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  • Log message Request and Response in ASP.NET WebAPI

    - by Fredrik N
    By logging both incoming and outgoing messages for services can be useful in many scenarios, such as debugging, tracing, inspection and helping customers with request problems etc.  I have a customer that need to have both incoming and outgoing messages to be logged. They use the information to see strange behaviors and also to help customers when they call in  for help (They can by looking in the log see if the customers sends in data in a wrong or strange way).   Concerns Most loggings in applications are cross-cutting concerns and should not be  a core concern for developers. Logging messages like this:   // GET api/values/5 public string Get(int id) { //Cross-cutting concerns Log(string.Format("Request: GET api/values/{0}", id)); //Core-concern var response = DoSomething(); //Cross-cutting concerns Log(string.Format("Reponse: GET api/values/{0}\r\n{1}", id, response)); return response; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } will only result in duplication of code, and unnecessarily concerns for the developers to be aware of, if they miss adding the logging code, no logging will take place. Developers should focus on the core-concern, not the cross-cutting concerns. By just focus on the core-concern the above code will look like this: // GET api/values/5 public string Get(int id) { return DoSomething(); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } The logging should then be placed somewhere else so the developers doesn’t need to focus care about the cross-concern. Using Message Handler for logging There are different ways we could place the cross-cutting concern of logging message when using WebAPI. We can for example create a custom ApiController and override the ApiController’s ExecutingAsync method, or add a ActionFilter, or use a Message Handler. The disadvantage with custom ApiController is that we need to make sure we inherit from it, the disadvantage of ActionFilter, is that we need to add the filter to the controllers, both will modify our ApiControllers. By using a Message Handler we don’t need to do any changes to our ApiControllers. So the best suitable place to add our logging would be in a custom Message Handler. A Message Handler will be used before the HttpControllerDispatcher (The part in the WepAPI pipe-line that make sure the right controller is used and called etc). Note: You can read more about message handlers here, it will give you a good understanding of the WebApi pipe-line. To create a Message Handle we can inherit from the DelegatingHandler class and override the SendAsync method: public class MessageHandler : DelegatingHandler { protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken) { return base.SendAsync(request, cancellationToken); } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   If we skip the call to the base.SendAsync our ApiController’s methods will never be invoked, nor other Message Handlers. Everything placed before base.SendAsync will be called before the HttpControllerDispatcher (before WebAPI will take a look at the request which controller and method it should be invoke), everything after the base.SendAsync, will be executed after our ApiController method has returned a response. So a message handle will be a perfect place to add cross-cutting concerns such as logging. To get the content of our response within a Message Handler we can use the request argument of the SendAsync method. The request argument is of type HttpRequestMessage and has a Content property (Content is of type HttpContent. The HttpContent has several method that can be used to read the incoming message, such as ReadAsStreamAsync, ReadAsByteArrayAsync and ReadAsStringAsync etc. Something to be aware of is what will happen when we read from the HttpContent. When we read from the HttpContent, we read from a stream, once we read from it, we can’t be read from it again. So if we read from the Stream before the base.SendAsync, the next coming Message Handlers and the HttpControllerDispatcher can’t read from the Stream because it’s already read, so our ApiControllers methods will never be invoked etc. The only way to make sure we can do repeatable reads from the HttpContent is to copy the content into a buffer, and then read from that buffer. This can be done by using the HttpContent’s LoadIntoBufferAsync method. If we make a call to the LoadIntoBufferAsync method before the base.SendAsync, the incoming stream will be read in to a byte array, and then other HttpContent read operations will read from that buffer if it’s exists instead directly form the stream. There is one method on the HttpContent that will internally make a call to the  LoadIntoBufferAsync for us, and that is the ReadAsByteArrayAsync. This is the method we will use to read from the incoming and outgoing message. public abstract class MessageHandler : DelegatingHandler { protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken) { var requestMessage = await request.Content.ReadAsByteArrayAsync(); var response = await base.SendAsync(request, cancellationToken); var responseMessage = await response.Content.ReadAsByteArrayAsync(); return response; } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } The above code will read the content of the incoming message and then call the SendAsync and after that read from the content of the response message. The following code will add more logic such as creating a correlation id to combine the request with the response, and create a log entry etc: public abstract class MessageHandler : DelegatingHandler { protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken) { var corrId = string.Format("{0}{1}", DateTime.Now.Ticks, Thread.CurrentThread.ManagedThreadId); var requestInfo = string.Format("{0} {1}", request.Method, request.RequestUri); var requestMessage = await request.Content.ReadAsByteArrayAsync(); await IncommingMessageAsync(corrId, requestInfo, requestMessage); var response = await base.SendAsync(request, cancellationToken); var responseMessage = await response.Content.ReadAsByteArrayAsync(); await OutgoingMessageAsync(corrId, requestInfo, responseMessage); return response; } protected abstract Task IncommingMessageAsync(string correlationId, string requestInfo, byte[] message); protected abstract Task OutgoingMessageAsync(string correlationId, string requestInfo, byte[] message); } public class MessageLoggingHandler : MessageHandler { protected override async Task IncommingMessageAsync(string correlationId, string requestInfo, byte[] message) { await Task.Run(() => Debug.WriteLine(string.Format("{0} - Request: {1}\r\n{2}", correlationId, requestInfo, Encoding.UTF8.GetString(message)))); } protected override async Task OutgoingMessageAsync(string correlationId, string requestInfo, byte[] message) { await Task.Run(() => Debug.WriteLine(string.Format("{0} - Response: {1}\r\n{2}", correlationId, requestInfo, Encoding.UTF8.GetString(message)))); } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   The code above will show the following in the Visual Studio output window when the “api/values” service (One standard controller added by the default WepAPI template) is requested with a Get http method : 6347483479959544375 - Request: GET http://localhost:3208/api/values 6347483479959544375 - Response: GET http://localhost:3208/api/values ["value1","value2"] .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   Register a Message Handler To register a Message handler we can use the Add method of the GlobalConfiguration.Configration.MessageHandlers in for example Global.asax: public class WebApiApplication : System.Web.HttpApplication { protected void Application_Start() { GlobalConfiguration.Configuration.MessageHandlers.Add(new MessageLoggingHandler()); ... } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   Summary By using a Message Handler we can easily remove cross-cutting concerns like logging from our controllers. You can also find the source code used in this blog post on ForkCan.com, feel free to make a fork or add comments, such as making the code better etc. Feel free to follow me on twitter @fredrikn if you want to know when I will write other blog posts etc.

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  • Willy Rotstein on Supply Chain Planning

