracle Enterprise Manager 12c Cloud Control for quick, easy and intuitive performance tuning of an Oracle Database Cloud. Session Objectives: • Leveraging Enterprise Manager 12c Cloud Control for Oracle Database Tuning/Monitoring • Limited Deep-Dive on Automatic Workload Repository (AWR) • Oracle Database Cloud Performance Tuning • Best Practices for Database Cloud Maintenance and Monitoring Featured Speaker: Tariq Farooq, CEO, BrainSurface and Mike Ault Date & Time: Wednesday, October 30 12:00 PM- 1:00 PM Central Time (USA) Register Here 

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• Ask the Readers: Do You Use the Command Line?

  - by Asian Angel

  Most people have heard of it but not everyone is familiar or comfortable with how to use this bastion of geekdom. This week we would like to know if you use the command line or not. The command line…the bastion of ultimate geekery in many peoples’ eyes. You often hear people referring to doing things using the command line, so there must be something to it, right? For some people using the command line is the best, most efficient, and easiest way to do things on their systems. These are the people that many of us wish we were like. Next you have those who are proficient at using the command line but do not rely on it for everything they do on their systems. Then there are people who know how to perform some tasks or hacks using the command line but may not be as comfortable or knowledgeable as they wish to be using it. Moving on you find those who are interested in learning how to use the command line and just need a small push to get started.  Perhaps you feel too intimidated to learn it and just need the right opportunity to come along. And maybe you do not care one way or the other so long as you get done what you want to do on your system. Or you may prefer to simply use a graphical interface since that is quicker and easier for you (along with being familiar). You can find the whole range of people when it comes to using the command line… This week we would like to know if you use the command line or not. What command line category do you fit into? Power user? Casual usage? Totally lost? Let us know in the comments! How-To Geek Polls require Javascript. Please Click Here to View the Poll. Latest Features How-To Geek ETC The How-To Geek Holiday Gift Guide (Geeky Stuff We Like) LCD? LED? Plasma? The How-To Geek Guide to HDTV Technology The How-To Geek Guide to Learning Photoshop, Part 8: Filters Improve Digital Photography by Calibrating Your Monitor Our Favorite Tech: What We’re Thankful For at How-To Geek The How-To Geek Guide to Learning Photoshop, Part 7: Design and Typography Fun and Colorful Firefox Theme for Windows 7 Happy Snow Bears Theme for Chrome and Iron [Holiday] Download Full Command and Conquer: Tiberian Sun Game for Free Scorched Cometary Planet Wallpaper Quick Fix: Add the RSS Button Back to the Firefox Awesome Bar Dropbox Desktop Client 1.0.0 RC for Windows, Linux, and Mac Released

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• Internet Protocol Suite: Transition Control Protocol (TCP) vs. User Datagram Protocol (UDP)

  How do we communicate over the Internet?  How is data transferred from one machine to another? These types of act ivies can only be done by using one of two Internet protocols currently. The collection of Internet Protocol consists of the Transition Control Protocol (TCP) and the User Datagram Protocol (UDP).  Both protocols are used to send data between two network end points, however they both have very distinct ways of transporting data from one endpoint to another. If transmission speed and reliability is the primary concern when trying to transfer data between two network endpoints then TCP is the proper choice. When a device attempts to send data to another endpoint using TCP it creates a direct connection between both devices until the transmission has completed. The direct connection between both devices ensures the reliability of the transmission due to the fact that no intermediate devices are needed to transfer the data. Due to the fact that both devices have to continuously poll the connection until transmission has completed increases the resources needed to perform the transmission. An example of this type of direct communication can be seen when a teacher tells a students to do their homework. The teacher is talking directly to the students in order to communicate that the homework needs to be done.  Students can then ask questions about the assignment to ensure that they have received the proper instructions for the assignment. UDP is a less resource intensive approach to sending data between to network endpoints. When a device uses UDP to send data across a network, the data is broken up and repackaged with the destination address. The sending device then releases the data packages to the network, but cannot ensure when or if the receiving device will actually get the data.  The sending device depends on other devices on the network to forward the data packages to the destination devices in order to complete the transmission. As you can tell this type of transmission is less resource intensive because not connection polling is needed,  but should not be used for transmitting data with speed or reliability requirements. This is due to the fact that the sending device can not ensure that the transmission is received.  An example of this type of communication can be seen when a teacher tells a student that they would like to speak with their parents. The teacher is relying on the student to complete the transmission to the parents, and the teacher has no guarantee that the student will actually inform the parents about the request. Both TCP and UPD are invaluable when attempting to send data across a network, but depending on the situation one protocol may be better than the other. Before deciding on which protocol to use an evaluation for transmission speed, reliability, latency, and overhead must be completed in order to define the best protocol for the situation.  

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• Ask the Readers: Do You Prefer Computers, Game Consoles, or Other Devices for Your Gaming Needs?

  - by Asian Angel

  Nearly everyone who has access to a computer will play games on it at some point, but many people also use a separate game platform as well. What we would like to know this week is if you prefer using a computer, game consoles, or other devices for your gaming needs. Photo of Faith and Kate Connors from Mirror’s Edge by Tamahikari Tammas. Video games are a perfect way to relax and have fun at home (or at work if you can sneak in some game time!). The increasing variety of devices available with each passing year are making it easier to have access to a gaming platform to suit your needs or “darkest gaming desires”. For many people their computers are the perfect platform…they can play Flash-based games in their browsers, use the default set of games that come with their system, and install any extras that catch their eyes. The added benefit is that when game time is over they can drop right into their browsing, e-mail, personal projects, or work without having to switch hardware. The convenience of the “all-in-one” platform is certainly appealing! Perhaps you prefer to use your computer for other activities outside of gaming and own one or more separate game consoles. You might have chosen an Xbox, Playstation, or Nintendo for example. Maybe a hand-held is preferable for its’ size and portability. Then there are mobile phones and the iPad… With so many options it may feel hard to choose the right platform(s) without a good bit of research regarding display, availability of games for a particular platform, how long before the platform starts to become “obsolete”, etc. What we would like to know this week is which gaming platform you prefer. Is there only one that you choose to use or do you use multiple platforms for gaming? Is there a particular reason such as convenience for your choices? You may even be keeping an older platform around just for a certain game (or games) made for it. Are there any recommendations or advice that you would like to share with your fellow readers? Let us know in the comments! How-To Geek Polls require Javascript. Please Click Here to View the Poll. Latest Features How-To Geek ETC HTG Projects: How to Create Your Own Custom Papercraft Toy How to Combine Rescue Disks to Create the Ultimate Windows Repair Disk What is Camera Raw, and Why Would a Professional Prefer it to JPG? The How-To Geek Guide to Audio Editing: The Basics How To Boot 10 Different Live CDs From 1 USB Flash Drive The 20 Best How-To Geek Linux Articles of 2010 Apture Highlights Turns Your Cursor into a Search Tool Add Classic Sci-Fi Goodness to Your Desktop with the Matrix Theme for Windows 7 You Can’t Walk Straight without Visual Markers [Video] Lord of the Rings Movie Parody Double Feature [Video] Turn a Webpage into an Asteroids-Styled Shooting Game in Opera Dolphin Browser Mini Leaves Beta; Sports New GUI, Easy Bookmarking, and More

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• HPC Server Dynamic Job Scheduling: when jobs spawn jobs

