Search Results

Search found 32453 results on 1299 pages for 'osr wls oracle service re'.

Page 733/1299 | < Previous Page | 729 730 731 732 733 734 735 736 737 738 739 740  | Next Page >

  • WebCenter Content Web Search Performance: Do you really need that folder path info?

    - by Nicolas Montoya
    End-users want content at their fingertips at the speed of thought if possible. When running search operations in the WebCenter Conter Web Interface every second or fraction of a second improvement does matter. When doing some trace analysis on the systemdatabase tracing on a customer environment, we came across some SQL queries that were unnecessarily being triggered! These were related to determining the folder path for every entry part of the search result set. However, this folder path was not even being used as part of the displayed information in the user interface.Why was the folder path information being collected when it was not even displayed in the UI? We found that the configuration parameter 'FolderPathInSearchResults' was set to 'true' under Administration > Admin Server > General Configuration > Additional Configuration Variables as shown below:When executing a quicksearch by keyword we were getting 100 out of 2280 entries in the first page of the result set.When thera 'FolderPathInSearchResults' configuration parameter is set to 'true', the following queries appear in the systemdatabase tracing:100 executions for a query on the FolderFiles table for each of the documents displayed in the first page:>systemdatabase/6       12.13 11:17:48.188      IdcServer-199   1.45 ms. SELECT * FROM FolderFiles WHERE dDocName='SLC02VGVUSORAC140641' AND fLinkRank=0[Executed. Returned row(s): true]382 executions for a query of the folders tables - most of the documents that match the keyword criteria are at a folder depth level of three or four:>systemdatabase/6       12.13 11:17:48.114      IdcServer-199   2.57 ms. SELECT FolderFolders.*,FolderMetaDefaults.* FROM FolderFolders,FolderMetaDefaults WHERE FolderFolders.fFolderGUID=FolderMetaDefaults.fFolderGUID(+) AND((FolderFolders.fFolderGUID = '1EB8E527E19B09ED3FE82EE310AEA13A' ) )[Executed.Returned row(s): true]By setting this 'FolderPathInSearchResults' configuration parameter to 'false', the above queries were no longer reported in the Server Output System Audit Information.Now, let's consider a practical scenario:Search result set page = 100Average folder depth der document in the search result set: 5The number of folder path related queries will be: 100 + 5*500 = 600If each query takes slightly over 3 ms. You would have 2000 ms (2 seconds) spent in server time to get this information.The overall performance impact goes beyond seerver time execution, as this information needs to travel from the server to the browser. If the documents are further nested into the folder hierarchy, additional hundreds of queries may be executed. If folder path is not being displayed in the end-user interface profile, your system may be better of with the 'FolderPathInSearchResults' configuration parameter disabled.

    Read the article

  • JavaOne 2012 - Why Should I Switch to Java SE 7

    - by sowmya
    At JavaOne 2012, David Keenan and Staffan Friberg gave a presentation to answer why it is beneficial to update your production environment to Java SE 7. The following resources will help you learn more about JDK 7 features and facilitate a smooth transition: * Features and Enhancements and Known Issues * Compatibility with earlier releases * JDK 7 and JRE 7 Certified System Configurations * JDK 7 and JRE 7 Supported Locales * JDK 7 Adoption Guide * Information About 7 Update Releases - Sowmya

    Read the article

  • Mercurial says "nothing changed", but it did. Sometimes my software is too clever.