    - by sarah.taylor(at)oracle.com
    Each time a merchandiser, buyer or planner in Retail makes a business decision around assortment, inventory, pricing and promotions there is an opportunity to improve both Profitability and Customer Service. Improving decision making, however, has always been a tricky business for retailers.  I have worked in this space for more than 15 years. I began my career as an academic, at Imperial College London, and then broadened this interest with Retailers, aiming to optimize their merchandising and supply chain decisions. Planning the business and optimizing profit is a complex process. The complexity arises from the variety of people involved, the large number of decisions to take across all business processes, the uncertainty intrinsic to the retail environment as well as the volume of data available for analysis.  Things are not getting any easier either. The advent of multi-channel, social media and mobile is taking these complexities to a new level and presenting additional opportunities for those willing to exploit them. I guess it is due to the complexities of the decision making process that, over the last couple of years working with Oracle Retail, I have witnessed a clear trend around the deployment of planning systems. Retailers are aiming to simplify their decision making processes. They want to use one joined up planning platform across the business and enhance it with "actionable" data mining and optimization techniques. At Oracle Retail, we have a vibrant community of international retailers who regularly come together to discuss the big issues in retail planning. It is a combination of fashion, grocery and speciality retailers, all sharing their best practice vision for planning and optimizing merchandise decisions. As part of the Retail Exchange program, at the recent National Retail Federation event in New York, I jointly hosted a Planning dinner with Peter Fitzgerald from Google UK, Retail Division. Those retailers from our international planning community who were in New York for the annual NRF event were able to attend. The group comprised some of Europe's great International Retail brands.  All sectors were represented by organisations like Mango, LVMH, Ahold, Morrisons, Shop Direct and River Island. They confirmed the current importance of engaging with Planning and Optimization issues. In particular the impact of the internet was a key topic. We had a great debate about new retail initiatives.  Peter highlighted how mobility is changing retail - in particular with the new "local availability search" initiative. We also had an exciting discussion around the opportunities to improve merchandising using the new data that is becoming available from search, social media and ecommerce sites. It will be our focus to continue to help retailers translate this data into better results while keeping their business operations simple. New developments in "actionable" analytics and computing capacity make this a very exciting area today. Watch this space for my contributions on these topics which will be made available through this blog. Oracle Retail has a strong Planning community. if you are a category manager, a planner, a buyer, a merchandiser, a retail supplier or any retail executive with a keen interest in planning then you would be very welcome to join Oracle Retail's Planning Community. As part of our community you will be able to join our in-person and virtual events, download topical white papers and best practice information specifically tailored to your area of interest.  If anyone would like to register their interest in joining our community of retailers discussing planning then please contact me at [email protected]   Willy Rotstein, Oracle Retail

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  • Blank black screen with cursor after login -- RHEL5

    - by Sean O.
    I have a RHEL 5 machine here which is a Dell Precision T3500. I'm an Ubuntu guy, but I'm having a heck of a time with this machine. After processing its first security update, we cannot log in via the gdm greeter. A new kernel was installed; then I installed the nVidia drivers for our Quadro NVS 295. I know the X configuration is valid because the gdm greeter does display; however, upon login all we can get is a blank, black screen with a cursor. I thought perhaps our python installation was corrupted but a reinstall via yum has not helped. I have searched & googled extensively for a potential fix for this and can find nothing. Below are outputs from uname, a tail of an error in /var/log/messages, and the Xorg.conf. Can anyone suggest a course of action? [sean@cheetah ~]$ uname -a Linux cheetah.*.* 2.6.18-308.8.1.el5 #1 SMP Fri May 4 16:43:02 EDT 2012 x86_64 x86_64 x86_64 GNU/Linux [sean@cheetah ~]$ sudo tail /var/log/messages Jun 5 15:03:04 cheetah gconfd (sean-4592): Resolved address "xml:readonly:/etc/gconf/gconf.xml.defaults" to a read-only configuration source at position 2 Jun 5 15:03:05 cheetah hcid[3855]: Default passkey agent (:1.8, /org/bluez/applet) registered Jun 5 15:03:05 cheetah pcscd: winscard.c:304:SCardConnect() Reader E-Gate 0 0 Not Found Jun 5 15:03:05 cheetah last message repeated 2 times Jun 5 15:03:06 cheetah gconfd (sean-4592): Resolved address "xml:readwrite:/home/sean/.gconf" to a writable configuration source at position 0 Jun 5 15:03:06 cheetah setroubleshoot: [program.ERROR] exception ImportError: /usr/lib/libatk-1.0.so.0: undefined symbol: g_assertion_message_expr Traceback (most recent call last): File "/usr/bin/sealert", line 952, in ? from setroubleshoot.gui_utils import * File "/usr/lib/python2.4/site-packages/setroubleshoot/gui_utils.py", line 26, in ? import gtk File "/usr/lib64/python2.4/site-packages/gtk-2.0/gtk/__init__.py", line 48, in ? from gtk import _gtk ImportError: /usr/lib/libatk-1.0.so.0: undefined symbol: g_assertion_message_expr Jun 5 15:03:07 cheetah setroubleshoot: [program.ERROR] exception ImportError: /usr/lib/libatk-1.0.so.0: undefined symbol: g_assertion_message_expr Traceback (most recent call last): File "/usr/bin/sealert", line 952, in ? from setroubleshoot.gui_utils import * File "/usr/lib/python2.4/site-packages/setroubleshoot/gui_utils.py", line 26, in ? import gtk File "/usr/lib64/python2.4/site-packages/gtk-2.0/gtk/__init__.py", line 48, in ? from gtk import _gtk ImportError: /usr/lib/libatk-1.0.so.0: undefined symbol: g_assertion_message_expr Jun 5 15:03:08 cheetah pcscd: winscard.c:304:SCardConnect() Reader E-Gate 0 0 Not Found Jun 5 15:07:01 cheetah ntpd[4114]: synchronized to 64.16.211.38, stratum 3 Jun 5 15:07:01 cheetah ntpd[4114]: kernel time sync enabled 0001 [sean@cheetah ~]$ cat /etc/X11/xorg.conf # nvidia-xconfig: X configuration file generated by nvidia-xconfig # nvidia-xconfig: version 295.53 ([email protected]) Sat May 12 00:34:20 PDT 2012 # Xorg configuration created by system-config-display Section "ServerLayout" Identifier "single head configuration" Screen 0 "Screen0" 0 0 InputDevice "Mouse0" "CorePointer" InputDevice "Keyboard0" "CoreKeyboard" EndSection Section "InputDevice" # generated from default Identifier "Mouse0" Driver "mouse" Option "Protocol" "auto" Option "Device" "/dev/input/mice" Option "Emulate3Buttons" "no" Option "ZAxisMapping" "4 5" EndSection Section "InputDevice" Identifier "Keyboard0" Driver "kbd" Option "XkbModel" "pc105" Option "XkbLayout" "us" EndSection Section "Monitor" ### Comment all HorizSync and VertSync values to use DDC: ### Comment all HorizSync and VertSync values to use DDC: Identifier "Monitor0" ModelName "LCD Panel 1600x1200" HorizSync 31.5 - 74.7 VertRefresh 56.0 - 65.0 Option "dpms" EndSection Section "Device" Identifier "Videocard0" Driver "nvidia" EndSection Section "Screen" Identifier "Screen0" Device "Videocard0" Monitor "Monitor0" DefaultDepth 24 SubSection "Display" Viewport 0 0 Depth 24 EndSubSection EndSection

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  • How do you re-mount an ext3 fs readwrite after it gets mounted readonly from a disk error?