  - by JoshReuben

  HPC Job Types HPC has 3 types of jobs http://technet.microsoft.com/en-us/library/cc972750(v=ws.10).aspx · Task Flow – vanilla sequence · Parametric Sweep – concurrently run multiple instances of the same program, each with a different work unit input · MPI – message passing between master & slave tasks But when you try go outside the box – job tasks that spawn jobs, blocking the parent task – you run the risk of resource starvation, deadlocks, and recursive, non-converging or exponential blow-up. The solution to this is to write some performance monitoring and job scheduling code. You can do this in 2 ways: manually control scheduling - allocate/ de-allocate resources, change job priorities, pause & resume tasks , restrict long running tasks to specific compute clusters Semi-automatically - set threshold params for scheduling. How – Control Job Scheduling In order to manage the tasks and resources that are associated with a job, you will need to access the ISchedulerJob interface - http://msdn.microsoft.com/en-us/library/microsoft.hpc.scheduler.ischedulerjob_members(v=vs.85).aspx This really allows you to control how a job is run – you can access & tweak the following features: max / min resource values whether job resources can grow / shrink, and whether jobs can be pre-empted, whether the job is exclusive per node the creator process id & the job pool timestamp of job creation & completion job priority, hold time & run time limit Re-queue count Job progress Max/ min Number of cores, nodes, sockets, RAM Dynamic task list – can add / cancel jobs on the fly Job counters When – poll perf counters Tweaking the job scheduler should be done on the basis of resource utilization according to PerfMon counters – HPC exposes 2 Perf objects: Compute Clusters, Compute Nodes http://technet.microsoft.com/en-us/library/cc720058(v=ws.10).aspx You can monitor running jobs according to dynamic thresholds – use your own discretion: Percentage processor time Number of running jobs Number of running tasks Total number of processors Number of processors in use Number of processors idle Number of serial tasks Number of parallel tasks Design Your algorithms correctly Finally , don’t assume you have unlimited compute resources in your cluster – design your algorithms with the following factors in mind: · Branching factor - http://en.wikipedia.org/wiki/Branching_factor - dynamically optimize the number of children per node · cutoffs to prevent explosions - http://en.wikipedia.org/wiki/Limit_of_a_sequence - not all functions converge after n attempts. You also need a threshold of good enough, diminishing returns · heuristic shortcuts - http://en.wikipedia.org/wiki/Heuristic - sometimes an exhaustive search is impractical and short cuts are suitable · Pruning http://en.wikipedia.org/wiki/Pruning_(algorithm) – remove / de-prioritize unnecessary tree branches · avoid local minima / maxima - http://en.wikipedia.org/wiki/Local_minima - sometimes an algorithm cant converge because it gets stuck in a local saddle – try simulated annealing, hill climbing or genetic algorithms to get out of these ruts   watch out for rounding errors – http://en.wikipedia.org/wiki/Round-off_error - multiple iterations can in parallel can quickly amplify & blow up your algo ! Use an epsilon, avoid floating point errors,  truncations, approximations Happy Coding !

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• Challenges in multi-player Android Game Server with RESTful Nature

  - by Kush

  I'm working on an Android Game based on Contract Bridge, as a part of my college Summer Internship project. The game will be multi-player such that 4 Android devices can play it, so there's no BOT or CPU player to be developed. At the time of getting project, I realized that most of the students had already worked on the project but none of their works is reusable now (for variety of reasons like, undocumented code and design architecture, different platform implementation). I have experience working on several open source projects and hence I emphasis to work out on this project such that components I make become reusable as much as possible. Now, as the game is multi-player and entire game progress will be handled on server, I'm currently working on Server's design, since I wanted to make game server reusable such that any client platform can use it, I was previously confused in selecting Socket or REST for Game Server's design, but later finalized to work on REST APIs for the server. Now, since I have to keep all players in-sync while they make movements in game, on server I've planned to use Database which will keep all players' progress, specific for each table (in Bridge, 4 players play on single table, and server will handle many such game tables). I don't know if its an appropriate decision to use database as shared medium to track progress of each game table (let me know if there's an appropriate or better option). Obviously, when game is completed for the table, data for that table on server's database is discarded. Now the problem is that, access to REST service is an HTTP call, so as long as client doesn't make any request, server will remain idle, and consider a situation where A player has played a card on his device and the device requests to apply this change on the server. Now, I need to let rest of the three devices know that the player has played a card, and also update view on their device. AFAIK, REST cannot provide a sort-of Push-notification system, since the connection to the server is not persistent. One solution that I thought was to make each device constantly poll the server for any change (like every 56 ms) and when changes are found, reflect it on the device. But I feel this is not an elegant way, as every HTTP request is expensive. (and I choose REST to make game play experience robust since, a mobile device tends to get disconnected from Internet, and if there's Socket-like persistent connection then entire game progress is subject to lost. Also, portability on client-end is important) Also, imagining a situation where 10 game tables are in progress and 40 players are playing, a server must be capable to handle flooded HTTP requests from all the devices which make it every 56 ms. So I wonder if the situation is assumed as DoS attack. So, explaining the situation, am I going on the right track for the server design? I wanted to be sure before I proceed much further with the code.

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• Global Cache CR Requested But Current Block Received

  - by Liu Maclean(???)