    - by user12608033
    It seems I have found a "bug" in Mercurial. It takes a shortcut when checking for differences in tracked files. If the file's size and modification time are unchanged, it assumes its contents are unchanged: $ hg init . $ cp -p .sccs2hg/2005-06-05_00\:00\:00\,nicstat.c nicstat.c $ ls -ogE nicstat.c -rw-r--r-- 1 14722 2012-08-24 11:22:48.819451726 -0700 nicstat.c $ hg add nicstat.c $ hg commit -m "added nicstat.c" $ cp -p .sccs2hg/2005-07-02_00\:00\:00\,nicstat.c nicstat.c $ ls -ogE nicstat.c -rw-r--r-- 1 14722 2012-08-24 11:22:48.819451726 -0700 nicstat.c $ hg diff $ hg commit nothing changed $ touch nicstat.c $ hg diff diff -r b49cf59d431d nicstat.c --- a/nicstat.c Fri Aug 24 11:21:27 2012 -0700 +++ b/nicstat.c Fri Aug 24 11:22:50 2012 -0700 @@ -2,7 +2,7 @@ * nicstat - print network traffic, Kb/s read and written. Solaris 8+. * "netstat -i" only gives a packet count, this program gives Kbytes. * - * 05-Jun-2005, ver 0.81 (check for new versions, http://www.brendangregg.com) + * 02-Jul-2005, ver 0.90 (check for new versions, http://www.brendangregg.com) * [...] Now, before you agree or disagree with me on whether this is a bug, I will also say that I believe it is a feature. Yes, I feel it is an acceptable shortcut because in "real" situations an edit to a file will change the modification time by at least one second (the resolution that hg diff or hg commit is looking for). The benefit of the shortcut is greatly improved performance of operations like "hg diff" and "hg status", particularly where your repository contains a lot of files. Why did I have no change in modification time? Well, my source file was generated by a script that I have written to convert SCCS change history to Mercurial commits. If my script can generate two revisions of a file within a second, and the files are the same size, then I run afoul of this shortcut. Solution - I will just change my script to apply the modification time from the SCCS history to the file prior to commit. A "touch -t " will do that easily.

    Read the article

  • Baseline for GIS Applications

    - by Geertjan
    The application I introduced here yesterday can best be understood via its author's explanation: "As I developed several different WorldWind-based applications, I noticed that they all started out the same. Terramenta was born so I wouldn't have to recreate the baseline every time, I could just provide NetBeans plugin modules to introduce the new features required by different projects." So, to try it out for myself, I checked out the sources from the Mercurial repo today, built them, and ran them. hg clone https://bitbucket.org/heidtmare/terramenta On Windows, things worked fine, on Ubuntu they didn't because the relevant native libraries aren't provided yet out of the box. Here's the result: The above provides the WorldWind globe, together with all the standard options, e.g., for showing names and other WorldWind features, together with several features that I don't understand yet, such as tools for creating shapes and a recorder for replaying sequences. The complete application is like this, i.e., one single functionality module is provided, which exposes several API packages that can be extended: It would really be cool if the above module could also be added to a Maven-based application via a reference to a Maven repository, in the way that Timon Veenstra and the AgroSense team have made available their GeoViewer. One cool thing from the GeoViewer solution is the Flamingo menubar, which I added to Terramenta by simply putting the dependency below into the application POM: <dependency>    <groupId>nl.cloudfarming.client</groupId>    <artifactId>menu</artifactId>    <version>1.0.24</version></dependency> The result, without doing anything other than the above: I am looking forward to helping to document the use cases and developer scenarios for Terramenta! Something like this, created by Timon to demonstrate the GeoViewer use case would be cool to have: http://java.net/projects/agrosense/pages/ExampleGeoviewerNormal

    Read the article

  • HTTP Session Invalidation in Servlet/GlassFish

    - by reza_rahman
    HTTP session invalidation is something most of us take for granted and don't think much about. However for security and performance sensitive applications it is helpful to have at least a basic understanding of how it works in Servlets. In a brief code centric blog post Servlet specification lead Shing Wai Chan introduces the APIs for session invalidation and explains how you can fine tune the underlying reaper thread for session invalidation when it is needed in GlassFish 4. Don't hesitate to post a question here if the blog is not clear, this is a relatively esoteric topic...

    Read the article

  • JHeadstart search with default values

    - by christian.bischof
    JHeadstart has a powerful generator for ADF Faces pages. One of the features of the generator is the generation of search functionality into a page. The search functionality offers a "Quicksearch" with a single search item and an "Advanced Search" for multiple search criteria. Sometimes it would be nice to have initial values for the search criteria, but this is not supplied by JHeadstart by default.