    - by cagenut
    Its a relatively common problem when something goes wrong in a SAN for ext3 to detect the disk write errors and remount the filesystem read-only. Thats all well and good, only when the SAN is fixed I can't figure out how to re-re-mount the filesystem read-write without rebooting. Behold: [root@localhost ~]# multipath -ll mpath0 (36001f93000a310000299000200000000) dm-2 XIOTECH,ISE1400 [size=1.1T][features=1 queue_if_no_path][hwhandler=0][rw] \_ round-robin 0 [prio=2][active] \_ 1:0:0:1 sdb 8:16 [active][ready] \_ 2:0:0:1 sdc 8:32 [active][ready] [root@localhost ~]# mount /dev/mapper/mpath0 /mnt/foo [root@localhost ~]# touch /mnt/foo/blah All good, now I yank the LUN out from under it. [root@localhost ~]# touch /mnt/foo/blah [root@localhost ~]# touch /mnt/foo/blah touch: cannot touch `/mnt/foo/blah': Read-only file system [root@localhost ~]# tail /var/log/messages Mar 18 13:17:33 localhost multipathd: sdb: tur checker reports path is down Mar 18 13:17:34 localhost multipathd: sdc: tur checker reports path is down Mar 18 13:17:35 localhost kernel: Aborting journal on device dm-2. Mar 18 13:17:35 localhost kernel: Buffer I/O error on device dm-2, logical block 1545 Mar 18 13:17:35 localhost kernel: lost page write due to I/O error on dm-2 Mar 18 13:17:36 localhost kernel: ext3_abort called. Mar 18 13:17:36 localhost kernel: EXT3-fs error (device dm-2): ext3_journal_start_sb: Detected aborted journal Mar 18 13:17:36 localhost kernel: Remounting filesystem read-only It only thinks its read-only, in reality its not even there. [root@localhost ~]# multipath -ll sdb: checker msg is "tur checker reports path is down" sdc: checker msg is "tur checker reports path is down" mpath0 (36001f93000a310000299000200000000) dm-2 XIOTECH,ISE1400 [size=1.1T][features=0][hwhandler=0][rw] \_ round-robin 0 [prio=0][enabled] \_ 1:0:0:1 sdb 8:16 [failed][faulty] \_ 2:0:0:1 sdc 8:32 [failed][faulty] [root@localhost ~]# ll /mnt/foo/ ls: reading directory /mnt/foo/: Input/output error total 20 -rw-r--r-- 1 root root 0 Mar 18 13:11 bar How it still remembers that 'bar' file being there... mystery, but not important right now. Now I re-present the LUN: [root@localhost ~]# tail /var/log/messages Mar 18 13:23:58 localhost multipathd: sdb: tur checker reports path is up Mar 18 13:23:58 localhost multipathd: 8:16: reinstated Mar 18 13:23:58 localhost multipathd: mpath0: queue_if_no_path enabled Mar 18 13:23:58 localhost multipathd: mpath0: Recovered to normal mode Mar 18 13:23:58 localhost multipathd: mpath0: remaining active paths: 1 Mar 18 13:23:58 localhost multipathd: dm-2: add map (uevent) Mar 18 13:23:58 localhost multipathd: dm-2: devmap already registered Mar 18 13:23:59 localhost multipathd: sdc: tur checker reports path is up Mar 18 13:23:59 localhost multipathd: 8:32: reinstated Mar 18 13:23:59 localhost multipathd: mpath0: remaining active paths: 2 Mar 18 13:23:59 localhost multipathd: dm-2: add map (uevent) Mar 18 13:23:59 localhost multipathd: dm-2: devmap already registered [root@localhost ~]# multipath -ll mpath0 (36001f93000a310000299000200000000) dm-2 XIOTECH,ISE1400 [size=1.1T][features=1 queue_if_no_path][hwhandler=0][rw] \_ round-robin 0 [prio=2][enabled] \_ 1:0:0:1 sdb 8:16 [active][ready] \_ 2:0:0:1 sdc 8:32 [active][ready] Great right? It says [rw] right there. Not so fast: [root@localhost ~]# touch /mnt/foo/blah touch: cannot touch `/mnt/foo/blah': Read-only file system OK, doesn't do it automatically, I'll just give it a little push: [root@localhost ~]# mount -o remount /mnt/foo mount: block device /dev/mapper/mpath0 is write-protected, mounting read-only Noooooooooo. I have tried all sorts of different mount/tune2fs/dmsetup commands and I cannot figure out how to get it to un-flag the block device as write-protected. Rebooting will fix it, but I'd much rather do it on-line. An hour of googling has gotten me nowhere either. Save me ServerFault.

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  • Low level programming - what's in it for me?

    - by back2dos
    For years I have considered digging into what I consider "low level" languages. For me this means C and assembly. However I had no time for this yet, nor has it EVER been neccessary. Now because I don't see any neccessity arising, I feel like I should either just schedule some point in time when I will study the subject or drop the plan forever. My Position For the past 4 years I have focused on "web technologies", which may change, and I am an application developer, which is unlikely to change. In application development, I think usability is the most important thing. You write applications to be "consumed" by users. The more usable those applications are, the more value you have produced. In order to achieve good usability, I believe the following things are viable Good design: Well-thought-out features accessible through a well-thought-out user interface. Correctness: The best design isn't worth anything, if not implemented correctly. Flexibility: An application A should constantly evolve, so that its users need not switch to a different application B, that has new features, that A could implement. Applications addressing the same problem should not differ in features but in philosophy. Performance: Performance contributes to a good user experience. An application is ideally always responsive and performs its tasks reasonably fast (based on their frequency). The value of performance optimization beyond the point where it is noticeable by the user is questionable. I think low level programming is not going to help me with that, except for performance. But writing a whole app in a low level language for the sake of performance is premature optimization to me. My Question What could low level programming teach me, what other languages wouldn't teach me? Am I missing something, or is it just a skill, that is of very little use for application development? Please understand, that I am not questioning the value of C and assembly. It's just that in my everyday life, I am quite happy that all the intricacies of that world are abstracted away and managed for me (mostly by layers written in C/C++ and assembly themselves). I just don't see any concepts, that could be new to me, only details I would have to stuff my head with. So what's in it for me? My Conclusion Thanks to everyone for their answers. I must say, nobody really surprised me, but at least now I am quite sure I will drop this area of interest until any need for it arises. To my understanding, writing assembly these days for processors as they are in use in today's CPUs is not only unneccesarily complicated, but risks to result in poorer runtime performance than a C counterpart. Optimizing by hand is nearly impossible due to OOE, while you do not get all kinds of optimizations a compiler can do automatically. Also, the code is either portable, because it uses a small subset of available commands, or it is optimized, but then it probably works on one architecture only. Writing C is not nearly as neccessary anymore, as it was in the past. If I were to write an application in C, I would just as much use tested and established libraries and frameworks, that would spare me implementing string copy routines, sorting algorithms and other kind of stuff serving as exercise at university. My own code would execute faster at the cost of type safety. I am neither keen on reeinventing the wheel in the course of normal app development, nor trying to debug by looking at core dumps :D I am currently experimenting with languages and interpreters, so if there is anything I would like to publish, I suppose I'd port a working concept to C, although C++ might just as well do the trick. Again, thanks to everyone for your answers and your insight.

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  • .Net Reflector 6.5 EAP now available

    - by CliveT
    With the release of CLR 4 being so close, we’ve been working hard on getting the new C# and VB language features implemented inside Reflector. The work isn’t complete yet, but we have some of the features working. Most importantly, there are going to be changes to the Reflector object model, and we though it would be useful for people to see the changes and have an opportunity to comment on them. Before going any further, we should tell you what the EAP contains that’s different from the released version. A number of bugs have been fixed, mainly bugs that were raised via the forum. This is slightly offset by the fact that this EAP hasn’t had a whole lot of testing and there may have been new bugs introduced during the development work we’ve been doing. The C# language writer has been changed to display in and out co- and contra-variance markers on interfaces and delegates, and to display default values for optional parameters in method definitions. We also concisely display values passed by reference into COM calls. However, we do not change callsites to display calls using named parameters; this looks like hard work to get right. The forthcoming version of the C# language introduces dynamic types and dynamic calls. The new version of Reflector should display a dynamic call rather than the generated C#: dynamic target = MyTestObject(); target.Hello("Mum"); We have a few bugs in this area where we are not casting to dynamic when necessary. These have been fixed on a branch and should make their way into the next EAP. To support the dynamic features, we’ve added the types IDynamicMethodReferenceExpression, IDynamicPropertyIndexerExpression, and IDynamicPropertyReferenceExpression to the object model. These types, based on the versions without “Dynamic” in the name, reflect the fact that we don’t have full information about the method that is going to be called, but only have its name (as a string). These interfaces are going to change – in an internal version, they have been extended to include information about which parameter positions use runtime types and which use compile time types. There’s also the interface, IDynamicVariableDeclaration, that can be used to determine if a particular variable is used at dynamic call sites as a target. A couple of these language changes have also been added to the Visual Basic language writer. The new features are exposed only when the optimization level is set to .NET 4. When the level is set this high, the other standard language writers will simply display a message to say that they do not handle such an optimization level. Reflector Pro now has 4.0 as an optional compilation target and we have done some work to get the pdb generation right for these new features. The EAP version of Reflector no longer installs the add-in on startup. The first time you run the EAP, it displays the integration options dialog. You can use the checkboxes to select the versions of Visual Studio into which you want to install the EAP version. Note that you can only have one version of Reflector Pro installed in Visual Studio; if you install into a Visual Studio that has another version installed, the previous version will be removed. Please try it out and send your feedback to the EAP forum.