  ????????«MINSCN?Cache Fusion Read Consistent» ????,???????????? ??????????????????: SQL> select * from V$version; BANNER -------------------------------------------------------------------------------- Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production PL/SQL Release 11.2.0.3.0 - Production CORE 11.2.0.3.0 Production TNS for Linux: Version 11.2.0.3.0 - Production NLSRTL Version 11.2.0.3.0 - Production SQL> select count(*) from gv$instance; COUNT(*) ---------- 2 SQL> select * from global_name; GLOBAL_NAME -------------------------------------------------------------------------------- www.oracledatabase12g.com ?11gR2 2??RAC??????????status???XG,????Xcurrent block???INSTANCE 2?hold?,?????INSTANCE 1?????????,?????: SQL> select * from test; ID ---------- 1 2 SQL> select dbms_rowid.rowid_block_number(rowid),dbms_rowid.rowid_relative_fno(rowid) from test; DBMS_ROWID.ROWID_BLOCK_NUMBER(ROWID) DBMS_ROWID.ROWID_RELATIVE_FNO(ROWID) ------------------------------------ ------------------------------------ 89233 1 89233 1 SQL> alter system flush buffer_cache; System altered. INSTANCE 1 Session A: SQL> update test set id=id+1 where id=1; 1 row updated. INSTANCE 1 Session B: SQL> select state,cr_scn_bas from x$bh where file#=1 and dbablk=89233 and state!=0; STATE CR_SCN_BAS ---------- ---------- 1 0 3 1755287 SQL> oradebug setmypid; Statement processed. SQL> oradebug dump gc_elements 255; Statement processed. SQL> oradebug tracefile_name; /s01/orabase/diag/rdbms/vprod/VPROD1/trace/VPROD1_ora_19111.trc GLOBAL CACHE ELEMENT DUMP (address: 0xa4ff3080): id1: 0x15c91 id2: 0x1 pkey: OBJ#76896 block: (1/89233) lock: X rls: 0x0 acq: 0x0 latch: 3 flags: 0x20 fair: 0 recovery: 0 fpin: 'kdswh11: kdst_fetch' bscn: 0x0.146e20 bctx: (nil) write: 0 scan: 0x0 lcp: (nil) lnk: [NULL] lch: [0xa9f6a6f8,0xa9f6a6f8] seq: 32 hist: 58 145:0 118 66 144:0 192 352 197 48 121 113 424 180 58 LIST OF BUFFERS LINKED TO THIS GLOBAL CACHE ELEMENT: flg: 0x02000001 lflg: 0x1 state: XCURRENT tsn: 0 tsh: 2 addr: 0xa9f6a5c8 obj: 76896 cls: DATA bscn: 0x0.1ac898 BH (0xa9f6a5c8) file#: 1 rdba: 0x00415c91 (1/89233) class: 1 ba: 0xa9e56000 set: 5 pool: 3 bsz: 8192 bsi: 0 sflg: 3 pwc: 0,15 dbwrid: 0 obj: 76896 objn: 76896 tsn: 0 afn: 1 hint: f hash: [0x91f4e970,0xbae9d5b8] lru: [0x91f58848,0xa9f6a828] lru-flags: debug_dump obj-flags: object_ckpt_list ckptq: [0x9df6d1d8,0xa9f6a740] fileq: [0xa2ece670,0xbdf4ed68] objq: [0xb4964e00,0xb4964e00] objaq: [0xb4964de0,0xb4964de0] st: XCURRENT md: NULL fpin: 'kdswh11: kdst_fetch' tch: 2 le: 0xa4ff3080 flags: buffer_dirty redo_since_read LRBA: [0x19.5671.0] LSCN: [0x0.1ac898] HSCN: [0x0.1ac898] HSUB: [1] buffer tsn: 0 rdba: 0x00415c91 (1/89233) scn: 0x0000.001ac898 seq: 0x01 flg: 0x00 tail: 0xc8980601 frmt: 0x02 chkval: 0x0000 type: 0x06=trans data ??????block: (1/89233)?GLOBAL CACHE ELEMENT DUMP?LOCK????X ??XG , ??????Current Block????Instance??modify???,????????????? ????Instance 2 ????: Instance 2 Session C: SQL> update test set id=id+1 where id=2; 1 row updated. Instance 2 Session D: SQL> select state,cr_scn_bas from x$bh where file#=1 and dbablk=89233 and state!=0; STATE CR_SCN_BAS ---------- ---------- 1 0 3 1756658 SQL> oradebug setmypid; Statement processed. SQL> oradebug dump gc_elements 255; Statement processed. SQL> oradebug tracefile_name; /s01/orabase/diag/rdbms/vprod/VPROD2/trace/VPROD2_ora_13038.trc GLOBAL CACHE ELEMENT DUMP (address: 0x89fb25a0): id1: 0x15c91 id2: 0x1 pkey: OBJ#76896 block: (1/89233) lock: XG rls: 0x0 acq: 0x0 latch: 3 flags: 0x20 fair: 0 recovery: 0 fpin: 'kduwh01: kdusru' bscn: 0x0.1acdf3 bctx: (nil) write: 0 scan: 0x0 lcp: (nil) lnk: [NULL] lch: [0x96f4cf80,0x96f4cf80] seq: 61 hist: 324 21 143:0 19 16 352 329 144:6 14 7 352 197 LIST OF BUFFERS LINKED TO THIS GLOBAL CACHE ELEMENT: flg: 0x0a000001 state: XCURRENT tsn: 0 tsh: 1 addr: 0x96f4ce50 obj: 76896 cls: DATA bscn: 0x0.1acdf6 BH (0x96f4ce50) file#: 1 rdba: 0x00415c91 (1/89233) class: 1 ba: 0x96bd4000 set: 5 pool: 3 bsz: 8192 bsi: 0 sflg: 2 pwc: 0,15 dbwrid: 0 obj: 76896 objn: 76896 tsn: 0 afn: 1 hint: f hash: [0x96ee1fe8,0xbae9d5b8] lru: [0x96f4d0b0,0x96f4cdc0] obj-flags: object_ckpt_list ckptq: [0xbdf519b8,0x96f4d5a8] fileq: [0xbdf519d8,0xbdf519d8] objq: [0xb4a47b90,0xb4a47b90] objaq: [0x96f4d0e8,0xb4a47b70] st: XCURRENT md: NULL fpin: 'kduwh01: kdusru' tch: 1 le: 0x89fb25a0 flags: buffer_dirty redo_since_read remote_transfered LRBA: [0x11.9e18.0] LSCN: [0x0.1acdf6] HSCN: [0x0.1acdf6] HSUB: [1] buffer tsn: 0 rdba: 0x00415c91 (1/89233) scn: 0x0000.001acdf6 seq: 0x01 flg: 0x00 tail: 0xcdf60601 frmt: 0x02 chkval: 0x0000 type: 0x06=trans data GCS CLIENT 0x89fb2618,6 resp[(nil),0x15c91.1] pkey 76896.0 grant 2 cvt 0 mdrole 0x42 st 0x100 lst 0x20 GRANTQ rl G0 master 1 owner 2 sid 0 remote[(nil),0] hist 0x94121c601163423c history 0x3c.0x4.0xd.0xb.0x1.0xc.0x7.0x9.0x14.0x1. cflag 0x0 sender 1 flags 0x0 replay# 0 abast (nil).x0.1 dbmap (nil) disk: 0x0000.00000000 write request: 0x0000.00000000 pi scn: 0x0000.00000000 sq[(nil),(nil)] msgseq 0x1 updseq 0x0 reqids[6,0,0] infop (nil) lockseq x2b8 pkey 76896.0 hv 93 [stat 0x0, 1->1, wm 32768, RMno 0, reminc 18, dom 0] kjga st 0x4, step 0.0.0, cinc 20, rmno 6, flags 0x0 lb 0, hb 0, myb 15250, drmb 15250, apifrz 0 ?Instance 2??????block: (1/89233)? GLOBAL CACHE ELEMENT Lock Convert?lock: XG ????GC_ELEMENTS DUMP???XCUR Cache Fusion?,???????X$ VIEW,??? X$LE X$KJBR X$KJBL, ???X$ VIEW???????????????????: INSTANCE 2 Session D: SELECT * FROM x$le WHERE le_addr IN (SELECT le_addr FROM x$bh WHERE obj IN (SELECT data_object_id FROM dba_objects WHERE owner = 'SYS' AND object_name = 'TEST') AND class = 1 AND state != 3); ADDR INDX INST_ID LE_ADDR LE_ID1 LE_ID2 ---------------- ---------- ---------- ---------------- ---------- ---------- LE_RLS LE_ACQ LE_FLAGS LE_MODE LE_WRITE LE_LOCAL LE_RECOVERY ---------- ---------- ---------- ---------- ---------- ---------- ----------- LE_BLKS LE_TIME LE_KJBL ---------- ---------- ---------------- 00007F94CA14CF60 7003 2 0000000089FB25A0 89233 1 0 0 32 2 0 1 0 1 0 0000000089FB2618 PCM Resource NAME?[ID1][ID2],[BL]???, ID1?ID2 ??blockno? fileno????, ??????????GC_elements dump?? id1: 0x15c91 id2: 0×1 pkey: OBJ#76896 block: (1/89233)?? ,?  kjblname ? kjbrname ??”[0x15c91][0x1],[BL]” ??: INSTANCE 2 Session D: SQL> set linesize 80 pagesize 1400 SQL> SELECT * 2 FROM x$kjbl l 3 WHERE l.kjblname LIKE '%[0x15c91][0x1],[BL]%'; ADDR INDX INST_ID KJBLLOCKP KJBLGRANT KJBLREQUE ---------------- ---------- ---------- ---------------- --------- --------- KJBLROLE KJBLRESP KJBLNAME ---------- ---------------- ------------------------------ KJBLNAME2 KJBLQUEUE ------------------------------ ---------- KJBLLOCKST KJBLWRITING ---------------------------------------------------------------- ----------- KJBLREQWRITE KJBLOWNER KJBLMASTER KJBLBLOCKED KJBLBLOCKER KJBLSID KJBLRDOMID ------------ ---------- ---------- ----------- ----------- ---------- ---------- KJBLPKEY ---------- 00007F94CA22A288 451 2 0000000089FB2618 KJUSEREX KJUSERNL 0 00 [0x15c91][0x1],[BL][ext 0x0,0x 89233,1,BL 0 GRANTED 0 0 1 0 0 0 0 0 76896 SQL> SELECT r.* FROM x$kjbr r WHERE r.kjbrname LIKE '%[0x15c91][0x1],[BL]%'; no rows selected Instance 1 session B: SQL> SELECT r.