    Read the article

  • YouTube: Up & Running with Twitter Bootstrap

    - by Geertjan
    "Twitter Bootstrap is a free collection of tools for creating websites and web applications. It contains HTML and CSS-based design templates for typography, forms, buttons, navigation and other interface components, as well as optional JavaScript extensions. It is the most popular project on GitHub and has been used by NASA and MSNBC among others." (Wikipedia) Normally, when you read "getting started" instructions for Twitter Bootstrap, you're told to download various things from various sites. Then you're told to set up various folders and files, etc. What if it could be much simpler than that? Spend 7 minutes with me in this (silent) screencast and you'll see a complete development environment for developing applications with Twitter Bootstrap: Two things that could be added to the movie are the JavaScript debugger, the support for responsive design via switching between form factors in the embedded browser and Chrome with the NetBeans plugin, as well as how to convert the application to a native Android or iOS package via in-built Cordova support.

    Read the article

  • JCP.Next Progress Updates

    - by heathervc
    JSR 355, JCP Executive Committee Merge, is currently nearing the end of the Public Review period.  Review the current draft here and provide feedback here.  The review closes on 12 June 2012.  The JCP Executive Committee met face to face in Sao Paulo, Brazil earlier in May, and has published a revision (version 2.1) of the EC Standing Rules.  The EC Standing Rules were introduced in October 2011 with the launch of JCP version 2.8 (JSR 348).  Version 2.1 of the EC Standing Rules will modify rules for attendance at EC face-to-face meetings. Remote observers will be permitted in "read-only" mode but unless a member attends in person they will be counted as absent.  The review period for these changes will close on June 30 2012.  Please comment on the proposed changes by logging an issue in the JCP EC issue tracker.

    Read the article

  • Ops Center 12c - Update - Provisioning Solaris on x86 Using a Card-Based NIC

    - by scottdickson
    Last week, I posted a blog describing how to use Ops Center to provision Solaris over the network via a NIC on a card rather than the built-in NIC.  Really, that was all about how to install Solaris on a SPARC system.  This week, we'll look at how to do the same thing for an x86-based server. Really, the overall process is exactly the same, at least for Solaris 11, with only minor updates. We will focus on Solaris 11 for this blog.  Once I verify that the same approach works for Solaris 10, I will provide another update. Booting Solaris 11 on x86 Just as before, in order to configure the server for network boot across a card-based NIC, it is necessary to declare the asset to associate the additional MACs with the server.  You likely will need to access the server console via the ILOM to figure out the MAC and to get a good idea of the network instance number.  The simplest way to find both of these is to start a network boot using the desired NIC and see where it appears in the list of network interfaces and what MAC is used when it tries to boot.  Go to the ILOM for the server.  Reset the server and start the console.  When the BIOS loads, select the boot menu, usually with Ctrl-P.  This will give you a menu of devices to boot from, including all of the NICs.  Select the NIC you want to boot from.  Its position in the list is a good indication of what network number Solaris will give the device. In this case, we want to boot from the 5th interface (GB_4, net4).  Pick it and start the boot processes.  When it starts to boot, you will see the MAC address for the interface Once you have the network instance and the MAC, go through the same process of declaring the asset as in the SPARC case.  This associates the additional network interface with the server.. Creating an OS Provisioning Plan The simplest way to do the boot via an alternate interface on an x86 system is to do a manual boot.  Update the OS provisioning profile as in the SPARC case to reflect the fact that we are booting from a different interface.  Update, in this case, the network boot device to be GB_4/net4, or the device corresponding to your network instance number.  Configure the profile to support manual network boot by checking the box for manual boot in the OS Provisioning profile. Booting the System Once you have created a profile and plan to support booting from the additional NIC, we are ready to install the server. Again, from the ILOM, reset the system and start the console.  When the BIOS loads, select boot from the Boot Menu as above.  Select the network interface from the list as before and start the boot process.  When the grub bootloader loads, the default boot image is the Solaris Text Installer.  On the grub menu, select Automated Installer and Ops Center takes over from there. Lessons The key lesson from all of this is that Ops Center is a valuable tool for provisioning servers whether they are connected via built-in network interfaces or via high-speed NICs on cards.  This is great news for modern datacenters using converged network infrastructures.  The process works for both SPARC and x86 Solaris installations.  And it's easy and repeatable.