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  • Clever memory usage through the years

    - by Ben Emmett
    A friend and I were recently talking about the really clever tricks people have used to get the most out of memory. I thought I’d share my favorites, and would love to hear yours too! Interleaving on drum memory Back in the ye olde days before I’d been born (we’re talking the 50s / 60s here), working memory commonly took the form of rotating magnetic drums. These would spin at a constant speed, and a fixed head would read from memory when the correct part of the drum passed it by, a bit like a primitive platter disk. Because each revolution took a few milliseconds, programmers took to manually arranging information non-sequentially on the drum, timing when an instruction or memory address would need to be accessed, then spacing information accordingly around the edge of the drum, thus reducing the access delay. Similar techniques were still used on hard disks and floppy disks into the 90s, but have become irrelevant with modern disk technologies. The Hashlife algorithm Conway’s Game of Life has attracted numerous implementations over the years, but Bill Gosper’s Hashlife algorithm is particularly impressive. Taking advantage of the repetitive nature of many cellular automata, it uses a quadtree structure to store the hashes of pieces of the overall grid. Over time there are fewer and fewer new structures which need to be evaluated, so it starts to run faster with larger grids, drastically outperforming other algorithms both in terms of speed and the size of grid which can be simulated. The actual amount of memory used is huge, but it’s used in a clever way, so makes the list . Elite’s procedural generation Ok, so this isn’t exactly a memory optimization – more a storage optimization – but it gets an honorable mention anyway. When writing Elite, David Braben and Ian Bell wanted to build a rich world which gamers could explore, but their 22K memory was something of a limitation (for comparison that’s about the size of my avatar picture at the top of this page). They procedurally generated all the characteristics of the 2048 planets in their virtual universe, including the names, which were stitched together using a lookup table of parts of names. In fact the original plans were for 2^52 planets, but it was decided that that was probably too many. Oh, and they did that all in assembly language. Other games of the time used similar techniques too – The Sentinel’s landscape generation algorithm being another example. Modern Garbage Collectors Garbage collection in managed languages like Java and .NET ensures that most of the time, developers stop needing to care about how they use and clean up memory as the garbage collector handles it automatically. Achieving this without killing performance is a near-miraculous feet of software engineering. Much like when learning chemistry, you find that every time you think you understand how the garbage collector works, it turns out to be a mere simplification; that there are yet more complexities and heuristics to help it run efficiently. Of course introducing memory problems is still possible (and there are tools like our memory profiler to help if that happens to you) but they’re much, much rarer. A cautionary note In the examples above, there were good and well understood reasons for the optimizations, but cunningly optimized code has usually had to trade away readability and maintainability to achieve its gains. Trying to optimize memory usage without being pretty confident that there’s actually a problem is doing it wrong. So what have I missed? Tell me about the ingenious (or stupid) tricks you’ve seen people use. Ben

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  • Detect Unicode Usage in SQL Column

    One optimization you can make to a SQL table that is overly large is to change from nvarchar (or nchar) to varchar (or char).  Doing so will cut the size used by the data in half, from 2 bytes per character (+ 2 bytes of overhead for varchar) to only 1 byte per character.  However, you will lose the ability to store Unicode characters, such as those used by many non-English alphabets.  If the tables are storing user-input, and your application is or might one day be used internationally, its likely that using Unicode for your characters is a good thing.  However, if instead the data is being generated by your application itself or your development team (such as lookup data), and you can be certain that Unicode character sets are not required, then switching such columns to varchar/char can be an easy improvement to make. Avoid Premature Optimization If you are working with a lookup table that has a small number of rows, and is only ever referenced in the application by its numeric ID column, then you wont see any benefit to using varchar vs. nvarchar.  More generally, for small tables, you wont see any significant benefit.  Thus, if you have a general policy in place to use nvarchar/nchar because it offers more flexibility, do not take this post as a recommendation to go against this policy anywhere you can.  You really only want to act on measurable evidence that suggests that using Unicode is resulting in a problem, and that you wont lose anything by switching to varchar/char. Obviously the main reason to make this change is to reduce the amount of space required by each row.  This in turn affects how many rows SQL Server can page through at a time, and can also impact index size and how much disk I/O is required to respond to queries, etc.  If for example you have a table with 100 million records in it and this table has a column of type nchar(5), this column will use 5 * 2 = 10 bytes per row, and with 100M rows that works out to 10 bytes * 100 million = 1000 MBytes or 1GB.  If it turns out that this column only ever stores ASCII characters, then changing it to char(5) would reduce this to 5*1 = 5 bytes per row, and only 500MB.  Of course, if it turns out that it only ever stores the values true and false then you could go further and replace it with a bit data type which uses only 1 byte per row (100MB  total). Detecting Whether Unicode Is In Use So by now you think that you have a problem and that it might be alleviated by switching some columns from nvarchar/nchar to varchar/char but youre not sure whether youre currently using Unicode in these columns.  By definition, you should only be thinking about this for a column that has a lot of rows in it, since the benefits just arent there for a small table, so you cant just eyeball it and look for any non-ASCII characters.  Instead, you need a query.  Its actually very simple: SELECT DISTINCT(CategoryName)FROM CategoriesWHERE CategoryName <> CONVERT(varchar, CategoryName) Summary Gregg Stark for the tip. Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • 12c - Utl_Call_Stack...