* FROM x$kjbr r WHERE r.kjbrname LIKE '%[0x15c91][0x1],[BL]%'; ADDR INDX INST_ID KJBRRESP KJBRGRANT KJBRNCVL ---------------- ---------- ---------- ---------------- --------- --------- KJBRROLE KJBRNAME KJBRMASTER KJBRGRANTQ ---------- ------------------------------ ---------- ---------------- KJBRCVTQ KJBRWRITER KJBRSID KJBRRDOMID KJBRPKEY ---------------- ---------------- ---------- ---------- ---------- 00007F801ACA68F8 1355 1 00000000B5A62AE0 KJUSEREX KJUSERNL 0 [0x15c91][0x1],[BL][ext 0x0,0x 0 00000000B48BB330 00 00 0 0 76896 ??????Instance 1???block: (1/89233),??????Instance 2 build cr block ????Instance 1, ?????????? ????? Instance 1? Foreground Process ? Instance 2?LMS??????RAC  TRACE: Instance 2: [oracle@vrh2 ~]$ ps -ef|grep ora_lms|grep -v grep oracle 23364 1 0 Apr29 ? 00:33:15 ora_lms0_VPROD2 SQL> oradebug setospid 23364 Oracle pid: 13, Unix process pid: 23364, image: [email protected] (LMS0) SQL> oradebug event 10046 trace name context forever,level 8:10708 trace name context forever,level 103: trace[rac.*] disk high; Statement processed. SQL> oradebug tracefile_name /s01/orabase/diag/rdbms/vprod/VPROD2/trace/VPROD2_lms0_23364.trc Instance 1 session B : SQL> select state,cr_scn_bas from x$bh where file#=1 and dbablk=89233 and state!=0; STATE CR_SCN_BAS ---------- ---------- 3 1756658 3 1756661 3 1755287 Instance 1 session A : SQL> alter session set events '10046 trace name context forever,level 8:10708 trace name context forever,level 103: trace[rac.*] disk high'; Session altered. SQL> select * from test; ID ---------- 2 2 SQL> select state,cr_scn_bas from x$bh where file#=1 and dbablk=89233 and state!=0; STATE CR_SCN_BAS ---------- ---------- 3 1761520 ?x$BH?????,???????Instance 1???build??CR block,????? TRACE ??: Instance 1 foreground Process: PARSING IN CURSOR #140336527348792 len=18 dep=0 uid=0 oct=3 lid=0 tim=1335939136125254 hv=1689401402 ad='b1a4c828' sqlid='c99yw1xkb4f1u' select * from test END OF STMT PARSE #140336527348792:c=2999,e=2860,p=0,cr=0,cu=0,mis=1,r=0,dep=0,og=1,plh=1357081020,tim=1335939136125253 EXEC #140336527348792:c=0,e=40,p=0,cr=0,cu=0,mis=0,r=0,dep=0,og=1,plh=1357081020,tim=1335939136125373 WAIT #140336527348792: nam='SQL*Net message to client' ela= 6 driver id=1650815232 #bytes=1 p3=0 obj#=0 tim=1335939136125420 *** 2012-05-02 02:12:16.125 kclscrs: req=0 block=1/89233 2012-05-02 02:12:16.125574 : kjbcro[0x15c91.1 76896.0][4] *** 2012-05-02 02:12:16.125 kclscrs: req=0 typ=nowait-abort *** 2012-05-02 02:12:16.125 kclscrs: bid=1:3:1:0:f:1e:0:0:10:0:0:0:1:2:4:1:20:0:0:0:c3:49:0:0:0:0:0:0:0:0:0:0:0:0:0:0:0:0:0:0:4:3:2:1:2:0:1c:0:4d:26:a3:52:0:0:0:0:c7:c:ca:62:c3:49:0:0:0:0:1:0:14:8e:47:76:1:2:dc:5:a9:fe:17:75:0:0:0:0:0:0:0:0:0:0:0:0:99:ed:0:0:0:0:0:0:10:0:0:0 2012-05-02 02:12:16.125718 : kjbcro[0x15c91.1 76896.0][4] 2012-05-02 02:12:16.125751 : GSIPC:GMBQ: buff 0xba0ee018, queue 0xbb79a7b8, pool 0x60013fa0, freeq 0, nxt 0xbb79a7b8, prv 0xbb79a7b8 2012-05-02 02:12:16.125780 : kjbsentscn[0x0.1ae0f0][to 2] 2012-05-02 02:12:16.125806 : GSIPC:SENDM: send msg 0xba0ee088 dest x20001 seq 177740 type 36 tkts xff0000 mlen x1680198 2012-05-02 02:12:16.125918 : kjbmscr(0x15c91.1)reqid=0x8(req 0xa4ff30f8)(rinst 1)hldr 2(infosz 200)(lseq x2b8) 2012-05-02 02:12:16.126959 : GSIPC:KSXPCB: msg 0xba0ee088 status 30, type 36, dest 2, rcvr 1 *** 2012-05-02 02:12:16.127 kclwcrs: wait=0 tm=1233 *** 2012-05-02 02:12:16.127 kclwcrs: got 1 blocks from ksxprcv WAIT #140336527348792: nam='gc cr block 2-way' ela= 1233 p1=1 p2=89233 p3=1 obj#=76896 tim=1335939136127199 2012-05-02 02:12:16.127272 : kjbcrcomplete[0x15c91.1 76896.0][0] 2012-05-02 02:12:16.127309 : kjbrcvdscn[0x0.1ae0f0][from 2][idx 2012-05-02 02:12:16.127329 : kjbrcvdscn[no bscn <= rscn 0x0.1ae0f0][from 2] ???? kjbcro[0x15c91.1 76896.0][4] kjbsentscn[0x0.1ae0f0][to 2] ?Instance 2??SCN=1ae0f0=1761520? block: (1/89233),???’gc cr block 2-way’ ??,?????????CR block? Instance 2 LMS TRACE 2012-05-02 02:12:15.634057 : GSIPC:RCVD: ksxp msg 0x7f16e1598588 sndr 1 seq 0.177740 type 36 tkts 0 2012-05-02 02:12:15.634094 : GSIPC:RCVD: watq msg 0x7f16e1598588 sndr 1, seq 177740, type 36, tkts 0 2012-05-02 02:12:15.634108 : GSIPC:TKT: collect msg 0x7f16e1598588 from 1 for rcvr -1, tickets 0 2012-05-02 02:12:15.634162 : kjbrcvdscn[0x0.1ae0f0][from 1][idx 2012-05-02 02:12:15.634186 : kjbrcvdscn[no bscn1, wm 32768, RMno 0, reminc 18, dom 0] kjga st 0x4, step 0.0.0, cinc 20, rmno 6, flags 0x0 lb 0, hb 0, myb 15250, drmb 15250, apifrz 0 GCS CLIENT END 2012-05-02 02:12:15.635211 : kjbdowncvt[0x15c91.1 76896.0][1][options x0] 2012-05-02 02:12:15.635230 : GSIPC:AMBUF: rcv buff 0x7f16e1c56420, pool rcvbuf, rqlen 1103 2012-05-02 02:12:15.635308 : GSIPC:GPBMSG: new bmsg 0x7f16e1c56490 mb 0x7f16e1c56420 msg 0x7f16e1c564b0 mlen 152 dest x101 flushsz -1 2012-05-02 02:12:15.635334 : kjbmslset(0x15c91.1)) seq 0x4 reqid=0x6 (shadow 0xb48bb330.xb)(rsn 2)(mas@1) 2012-05-02 02:12:15.635355 : GSIPC:SPBMSG: send bmsg 0x7f16e1c56490 blen 184 msg 0x7f16e1c564b0 mtype 33 attr|dest x30101 bsz|fsz x1ffff 2012-05-02 02:12:15.635377 : GSIPC:SNDQ: enq msg 0x7f16e1c56490, type 65521 seq 118669, inst 1, receiver 1, queued 1 *** 2012-05-02 02:12:15.635 kclccctx: cleanup copy 0x7f16e1d94798 2012-05-02 02:12:15.635479 : [kjmpmsgi:compl][type 36][msg 0x7f16e1598588][seq 177740.0][qtime 0][ptime 1257] 2012-05-02 02:12:15.635511 : GSIPC:BSEND: flushing sndq 0xb491dd28, id 1, dcx 0xbc516778, inst 1, rcvr 1 qlen 0 1 2012-05-02 02:12:15.635536 : GSIPC:BSEND: no batch1 msg 0x7f16e1c56490 type 65521 len 184 dest (1:1) 2012-05-02 02:12:15.635557 : kjbsentscn[0x0.1ae0f1][to 1] 2012-05-02 02:12:15.635578 : GSIPC:SENDM: send msg 0x7f16e1c56490 dest x10001 seq 118669 type 65521 tkts x10002 mlen xb800e8 WAIT #0: nam='gcs remote message' ela= 180 waittime=1 poll=0 event=0 obj#=0 tim=1335939135635819 2012-05-02 02:12:15.635853 : GSIPC:RCVD: ksxp msg 0x7f16e167e0b0 sndr 1 seq 0.177741 type 32 tkts 0 2012-05-02 02:12:15.635875 : GSIPC:RCVD: watq msg 0x7f16e167e0b0 sndr 1, seq 177741, type 32, tkts 0 2012-05-02 02:12:15.636012 : GSIPC:TKT: collect msg 0x7f16e167e0b0 from 1 for rcvr -1, tickets 0 2012-05-02 02:12:15.636040 : kjbrcvdscn[0x0.1ae0f1][from 1][idx 2012-05-02 02:12:15.636060 : kjbrcvdscn[no bscn <= rscn 0x0.1ae0f1][from 1] 2012-05-02 02:12:15.636082 : GSIPC:TKT: dest (1:1) rtkt not acked 1  unassigned bufs 0  tkts 0  newbufs 0 2012-05-02 02:12:15.636102 : GSIPC:TKT: remove ctx dest (1:1) 2012-05-02 02:12:15.636125 : [kjmxmpm][type 32][seq 0.177741][msg 0x7f16e167e0b0][from 1] 2012-05-02 02:12:15.636146 : kjbmpocr(0xb0.6)seq 0x1,reqid=0x23a,(client 0x9fff7b58,0x1)(from 1)(lseq xdf0) 2????LMS????????? ??gcs remote message GSIPC ????SCN=[0x0.1ae0f0] block=1/89233???,??BAST kjbmpbast(0x15c91.1),?? block=1/89233??????? ??fairness??(?11.2.0.3???_fairness_threshold=2),?current block?KCL: F156: fairness downconvert,?Xcurrent DownConvert? Scurrent: Instance 2: SQL> select state,cr_scn_bas from x$bh where file#=1 and dbablk=89233 and state!=0; STATE CR_SCN_BAS ---------- ---------- 2 0 3 1756658 ??Instance 2 LMS ?cr block??? kjbmslset(0x15c91.1)) ????SEND QUEUE GSIPC:SNDQ: enq msg 0x7f16e1c56490? ???????Instance 1???? block: (1/89233)??? ??????: Instance 2: SQL> select CURRENT_RESULTS,LIGHT_WORKS from v$cr_block_server; CURRENT_RESULTS LIGHT_WORKS --------------- ----------- 29273 437 Instance 1 session A: SQL> SQL> select * from test; ID ---------- 2 2 SQL> select state,cr_scn_bas from x$bh where file#=1 and dbablk=89233 and state!