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  • Share Files and Folders and Internet between Guest OS and the Host in Hyper-V

    - by Manesh Karunakaran
    For those who are familiar with the VirtualPC, vmWare and VirtualBox environments will be quite irritated to find out that there is no direct way to share files from the Host machine to the Virtualized guest environment. This is a good thing from a CIO perspective because there’s excellent isolation for the virtualized environments this way, but for the developer junkies like us, this is an irritant, especially for those who have nuked their Windows 7 OS and installed Windows Server 2008 R2 for all the the SharePoint friendliness that it offers. Here’s a quick 5 minutes howto on Enabling Shared Folders and Internet Access for the Hyper-V images, for those who are still struggling with this. Step 1: Add a Virtual Network Adapter to your Guest OS For this, shut down the guest machine, go to its settings and add a Virtual Network Adapter as given in the images below     Step 2: Enable Virtual Networking in Hyper-V   Setting this up is very easy. In the Hyper-V Manager, under Actions (right panel), click the Virtual Network Manager. In the Virtual Network Manager in the Create virtual network panel, select Internal and click the Add button.        At this point if you open Control Panel\Network and Internet\Network Connections you will be able to see the new Network Adapter, Now name it to something meaningful other than Network Adapter X. Now you can add this network to each of your virtual machines, but at this point, unless you assign an IP address in each connection, you won't be able to do much.   Step 3: Enable Internet Connection Sharing so that Guest OS’es also can connect to the internet. To enable ICS follow these steps: Click on the network icon in the tray of your host machine and select Network and Sharing Center. From there click Manage network connections. Select the network adapter that you use to access the Internet. Right click it and select Properties. In the properties dialog select the Sharing tab. On this tab check the box that says "Allow other network users..." and then set the Home networking connection to be the network adapter that was created above (now you see why I said to rename it to something useful). Now your virtual machines that have this network connection will automatically get an IP address and will be able to connect to the Internet (provided your internet connection is working). Because each adapter also gets an automatic address you can now share files and folders between your host and your virtual machines which is important since you can't just drag-and-drop files like you can with Virtual PC.   Step 4: Create a Shared Folder in the Host Machine and use it in the Guest machine. Right click on the folder that you want to Share and select ‘Share with\Specific People’ and specify who all can access the share. Open the Guest OS from Hyper V Navigate to Start > Run and type in the Address of the Share (Or Map a Drive to the Share) Bingo! The Share opens!! :)   Now you can share as many files and folders as you want between the host and the guest, and you also have internet access inside the Virtual machines. Hope that helps.   Technorati Tags: Shared folder,Hyper-V,Share Files,Share files and folders between guest and host,Hyper-V Networking,Share Internet Access in Hyper-V,Internet,Files,Shared folders in Hyper-V

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  • Release Management as Orchestra

    - by ericajanine
    I read an excellent, concise article (http://www.buildmeister.com/articles/software_release_management_best_practices) on the basics of release management practices. In the article, it states "Release Management is often likened to the conductor of an orchestra, with the individual changes to be implemented the various instruments within it." I played in music ensembles for years, so this is especially close to my heart as example. I learned most of my discipline from hours and hours of practice at the hand of a very skilled conductor and leader. I also learned that the true magic in symphonic performance is one where everyone involved is focused on one sound, one goal. In turn, that solid focus creates a sound and experience bigger than just mechanics alone accomplish. In symphony, a conductor's true purpose is to make you, a performer, better so the overall sound and end product is better. The big picture (the performance of the composition) is the end-game, and all musicians in the orchestra know without question their part makes up an important but incomplete piece of that performance. A good conductor works with each section (e.g. group) to ensure their individual pieces are solid. Let's restate: The conductor leads and is responsible for ensuring those pieces are solid. While the performers themselves are doing the work, the conductor is the final authority on when the pieces are ready or not. If not, the conductor initiates the efforts to get them ready or makes the decision to scrap their parts altogether for the sake of an overall performance. Let it sink in, because it's clear--It is not the performer's call if they play their part as agreed, it's the conductor's final call to allow it. In comparison, if a software release manager is a conductor, the only way for that manager to be effective is to drive the overarching process and execution of individual pieces of a software development lifecycle. It does not mean the release manager performs each and every piece, it means the release manager has oversight and influence because the end-game is a successful software enhancin a useable environment. It means the release manager, not the developer or development manager, has the final call if something goes into a software release. Of course, this is not a process of autocracy or dictation of absolute rule, it's cooperative effort. But the release manager must have the final authority to make a decision if something is ready to be added to the bigger piece, the overall symphony of software changes being considered for package and release. It also goes without saying a release manager, like a conductor, must have full autonomy and isolation from other software groups. A conductor is the one on the podium waving a little stick at the each section and cueing them for their parts, not yelling from the back of the room while also playing a tuba and taking direction from the horn section. I have personally seen where release managers are relegated to being considered little more than coordinators, red-tapers to "satisfy" the demands of an audit group without being bothered to actually respect all that a release manager gives a group willing to employ them fully. In this dysfunctional scenario, development managers, project managers, business users, and other stakeholders have been given nearly full clearance to demand and push their agendas forward, causing a tail-wagging-the-dog scenario where an inherent conflict will ensue. Depending on the strength, determination for peace, and willingness to overlook a built-in expectation that is wrong, the release manager here must face the crafted conflict head-on and diffuse it as quickly as possible. Then, the release manager must clearly make a case why a change cannot be released without negative impact to all parties involved. If a political agenda is solely driving a software release, there IS no symphony, there is no "software lifecycle". It's just out-of-tune noise. More importantly, there is no real conductor. Sometimes, just wanting to make a beautiful sound is not enough. If you are a release manager, are you freed up enough to move, to conduct the sections of software creation to ensure a solid release performance is possible? If not, it's time to take stock in what your role actually is and see if that is what you truly want to achieve in your position. If you are, then you can successfully build your career and that of the people in your groups to create truly beautiful software (music) together.

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  • concurrency::accelerator_view