    Read the article

  • Getting Audio from a Zone

    - by bleonard
    Now that I have Firefox and Java Web Start running from a zone, the last piece of the puzzle was audio (essential because most Flash content is accompanied by sound).  In the global zone there's a nice little utility called audiotest for testing your sound: bleonard@solaris:~$ audiotest Sound subsystem and version: SunOS Audio 4.0 (0x00040003) Platform: SunOS 5.11 snv_151a i86pc *** Scanning sound adapter #1 *** /dev/sound/audio810:0dsp (audio engine 0): audio810#0 - Performing audio playback test... <left> ................OK <right> ...............OK <stereo> ..............OK <measured sample rate 47727.00 Hz (-0.57%)> *** All tests completed OK *** Of course, before you can try audiotest in a zone, it must be installed: root@myzone:~# pkg install audio-utilities Packages to install: 1 Create boot environment: No DOWNLOAD PKGS FILES XFER (MB) Completed 1/1 6/6 0.4/0.4 PHASE ACTIONS Install Phase 20/20 PHASE ITEMS Package State Update Phase 1/1 Image State Update Phase 2/2 However, we'll need to do more than just install audiotest: root@myzone:~# audiotest /dev/mixer: No such file or directory The device file is missing from /dev. The audio devices also need to be added to the zone. For this we modify the zone configuration as follows: bleonard@solaris:~$ sudo zonecfg -z myzone Password: zonecfg:myzone> add device zonecfg:myzone:device> set match=/dev/audio* zonecfg:myzone:device> end zonecfg:myzone> add device zonecfg:myzone:device> set match=/dev/sound/* zonecfg:myzone:device> end zonecfg:myzone> add device zonecfg:myzone:device> set match=/dev/mixer* zonecfg:myzone:device> end zonecfg:myzone> add device zonecfg:myzone:device> set match=/dev/sndstat zonecfg:myzone:device> end zonecfg:myzone> verify zonecfg:myzone> exit Then reboot the zone: bleonard@solaris:~$ sudo zoneadm -z myzone reboot After which, audiotest should work: root@myzone:~# audiotest Sound subsystem and version: SunOS Audio 4.0 (0x00040003) Platform: SunOS 5.11 snv_151a i86pc *** Scanning sound adapter #1 *** /dev/sound/audio810:0dsp (audio engine 0): audio810#0 - Performing audio playback test... <left> ................OK <right> ...............OK <stereo> ..............OK <measured sample rate 48208.00 Hz (0.43%)> *** All tests completed OK *** You can also examine /dev/sndstat for additional information: root@myzone:~# cat /dev/sndstat SunOS Audio Framework Audio Devices: 0: audio810#0 Intel AC'97, ICH (DUPLEX) Mixers: 0: audio810#0 Intel AC'97, ICH AC'97 codec: SigmaTel STAC9700 However, when testing the sound from Firefox (from a user account other than root), such as this recent Flash presentation on Solaris availability, you may still be disappointed. This is simply a permissions problem, as the devices only have read and write permissions for root: root@myzone:~# ls -l /dev/audio* crw------- 1 root root 99, 3 Jul 1 10:21 /dev/audio crw------- 1 root root 99, 4 Jul 1 10:21 /dev/audioctl To address this: root@myzone:~# chmod 777 /dev/audio* root@myzone:~# chmod 777 /dev/sound/* And you should be all set.

    Read the article

  • Grails project structure

    - by Martin Janicek
    Good news everyone! I've changed the structure of the Grails project as requested in the issue 160028 and it should be much more user friendly than before. There are actually two things I've fixed/implemented. First of all the source folders are finally represented in the same way as for the Java projects (which means instead of the folder based structure it uses package based structure). The difference can be seen on pictures bellow:    Folder based structure:                                                 Package based structure: Second, minor and quite related change could be seen on those pictures too. There are different icons for different structures. For example Views and Layouts items are folder based, Domain Classes are package based and so on.