=0; STATE CR_SCN_BAS ---------- ---------- 3 1761942 3 1761932 1 0 3 1761520 Instance 2: SQL> select CURRENT_RESULTS,LIGHT_WORKS from v$cr_block_server; CURRENT_RESULTS LIGHT_WORKS --------------- ----------- 29274 437 select * from test END OF STMT PARSE #140336529675592:c=0,e=337,p=0,cr=0,cu=0,mis=0,r=0,dep=0,og=1,plh=1357081020,tim=1335939668940051 EXEC #140336529675592:c=0,e=96,p=0,cr=0,cu=0,mis=0,r=0,dep=0,og=1,plh=1357081020,tim=1335939668940204 WAIT #140336529675592: nam='SQL*Net message to client' ela= 5 driver id=1650815232 #bytes=1 p3=0 obj#=0 tim=1335939668940348 *** 2012-05-02 02:21:08.940 kclscrs: req=0 block=1/89233 2012-05-02 02:21:08.940676 : kjbcro[0x15c91.1 76896.0][5] *** 2012-05-02 02:21:08.940 kclscrs: req=0 typ=nowait-abort *** 2012-05-02 02:21:08.940 kclscrs: bid=1:3:1:0:f:21:0:0:10:0:0:0:1:2:4:1:20:0:0:0:c3:49:0:0:0:0:0:0:0:0:0:0:0:0:0:0:0:0:0:0:4:3:2:1:2:0:1f:0:4d:26:a3:52:0:0:0:0:c7:c:ca:62:c3:49:0:0:0:0:1:0:17:8e:47:76:1:2:dc:5:a9:fe:17:75:0:0:0:0:0:0:0:0:0:0:0:0:99:ed:0:0:0:0:0:0:10:0:0:0 2012-05-02 02:21:08.940799 : kjbcro[0x15c91.1 76896.0][5] 2012-05-02 02:21:08.940833 : GSIPC:GMBQ: buff 0xba0ee018, queue 0xbb79a7b8, pool 0x60013fa0, freeq 0, nxt 0xbb79a7b8, prv 0xbb79a7b8 2012-05-02 02:21:08.940859 : kjbsentscn[0x0.1ae28c][to 2] 2012-05-02 02:21:08.940870 : GSIPC:SENDM: send msg 0xba0ee088 dest x20001 seq 177810 type 36 tkts xff0000 mlen x1680198 2012-05-02 02:21:08.940976 : kjbmscr(0x15c91.1)reqid=0xa(req 0xa4ff30f8)(rinst 1)hldr 2(infosz 200)(lseq x2b8) 2012-05-02 02:21:08.941314 : GSIPC:KSXPCB: msg 0xba0ee088 status 30, type 36, dest 2, rcvr 1 *** 2012-05-02 02:21:08.941 kclwcrs: wait=0 tm=707 *** 2012-05-02 02:21:08.941 kclwcrs: got 1 blocks from ksxprcv 2012-05-02 02:21:08.941818 : kjbassume[0x15c91.1][sender 2][mymode x1][myrole x0][srole x0][flgs x0][spiscn 0x0.0][swscn 0x0.0] 2012-05-02 02:21:08.941852 : kjbrcvdscn[0x0.1ae28d][from 2][idx 2012-05-02 02:21:08.941871 : kjbrcvdscn[no bscn ??????????????SCN=[0x0.1ae28c]=1761932 Version?CR block, ????receive????Xcurrent Block??SCN=1ae28d=1761933,Instance 1???Xcurrent Block???build????????SCN=1761932?CR BLOCK, ????????Current block,?????????'gc current block 2-way'? ?????????????request current block,?????kjbcro;?????Instance 2?LMS???????Current Block: Instance 2 LMS trace: 2012-05-02 02:21:08.448743 : GSIPC:RCVD: ksxp msg 0x7f16e14a4398 sndr 1 seq 0.177810 type 36 tkts 0 2012-05-02 02:21:08.448778 : GSIPC:RCVD: watq msg 0x7f16e14a4398 sndr 1, seq 177810, type 36, tkts 0 2012-05-02 02:21:08.448798 : GSIPC:TKT: collect msg 0x7f16e14a4398 from 1 for rcvr -1, tickets 0 2012-05-02 02:21:08.448816 : kjbrcvdscn[0x0.1ae28c][from 1][idx 2012-05-02 02:21:08.448834 : kjbrcvdscn[no bscn <= rscn 0x0.1ae28c][from 1] 2012-05-02 02:21:08.448857 : GSIPC:TKT: dest (1:1) rtkt not acked 2  unassigned bufs 0  tkts 0  newbufs 0 2012-05-02 02:21:08.448875 : GSIPC:TKT: remove ctx dest (1:1) 2012-05-02 02:21:08.448970 : [kjmxmpm][type 36][seq 0.177810][msg 0x7f16e14a4398][from 1] 2012-05-02 02:21:08.448993 : kjbmpbast(0x15c91.1) reqid=0x6 (req 0xa4ff30f8)(reqinst 1)(reqid 10)(flags x0) *** 2012-05-02 02:21:08.449 kclcrrf: req=48054 block=1/89233 *** 2012-05-02 02:21:08.449 kcl_compress_block: compressed: 6 free space: 7680 2012-05-02 02:21:08.449085 : kjbsentscn[0x0.1ae28d][to 1] 2012-05-02 02:21:08.449142 : kjbdeliver[to 1][0xa4ff30f8][10][current 1] 2012-05-02 02:21:08.449164 : kjbmssch(reqlock 0xa4ff30f8,10)(to 1)(bsz 344) 2012-05-02 02:21:08.449183 : GSIPC:AMBUF: rcv buff 0x7f16e18bcec8, pool rcvbuf, rqlen 1102 *** 2012-05-02 02:21:08.449 kclccctx: cleanup copy 0x7f16e1d94838 *** 2012-05-02 02:21:08.449 kcltouched: touch seconds 3271 *** 2012-05-02 02:21:08.449 kclgrantlk: req=48054 2012-05-02 02:21:08.449347 : [kjmpmsgi:compl][type 36][msg 0x7f16e14a4398][seq 177810.0][qtime 0][ptime 1119] WAIT #0: nam='gcs remote message' ela= 568 waittime=1 poll=0 event=0 obj#=0 tim=1335939668449962 2012-05-02 02:21:08.450001 : GSIPC:RCVD: ksxp msg 0x7f16e1bb22a0 sndr 1 seq 0.177811 type 32 tkts 0 2012-05-02 02:21:08.450024 : GSIPC:RCVD: watq msg 0x7f16e1bb22a0 sndr 1, seq 177811, type 32, tkts 0 2012-05-02 02:21:08.450043 : GSIPC:TKT: collect msg 0x7f16e1bb22a0 from 1 for rcvr -1, tickets 0 2012-05-02 02:21:08.450060 : kjbrcvdscn[0x0.1ae28e][from 1][idx 2012-05-02 02:21:08.450078 : kjbrcvdscn[no bscn <= rscn 0x0.1ae28e][from 1] 2012-05-02 02:21:08.450097 : GSIPC:TKT: dest (1:1) rtkt not acked 3  unassigned bufs 0  tkts 0  newbufs 0 2012-05-02 02:21:08.450116 : GSIPC:TKT: remove ctx dest (1:1) 2012-05-02 02:21:08.450136 : [kjmxmpm][type 32][seq 0.177811][msg 0x7f16e1bb22a0][from 1] 2012-05-02 02:21:08.450155 : kjbmpocr(0xb0.6)seq 0x1,reqid=0x23e,(client 0x9fff7b58,0x1)(from 1)(lseq xdf4) ???Instance 2??LMS???,???build cr block,??????Instance 1?????Current Block??????Instance 2??v$cr_block_server??????LIGHT_WORKS?????current block transfer??????,??????? CR server? Light Work Rule(Light Work Rule?8i Cr Server?????????,?Remote LMS?? build CR????????,resource holder?LMS???????block,????CR build If creating the consistent read version block involves too much work (such as reading blocks from disk), then the holder sends the block to the requestor, and the requestor completes the CR fabrication. The holder maintains a fairness counter of CR requests. After the fairness threshold is reached, the holder downgrades it to lock mode.)? ??????? CR Request ????Current Block?? ???:??????class?block,CR server??????? ??undo block?? undo header block?CR quest, LMS????Current Block, ????? ???? ??????? block cleanout? CR  Version??????? ???????? data blocks, ??????? CR quest  & CR received?(???????Light Work Rule,LMS"??"), ??Current Block??DownConvert???S lock,??LMS???????ship??current version?block? ??????? , ?????? ,???????DownConvert?????”_fairness_threshold“???200,????Xcurrent Block?????Scurrent, ????LMS?????Current Version?Data Block: SQL> show parameter fair NAME TYPE VALUE ------------------------------------ ----------- ------------------------------ _fairness_threshold integer 200 Instance 1: SQL> update test set id=id+1 where id=4; 1 row updated. Instance 2: SQL> update test set id=id+1 where id=2; 1 row updated. SQL> select state,cr_scn_bas from x$bh where file#=1 and dbablk=89233 and state!=0; STATE CR_SCN_BAS ---------- ---------- 1 0 3 1838166 ?Instance 1? ????,? ??instance 2? v$cr_block_server?? instance 1 SQL> select * from test; ID ---------- 10 3 instance 2: SQL> select state,cr_scn_bas from x$bh where file#=1 and dbablk=89233 and state!=0; STATE CR_SCN_BAS ---------- ---------- 1 0 3 1883707 8 0 SQL> select * from test; ID ---------- 10 3 SQL> select state,cr_scn_bas from x$bh where file#=1 and dbablk=89233 and state!=0; STATE CR_SCN_BAS ---------- ---------- 1 0 3 1883707 8 0 ................... SQL> / STATE CR_SCN_BAS ---------- ---------- 2 0 3 1883707 3 1883695 repeat cr request on Instance 1 SQL> / STATE CR_SCN_BAS ---------- ---------- 8 0 3 1883707 3 1883695 ??????_fairness_threshold????????,?????200 ????????CR serve??Downgrade?lock, ????data block? CR Request????Receive? Current Block?