    - by Daniel Moth
    Overview We saw previously that accelerator represents a target for our C++ AMP computation or memory allocation and that there is a notion of a default accelerator. We ended that post by introducing how one can obtain accelerator_view objects from an accelerator object through the accelerator class's default_view property and the create_view method. The accelerator_view objects can be thought of as handles to an accelerator. You can also construct an accelerator_view given another accelerator_view (through the copy constructor or the assignment operator overload). Speaking of operator overloading, you can also compare (for equality and inequality) two accelerator_view objects between them to determine if they refer to the same underlying accelerator. We'll see later that when we use concurrency::array objects, the allocation of data takes place on an accelerator at array construction time, so there is a constructor overload that accepts an accelerator_view object. We'll also see later that a new concurrency::parallel_for_each function overload can take an accelerator_view object, so it knows on what target to execute the computation (represented by a lambda that the parallel_for_each also accepts). Beyond normal usage, accelerator_view is a quality of service concept that offers isolation to multiple "consumers" of an accelerator. If in your code you are accessing the accelerator from multiple threads (or, in general, from different parts of your app), then you'll want to create separate accelerator_view objects for each thread. flush, wait, and queuing_mode When you create an accelerator_view via the create_view method of the accelerator, you pass in an option of immediate or deferred, which are the two members of the queuing_mode enum. At any point you can access this value from the queuing_mode property of the accelerator_view. When the queuing_mode value is immediate (which is the default), any commands sent to the device such as kernel invocations and data transfers (e.g. parallel_for_each and copy, as we'll see in future posts), will get submitted as soon as the runtime sees fit (that is the definition of immediate). When the value of queuing_mode is deferred, the commands will be batched up. To send all buffered commands to the device for execution, there is a non-blocking flush method that you can call. If you wish to block until all the commands have been sent, there is a wait method you can call. Deferring is a more advanced scenario aimed at performance gains when you are submitting many device commands and you want to avoid the tiny overhead of flushing/submitting each command separately. Querying information Just like accelerator, accelerator_view exposes the is_debug and version properties. In fact, you can always access the accelerator object from the accelerator property on the accelerator_view class to access the accelerator interface we looked at previously. Interop with D3D (aka DX) In a later post I'll show an example of an app that uses C++ AMP to compute data that is used in pixel shaders. In those scenarios, you can benefit by integrating C++ AMP into your graphics pipeline and one of the building blocks for that is being able to use the same device context from both the compute kernel and the other shaders. You can do that by going from accelerator_view to device context (and vice versa), through part of our interop API in amp.h: *get_device, create_accelerator_view. More on those in a later post. Comments about this post by Daniel Moth welcome at the original blog.

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  • Big Data – Operational Databases Supporting Big Data – Key-Value Pair Databases and Document Databases – Day 13 of 21

    - by Pinal Dave
    In yesterday’s blog post we learned the importance of the Relational Database and NoSQL database in the Big Data Story. In this article we will understand the role of Key-Value Pair Databases and Document Databases Supporting Big Data Story. Now we will see a few of the examples of the operational databases. Relational Databases (Yesterday’s post) NoSQL Databases (Yesterday’s post) Key-Value Pair Databases (This post) Document Databases (This post) Columnar Databases (Tomorrow’s post) Graph Databases (Tomorrow’s post) Spatial Databases (Tomorrow’s post) Key Value Pair Databases Key Value Pair Databases are also known as KVP databases. A key is a field name and attribute, an identifier. The content of that field is its value, the data that is being identified and stored. They have a very simple implementation of NoSQL database concepts. They do not have schema hence they are very flexible as well as scalable. The disadvantages of Key Value Pair (KVP) database are that they do not follow ACID (Atomicity, Consistency, Isolation, Durability) properties. Additionally, it will require data architects to plan for data placement, replication as well as high availability. In KVP databases the data is stored as strings. Here is a simple example of how Key Value Database will look like: Key Value Name Pinal Dave Color Blue Twitter @pinaldave Name Nupur Dave Movie The Hero As the number of users grow in Key Value Pair databases it starts getting difficult to manage the entire database. As there is no specific schema or rules associated with the database, there are chances that database grows exponentially as well. It is very crucial to select the right Key Value Pair Database which offers an additional set of tools to manage the data and provides finer control over various business aspects of the same. Riak Rick is one of the most popular Key Value Database. It is known for its scalability and performance in high volume and velocity database. Additionally, it implements a mechanism for collection key and values which further helps to build manageable system. We will further discuss Riak in future blog posts. Key Value Databases are a good choice for social media, communities, caching layers for connecting other databases. In simpler words, whenever we required flexibility of the data storage keeping scalability in mind – KVP databases are good options to consider. Document Database There are two different kinds of document databases. 1) Full document Content (web pages, word docs etc) and 2) Storing Document Components for storage. The second types of the document database we are talking about over here. They use Javascript Object Notation (JSON) and Binary JSON for the structure of the documents. JSON is very easy to understand language and it is very easy to write for applications. There are two major structures of JSON used for Document Database – 1) Name Value Pairs and 2) Ordered List. MongoDB and CouchDB are two of the most popular Open Source NonRelational Document Database. MongoDB MongoDB databases are called collections. Each collection is build of documents and each document is composed of fields. MongoDB collections can be indexed for optimal performance. MongoDB ecosystem is highly available, supports query services as well as MapReduce. It is often used in high volume content management system. CouchDB CouchDB databases are composed of documents which consists fields and attachments (known as description). It supports ACID properties. The main attraction points of CouchDB are that it will continue to operate even though network connectivity is sketchy. Due to this nature CouchDB prefers local data storage. Document Database is a good choice of the database when users have to generate dynamic reports from elements which are changing very frequently. A good example of document usages is in real time analytics in social networking or content management system. Tomorrow In tomorrow’s blog post we will discuss about various other Operational Databases supporting Big Data. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Big Data, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

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  • Inspiring a co-worker to adopt better coding practices?

    - by Aaronaught
    In the Handling my antiquated coworker question, various people discussed strategies for dealing with coworkers who are unwilling to integrate their workflow with the team's. I'd like, if possible, to learn some strategies for "teaching" a coworker who is merely ignorant of modern techniques and tools, and possibly a little apathetic. I've started working with a programmer who until recently has been working in relative isolation, in a different part of the company. He has extensive domain knowledge and most importantly he has demonstrated good problem-solving skills, something which many candidates seem to lack. However, the actual (C#) code I've seen is a throwback to the VB6 days. Procedural structure, Hungarian notation, global variables (abuse of static), no interfaces, no tests, non-use of Generics, throwing System.Exception... you get the idea. This programmer is a fair bit older than I am and, by first impressions at least, doesn't actively seek positive change. I'm not going to say resistant to change, because I think that is largely an issue of how the topic gets broached, and I want to be prepared. Programmers tend to be stubborn people, and going in with guns blazing and instituting rip-it-to-shreds code reviews and strictly-enforced policies is very likely not going to produce the end result that I want. If this were a new hire, a junior programmer, I wouldn't think twice about taking a "mentor" stance, but I'm extremely wary of treating an experienced employee as a clueless newbie (which he's not - he just hasn't kept pace with certain advancements in the field). How might I go about raising this developer's code quality standard the Dale Carnegie way, through gentle persuasion and non-material incentives? What would be the best strategy for effecting subtle, gradual changes, without creating an adversarial situation? Have other people - especially lead developers - been in this type of situation before? Which strategies were successful at stimulating interest and creating a positive group dynamic? Which strategies weren't successful and would be better to avoid? Clarifications: I really feel that several people are answering based on personal feelings without actually reading all of the details of the question. Please note the following, which should have been implied but I am now making explicit: This coworker is only my "senior" by virtue of age. I never said that his title, sphere of influence, or years at the organization exceed mine, and in fact, none of those things are true. He's a LOB programmer who's been absorbed into the main development shop. That's it. I am not a new hire, junior programmer, or other naïve idiot with grand plans to transform the company overnight. I am basically in charge of the software process, but as many who've worked as "leads" will know, responsibilities don't always correlate precisely with the org chart. I'm not asking people how to get my way, come hell or high water. I could do that if I wanted to, with the net result being that this person would become resentful and/or quit. Please try to understand that I am looking for a social, cooperative method of driving change. The mention of "...global variables... no tests... throwing System.Exception" was intended to demonstrate that the problems are not just superficial or aesthetic. Practices that may work for relatively small CRUD apps do not necessarily work for large enterprise apps, and in fact, none of the code so far has actually passed the integration tests. Please, try to take the question at face value, accept that I actually know what I'm talking about, and either answer the question that I actually asked or move on. P.S. My sincerest gratitude to those who -did- offer constructive advice rather than arguing with the premise. I'm going to leave this open for a while longer as I'm hoping to hear more in the way of real-world experiences.