    Read the article

  • Using irc in NetBeans IDE 7.2

    - by Geertjan
    Turns out to be easy to use irc in NetBeans IDE 7.2. Install Irssi (I was able to do apt-get to install it), which has a handy guide here, and then use the Terminal window in NetBeans IDE (Window | Output | Terminal): In the above, do this: irssi /connect irc.freenode.net /join #netbeans Then, next time you have a problem in NetBeans IDE or there's some question you have about how to do something, just type your question in the Terminal window and someone will help you, if someone is there who knows the answer.

    Read the article

  • Project OpenPTK Release 2.1 Available

    - by Scott Fehrman
    The OpenPTK owners are pleased to announce that release 2.1 is available.  It has been "tagged" in the svn repository. See the download page for details.   This release is an update to version 2.0.  This release contains bug fixes, enhancements to existing capabilities, and new features.  The most notable change in this release is the use of maven, instead of ant, for the build process.  The adoption of maven has made the project more modular, reduced its download size (less bundled jar files) and will enable the future support of Project OpenPTK in a maven repository. For full details, see the OpenPTK version 2.1 Release Notes

    Read the article

  • The Minimalist Approach to Content Governance - Request Phase

    - by Kellsey Ruppel
    Originally posted by John Brunswick. For each project, regardless of size, it is critical to understand the required ownership, business purpose, prerequisite education / resources needed to execute and success criteria around it. Without doing this, there is no way to get a handle on the content life-cyle, resulting in a mass of orphaned material. This lowers the quality of end user experiences.     The good news is that by using a simple process in this request phase - we will not have to revisit this phase unless something drastic changes in the project. For each of the elements mentioned above in this stage, the why, how (technically focused) and impact are outlined with the intent of providing the most value to a small team. 1. Ownership Why - Without ownership information it will not be possible to track and manage any of the content and take advantage of many features of enterprise content management technology. To hedge against this, we need to ensure that both a individual and their group or department within the organization are associated with the content. How - Apply metadata that indicates the owner and department or group that has responsibility for the content. Impact - It is possible to keep the content system optimized by running native reports against the meta-data and acting on them based on what has been outlined for success criteria. This will maximize end user experience, as content will be faster to locate and more relevant to the user by virtue of working through a smaller collection. 2. Business Purpose Why - This simple step will weed out requests that have tepid justification, as users will most likely not spend the effort to request resources if they do not have a real need. How - Use a simple online form to collect and workflow the request to management native to the content system. Impact - Minimizes the amount user generated content that is of low value to the organization. 3. Prerequisite Education Resources Needed Why - If a project cannot be properly staffed the probability of its success is going to be low. By outlining the resources needed - in both skill set and duration - it will cause the requesting party to think critically about the commitment needed to complete their project and what gap must be closed with regard to education of those resources. How - In the simple request form outlined above, resources and a commitment to fulfilling any needed education should be included with a brief acceptance clause that outlines the requesting party's commitment. Impact - This stage acts as a formal commitment to ensuring that resources are able to execute on the vision for the project. 4. Success Criteria Why - Similar to the business purpose, this is a key element in helping to determine if the project and its respective content should continue to exist if it does not meet its intended goal. How - Set a review point for the project content that will check the progress against the originally outlined success criteria and then determine the fate of the content. This can even include logic that will tell the content system to remove items that have not been opened by any users in X amount of time. Impact - This ensures that projects and their contents do not live past their useful lifespans. Just as with orphaned content, non-relevant information will slow user's access to relevant materials for the jobs. Request Phase Summary With a simple form that outlines the ownership of a project and its content, business purpose, education and resources, along with success criteria, we can ensure that an enterprise content management system will stay clean and relevant to end users - allowing it to deliver the most value possible. The key here is to make it straightforward to make the request and let the content management technology manage as much as possible through metadata, retention policies and workflow. Doing these basic steps will allow project content to get off to a great start in the enterprise! Stay tuned for the next installment - the "Create Phase" - covering security access and workflow involved in content creation, enabling a practical layer of governance over our enterprise content repository.