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• The Kids Are Alright. With Facebook and SMS. But Not Twitter

  - by ultan o'broin

  I delivered a lecture to business and technology freshmen (late teens, I reckon) in Trinity College Dublin recently. I spoke about user experience in enterprise applications, trends that UX pros need to be aware of such as social media, community support, mobile and tablet platforms and a bunch of nuances around those areas (data and device security, privacy, reputation, branding, and so on). It was all fairly high level stuff given the audience, and I included lots of colorful screenshots. Irish-related examples helped to get the message across. During the lecture I did a quick poll. “How many students here use Twitter?” Answer: None. “How many use Facebook?” All (pretty much). So what do these guys like to use instead of Twitter? Easy - text messaging (or SMS if you like). They all had phones. Perhaps I should not have been so surprised about Twitter, but it’s always great to have research validated by some guerilla UX research on the street. There’s already quite a bit of research about teen uptake (or lack) of Twitter, telling us young adults don’t tweet. Twitter is seen as something for er, older people. Affordable devices and data plans that allow students to text really quickly are also popular (BlackBerry, for example). Younger people just luuurve to text each other. A lot.  Facebook versus Twitter for younger folks? Well, we know the story. No contest. I would love to engage more with students like these. I’ll plan for it. It will also be interesting to see if Twitter becomes more important to them over time. There were a few other interesting observations about the lack of uptake of Foursquare, Gowalla and mobile apps like that. I  don’t think there’s a huge uptake in these kind of apps in Ireland anyway, but maybe students have different priorities anyway?   I’ll return to that another day. Technorati Tags: Gowalla,FourSquare,Twitter,UX,user experience,user assistance,Trinity College Dublin

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• Data validation best practices: how can I better construct user feedback?

  - by Cory Larson

  Data validation, whether it be domain object, form, or any other type of input validation, could theoretically be part of any development effort, no matter its size or complexity. I sometimes find myself writing informational or error messages that might seem harsh or demanding to unsuspecting users, and frankly I feel like there must be a better way to describe the validation problem to the user. I know that this topic is subjective and argumentative. I've migrated this question from StackOverflow where I originally asked it with little response. Basically, I'm looking for good resources on data validation and user feedback that results from it at a theoretical level. Topics and questions I'm interested in are: Content Should I be describing what the user did correctly or incorrectly, or simply what was expected? How much detail can the user read before they get annoyed? (e.g. Is "Username cannot exceed 20 characters." enough, or should it be described more fully, such as "The username cannot be empty, and must be at least 6 characters but cannot exceed 30 characters."?) Grammar How do I decide between phrases like "must not," "may not," or "cannot"? Delivery This can depend on the project, but how should the information be delivered to the user? Should it be obtrusive (e.g. JavaScript alerts) or friendly? Should they be displayed prominently? Immediately (i.e. without confirmation steps, etc.)? Logging Do you bother logging validation errors? Internationalization Some cultures prefer or better understand directness over subtlety and vice-versa (e.g. "Don't do that!" vs. "Please check what you've done."). How do I cater to the majority of users? I may edit this list as I think more about the topic, but I'm genuinely interested in proper user feedback techniques. I'm looking for things like research results, poll results, etc. I've developed and refined my own techniques over the years that users seem to be okay with, but I work in an environment where the users prefer to adapt to what you give them over speaking up about things they don't like. I'm interested in hearing your experiences in addition to any resources to which you may be able to point me.