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  • Xsigo and Oracle's Storage

    - by Philippe Deverchère
    Xsigo, a virtual network infrastructure provider, has recently been acquired by Oracle. Following this acquisition, one might ask ourselves why it is important to Oracle and how Oracle's storage is going to benefit on the long term from this virtualized infrastructure layer. Well, the first thing to understand is that Virtual Networking addresses both network and storage connectivity. Oracle Virtual Networking, as the Xsigo technology is now called, connects any server to any network and storage, so this is not just about connecting servers to the Internet or Intranet. It is also for a large part connecting servers to NAS and SAN storage. Connecting servers to storage has become increasingly complex in the past few years because of the strong emergence of virtualization at the Operating System level. 50% of enterprise workloads are now virtualized, up from 18% in 2009, resulting in a strong consolidation of various applications in a high density server footprint. At the same time, server I/O capability increased 8x in the last 8 years. All this has pushed IT administrators to multiply the number of I/O connections in the back-end of their physical servers, resulting in a messy and very hard to manage networking infrastructure. Here is a typical view of a rack back-end when no virtual networking is used. We consider that today: - 75% of users have ten or more Ethernet ports per server - 85% of users have two or more SAN ports per server - 58% have had to add connectivity to a server specifically for VMs - 65% consider cable reduction a priority The average is 12 or more ports per server, resulting in an extremely complex infrastructure to manage. What Oracle wants to achieve with its Oracle Virtual Networking offering is pretty simple. The objective is to eliminate the complexity through a dramatic reduction of cabling between servers and storage/networks. It is also to provide a software based management system so that any server can be connected to any network or any storage, on demand, and without physical intervention on the infrastructure. At the end of the day, the picture on the left shows what one wants to get for the back-end of customer's racks: just a couple of connections on each physical server to provide a simple, agile and fast network infrastructure for both storage and networking access. This is exactly what the Oracle Virtual Networking solution does. It transforms a complex, error-prone, difficult to manage and expensive networking infrastructure into a simple, high performance and agile solution for the data center. Practically speaking, and for the sake of simplicity, imagine that each server just hosts a minimal number of physical InfiniBand HCAs (Host Channel Adapter) with two links (for redundancy) onto the Oracle Fabric Interconnect director. Using the Oracle Fabric Manager software, you'll then be able to create virtual NICs and HBAs (called vNIC and vHBA) that will be seen by the servers as standard NICs and HBAs and associate them to networks and storage systems which are physically connected to the back-end of the director through standard Fibre Channel and Ethernet GbE/10GbE ports. In addition to this incredibly simple "at-a-click" connectivity capability, the Oracle Virtual Networking solution offers powerful features such as network isolation, Quality of Service, advanced performance monitoring and non-disruptive reconfiguration, migration and scalability of networking infrastructure. So let's go back now to our initial question: why is Oracle Virtual Networking especially important to Oracle's storage solutions? After all, one could connect any storage in the back-end of the Oracle Fabric Interconnect directors, right? The answer is pretty simple: since Oracle owns both the virtualized networking infrastructure and the storage (ZFS-SA, Pillar Axiom and tape), it is possible to imagine several ways in the future to add value when it comes to connect storage to a virtualized storage network: enhanced storage capabilities, converged management between storage and network, improved diagnostic capabilities and optimized integration resulting in higher performance and unique features/functions. Of course, all this is not going to be done overnight, and future will tell us is which evolutions come first. But there is little doubt that the integration of Xsigo within Oracle is going to create opportunities for Oracle's storage!

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  • Security and the Mobile Workforce

    - by tobyehatch
    Now that many organizations are moving to the BYOD philosophy (bring your own devices), security for phones and tablets accessing company sensitive information is of paramount importance. I had the pleasure to interview Brian MacDonald, Principal Product Manager for Oracle Business Intelligence (BI) Mobile Products, about this subject, and he shared some wonderful insight about how the Oracle Mobile Security Tool Kit is addressing mobile security and doing some pretty cool things.  With the rapid proliferation of phones and tablets, there is a perception that mobile devices are a security threat to corporate IT, that mobile operating systems are not secure, and that there are simply too many ways to inadvertently provide access to critical analytic data outside the firewall. Every day, I see employees working on mobile devices at the airport, while waiting for their airplanes, and using public WIFI connections at coffee houses and in restaurants. These methods are not typically secure ways to access confidential company data. I asked Brian to explain why. “The native controls for mobile devices and applications are indeed insufficiently secure for corporate deployments of Business Intelligence and most certainly for businesses where data is extremely critical - such as financial services or defense - although it really applies across the board. The traditional approach for accessing data from outside a firewall is using a VPN connection which is not a viable solution for mobile. The problem is that once you open up a VPN connection on your phone or tablet, you are creating an opening for the whole device, for all the software and installed applications. Often the VPN connection by itself provides insufficient encryption – if any – which means that data can be potentially intercepted.” For this reason, most organizations that deploy Business Intelligence data via mobile devices will only do so with some additional level of control. So, how has the industry responded? What are companies doing to address this very real threat? Brian explained that “Mobile Device Management (MDM) and Mobile Application Management (MAM) software vendors have rapidly created solutions for mobile devices that provide a vast array of services for controlling, managing and establishing enterprise mobile usage policies. On the device front, vendors now support full levels of encryption behind the firewall, encrypted local data storage, credential management such as federated single-sign-on as well as remote wipe, geo-fencing and other risk reducing features (should a device be lost or stolen). More importantly, these software vendors have created methods for providing these capabilities on a per application basis, allowing for complete isolation of the application from the mobile operating system. Finally, there are tools which allow the applications themselves to be distributed through enterprise application stores allowing IT organizations to manage who has access to the apps, when updates to the applications will happen, and revoke access after an employee leaves. So even though an employee may be using a personal device, access to company data can be controlled while on or near the company premises. So do the Oracle BI mobile products integrate with the MDM and MAM vendors? Brian explained that our customers use a wide variety of mobile security vendors and may even have more than one in-house. Therefore, Oracle is ensuring that users have a choice and a mechanism for linking together Oracle’s BI offering with their chosen vendor’s secure technology. The Oracle BI Mobile Security Toolkit, which is a version of the Oracle BI Mobile HD application, delivered through the Oracle Technology Network (OTN) in its component parts, helps Oracle users to build their own version of the Mobile HD application, sign it with their own enterprise development certificates, link with their security vendor of choice, then deploy the combined application through whichever means they feel most appropriate, including enterprise application stores.  Brian further explained that Oracle currently supports most of the major mobile security vendors, has close relationships with each, and maintains strong partnerships enabling both Oracle and the vendors to test, update and release a cooperating solution in lock-step. Oracle also ensures that as new versions of the Oracle HD application are made available on the Apple iTunes store, the same version is also immediately made available through the Security Toolkit on OTN.  Rest assured that as our workforce continues down the mobile path, company sensitive information can be secured.  To listen to the entire podcast, click here. To learn more about the Oracle BI Mobile HD, click  here To learn more about the BI Mobile Security Toolkit, click here 