    Read the article

  • JCP Open EC Meeting on 30 September 2012

    - by heathervc
    The JCP program office and Executive Committee invites all Java Community members to attend the OPEN EC Meeting on Sunday, 30 September at the Clift Hotel in San Francisco.  The meeting is adjacent to The Zone at JavaOne, but no JavaOne (or any other kind) of pass is required to attend.  It is OPEN to all!  Agenda topics include: JCP.Next status/overview of JSRs 355 and 358, improving communications between the EC and the community; Open Q&A and reminders of JCP events at JavaOne & Annual awards.  Any other suggestions?  This meeting is for you.  Let us know your questions pmo at jcp.org. Or bring them with you.  Details below. JCP Public Executive Committee Face-to-Face Meeting Open to Executive Committee Members and the Java Developer Community Location: Clift Hotel, 495 Geary Street, San Francisco - Rita Room (downstairs from Lobby) Date and Time: 9/30/12, 2:00 PM - 3:30 PM See you there.  Check out all of the JCP @ JavaOne events.

    Read the article

  • Concurrency Utilities for Java EE 6: JSR 236 Rebooting

    - by arungupta
    JSR 166 added support for concurrency utilities in the Java platform. The JSR 236's, a.k.a Concurrency Utilities for Java EE, goal was to extend that support to the Java EE platform by adding asynchronous abilities to different application components. The EG was however stagnant since Dec 2003. Its coming back to life with the co-spec lead Anthony Lai's message to the JSR 236 EG (archived here). The JSR will be operating under JCP 2.8's transparency rules and can be tracked at concurrency-spec.java.net. All the mailing lists are archived here. The final release is expected in Q1 2013 and the APIs will live in the javax.enterprise.concurrent package. Please submit your nomination if you would like to join this EG.

    Read the article

  • 5 Step Procedure for Android Deployment with NetBeans IDE

    - by Geertjan
    I'm finding that it's so simple to deploy apps to Android that I'm not needing to use the Android emulator at all, haven't been able to figure out how it works anyway (big blinky screen pops up that I don't know what to do with). I just simply deploy the app straight to Android, try it out there, and then uninstall it, if needed. The whole process (only step 4 and 5 below need to be done for each deployment iteration, after you've done steps 1, 2, and 3 once to set up the deployment environment), takes a few seconds. Here's what I do: On Android, go to Settings | Applications. Check "Unknown sources". In "Development", check "USB debugging". Connect Android to your computer via a USB cable. Start up NetBeans IDE, with NBAndroid installed, as described yesterday. and create your "Hello World" app. Right-click the project in the IDE and choose "Export Signed Android Package". Create a new keystore, or choose an existing one, via the wizard that appears. At the end of the wizard (would be nice if NBAndroid would let you set up a keystore once and then reuse it for all your projects, without needing to work through the whole wizard step by step each time), you'll have a new release APK file (Android deployment archive) in the project's 'bin' folder, which you can see in the Files window. Go to the command line (would be nice if NBAndroid were to support adb, would mean I wouldn't need the command line at all), browse to the location of the APK file above. Type "adb install helloworld-release.apk" or whatever the APK file is called. You should see a "Success" message in the command line. Now the application is installed. On your Android, go to "Applications", and there you'll see your brand new app. Then try it out there and delete it if you're not happy with it. After you've made a change in your app, simply repeat step 4 and 5, i.e., create a new APK and install it via adb. Step 4 and 5 take a couple of seconds. And, given that it's all so simple, I don't see the value of the Android emulator, at all.

    Read the article

  • For business information and web traffic T4 and Solaris 11 stand head and shoulders above the crowd

    - by rituchhibber
    Everyone is talking about encryption of business information and web traffic. T4 and Solaris 11 stand head and shoulders above the crowd. Each T4 chip has 8 crypto accelerators inside the chip - that means there are 32 in a T4-4.  These are faster and offer more algorithms than almost all standalone devices and it is all free with T4!  What are you waiting for?Please contact Lucy Hillman or Graham Scattergood for more details.Your weekly tea time soundbite of the latest UK news, updates and initiatives on the SPARC T Series servers. T4 good news, best practice and feedback is always welcome.

    Read the article

  • Developer Preview of JDK8, JavaFX8 *HARD-FLOAT ABI* for Linux/ARM Now Available!