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• Inverted schedctl usage in the JVM

  - by Dave

  The schedctl facility in Solaris allows a thread to request that the kernel defer involuntary preemption for a brief period. The mechanism is strictly advisory - the kernel can opt to ignore the request. Schedctl is typically used to bracket lock critical sections. That, in turn, can avoid convoying -- threads piling up on a critical section behind a preempted lock-holder -- and other lock-related performance pathologies. If you're interested see the man pages for schedctl_start() and schedctl_stop() and the schedctl.h include file. The implementation is very efficient. schedctl_start(), which asks that preemption be deferred, simply stores into a thread-specific structure -- the schedctl block -- that the kernel maps into user-space. Similarly, schedctl_stop() clears the flag set by schedctl_stop() and then checks a "preemption pending" flag in the block. Normally, this will be false, but if set schedctl_stop() will yield to politely grant the CPU to other threads. Note that you can't abuse this facility for long-term preemption avoidance as the deferral is brief. If your thread exceeds the grace period the kernel will preempt it and transiently degrade its effective scheduling priority. Further reading : US05937187 and various papers by Andy Tucker. We'll now switch topics to the implementation of the "synchronized" locking construct in the HotSpot JVM. If a lock is contended then on multiprocessor systems we'll spin briefly to try to avoid context switching. Context switching is wasted work and inflicts various cache and TLB penalties on the threads involved. If context switching were "free" then we'd never spin to avoid switching, but that's not the case. We use an adaptive spin-then-park strategy. One potentially undesirable outcome is that we can be preempted while spinning. When our spinning thread is finally rescheduled the lock may or may not be available. If not, we'll spin and then potentially park (block) again, thus suffering a 2nd context switch. Recall that the reason we spin is to avoid context switching. To avoid this scenario I've found it useful to enable schedctl to request deferral while spinning. But while spinning I've arranged for the code to periodically check or poll the "preemption pending" flag. If that's found set we simply abandon our spinning attempt and park immediately. This avoids the double context-switch scenario above. One annoyance is that the schedctl blocks for the threads in a given process are tightly packed on special pages mapped from kernel space into user-land. As such, writes to the schedctl blocks can cause false sharing on other adjacent blocks. Hopefully the kernel folks will make changes to avoid this by padding and aligning the blocks to ensure that one cache line underlies at most one schedctl block at any one time.

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• Why Does Ejabberd Start Fail?

  - by Andrew

  I am trying to install ejabberd 2.1.10-2 on my Ubuntu 12.04.1 server. This is a fresh install, and ejabberd is never successfully installed. The Install Every time, apt-get hangs on this: Setting up ejabberd (2.1.10-2ubuntu1) ... Generating SSL certificate /etc/ejabberd/ejabberd.pem... Creating config file /etc/ejabberd/ejabberd.cfg with new version Starting jabber server: ejabberd............................................................ failed. The dots just go forever until it times out or I 'killall' beam, beam.smp, epmd, and ejabberd processes. I've turned off all firewall restrictions. Here's the output of epmd -names while the install is hung: epmd: up and running on port 4369 with data: name ejabberdctl at port 42108 name ejabberd at port 39621 And after it fails: epmd: up and running on port 4369 with data: name ejabberd at port 39621 At the same time (during and after), the output of both netstat -atnp | grep 5222 and netstat -atnp | grep 5280 is empty. The Crash File A crash dump file is create at /var/log/ejabber/erl_crash.dump. The slogan (i.e. reason for the crash) is: Slogan: Kernel pid terminated (application_controller) ({application_start_failure,kernel,{shutdown,{kernel,start,[normal,[]]}}}) It's alive? Whenever I try to relaunch ejabberd with service ejabberd start, the same thing happens - even if I've killed all processes before doing so. However, when I killall the processes listed above again, and run su - ejabberd -c /usr/sbin/ejabberd, this is the output I get: Erlang R14B04 (erts-5.8.5) [source] [64-bit] [rq:1] [async-threads:0] [kernel-poll:false] Eshell V5.8.5 (abort with ^G) (ejabberd@ns1)1> =INFO REPORT==== 15-Oct-2012::12:26:13 === I(<0.478.0>:ejabberd_listener:166) : Reusing listening port for 5222 =INFO REPORT==== 15-Oct-2012::12:26:13 === I(<0.479.0>:ejabberd_listener:166) : Reusing listening port for 5269 =INFO REPORT==== 15-Oct-2012::12:26:13 === I(<0.480.0>:ejabberd_listener:166) : Reusing listening port for 5280 =INFO REPORT==== 15-Oct-2012::12:26:13 === I(<0.40.0>:ejabberd_app:72) : ejabberd 2.1.10 is started in the node ejabberd@ns1 Then, the server appears to be running. I get a login prompt when I access http://mydomain.com:5280/admin/. Of course I can't login unless I create an account. At this time, the output of netstat -atnp | grep 5222 and netstat -atnp | grep 5280 is as follows: tcp 0 0 0.0.0.0:5222 0.0.0.0:* LISTEN 19347/beam tcp 0 0 0.0.0.0:5280 0.0.0.0:* LISTEN 19347/beam ejabberdctl Even when it appears ejabberd is running, trying to do anything with ejabberdctl fails. For example: trying to register a user: root@ns1:~# ejabberdctl register myusername mydomain.com mypassword Failed RPC connection to the node ejabberd@ns1: nodedown I have no idea what I'm doing wrong. This happens on two different servers I have with identical software installed (really not much of anything). Please help. Thanks.

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• What is Database Continuous Integration?

  - by SQLDev

  Although not everyone is practicing continuous integration, many have at least heard of the concept. A recent poll on www.simple-talk.com indicates that 40% of respondents are employing the technique. It is widely accepted that the earlier issues are identified in the development process, the lower the cost to the development process. The worst case scenario, of course, is for the bug to be found by the customer following the product release. A number of Agile development best practices have evolved to combat this problem early in the development process, including pair programming, code inspections and unit testing. Continuous integration is one such Agile concept that tackles the problem at the point of committing a change to source control. This can alternatively be run on a regular schedule. This triggers a sequence of events that compiles the code and performs a variety of tests. Often the continuous integration process is regarded as a build validation test, and if issues were to be identified at this stage, the testers would simply not 'waste their time ' and touch the build at all. Such a ‘broken build’ will trigger an alert and the development team’s number one priority should be to resolve the issue. How application code is compiled and tested as part of continuous integration is well understood. However, this isn’t so clear for databases. Indeed, before I cover the mechanics of implementation, we need to decide what we mean by database continuous integration. For me, database continuous integration can be implemented as one or more of the following: 1)      Your application code is being compiled and tested. You therefore need a database to be maintained at the corresponding version. 2)      Just as a valid application should compile, so should the database. It should therefore be possible to build a new database from scratch. 3)     Likewise, it should be possible to generate an upgrade script to take your already deployed databases to the latest version. I will be covering these in further detail in future blogs. In the meantime, more information can be found in the whitepaper linked off www.red-gate.com/ci If you have any questions, feel free to contact me directly or post a comment to this blog post.

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• What is Database Continuous Integration?

  - by David Atkinson

  Although not everyone is practicing continuous integration, many have at least heard of the concept. A recent poll on www.simple-talk.com indicates that 40% of respondents are employing the technique. It is widely accepted that the earlier issues are identified in the development process, the lower the cost to the development process. The worst case scenario, of course, is for the bug to be found by the customer following the product release. A number of Agile development best practices have evolved to combat this problem early in the development process, including pair programming, code inspections and unit testing. Continuous integration is one such Agile concept that tackles the problem at the point of committing a change to source control. This can alternatively be run on a regular schedule. This triggers a sequence of events that compiles the code and performs a variety of tests. Often the continuous integration process is regarded as a build validation test, and if issues were to be identified at this stage, the testers would simply not 'waste their time ' and touch the build at all. Such a ‘broken build’ will trigger an alert and the development team’s number one priority should be to resolve the issue. How application code is compiled and tested as part of continuous integration is well understood. However, this isn’t so clear for databases. Indeed, before I cover the mechanics of implementation, we need to decide what we mean by database continuous integration. For me, database continuous integration can be implemented as one or more of the following: 1)      Your application code is being compiled and tested. You therefore need a database to be maintained at the corresponding version. 2)      Just as a valid application should compile, so should the database. It should therefore be possible to build a new database from scratch. 3)     Likewise, it should be possible to generate an upgrade script to take your already deployed databases to the latest version. I will be covering these in further detail in future blogs. In the meantime, more information can be found in the whitepaper linked off www.red-gate.com/ci If you have any questions, feel free to contact me directly or post a comment to this blog post.