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  • When row estimation goes wrong

    - by Dave Ballantyne
    Whilst working at a client site, I hit upon one of those issues that you are not sure if that this is something entirely new or a bug or a gap in your knowledge. The client had a large query that needed optimizing.  The query itself looked pretty good, no udfs, UNION ALL were used rather than UNION, most of the predicates were sargable other than one or two minor ones.  There were a few extra joins that could be eradicated and having fixed up the query I then started to dive into the plan. I could see all manor of spills in the hash joins and the sort operations,  these are caused when SQL Server has not reserved enough memory and has to write to tempdb.  A VERY expensive operation that is generally avoidable.  These, however, are a symptom of a bad row estimation somewhere else, and when that bad estimation is combined with other estimation errors, chaos can ensue. Working my way back down the plan, I found the cause, and the more I thought about it the more i came convinced that the optimizer could be making a much more intelligent choice. First step is to reproduce and I was able to simplify the query down a single join between two tables, Product and ProductStatus,  from a business point of view, quite fundamental, find the status of particular products to show if ‘active’ ,’inactive’ or whatever. The query itself couldn’t be any simpler The estimated plan looked like this: Ignore the “!” warning which is a missing index, but notice that Products has 27,984 rows and the join outputs 14,000. The actual plan shows how bad that estimation of 14,000 is : So every row in Products has a corresponding row in ProductStatus.  This is unsurprising, in fact it is guaranteed,  there is a trusted FK relationship between the two columns.  There is no way that the actual output of the join can be different from the input. The optimizer is already partly aware of the foreign key meta data, and that can be seen in the simplifiction stage. If we drop the Description column from the query: the join to ProductStatus is optimized out. It serves no purpose to the query, there is no data required from the table and the optimizer knows that the FK will guarantee that a matching row will exist so it has been removed. Surely the same should be applied to the row estimations in the initial example, right ?  If you think so, please upvote this connect item. So what are our options in fixing this error ? Simply changing the join to a left join will cause the optimizer to think that we could allow the rows not to exist. or a subselect would also work However, this is a client site, Im not able to change each and every query where this join takes place but there is a more global switch that will fix this error,  TraceFlag 2301. This is described as, perhaps loosely, “Enable advanced decision support optimizations”. We can test this on the original query in isolation by using the “QueryTraceOn” option and lo and behold our estimated plan now has the ‘correct’ estimation. Many thanks goes to Paul White (b|t) for his help and keeping me sane through this

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  • Observing flow control idle time in TCP

    - by user12820842
    Previously I described how to observe congestion control strategies during transmission, and here I talked about TCP's sliding window approach for handling flow control on the receive side. A neat trick would now be to put the pieces together and ask the following question - how often is TCP transmission blocked by congestion control (send-side flow control) versus a zero-sized send window (which is the receiver saying it cannot process any more data)? So in effect we are asking whether the size of the receive window of the peer or the congestion control strategy may be sub-optimal. The result of such a problem would be that we have TCP data that we could be transmitting but we are not, potentially effecting throughput. So flow control is in effect: when the congestion window is less than or equal to the amount of bytes outstanding on the connection. We can derive this from args[3]-tcps_snxt - args[3]-tcps_suna, i.e. the difference between the next sequence number to send and the lowest unacknowledged sequence number; and when the window in the TCP segment received is advertised as 0 We time from these events until we send new data (i.e. args[4]-tcp_seq = snxt value when window closes. Here's the script: #!/usr/sbin/dtrace -s #pragma D option quiet tcp:::send / (args[3]-tcps_snxt - args[3]-tcps_suna) = args[3]-tcps_cwnd / { cwndclosed[args[1]-cs_cid] = timestamp; cwndsnxt[args[1]-cs_cid] = args[3]-tcps_snxt; @numclosed["cwnd", args[2]-ip_daddr, args[4]-tcp_dport] = count(); } tcp:::send / cwndclosed[args[1]-cs_cid] && args[4]-tcp_seq = cwndsnxt[args[1]-cs_cid] / { @meantimeclosed["cwnd", args[2]-ip_daddr, args[4]-tcp_dport] = avg(timestamp - cwndclosed[args[1]-cs_cid]); @stddevtimeclosed["cwnd", args[2]-ip_daddr, args[4]-tcp_dport] = stddev(timestamp - cwndclosed[args[1]-cs_cid]); @numclosed["cwnd", args[2]-ip_daddr, args[4]-tcp_dport] = count(); cwndclosed[args[1]-cs_cid] = 0; cwndsnxt[args[1]-cs_cid] = 0; } tcp:::receive / args[4]-tcp_window == 0 && (args[4]-tcp_flags & (TH_SYN|TH_RST|TH_FIN)) == 0 / { swndclosed[args[1]-cs_cid] = timestamp; swndsnxt[args[1]-cs_cid] = args[3]-tcps_snxt; @numclosed["swnd", args[2]-ip_saddr, args[4]-tcp_dport] = count(); } tcp:::send / swndclosed[args[1]-cs_cid] && args[4]-tcp_seq = swndsnxt[args[1]-cs_cid] / { @meantimeclosed["swnd", args[2]-ip_daddr, args[4]-tcp_sport] = avg(timestamp - swndclosed[args[1]-cs_cid]); @stddevtimeclosed["swnd", args[2]-ip_daddr, args[4]-tcp_sport] = stddev(timestamp - swndclosed[args[1]-cs_cid]); swndclosed[args[1]-cs_cid] = 0; swndsnxt[args[1]-cs_cid] = 0; } END { printf("%-6s %-20s %-8s %-25s %-8s %-8s\n", "Window", "Remote host", "Port", "TCP Avg WndClosed(ns)", "StdDev", "Num"); printa("%-6s %-20s %-8d %@-25d %@-8d %@-8d\n", @meantimeclosed, @stddevtimeclosed, @numclosed); } So this script will show us whether the peer's receive window size is preventing flow ("swnd" events) or whether congestion control is limiting flow ("cwnd" events). As an example I traced on a server with a large file transfer in progress via a webserver and with an active ssh connection running "find / -depth -print". Here is the output: ^C Window Remote host Port TCP Avg WndClosed(ns) StdDev Num cwnd 10.175.96.92 80 86064329 77311705 125 cwnd 10.175.96.92 22 122068522 151039669 81 So we see in this case, the congestion window closes 125 times for port 80 connections and 81 times for ssh. The average time the window is closed is 0.086sec for port 80 and 0.12sec for port 22. So if you wish to change congestion control algorithm in Oracle Solaris 11, a useful step may be to see if congestion really is an issue on your network. Scripts like the one posted above can help assess this, but it's worth reiterating that if congestion control is occuring, that's not necessarily a problem that needs fixing. Recall that congestion control is about controlling flow to prevent large-scale drops, so looking at congestion events in isolation doesn't tell us the whole story. For example, are we seeing more congestion events with one control algorithm, but more drops/retransmission with another? As always, it's best to start with measures of throughput and latency before arriving at a specific hypothesis such as "my congestion control algorithm is sub-optimal".