    - by HecklerMark
    Just a quick post to spread the good word: the Developer Preview of JDK8 and JavaFX8 for Linux on ARM processors - hard-float ABI - is now available here. Right here. It's been tested on the Raspberry Pi, and many of us plan to (unofficially) test it on a variety of other ARM platforms. This could be the beginning of something big. So...what are you still doing here? Go download it already! (Did I mention you could get it here?) :-D All the best,Mark

    Read the article

  • Coherence Data Guarantees for Data Reads - Basic Terminology

    - by jpurdy
    When integrating Coherence into applications, each application has its own set of requirements with respect to data integrity guarantees. Developers often describe these requirements using expressions like "avoiding dirty reads" or "making sure that updates are transactional", but we often find that even in a small group of people, there may be a wide range of opinions as to what these terms mean. This may simply be due to a lack of familiarity, but given that Coherence sits at an intersection of several (mostly) unrelated fields, it may be a matter of conflicting vocabularies (e.g. "consistency" is similar but different in transaction processing versus multi-threaded programming). Since almost all data read consistency issues are related to the concept of concurrency, it is helpful to start with a definition of that, or rather what it means for two operations to be concurrent. Rather than implying that they occur "at the same time", concurrency is a slightly weaker statement -- it simply means that it can't be proven that one event precedes (or follows) the other. As an example, in a Coherence application, if two client members mutate two different cache entries sitting on two different cache servers at roughly the same time, it is likely that one update will precede the other by a significant amount of time (say 0.1ms). However, since there is no guarantee that all four members have their clocks perfectly synchronized, and there is no way to precisely measure the time it takes to send a given message between any two members (that have differing clocks), we consider these to be concurrent operations since we can not (easily) prove otherwise. So this leads to a question that we hear quite frequently: "Are the contents of the near cache always synchronized with the underlying distributed cache?". It's easy to see that if an update on a cache server results in a message being sent to each near cache, and then that near cache being updated that there is a window where the contents are different. However, this is irrelevant, since even if the application reads directly from the distributed cache, another thread update the cache before the read is returned to the application. Even if no other member modifies a cache entry prior to the local near cache entry being updated (and subsequently read), the purpose of reading a cache entry is to do something with the result, usually either displaying for consumption by a human, or by updating the entry based on the current state of the entry. In the former case, it's clear that if the data is updated faster than a human can perceive, then there is no problem (and in many cases this can be relaxed even further). For the latter case, the application must assume that the value might potentially be updated before it has a chance to update it. This almost aways the case with read-only caches, and the solution is the traditional optimistic transaction pattern, which requires the application to explicitly state what assumptions it made about the old value of the cache entry. If the application doesn't want to bother stating those assumptions, it is free to lock the cache entry prior to reading it, ensuring that no other threads will mutate the entry, a pessimistic approach. The optimistic approach relies on what is sometimes called a "fuzzy read". In other words, the application assumes that the read should be correct, but it also acknowledges that it might not be. (I use the qualifier "sometimes" because in some writings, "fuzzy read" indicates the situation where the application actually sees an original value and then later sees an updated value within the same transaction -- however, both definitions are roughly equivalent from an application design perspective). If the read is not correct it is called a "stale read". Going back to the definition of concurrency, it may seem difficult to precisely define a stale read, but the practical way of detecting a stale read is that is will cause the encompassing transaction to roll back if it tries to update that value. The pessimistic approach relies on a "coherent read", a guarantee that the value returned is not only the same as the primary copy of that value, but also that it will remain that way. In most cases this can be used interchangeably with "repeatable read" (though that term has additional implications when used in the context of a database system). In none of cases above is it possible for the application to perform a "dirty read". A dirty read occurs when the application reads a piece of data that was never committed. In practice the only way this can occur is with multi-phase updates such as transactions, where a value may be temporarily update but then withdrawn when a transaction is rolled back. If another thread sees that value prior to the rollback, it is a dirty read. If an application uses optimistic transactions, dirty reads will merely result in a lack of forward progress (this is actually one of the main risks of dirty reads -- they can be chained and potentially cause cascading rollbacks). The concepts of dirty reads, fuzzy reads, stale reads and coherent reads are able to describe the vast majority of requirements that we see in the field. However, the important thing is to define the terms used to define requirements. A quick web search for each of the terms in this article will show multiple meanings, so I've selected what are generally the most common variations, but it never hurts to state each definition explicitly if they are critical to the success of a project (many applications have sufficiently loose requirements that precise terminology can be avoided).