    - by noreply(at)blogger.com (Thomas Kyte)
    Over the next couple of months, I'll be writing about some cool new little features of Oracle Database 12c - things that might not make the front page of Oracle.com.  I'm going to start with a new package - UTL_CALL_STACK.In the past, developers have had access to three functions to try to figure out "where the heck am I in my code", they were:dbms_utility.format_call_stackdbms_utility.format_error_backtracedbms_utility.format_error_stackNow these routines, while useful, were of somewhat limited use.  Let's look at the format_call_stack routine for a reason why.  Here is a procedure that will just print out the current call stack for us:ops$tkyte%ORA12CR1> create or replace  2  procedure Print_Call_Stack  3  is  4  begin  5    DBMS_Output.Put_Line(DBMS_Utility.Format_Call_Stack());  6  end;  7  /Procedure created.Now, if we have a package - with nested functions and even duplicated function names:ops$tkyte%ORA12CR1> create or replace  2  package body Pkg is  3    procedure p  4    is  5      procedure q  6      is  7        procedure r  8        is  9          procedure p is 10          begin 11            Print_Call_Stack(); 12            raise program_error; 13          end p; 14        begin 15          p(); 16        end r; 17      begin 18        r(); 19      end q; 20    begin 21      q(); 22    end p; 23  end Pkg; 24  /Package body created.When we execute the procedure PKG.P - we'll see as a result:ops$tkyte%ORA12CR1> exec pkg.p----- PL/SQL Call Stack -----  object      line  object  handle    number  name0x6e891528         4  procedure OPS$TKYTE.PRINT_CALL_STACK0x6ec4a7c0        10  package body OPS$TKYTE.PKG0x6ec4a7c0        14  package body OPS$TKYTE.PKG0x6ec4a7c0        17  package body OPS$TKYTE.PKG0x6ec4a7c0        20  package body OPS$TKYTE.PKG0x76439070         1  anonymous blockBEGIN pkg.p; END;*ERROR at line 1:ORA-06501: PL/SQL: program errorORA-06512: at "OPS$TKYTE.PKG", line 11ORA-06512: at "OPS$TKYTE.PKG", line 14ORA-06512: at "OPS$TKYTE.PKG", line 17ORA-06512: at "OPS$TKYTE.PKG", line 20ORA-06512: at line 1The bit in red above is the output from format_call_stack whereas the bit in black is the error message returned to the client application (it would also be available to you via the format_error_backtrace API call). As you can see - it contains useful information but to use it you would need to parse it - and that can be trickier than it seems.  The format of those strings is not set in stone, they have changed over the years (I wrote the "who_am_i", "who_called_me" functions, I did that by parsing these strings - trust me, they change over time!).Starting in 12c - we'll have structured access to the call stack and a series of API calls to interrogate this structure.  I'm going to rewrite the print_call_stack function as follows:ops$tkyte%ORA12CR1> create or replace 2  procedure Print_Call_Stack  3  as  4    Depth pls_integer := UTL_Call_Stack.Dynamic_Depth();  5    6    procedure headers  7    is  8    begin  9        dbms_output.put_line( 'Lexical   Depth   Line    Name' ); 10        dbms_output.put_line( 'Depth             Number      ' ); 11        dbms_output.put_line( '-------   -----   ----    ----' ); 12    end headers; 13    procedure print 14    is 15    begin 16        headers; 17        for j in reverse 1..Depth loop 18          DBMS_Output.Put_Line( 19            rpad( utl_call_stack.lexical_depth(j), 10 ) || 20                    rpad( j, 7) || 21            rpad( To_Char(UTL_Call_Stack.Unit_Line(j), '99'), 9 ) || 22            UTL_Call_Stack.Concatenate_Subprogram 23                       (UTL_Call_Stack.Subprogram(j))); 24        end loop; 25    end; 26  begin 27    print; 28  end; 29  /Here we are able to figure out what 'depth' we are in the code (utl_call_stack.dynamic_depth) and then walk up the stack using a loop.  We will print out the lexical_depth, along with the line number within the unit we were executing plus - the unit name.  And not just any unit name, but the fully qualified, all of the way down to the subprogram name within a package.  Not only that - but down to the subprogram name within a subprogram name within a subprogram name.  For example - running the PKG.P procedure again results in:ops$tkyte%ORA12CR1> exec pkg.pLexical   Depth   Line    NameDepth             Number-------   -----   ----    ----1         6       20      PKG.P2         5       17      PKG.P.Q3         4       14      PKG.P.Q.R4         3       10      PKG.P.Q.R.P0         2       26      PRINT_CALL_STACK1         1       17      PRINT_CALL_STACK.PRINTBEGIN pkg.p; END;*ERROR at line 1:ORA-06501: PL/SQL: program errorORA-06512: at "OPS$TKYTE.PKG", line 11ORA-06512: at "OPS$TKYTE.PKG", line 14ORA-06512: at "OPS$TKYTE.PKG", line 17ORA-06512: at "OPS$TKYTE.PKG", line 20ORA-06512: at line 1This time - we get much more than just a line number and a package name as we did previously with format_call_stack.  We not only got the line number and package (unit) name - we got the names of the subprograms - we can see that P called Q called R called P as nested subprograms.  Also note that we can see a 'truer' calling level with the lexical depth, we can see we "stepped" out of the package to call print_call_stack and that in turn called another nested subprogram.This new package will be a nice addition to everyone's error logging packages.  Of course there are other functions in there to get owner names, the edition in effect when the code was executed and more. See UTL_CALL_STACK for all of the details.

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  • Investigating on xVelocity (VertiPaq) column size

    - by Marco Russo (SQLBI)
      In January I published an article about how to optimize high cardinality columns in VertiPaq. In the meantime, VertiPaq has been rebranded to xVelocity: the official name is now “xVelocity in-memory analytics engine (VertiPaq)” but using xVelocity and VertiPaq when we talk about Analysis Services has the same meaning. In this post I’ll show how to investigate on columns size of an existing Tabular database so that you can find the most important columns to be optimized. A first approach can be looking in the DataDir of Analysis Services and look for the folder containing the database. Then, look for the biggest files in all subfolders and you will find the name of a file that contains the name of the most expensive column. However, this heuristic process is not very optimized. A better approach is using a DMV that provides the exact information. For example, by using the following query (open SSMS, open an MDX query on the database you are interested to and execute it) you will see all database objects sorted by used size in a descending way. SELECT * FROM $SYSTEM.DISCOVER_STORAGE_TABLE_COLUMN_SEGMENTS ORDER BY used_size DESC You can look at the first rows in order to understand what are the most expensive columns in your tabular model. The interesting data provided are: TABLE_ID: it is the name of the object – it can be also a dictionary or an index COLUMN_ID: it is the column name the object belongs to – you can also see ID_TO_POS and POS_TO_ID in case they refer to internal indexes RECORDS_COUNT: it is the number of rows in the column USED_SIZE: it is the used memory for the object By looking at the ration between USED_SIZE and RECORDS_COUNT you can understand what you can do in order to optimize your tabular model. Your options are: Remove the column. Yes, if it contains data you will never use in a query, simply remove the column from the tabular model Change granularity. If you are tracking time and you included milliseconds but seconds would be enough, round the data source column to the nearest second. If you have a floating point number but two decimals are good enough (i.e. the temperature), round the number to the nearest decimal is relevant to you. Split the column. Create two or more columns that have to be combined together in order to produce the original value. This technique is described in VertiPaq optimization article. Sort the table by that column. When you read the data source, you might consider sorting data by this column, so that the compression will be more efficient. However, this technique works better on columns that don’t have too many distinct values and you will probably move the problem to another column. Sorting data starting from the lower density columns (those with a few number of distinct values) and going to higher density columns (those with high cardinality) is the technique that provides the best compression ratio. After the optimization you should be able to reduce the used size and improve the count/size ration you measured before. If you are interested in a longer discussion about internal storage in VertiPaq and you want understand why this approach can save you space (and time), you can attend my 24 Hours of PASS session “VertiPaq Under the Hood” on March 21 at 08:00 GMT.

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  • Nashorn in the Twitterverse, Continued