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  • Essbase BSO Data Fragmentation

    - by Ann Donahue
    Essbase BSO Data Fragmentation Data fragmentation naturally occurs in Essbase Block Storage (BSO) databases where there are a lot of end user data updates, incremental data loads, many lock and send, and/or many calculations executed.  If an Essbase database starts to experience performance slow-downs, this is an indication that there may be too much fragmentation.  See Chapter 54 Improving Essbase Performance in the Essbase DBA Guide for more details on measuring and eliminating fragmentation: http://docs.oracle.com/cd/E17236_01/epm.1112/esb_dbag/daprcset.html Fragmentation is likely to occur in the following situations: Read/write databases that users are constantly updating data Databases that execute calculations around the clock Databases that frequently update and recalculate dense members Data loads that are poorly designed Databases that contain a significant number of Dynamic Calc and Store members Databases that use an isolation level of uncommitted access with commit block set to zero There are two types of data block fragmentation Free space tracking, which is measured using the Average Fragmentation Quotient statistic. Block order on disk, which is measured using the Average Cluster Ratio statistic. Average Fragmentation Quotient The Average Fragmentation Quotient ratio measures free space in a given database.  As you update and calculate data, empty spaces occur when a block can no longer fit in its original space and will either append at the end of the file or fit in another empty space that is large enough.  These empty spaces take up space in the .PAG files.  The higher the number the more empty spaces you have, therefore, the bigger the .PAG file and the longer it takes to traverse through the .PAG file to get to a particular record.  An Average Fragmentation Quotient value of 3.174765 means the database is 3% fragmented with free space. Average Cluster Ratio Average Cluster Ratio describes the order the blocks actually exist in the database. An Average Cluster Ratio number of 1 means all the blocks are ordered in the correct sequence in the order of the Outline.  As you load data and calculate data blocks, the sequence can start to be out of order.  This is because when you write to a block it may not be able to place back in the exact same spot in the database that it existed before.  The lower this number the more out of order it becomes and the more it affects performance.  An Average Cluster Ratio value of 1 means no fragmentation.  Any value lower than 1 i.e. 0.01032828 means the data blocks are getting further out of order from the outline order. Eliminating Data Block Fragmentation Both types of data block fragmentation can be removed by doing a dense restructure or export/clear/import of the data.  There are two types of dense restructure: 1. Implicit Restructures Implicit dense restructure happens when outline changes are done using EAS Outline Editor or Dimension Build. Essbase restructures create new .PAG files restructuring the data blocks in the .PAG files. When Essbase restructures the data blocks, it regenerates the index automatically so that index entries point to the new data blocks. Empty blocks are NOT removed with implicit restructures. 2. Explicit Restructures Explicit dense restructure happens when a manual initiation of the database restructure is executed. An explicit dense restructure is a full restructure which comprises of a dense restructure as outlined above plus the removal of empty blocks Empty Blocks vs. Fragmentation The existence of empty blocks is not considered fragmentation.  Empty blocks can be created through calc scripts or formulas.  An empty block will add to an existing database block count and will be included in the block counts of the database properties.  There are no statistics for empty blocks.  The only way to determine if empty blocks exist in an Essbase database is to record your current block count, export the entire database, clear the database then import the exported data.  If the block count decreased, the difference is the number of empty blocks that had existed in the database.

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  • Process for Securing Web Sites and Applications

    - by Aamir Hasan
    The following quick-start guide provides a detailed overview of how to configure security for IIS 6.0. Reduce the Attack Surface of the Web Server 1.       Enable only essential Windows Server 2003 components and services. 2.       Enable only essential IIS 6.0 components and services. 3.       Enable only essential Web service extensions. 4.       Enable only essential Multipurpose Internet Mail Extensions (MIME) types. 5.       Configure Windows Server 2003 security settings. Prevent Unauthorized Access to Web Sites and Applications 1.       Store content on a dedicated disk volume. 2.       Set IIS Web site permissions. 3.       Set IP address and domain name restrictions. 4.       Set the NTFS file system permissions. Isolate Web Sites and Applications 1.       Evaluate the effects of impersonation on application compatibility: 2·         Identify the impersonation behavior for ASP applications. 3·         Select the impersonation behavior for ASP.NET applications. 4.       Configure Web sites and applications for isolation. Configure User Authentication 1.       Configure Web site authentication. 2·         Select the Web site authentication method. 3·         Configure the Web site authentication method. 4.       Configure File Transfer Protocol (FTP) site authentication. Encrypt Confidential Data Exchanged with Clients 1.       Use Secure Sockets Layer (SSL) to encrypt confidential data. 2.       Use Internet Protocol security (IPSec) or virtual private network (VPN) with remote administration. Maintain Web Site and Application Security 1.       Obtain and apply current security patches. 2.       Enable Windows Server 2003 security logs. 3.       Enable file access auditing for Web site content. 4.       Configure IIS logs. 5.       Review security policies, processes, and procedures.  Note:To secure the Web sites and applications in a Web farm, use the process described in this chapter to configure security for each server in the Web farm. Link:http://www.studentacad.com/post/2010/04/28/Process-for-Securing-Web-Sites-and-Applications.aspx

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  • The Growing Importance of Network Virtualization