    Read the article

  • Don't Miss OPN Exchange @ OpenWorld: Register NOW!

    - by Cinzia Mascanzoni
    Don't miss the opportunity to register to OPN Exchange @ OpenWorld at Early Bird pricing : $ 595. The promotion will end September 7th. OPN Exchange is the only pass that gives you access to more than 40 Partner dedicated sessions, held Monday-Thursday, to OPN Lounge and OPN Test Fest. If you have registered with Full Conference pass, here is what you can do to add OPN Exchange to your registration: Go to My Account and add (add-on section) the OPN Exchange pass for $ 100. If you have registered for a Discover Pass: contact the registration team and ask for the upgrade at Tel: +1.650.226.0812 (International) Monday through Friday, 6:00 a.m. to 6:00 p.m. (Pacific time) or Email: [email protected].

    Read the article

  • TXPAUSE : polite waiting for hardware transactional memory

    - by Dave
    Classic locks are an appropriate tool to prevent potentially conflicting operations A and B, invoked by different threads, from running at the same time. In a sense the locks cause either A to run before B or vice-versa. Similarly, we can replace the locks with hardware transactional memory, or use transactional lock elision to leverage potential disjoint access parallelism between A and B. But often we want A to wait until B has run. In a Pthreads environment we'd usually use locks in conjunction with condition variables to implement our "wait until" constraint. MONITOR-MWAIT is another way to wait for a memory location to change, but it only allows us to track one cache line and it's only available on x86. There's no similar "wait until" construct for hardware transactions. At the instruction-set level a simple way to express "wait until" in transactions would be to add a new TXPAUSE instruction that could be used within an active hardware transaction. TXPAUSE would politely stall the invoking thread, possibly surrendering or yielding compute resources, while at the same time continuing to track the transaction's address-set. Once a transaction has executed TXPAUSE it can only abort. Ideally that'd happen when some other thread modifies a variable that's in the transaction's read-set or write-set. And since we're aborting all writes would be discarded. In a sense this gives us multi-location MWAIT but with much more flexibility. We could also augment the TXPAUSE with a cycle-count bound to cap the time spent stalled. I should note that we can already enter a tight spin loop in a transaction to wait for updates to address-set to cause an abort. Assuming that the implementation monitors the address-set via cache-coherence probes, by waiting in this fashion we actually communicate via the probes, and not via memory values. That is the updating thread signals the waiter via probes instead of by traditional memory values. But TXPAUSE gives us a polite way to spin.

    Read the article

  • Extreme Portability: OpenJDK 7 and GlassFish 3.1.1 on Power Mac G5!

    - by MarkH
    Occasionally you hear someone grumble about platform support for some portion or combination of the Java product "stack". As you're about to see, this really is not as much of a problem as you might think. Our friend John Yeary was able to pull off a pretty slick feat with his vintage Power Mac G5. In his words: Using a build script sent to me by Kurt Miller, build recommendations from Kelly O'Hair, and the great work of the BSD Port team... I created a new build of OpenJDK 7 for my PPC based system using the Zero VM. The results are fantastic. I can run GlassFish 3.1.1 along with all my enterprise applications. I recently had the opportunity to pick up an old G5 for little money and passed on it. What would I do with it? At the time, I didn't think it would be more than a space-consuming novelty. Turns out...I could have had some fun and a useful piece of hardware at the same time. Maybe it's time to go bargain-hunting again. For more information about repurposing classic Apple hardware and learning a few JDK-related tricks in the process, visit John's site for the full article, available here. All the best,Mark

    Read the article

< Previous Page | 729 730 731 732 733 734 735 736 737 738 739 740  | Next Page >