    - by jlaskey
    After doing the Twitter example, it seemed reasonable to try graphing the result with JavaFX.  At this time the Nashorn project doesn't have an JavaFX shell, so we have to go through some hoops to create an JavaFX application.  I thought showing you some of those hoops might give you some idea about what you can do mixing Nashorn and Java (we'll add a JavaFX shell to the todo list.) First, let's look at the meat of the application.  Here is the repackaged version of the original twitter example. var twitter4j      = Packages.twitter4j; var TwitterFactory = twitter4j.TwitterFactory; var Query          = twitter4j.Query; function getTrendingData() {     var twitter = new TwitterFactory().instance;     var query   = new Query("nashorn OR nashornjs");     query.since("2012-11-21");     query.count = 100;     var data = {};     do {         var result = twitter.search(query);         var tweets = result.tweets;         for each (tweet in tweets) {             var date = tweet.createdAt;             var key = (1900 + date.year) + "/" +                       (1 + date.month) + "/" +                       date.date;             data[key] = (data[key] || 0) + 1;         }     } while (query = result.nextQuery());     return data; } Instead of just printing out tweets, getTrendingData tallies "tweets per date" during the sample period (since "2012-11-21", the date "New Project: Nashorn" was posted.)   getTrendingData then returns the resulting tally object. Next, use JavaFX BarChart to display that data. var javafx         = Packages.javafx; var Stage          = javafx.stage.Stage var Scene          = javafx.scene.Scene; var Group          = javafx.scene.Group; var Chart          = javafx.scene.chart.Chart; var FXCollections  = javafx.collections.FXCollections; var ObservableList = javafx.collections.ObservableList; var CategoryAxis   = javafx.scene.chart.CategoryAxis; var NumberAxis     = javafx.scene.chart.NumberAxis; var BarChart       = javafx.scene.chart.BarChart; var XYChart        = javafx.scene.chart.XYChart; var Series         = XYChart.Series; var Data           = XYChart.Data; function graph(stage, data) {     var root = new Group();     stage.scene = new Scene(root);     var dates = Object.keys(data);     var xAxis = new CategoryAxis();     xAxis.categories = FXCollections.observableArrayList(dates);     var yAxis = new NumberAxis("Tweets", 0.0, 200.0, 50.0);     var series = FXCollections.observableArrayList();     for (var date in data) {         series.add(new Data(date, data[date]));     }     var tweets = new Series("Tweets", series);     var barChartData = FXCollections.observableArrayList(tweets);     var chart = new BarChart(xAxis, yAxis, barChartData, 25.0);     root.children.add(chart); } I should point out that there is a lot of subtlety going on in the background.  For example; stage.scene = new Scene(root) is equivalent to stage.setScene(new Scene(root)). If Nashorn can't find a property (scene), then it searches (via Dynalink) for the Java Beans equivalent (setScene.)  Also note, that Nashorn is magically handling the generic class FXCollections.  Finally,  with the call to observableArrayList(dates), Nashorn is automatically converting the JavaScript array dates to a Java collection.  It really is hard to identify which objects are JavaScript and which are Java.  Does it really matter? Okay, with the meat out of the way, let's talk about the hoops. When working with JavaFX, you start with a main subclass of javafx.application.Application.  This class handles the initialization of the JavaFX libraries and the event processing.  This is what I used for this example; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import javafx.application.Application; import javafx.stage.Stage; import javax.script.ScriptEngine; import javax.script.ScriptEngineManager; import javax.script.ScriptException; public class TrendingMain extends Application { private static final ScriptEngineManager MANAGER = new ScriptEngineManager(); private final ScriptEngine engine = MANAGER.getEngineByName("nashorn"); private Trending trending; public static void main(String[] args) { launch(args); } @Override public void start(Stage stage) throws Exception { trending = (Trending) load("Trending.js"); trending.start(stage); } @Override public void stop() throws Exception { trending.stop(); } private Object load(String script) throws IOException, ScriptException { try (final InputStream is = TrendingMain.class.getResourceAsStream(script)) { return engine.eval(new InputStreamReader(is, "utf-8")); } } } To initialize Nashorn, we use JSR-223's javax.script.  private static final ScriptEngineManager MANAGER = new ScriptEngineManager(); private final ScriptEngine engine = MANAGER.getEngineByName("nashorn"); This code sets up an instance of the Nashorn engine for evaluating scripts. The  load method reads a script into memory and then gets engine to eval that script.  Note, that load also returns the result of the eval. Now for the fun part.  There are several different approaches we could use to communicate between the Java main and the script.  In this example we'll use a Java interface.  The JavaFX main needs to do at least start and stop, so the following will suffice as an interface; public interface Trending {     public void start(Stage stage) throws Exception;     public void stop() throws Exception; } At the end of the example's script we add; (function newTrending() {     return new Packages.Trending() {         start: function(stage) {             var data = getTrendingData();             graph(stage, data);             stage.show();         },         stop: function() {         }     } })(); which instantiates a new subclass instance of Trending and overrides the start and stop methods.  The result of this function call is what is returned to main via the eval. trending = (Trending) load("Trending.js"); To recap, the script Trending.js contains functions getTrendingData, graph and newTrending, plus the call at the end to newTrending.  Back in the Java code, we cast the result of the eval (call to newTrending) to Trending, thus, we end up with an object that we can then use to call back into the script.  trending.start(stage); Voila. ?

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  • Investigating on xVelocity (VertiPaq) column size

    - by Marco Russo (SQLBI)
      In January I published an article about how to optimize high cardinality columns in VertiPaq. In the meantime, VertiPaq has been rebranded to xVelocity: the official name is now “xVelocity in-memory analytics engine (VertiPaq)” but using xVelocity and VertiPaq when we talk about Analysis Services has the same meaning. In this post I’ll show how to investigate on columns size of an existing Tabular database so that you can find the most important columns to be optimized. A first approach can be looking in the DataDir of Analysis Services and look for the folder containing the database. Then, look for the biggest files in all subfolders and you will find the name of a file that contains the name of the most expensive column. However, this heuristic process is not very optimized. A better approach is using a DMV that provides the exact information. For example, by using the following query (open SSMS, open an MDX query on the database you are interested to and execute it) you will see all database objects sorted by used size in a descending way. SELECT * FROM $SYSTEM.DISCOVER_STORAGE_TABLE_COLUMN_SEGMENTS ORDER BY used_size DESC You can look at the first rows in order to understand what are the most expensive columns in your tabular model. The interesting data provided are: TABLE_ID: it is the name of the object – it can be also a dictionary or an index COLUMN_ID: it is the column name the object belongs to – you can also see ID_TO_POS and POS_TO_ID in case they refer to internal indexes RECORDS_COUNT: it is the number of rows in the column USED_SIZE: it is the used memory for the object By looking at the ration between USED_SIZE and RECORDS_COUNT you can understand what you can do in order to optimize your tabular model. Your options are: Remove the column. Yes, if it contains data you will never use in a query, simply remove the column from the tabular model Change granularity. If you are tracking time and you included milliseconds but seconds would be enough, round the data source column to the nearest second. If you have a floating point number but two decimals are good enough (i.e. the temperature), round the number to the nearest decimal is relevant to you. Split the column. Create two or more columns that have to be combined together in order to produce the original value. This technique is described in VertiPaq optimization article. Sort the table by that column. When you read the data source, you might consider sorting data by this column, so that the compression will be more efficient. However, this technique works better on columns that don’t have too many distinct values and you will probably move the problem to another column. Sorting data starting from the lower density columns (those with a few number of distinct values) and going to higher density columns (those with high cardinality) is the technique that provides the best compression ratio. After the optimization you should be able to reduce the used size and improve the count/size ration you measured before. If you are interested in a longer discussion about internal storage in VertiPaq and you want understand why this approach can save you space (and time), you can attend my 24 Hours of PASS session “VertiPaq Under the Hood” on March 21 at 08:00 GMT.

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  • How do you re-mount an ext3 fs readwrite after it gets mounted readonly from a disk error?