    - by user12608550
    The Growing Importance of Network Virtualization We often focus on server virtualization when we discuss cloud computing, but just as often we neglect to consider some of the critical implications of that technology. The ability to create virtual environments (or VEs [1]) means that we can create, destroy, activate and deactivate, and more importantly, MOVE them around within the cloud infrastructure. This elasticity and mobility has profound implications for how network services are defined, managed, and used to provide cloud services. It's not just servers that benefit from virtualization, it's the network as well. Network virtualization is becoming a hot topic, and not just for discussion but for companies like Oracle and others who have recently acquired net virtualization companies [2,3]. But even before this topic became so prominent, Solaris engineers were working on technologies in Solaris 11 to virtualize network services, known as Project Crossbow [4]. And why is network virtualization so important? Because old assumptions about network devices, topology, and management must be re-examined in light of the self-service, elasticity, and resource sharing requirements of cloud computing infrastructures. Static, hierarchical network designs, and inter-system traffic flows, need to be reconsidered and quite likely re-architected to take advantage of new features like virtual NICs and switches, bandwidth control, load balancing, and traffic isolation. For example, traditional multi-tier Web services (Web server, App server, DB server) that share net traffic over Ethernet wires can now be virtualized and hosted on shared-resource systems that communicate within a larger server at system bus speeds, increasing performance and reducing wired network traffic. And virtualized traffic flows can be monitored and adjusted as needed to optimize network performance for dynamically changing cloud workloads. Additionally, as VEs come and go and move around in the cloud, static network configuration methods cannot easily accommodate the routing and addressing flexibility that VE mobility implies; virtualizing the network itself is a requirement. Oracle Solaris 11 [5] includes key network virtualization technologies needed to implement cloud computing infrastructures. It includes features for the creation and management of virtual NICs and switches, and for the allocation and control of the traffic flows among VEs [6]. Additionally it allows for both sharing and dedication of hardware components to network tasks, such as allocating specific CPUs and vNICs to VEs, and even protocol-specific management of traffic. So, have a look at your current network topology and management practices in view of evolving cloud computing technologies. And don't simply duplicate the physical architecture of servers and connections in a virtualized environment…rethink the traffic flows among VEs and how they can be optimized using Oracle Solaris 11 and other Oracle products and services. [1] I use the term "virtual environment" or VE here instead of the more commonly used "virtual machine" or VM, because not all virtualized operating system environments are full OS kernels under the control of a hypervisor…in other words, not all VEs are VMs. In particular, VEs include Oracle Solaris zones, as well as SPARC VMs (previously called LDoms), and x86-based Solaris and Linux VMs running under hypervisors such as OEL, Xen, KVM, or VMware. [2] Oracle follows VMware into network virtualization space with Xsigo purchase; http://www.mercurynews.com/business/ci_21191001/oracle-follows-vmware-into-network-virtualization-space-xsigo [3] Oracle Buys Xsigo; http://www.oracle.com/us/corporate/press/1721421 [4] Oracle Solaris 11 Networking Virtualization Technology, http://www.oracle.com/technetwork/server-storage/solaris11/technologies/networkvirtualization-312278.html [5] Oracle Solaris 11; http://www.oracle.com/us/products/servers-storage/solaris/solaris11/overview/index.html [6] For example, the Solaris 11 'dladm' command can be used to limit the bandwidth of a virtual NIC, as follows: dladm create-vnic -l net0 -p maxbw=100M vnic0

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  • Concurrent Affairs

    - by Tony Davis
    I once wrote an editorial, multi-core mania, on the conundrum of ever-increasing numbers of processor cores, but without the concurrent programming techniques to get anywhere near exploiting their performance potential. I came to the.controversial.conclusion that, while the problem loomed for all procedural languages, it was not a big issue for the vast majority of programmers. Two years later, I still think most programmers don't concern themselves overly with this issue, but I do think that's a bigger problem than I originally implied. Firstly, is the performance boost from writing code that can fully exploit all available cores worth the cost of the additional programming complexity? Right now, with quad-core processors that, at best, can make our programs four times faster, the answer is still no for many applications. But what happens in a few years, as the number of cores grows to 100 or even 1000? At this point, it becomes very hard to ignore the potential gains from exploiting concurrency. Possibly, I was optimistic to assume that, by the time we have 100-core processors, and most applications really needed to exploit them, some technology would be around to allow us to do so with relative ease. The ideal solution would be one that allows programmers to forget about the problem, in much the same way that garbage collection removed the need to worry too much about memory allocation. From all I can find on the topic, though, there is only a remote likelihood that we'll ever have a compiler that takes a program written in a single-threaded style and "auto-magically" converts it into an efficient, correct, multi-threaded program. At the same time, it seems clear that what is currently the most common solution, multi-threaded programming with shared memory, is unsustainable. As soon as a piece of state can be changed by a different thread of execution, the potential number of execution paths through your program grows exponentially with the number of threads. If you have two threads, each executing n instructions, then there are 2^n possible "interleavings" of those instructions. Of course, many of those interleavings will have identical behavior, but several won't. Not only does this make understanding how a program works an order of magnitude harder, but it will also result in irreproducible, non-deterministic, bugs. And of course, the problem will be many times worse when you have a hundred or a thousand threads. So what is the answer? All of the possible alternatives require a change in the way we write programs and, currently, seem to be plagued by performance issues. Software transactional memory (STM) applies the ideas of database transactions, and optimistic concurrency control, to memory. However, working out how to break down your program into sufficiently small transactions, so as to avoid contention issues, isn't easy. Another approach is concurrency with actors, where instead of having threads share memory, each thread runs in complete isolation, and communicates with others by passing messages. It simplifies concurrent programs but still has performance issues, if the threads need to operate on the same large piece of data. There are doubtless other possible solutions that I haven't mentioned, and I would love to know to what extent you, as a developer, are considering the problem of multi-core concurrency, what solution you currently favor, and why. Cheers, Tony.

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  • Default Transaction Timeout

    - by MattH
    I used to set Transaction timeouts by using TransactionOptions.Timeout, but have decided for ease of maintenance to use the config approach: <system.transactions> <defaultSettings timeout="00:01:00" /> </system.transactions> Of course, after putting this in, I wanted to test it was working, so reduced the timeout to 5 seconds, then ran a test that lasted longer than this - but the transaction does not appear to abort! If I adjust the test to set TransactionOptions.Timeout to 5 seconds, the test works as expected After Investigating I think the problem appears to relate to TransactionOptions.Timeout, even though I'm no longer using it. I still need to use TransactionOptions so I can set IsolationLevel, but I no longer set the Timeout value, if I look at this object after I create it, the timeout value is 00:00:00, which equates to infinity. Does this mean my value set in the config file is being ignored? To summarise: Is it impossible to mix the config setting, and use of TransactionOptions If not, is there any way to extract the config setting at runtime, and use this to set the Timeout property [Edit] OR Set the default isolation-level without using TransactionOptions

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  • Atomic UPSERT in SQL Server 2005

    - by rabidpebble
    What is the correct pattern for doing an atomic "UPSERT" (UPDATE where exists, INSERT otherwise) in SQL Server 2005? I see a lot of code on SO (e.g. see http://stackoverflow.com/questions/639854/tsql-check-if-a-row-exists-otherwise-insert) with the following two-part pattern: UPDATE ... FROM ... WHERE <condition> -- race condition risk here IF @@ROWCOUNT = 0 INSERT ... or IF (SELECT COUNT(*) FROM ... WHERE <condition>) = 0 -- race condition risk here INSERT ... ELSE UPDATE ... where will be an evaluation of natural keys. None of the above approaches seem to deal well with concurrency. If I cannot have two rows with the same natural key, it seems like all of the above risk inserting rows with the same natural keys in race condition scenarios. I have been using the following approach but I'm surprised not to see it anywhere in people's responses so I'm wondering what is wrong with it: INSERT INTO <table> SELECT <natural keys>, <other stuff...> FROM <table> WHERE NOT EXISTS -- race condition risk here? ( SELECT 1 FROM <table> WHERE <natural keys> ) UPDATE ... WHERE <natural keys> (Note: I'm assuming that rows will not be deleted from this table. Although it would be nice to discuss how to handle the case where they can be deleted -- are transactions the only option? Which level of isolation?) Is this atomic? I can't locate where this would be documented in SQL Server documentation.