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• Oracle WebCenter: Social Networking & Collaboration

  - by kellsey.ruppel(at)oracle.com

  We’ve talked in previous weeks about the key goals of the new release of WebCenter are providing a Modern User Experience, unparalleled Application Integration, converging all the best of the existing portal platforms into WebCenter and delivering a Common User Experience Architecture.  We’ve provided an overview of Oracle WebCenter and discussed some of the other key goals in previous weeks, and this week, we’ll focus on how the new release of Oracle WebCenter provides unprecedented Social Networking and Collaboration.We recently talked with Carin Chan, Principal Product Manager at Oracle, around the topic of Social Networking and Collaboration. In today’s work environment, employees have come to expect social and collaborative services to augment their work environment. Whether it is to post a blog or to poll fellow coworkers, employees expect and demand access to highly integrated, collaborative work environments that allow them to quickly contribute at work -- whether it is to make informed decisions, contribute on projects, or share knowledge.Social and collaborative services from Oracle WebCenter add an immeasurable amount of value to achieving a modern user experience. Oracle WebCenter Services provides rich and comprehensive social computing services that include services such as wikis, blogs, instant messaging, presence, activity streams and graphs, and polls/surveys that offer employees access to rich collaborative services to work efficiently.Employees can create pages or spaces that mix and match collaborative services while bringing in data from other applications to share with groups, teams, or organizations. These out of the box social and collaborative services include: People Connections and Activity Streams enable users to quickly assemble and visualize their social business networks and track user activities.Activity Graphs tracks all user activities in real-time and gathers intelligence about these users, their connections and the way they use information to make educated recommendations and provide on the spot information discovery.Wikis and blogs enable the community authoring of documents and sharing of ideas and also allow for the gathering of feedback and comments on those ideas.Tags and links allow users to easily mark, connect and share information with others.RSS feeds are available to track new or changed information related to discussion forums, processes or activities in an Oracle WebCenter environment.Discussion forums enable sharing of group knowledge and easy creation of communities around specific topics.Announcements allow you to manage and publish important news to your user base.Instant Messaging and Presence enable real-time awareness and communication with available users in the context of a business task.Web and Voice Conferencing enables real-time communication with internal and external business users.Lists provide a way to manage list data directly on the web as well as export and import it from and to Microsoft Excel.Oracle WebCenter Analytics provides comprehensive reporting metrics on activity and content usage within portals or composite applications.Activity Streams allow you to track activities and visualize your business networks.While being able to integrate into your portal deployment, these services are also integrated into how users are already working. This includes integration with software such as Microsoft Outlook, Microsoft Office and mobile devices such as the Apple iPhone. These services are just a tip of the iceberg regarding social and collaborative services that Oracle WebCenter has to offer your employees. Be sure to keep checking back this week for in future posts, we’ll delve deeper into a few of these collaborative services and discuss how a combination of collaborative services offer a better portal deployment to empower business users. Technorati Tags: UXP, collaboration, enterprise 2.0, modern user experience, oracle, portals, webcenter, social, activity streams, blogs, wikis

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• Data validation best practices: how can I better construct user feedback?

  - by Cory Larson

  Data validation, whether it be domain object, form, or any other type of input validation, could theoretically be part of any development effort, no matter its size or complexity. I sometimes find myself writing informational or error messages that might seem harsh or demanding to unsuspecting users, and frankly I feel like there must be a better way to describe the validation problem to the user. I know that this topic is subjective and argumentative. StackOverflow might not be the proper channel for diving into this subject, but like I've mentioned, we all run into this at some point or another. There are so many StackExchange sites now; if there is a better one, feel free to share! Basically, I'm looking for good resources on data validation and user feedback that results from it at a theoretical level. Topics and questions I'm interested in are: Content Should I be describing what the user did correctly or incorrectly, or simply what was expected? How much detail can the user read before they get annoyed? (e.g. Is "Username cannot exceed 20 characters." enough, or should it be described more fully, such as "The username cannot be empty, and must be at least 6 characters but cannot exceed 30 characters."?) Grammar How do I decide between phrases like "must not," "may not," or "cannot"? Delivery This can depend on the project, but how should the information be delivered to the user? Should it be obtrusive (e.g. JavaScript alerts) or friendly? Should they be displayed prominently? Immediately (i.e. without confirmation steps, etc.)? Logging Do you bother logging validation errors? Internationalization Some cultures prefer or better understand directness over subtlety and vice-versa (e.g. "Don't do that!" vs. "Please check what you've done."). How do I cater to the majority of users? I may edit this list as I think more about the topic, but I'm genuinely interest in proper user feedback techniques. I'm looking for things like research results, poll results, etc. I've developed and refined my own techniques over the years that users seem to be okay with, but I work in an environment where the users prefer to adapt to what you give them over speaking up about things they don't like. I'm interested in hearing your experiences in addition to any resources to which you may be able to point me.

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• links for 2011-02-16

  - by Bob Rhubart

  On the Software Architect Trail Software architect is the #1 job, according to a 2010 CNN-Money poll. In this article in Oracle Magazine, several members of the OTN architect community talk about the career paths that led them to this lucrative role.  (tags: oracle oraclemagazine softwarearchitect) Oracle Technology Network Architect Day: Denver Registration opens soon for this event to be held in Denver on March 23, 2011.  (tags: oracle otn entarch) How the Internet Gets Inside Us : The New Yorker "It isn’t just that we’ve lived one technological revolution among many; it’s that our technological revolution is the big social revolution that we live with." - Adam Gopnik (tags: internet progress technology innovation) The Insider Threat: Understand and Mitigate Your Risks: CSO Webcast February 23, 2011 at 1:00 PM EST/ 10:00 AM PST .  Speakers: Randy Trzeciak, lead for the CERT Insider Threat research team, and  Roxana Bradescu, Director of Database Security at Oracle. (tags: oracle CERT security) The Tom Kyte Blog: An Interesting Read... Tom looks at "an internet security firm brought down by not following the most *basic* of security principals." (tags: security oracle) Jason Williamson: Oracle as a Service in the Cloud "It is not trivial to migrate large amounts of pre-relational or 'devolved' relational data. To do this, we again must revert back to a tight roadmap to migration and leverage the growing tools and services that we have." - Jason Williamson (tags: oracle cloud soa) Edwin Biemond: Java / Oracle SOA blog: Building an asynchronous web service with JAX-WS "Building an asynchronous web service can be complex especially when you are used to synchronous Web services where you can wait for the response in your favorite tool." - Oracle ACE Edwin Biemond (tags: oracle oracleace java soa) Shared Database Servers (The SaaS Report) "Outside the virtualization world, there are capabilities of Oracle Database which can be used to prevent resource contention and guarantee SLA." - Shivanshu Upadhyay (tags: oracle database cloud SaaS) White Paper: Experiencing the New Social Enterprise "Increasingly organizations recognize the mandate to create a modern user experience that transforms existing business processes and increases business efficiency and agility." (tags: e20 enterprise2.0 socialcomputing oracle) Clusterware 11gR2 - Setting up an Active/Passive failover configuration Gilles Haro illustrates the steps necessary to achieve "a fully operational 11gR2 database protected by automatic failover capabilities." (tags: oracle clusterware) Oracle ERP: How to overcome local hurdles in a global implementation "The corporate world becomes a global village as many companies expand their business and offices around different countries and even continents. And this number keeps increasing. This globalization raises interesting questions..." - Jan Verhallen (tags: oracle capgemini entarch erp) Webcast: Successful Strategies for Optimizing Your Data Warehouse. March 3. 10 a.m. PT/1 p.m. ET Thursday, March 3, 2011. 10 a.m. PT/1 p.m. ET. Speakers: Mala Narasimharajan (Senior Product Marketing Manager, Oracle Data Integration) and Denis Gray (Principal Product Manager, Oracle Data Integration) (tags: oracle dataintegration datawarehousing)

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