    - by cagenut
    Its a relatively common problem when something goes wrong in a SAN for ext3 to detect the disk write errors and remount the filesystem read-only. Thats all well and good, only when the SAN is fixed I can't figure out how to re-re-mount the filesystem read-write without rebooting. Behold: [root@localhost ~]# multipath -ll mpath0 (36001f93000a310000299000200000000) dm-2 XIOTECH,ISE1400 [size=1.1T][features=1 queue_if_no_path][hwhandler=0][rw] \_ round-robin 0 [prio=2][active] \_ 1:0:0:1 sdb 8:16 [active][ready] \_ 2:0:0:1 sdc 8:32 [active][ready] [root@localhost ~]# mount /dev/mapper/mpath0 /mnt/foo [root@localhost ~]# touch /mnt/foo/blah All good, now I yank the LUN out from under it. [root@localhost ~]# touch /mnt/foo/blah [root@localhost ~]# touch /mnt/foo/blah touch: cannot touch `/mnt/foo/blah': Read-only file system [root@localhost ~]# tail /var/log/messages Mar 18 13:17:33 localhost multipathd: sdb: tur checker reports path is down Mar 18 13:17:34 localhost multipathd: sdc: tur checker reports path is down Mar 18 13:17:35 localhost kernel: Aborting journal on device dm-2. Mar 18 13:17:35 localhost kernel: Buffer I/O error on device dm-2, logical block 1545 Mar 18 13:17:35 localhost kernel: lost page write due to I/O error on dm-2 Mar 18 13:17:36 localhost kernel: ext3_abort called. Mar 18 13:17:36 localhost kernel: EXT3-fs error (device dm-2): ext3_journal_start_sb: Detected aborted journal Mar 18 13:17:36 localhost kernel: Remounting filesystem read-only It only thinks its read-only, in reality its not even there. [root@localhost ~]# multipath -ll sdb: checker msg is "tur checker reports path is down" sdc: checker msg is "tur checker reports path is down" mpath0 (36001f93000a310000299000200000000) dm-2 XIOTECH,ISE1400 [size=1.1T][features=0][hwhandler=0][rw] \_ round-robin 0 [prio=0][enabled] \_ 1:0:0:1 sdb 8:16 [failed][faulty] \_ 2:0:0:1 sdc 8:32 [failed][faulty] [root@localhost ~]# ll /mnt/foo/ ls: reading directory /mnt/foo/: Input/output error total 20 -rw-r--r-- 1 root root 0 Mar 18 13:11 bar How it still remembers that 'bar' file being there... mystery, but not important right now. Now I re-present the LUN: [root@localhost ~]# tail /var/log/messages Mar 18 13:23:58 localhost multipathd: sdb: tur checker reports path is up Mar 18 13:23:58 localhost multipathd: 8:16: reinstated Mar 18 13:23:58 localhost multipathd: mpath0: queue_if_no_path enabled Mar 18 13:23:58 localhost multipathd: mpath0: Recovered to normal mode Mar 18 13:23:58 localhost multipathd: mpath0: remaining active paths: 1 Mar 18 13:23:58 localhost multipathd: dm-2: add map (uevent) Mar 18 13:23:58 localhost multipathd: dm-2: devmap already registered Mar 18 13:23:59 localhost multipathd: sdc: tur checker reports path is up Mar 18 13:23:59 localhost multipathd: 8:32: reinstated Mar 18 13:23:59 localhost multipathd: mpath0: remaining active paths: 2 Mar 18 13:23:59 localhost multipathd: dm-2: add map (uevent) Mar 18 13:23:59 localhost multipathd: dm-2: devmap already registered [root@localhost ~]# multipath -ll mpath0 (36001f93000a310000299000200000000) dm-2 XIOTECH,ISE1400 [size=1.1T][features=1 queue_if_no_path][hwhandler=0][rw] \_ round-robin 0 [prio=2][enabled] \_ 1:0:0:1 sdb 8:16 [active][ready] \_ 2:0:0:1 sdc 8:32 [active][ready] Great right? It says [rw] right there. Not so fast: [root@localhost ~]# touch /mnt/foo/blah touch: cannot touch `/mnt/foo/blah': Read-only file system OK, doesn't do it automatically, I'll just give it a little push: [root@localhost ~]# mount -o remount /mnt/foo mount: block device /dev/mapper/mpath0 is write-protected, mounting read-only The hell you are: [root@localhost ~]# mount -o remount,rw /mnt/foo mount: block device /dev/mapper/mpath0 is write-protected, mounting read-only Noooooooooo. I have tried all sorts of different mount/tune2fs/dmsetup commands and I cannot figure out how to get it to un-flag the block device as write-protected. Rebooting will fix it, but I'd much rather do it on-line. An hour of googling has gotten me nowhere either. Save me ServerFault.

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  • ADO and Two Way Storage Tiering

    - by Andy-Oracle
    Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 We get asked the following question about Automatic Data Optimization (ADO) storage tiering quite a bit. Can you tier back to the original location if the data gets hot again? The answer is yes but not with standard Automatic Data Optimization policies, at least not reliably. That's not how ADO is meant to operate. ADO is meant to mirror a traditional view of Information Lifecycle Management (ILM) where data will be very volatile when first created, will become less active or cool, and then will eventually cease to be accessed at all (i.e. cold). I think the reason this question gets asked is because customers realize that many of their business processes are cyclical and the thinking goes that those segments that only get used during month end or year-end cycles could sit on lower cost storage when not being used. Unfortunately this doesn't fit very well with the ADO storage tiering model. ADO storage tiering is based on the amount of free and used space in the source tablespace. There are two parameters that control this behavior, TBS_PERCENT_USED and TBS_PERCENT_FREE. When the space in the tablespace exceeds the TBS_PERCENT_USED value then segments specified in storage tiering clause(s) can be moved until the percent of free space reaches the TBS_PERCENT_FREE value. It is worth mentioning that no checks are made for available space in the target tablespace. Now, it is certainly possible to create custom functions to control storage tiering, but this can get complicated. The biggest problem is insuring that there is enough space to move the segment back to tier 1 storage, assuming that that's the goal. This isn't as much of a problem when moving from tier 1 to tier 2 storage because there is typically more tier 2 storage available. At least that's the premise since it is supposed to be less costly, lower performing and higher capacity storage. In either case though, if there isn't enough space then the operation fails. In the case of a customized function, the question becomes do you attempt to free the space so the move can be made or do you just stop and return false so that the move cannot take place? This is really the crux of the issue. Once you cross into this territory you're really going to have to implement two-way hierarchical storage and the whole point of ADO was to provide automatic storage tiering. You're probably better off using heat map and/or business access requirements and building your own hierarchical storage management infrastructure if you really want two way storage tiering. /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}

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  • Rethinking Oracle Optimizer Statistics for P6 Part 2

    - by Brian Diehl
    In the previous post (Part 1), I tried to draw some key insights about the relationship between P6 and Oracle Optimizer Statistics.  The first is that average cardinality has the greatest impact on query optimization and that the particular queries generated by P6 are more likely to use this average during calculations. The second is that these are statistics that are unlikely to change greatly over the life of the application. Ultimately, our goal is to get the best query optimization possible.  Or is it? Stability No application administrator wants to get the call at 9am that their application users cannot get there work done because everything is running slow. This is a possibility with a regularly scheduled nightly collection of statistics. It may not just be slow performance, but a complete loss of service because one or more queries are optimized poorly. Ideally, this should not be the case. The database optimizer should make better decisions with more up-to-date data. Better statistics may give incremental performance benefit. However, this benefit must be balanced against the potential cost of system down time.  It is stability that we ultimately desire and not absolute optimal performance. We do want the benefit from more accurate statistics and better query plans, but not at the risk of an unusable system. As a result, I've developed the following methodology around managing database statistics for the P6 database.  1. No Automatic Re-Gathering - The daily, weekly, or other interval of statistic gathering is unlikely to be beneficial. Quite the opposite. It is more likely to cause problems. 2. Smart Re-Gathering - The time to collect statistics is when things have changed significantly. For a new installation of P6, this is happening more often because the data is growing from a few rows to thousands and more. But for a mature system, the data is not changing significantly from week-to-week. There are times to collect statistics: New releases of the application Changes in the underlying hardware or software versions (ex. new Oracle RDBMS version) When additional user groups are added. The new groups may use the software in significantly different ways. After significant changes in the data. This may be monthly, quarterly or yearly.  3. Always Test - If you take away one thing from this post, it would be to always have a plan to test after changing statistics. In reality, statistics can be collected as often as you desire provided there are tests in place to verify that performance is the same or better. These might be automated tests or simply a manual script of application functions. 4. Have a Way Out - Never change the statistics without a way to return to the previous set. Think of the statistics as one part of the overall application code that also includes the source code--both application and RDBMS. It would be foolish to change to the new code without a way to get back to the previous version. In the final post, I will talk about the actual script I created for P6 PMDB and possible future direction for managing query performance. 

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  • Can you use gzip over SSL? And Connection: Keep-Alive headers

    - by magenta
    I'm evaluating the front end performance of a secure (SSL) web app here at work and I'm wondering if it's possible to compress text files (html/css/javascript) over SSL. I've done some googling around but haven't found anything specifically related to SSL. If it's possible, is it even worth the extra CPU cycles since responses are also being encrypted? Would compressing responses hurt performance? Also, I'm wanting to make sure we're keeping the SSL connection alive so we're not making SSL handshakes over and over. I'm not seeing Connection: Keep-Alive in the response headers. I do see Keep-Alive: 115 in the request headers but that's only keeping the connection alive for 115 milliseconds (seems like the app server is closing the connection after a single request is processed?) Wouldn't you want the server to be setting that response header for as long as the session inactivity timeout is? I understand browsers don't cache SSL content to disk so we're serving the same files over and over and over on subsequent visits even though nothing has changed. The main optimization recommendations are reducing the number of http requests, minification, moving scripts to bottom, image optimization, possible domain sharding (though need to weigh the cost of another SSL handshake), things of that nature.