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  • Mysql SELECT FOR UPDATE - strange issue

    - by Michal Fronczyk
    Hi, I have a strange issue (at least for me :)) with the MySQL's locking facility. I have a table: Create Table: CREATE TABLE test ( id int(11) NOT NULL AUTO_INCREMENT, PRIMARY KEY (id) ) ENGINE=InnoDB AUTO_INCREMENT=13 DEFAULT CHARSET=latin1 With this data: +----+ | id | +----+ | 3 | | 4 | | 5 | | 6 | | 7 | | 8 | | 10 | | 11 | | 12 | +----+ Now I have 2 clients with these commands executed at the beginning: set autocommit=0; set session transaction isolation level serializable; begin; Now the most interesting part. The first client executes this query: (makes an intent to insert a row with id equal to 9) SELECT * from test where id = 9 FOR UPDATE; Empty set (0.00 sec) Then the second client does the same: SELECT * from test where id = 9 FOR UPDATE; Empty set (0.00 sec) My question is: Why the second client does not block ? An exclusive gap lock should have been set by the first query because FOR UPDATE have been used and the second client should block. If I am wrong, could somebody tell me how to do it correctly ? The MySql version I use is: 5.1.37-1ubuntu5.1 Thanks, Michal

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  • simpletest - Why does setReturnValue() seem to change behaviour depending on if test is run in isola

    - by JW
    I am using SimpleTest version 1.0.1 for a unit test. I create a new mock object within a test method and on it i do: $MockDbAdaptor->setReturnValue('query',1); Now, when i run this in a standalone unit test my tested object is happy to see 1 returned when query() is called on the mock db adaptor. However, when this exact same test is run as part of my 'all_tests' TestSuite, the test is failing. This happens because a call to the mock's query() method does not appear to return any value - thus causing my test subject to complain and trigger an unexpected exception that fails the test. So, the behaviour of setReturnValue() seems to change depending on whether the test is run in isolation or not. I can get it to work in both a standalone and TestSuite contexts by using this instead: $MockDbAdaptor->setReturnValueAt(0,'query',1); So my immediate problem can be fixed ...but it feels like a hack. I thought if i create a new mock within a test method then why is the setReturnValue() behaviour getting affected by the context in which the test class instance is run? It feel like a bug.

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  • Lost Update Anomaly in Sql Server Update Command

    - by Javed
    Hi, I am very much confused. I have a transaction in ReadCommitted Isolation level. Among other things I am also updating a counter value in it, something similar to below: Update tblCount set counter = counter + 1 My application is a desktop application and this transaction happens to occur quite frequently and concurrently. We recently noticed an error that sometimes the counter value doesn't get updated or is missed. We also insert one record on each counter update so we are sure that records have been inserted but somehow counter fails to update. This happens once in 2000 simulaneous transactions. I seriously doubt it is a lost update anomaly I am facing but if you look at the command above, it's just update the counter from its own value: if I have started a transaction and the transaction has reached this statement, it should have locked the row. This should not cause lost update, but it's happening somehow. Is the thing that this update command works in two parts? Like first it reads the counter value (during which it doesn't get the exclusive lock) and then writes the new calculated value (when it does get an exclusive lock)? Please help, I have got really confused.

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  • ASP.NET Applications Requests/Sec suddenly jumps to a value of about 70 million/sec. on 8 core web

    - by Subhrajit Roy
    We are doing performance testing of an ASP.NET web application with VSTS 2008. We start with 2000 users and slowly ramp up to 5000 users (reaches this user load at around 2.5 hours after the tests start, after this we stay at this user load). The total test duration is of about 6 hours During these runs we have found that the counter Requests/Sec (under category ASP.NET applications) suddenly spikes to a values of 36-72 millions !!!. This keeps on happening intermittently i.e we see this issue once in every 3 performance runs that we give on the same application. In our testing environment we have 4 web servers and interestingly enough we have found that this issue occurs only in the 8 core web servers. Summarizing ... Issue : The counter Requests/Sec (under category ASP.NET Applications) suddenly jumps to a value of about 70 million/sec. on 8 core web servers. This results in an increase in SQL server connections opened by the application. Response time goes for a toss. Error rates also show similar behaviour. However the counter ISAPI Extention Requests/sec does not show any abnormal increase. The graph of this counter almost overlaps with that of counter Requests/Sec till the time of the appearance of the spike.When the spike appears , this counter (ISAPI Extention Requests/sec) actually shows a drop. Test Settings : Performance test run with Visual Studio Team System 2008. Soak test run for 6 hours. Maximum user load 5000 users. This is load is attained at about 2.5 hours into the run and mainted for remaining duration.(i.e for around 3.5 more hrs) This issue is reproducible though happens intermittently. (i.e occurs one in three or four runs) Test Environment : Web site deployed on 4 Web Servers (Windows Server 2003). Of these 2 are 4 core machines and the remaining 2 are 8 core ones. .NET Framework 3.5 SP1 installed on all 4 web servers. Application hosted on IIS 6.0 run in Worker process isolation mode.

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  • SQL (mySQL) update some value in all records processed by a select

    - by jdmuys
    I am using mySQL from their C API, but that shouldn't be relevant. My code must process records from a table that match some criteria, and then update the said records to flag them as processed. The lines in the table are modified/inserted/deleted by another process I don't control. I am afraid in the following, the UPDATE might flag some records erroneously since the set of records matching might have changed between step 1 and step 3. SELECT * FROM myTable WHERE <CONDITION>; # step 1 <iterate over the selected set of lines. This may take some time.> # step 2 UPDATE myTable SET processed=1 WHERE <CONDITION> # step 3 What's the smart way to ensure that the UPDATE updates all the lines processed, and only them? A transaction doesn't seem to fit the bill as it doesn't provide isolation of that sort: a recently modified record not in the originally selected set might still be targeted by the UPDATE statement. For the same reason, SELECT ... FOR UPDATE doesn't seem to help, though it sounds promising :-) The only way I can see is to use a temporary table to memorize the set of rows to be processed, doing something like: CREATE TEMPORARY TABLE workOrder (jobId INT(11)); INSERT INTO workOrder SELECT myID as jobId FROM myTable WHERE <CONDITION>; SELECT * FROM myTable WHERE myID IN (SELECT * FROM workOrder); <iterate over the selected set of lines. This may take some time.> UPDATE myTable SET processed=1 WHERE myID IN (SELECT * FROM workOrder); DROP TABLE workOrder; But this seems wasteful and not very efficient. Is there anything smarter? Many thanks from a SQL newbie.

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  • How to implement properly plugins in C#?

    - by MartyIX
    I'm trying to add plugins to my game and what I'm trying to implement is this: Plugins will be either mine or 3rd party's so I would like a solution where crashing of the plugin would not mean crashing of the main application. Methods of plugins are called very often (for example because of drawing of game objects). What I've found so far: 1) http://www.codeproject.com/KB/cs/pluginsincsharp.aspx - simple concept that seems like it should work nicely. Since plugins are used in my game for every round I would suffice to add the Restart() method and if a plugin is no longer needed Unload() method + GC should take care of that. 2) http://mef.codeplex.com/Wikipage - Managed Extensibility Framework - my program should work on .NET 3.5 and I don't want to add any other framework separately I want to write my plugin system myself. Therefore this solution is out of question. 3) Microsoft provides: http://msdn.microsoft.com/en-us/library/system.addin.aspx but according to a few articles I've read it is very complex. 4) Different AppDomains for plugins. According to Marc Gravell ( http://stackoverflow.com/questions/665668/usage-of-appdomain-in-c ) different AppDomains allow isolation. Unloading of plugins would be easy. What would the performance load be? I need to call methods of plugins very often (to draw objects for example). Using Application Domains - http://msdn.microsoft.com/en-us/library/yb506139.aspx A few tutorials on java2s.com Could you please comment on my findings? New approaches are also welcomed! Thanks!

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  • how to atomically claim a row or resource using UPDATE in mysql

    - by Igor
    i have a table of resources (lets say cars) which i want to claim atomically. if there's a limit of one resource per one user, i can do the following trick: UPDATE cars SET user = 'bob' WHERE user IS NULL LIMIT 1 SELECT * FROM cars WHERE user IS bob that way, i claim the resource atomically and then i can see which row i just claimed. this doesn't work when 'bob' can claim multiple cars. i realize i can get a list of cars already claimed by bob, claim another one, and then SELECT again to see what's changed, but that feels hackish. What I'm wondering is, is there some way to see which rows i just updated with my last UPDATE? failing that, is there some other trick to atomically claiming a row? i really want to avoid using SERIALIZABLE isolation level. If I do something like this: 1 SELECT id FROM cars WHERE user IS NULL 2 <here, my PHP or whatever picks a car id> 3 UPDATE cars SET user = 'bob' WHERE id = <the one i picked> would REPEATABLE READ be sufficient here? in other words, could i be guaranteed that some other transactions won't claim the row my software has picked during step 2?

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  • Silverlight unit testing. Error while running tests.

    - by 1gn1ter
    I'm using VS2010. Silverlight 4, NUnit 2.5.5, and TypeMock TypemockIsolatorSetup6.0.3.619.msi In the test project MVVM is implemented, PeopleViewModel is a ViewModel which I want to test. Please advise if you use other products for unit testing of MVVM Silverlight. Or please help to win this TypeMock. TIA This is the code of the test: [Test] [SilverlightUnitTest] public void SomeTestAgainstSilverlight() { PeopleViewModel o = new PeopleViewModel(); var res = o.People; Assert.AreEqual(15, res.Count()); } While running the test in ReSharper i get the following error: TestA.SomeTestAgainstSilverlight : Failed****************************************** *Loading Silverlight Isolation Aspects...* ****************************************** TEST RESULTS: --------------------------------------------- System.MissingMethodException : Method not found: 'hv TypeMock.ArrangeActAssert.Isolate.a(System.Delegate)'. at a4.a(ref Delegate A_0) at a4.a(Boolean A_0) at il.b() at CThru.Silverlight.SilverlightUnitTestAttribute.Init() at CThru.Silverlight.SilverlightUnitTestAttribute.Execute() at TypeMock.MockManager.a(String A_0, String A_1, Object A_2, Object A_3, Boolean A_4, Object[] A_5) at TypeMock.InternalMockManager.getReturn(Object that, String typeName, String methodName, Object methodParameters, Boolean isInjected) at Tests.TestA.SomeTestAgainstSilverlight() in TestA.cs: line 21 While running test in NUnit i get: Tests.TestA.SomeTestAgainstSilverlight: System.DllNotFoundException : Unable to load DLL 'agcore': The specified module could not be found. (Exception from HRESULT: 0x8007007E) at MS.Internal.XcpImports.Application_GetCurrentNative(IntPtr context, IntPtr& obj) at MS.Internal.XcpImports.Application_GetCurrent(IntPtr& pApp) at System.Windows.Application.get_Current() at ViewModelExample.ViewModel.ViewModelBase.get_IsDesignTime() in C:\Documents and Settings\USER\Desktop\ViewModelExample\ViewModelExample\ViewModel\ViewModelBase.cs:line 20 at ViewModelExample.ViewModel.PeopleViewModel..ctor(IServiceAgent serviceAgent) in C:\Documents and Settings\USER\Desktop\ViewModelExample\ViewModelExample\ViewModel\PeopleViewModel.cs:line 28 at ViewModelExample.ViewModel.PeopleViewModel..ctor() in C:\Documents and Settings\USER\Desktop\ViewModelExample\ViewModelExample\ViewModel\PeopleViewModel.cs:line 24 at Tests.TestA.SomeTestAgainstSilverlight() in C:\Documents and Settings\USER\Desktop\ViewModelExample\Tests\TestA.cs:line 22

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  • nhibernate error recovery

    - by Berryl
    I downloaded Rhino Security today and started going through some of the tests. Several that run perfectly in isolation start getting errors after one that purposely raises an exception runs though. Here is that test: [Test] public void EntitesGroup_CanCreate() { var group = _authorizationRepository.CreateEntitiesGroup("Accounts"); _session.Flush(); _session.Evict(group); var fromDb = _session.Get<EntitiesGroup>(group.Id); Assert.NotNull(fromDb); Assert.That(fromDb.Name, Is.EqualTo(group.Name)); } And here are the tests and error messages that fail: [Test] public void User_CanSave() { var ayende = new User {Name = "ayende"}; _session.Save(ayende); _session.Flush(); _session.Evict(ayende); var fromDb = _session.Get<User>(ayende.Id); Assert.That(fromDb, Is.Not.Null); Assert.That(ayende.Name, Is.EqualTo(fromDb.Name)); } ----> System.Data.SQLite.SQLiteException : Abort due to constraint violation column Name is not unique [Test] public void UsersGroup_CanCreate() { var group = _authorizationRepository.CreateUsersGroup("Admininstrators"); _session.Flush(); _session.Evict(group); var fromDb = _session.Get<UsersGroup>(group.Id); Assert.NotNull(fromDb); Assert.That(fromDb.Name, Is.EqualTo(group.Name)); } failed: NHibernate.AssertionFailure : null id in Rhino.Security.Tests.User entry (don't flush the Session after an exception occurs) Does anyone see how I can reset the state of the in memory SQLite db after the first test? I changed the code to use nunit instead of xunit so maybe that is part of the problem here as well. Cheers, Berryl

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  • simpletest - Why does setReturnValue() seem to change behaviour depending whether test is run in iso

    - by JW
    I am using SimpleTest version 1.0.1 for a unit test. I create a new mock object within a test method and on it i do: $MockDbAdaptor->setReturnValue('query',1); Now, when i run this in a standalone unit test my tested object is happy to see 1 returned when query() is called on the mock db adaptor. However, when this exact same test is run as part of my 'all_tests' TestSuite, the test is failing. This happens because a call to the mock's query() method does not appear to return any value - thus causing my test subject to complain and trigger an unexpected exception that fails the test. So, the behaviour of setReturnValue() seems to change depending on whether the test is run in isolation or not. I can get it to work in both a standalone and TestSuite contexts by using this instead: $MockDbAdaptor->setReturnValueAt(0,'query',1); So my immediate problem can be fixed ...but it feels like a hack. I thought if i create a new mock within a test method then why is the setReturnValue() behaviour getting affected by the context in which the test class instance is run? It feel like a bug.

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