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  • Using Traveling Salesman Solver to Decide Hamiltonian Path

    - by Firas Assaad
    This is for a project where I'm asked to implement a heuristic for the traveling salesman optimization problem and also the Hamiltonian path or cycle decision problem. I don't need help with the implementation itself, but have a question on the direction I'm going in. I already have a TSP heuristic based on a genetic algorithm: it assumes a complete graph, starts with a set of random solutions as a population, and works to improve the population for a number of generations. Can I also use it to solve the Hamiltonian path or cycle problems? Instead of optimizing to get the shortest path, I just want to check if there is a path. Now any complete graph will have a Hamiltonian path in it, so the TSP heuristic would have to be extended to any graph. This could be done by setting the edges to some infinity value if there is no path between two cities, and returning the first path that is a valid Hamiltonian path. Is that the right way to approach it? Or should I use a different heuristic for Hamiltonian path? My main concern is whether it's a viable approach since I can be somewhat sure that TSP optimization works (because you start with solutions and improve them) but not if a Hamiltonian path decider would find any path in a fixed number of generations. I assume the best approach would be to test it myself, but I'm constrained by time and thought I'd ask before going down this route... (I could find a different heuristic for Hamiltonian path instead)

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  • Iterating through String word at a time in Python

    - by AlgoMan
    I have a string buffer of a huge text file. I have to search a given words/phrases in the string buffer. Whats the efficient way to do it ? I tried using re module matches. But As i have a huge text corpus that i have to search through. This is taking large amount of time. Given a Dictionary of words and Phrases. I iterate through the each file, read that into string , search all the words and phrases in the dictionary and increment the count in the dictionary if the keys are found. One small optimization that we thought was to sort the dictionary of phrases/words with the max number of words to lowest. And then compare each word start position from the string buffer and compare the list of words. If one phrase is found, we don search for the other phrases (as it matched the longest phrase ,which is what we want) Can some one suggest how to go about word by word in the string buffer. (Iterate string buffer word by word) ? Also, Is there any other optimization that can be done on this ?

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  • efficiently determining if a polynomial has a root in the interval [0,T]

    - by user168715
    I have polynomials of nontrivial degree (4+) and need to robustly and efficiently determine whether or not they have a root in the interval [0,T]. The precise location or number of roots don't concern me, I just need to know if there is at least one. Right now I'm using interval arithmetic as a quick check to see if I can prove that no roots can exist. If I can't, I'm using Jenkins-Traub to solve for all of the polynomial roots. This is obviously inefficient since it's checking for all real roots and finding their exact positions, information I don't end up needing. Is there a standard algorithm I should be using? If not, are there any other efficient checks I could do before doing a full Jenkins-Traub solve for all roots? For example, one optimization I could do is to check if my polynomial f(t) has the same sign at 0 and T. If not, there is obviously a root in the interval. If so, I can solve for the roots of f'(t) and evaluate f at all roots of f' in the interval [0,T]. f(t) has no root in that interval if and only if all of these evaluations have the same sign as f(0) and f(T). This reduces the degree of the polynomial I have to root-find by one. Not a huge optimization, but perhaps better than nothing.

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  • Moving inserted container element if possible

    - by doublep
    I'm trying to achieve the following optimization in my container library: when inserting an lvalue-referenced element, copy it to internal storage; but when inserting rvalue-referenced element, move it if supported. The optimization is supposed to be useful e.g. if contained element type is something like std::vector, where moving if possible would give substantial speedup. However, so far I was unable to devise any working scheme for this. My container is quite complicated, so I can't just duplicate insert() code several times: it is large. I want to keep all "real" code in some inner helper, say do_insert() (may be templated) and various insert()-like functions would just call that with different arguments. My best bet code for this (a prototype, of course, without doing anything real): #include <iostream> #include <utility> struct element { element () { }; element (element&&) { std::cerr << "moving\n"; } }; struct container { void insert (const element& value) { do_insert (value); } void insert (element&& value) { do_insert (std::move (value)); } private: template <typename Arg> void do_insert (Arg arg) { element x (arg); } }; int main () { { // Shouldn't move. container c; element x; c.insert (x); } { // Should move. container c; c.insert (element ()); } } However, this doesn't work at least with GCC 4.4 and 4.5: it never prints "moving" on stderr. Or is what I want impossible to achieve and that's why emplace()-like functions exist in the first place?

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  • VS 2008 C++ build output?

    - by STingRaySC
    Why when I watch the build output from a VC++ project in VS do I see: 1Compiling... 1a.cpp 1b.cpp 1c.cpp 1d.cpp 1e.cpp [etc...] 1Generating code... 1x.cpp 1y.cpp [etc...] The output looks as though several compilation units are being handled before any code is generated. Is this really going on? I'm trying to improve build times, and by using pre-compiled headers, I've gotten great speedups for each ".cpp" file, but there is a relatively long pause during the "Generating Code..." message. I do not have "Whole Program Optimization" nor "Link Time Code Generation" turned on. If this is the case, then why? Why doesn't VC++ compile each ".cpp" individually (which would include the code generation phase)? If this isn't just an illusion of the output, is there cross-compilation-unit optimization potentially going on here? There don't appear to be any compiler options to control that behavior (I know about WPO and LTCG, as mentioned above). EDIT: The build log just shows the ".obj" files in the output directory, one per line. There is no indication of "Compiling..." vs. "Generating code..." steps. EDIT: I have confirmed that this behavior has nothing to do with the "maximum number of parallel project builds" setting in Tools - Options - Projects and Solutions - Build and Run. Nor is it related to the MSBuild project build output verbosity setting. Indeed if I cancel the build before the "Generating code..." step, the ".obj" files will not exist for the most recent set of "compiled" files. E.g., if I cancel the build during "c.cpp" above, I will see only "a.obj" and "b.obj".

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  • Thread management advice - Is TPL a good idea?

    - by Ian
    I'm hoping to get some advice on the use of thread managment and hopefully the task parallel library, because I'm not sure I've been going down the correct route. Probably best is that I give an outline of what I'm trying to do. Given a Problem I need to generate a Solution using a heuristic based algorithm. I start of by calculating a base solution, this operation I don't think can be parallelised so we don't need to worry about. Once the inital solution has been generated, I want to trigger n threads, which attempt to find a better solution. These threads need to do a couple of things: They need to be initalized with a different 'optimization metric'. In other words they are attempting to optimize different things, with a precedence level set within code. This means they all run slightly different calculation engines. I'm not sure if I can do this with the TPL.. If one of the threads finds a better solution that the currently best known solution (which needs to be shared across all threads) then it needs to update the best solution, and force a number of other threads to restart (again this depends on precedence levels of the optimization metrics). I may also wish to combine certain calculations across threads (e.g. keep a union of probabilities for a certain approach to the problem). This is probably more optional though. The whole system needs to be thread safe obviously and I want it to be running as fast as possible. I tried quite an implementation that involved managing my own threads and shutting them down etc, but it started getting quite complicated, and I'm now wondering if the TPL might be better. I'm wondering if anyone can offer any general guidance? Thanks...

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  • In sync query calls, one query causing other query to run slower. Why?

    - by Irchi
    Sorry for the long question, but I think this is an interesting situation and I couldn't find any explanations for it: I was involved in optimization of an application that performed a large number of sequential SELECT and INSERT statements on a single dedicated SQL Server database. The process needs to INSERT a large number of records into a table, but for each of them there should be some value mappings, which performed using SELECT statements on another table in the same database. For a specific execution, it took 90 minutes to run. I used a profiler (JProfiler - the application is Java-based) to determine how much time does each part of the application take. It yields that 60% of the time was spent on INSERT method calls, and almost 20% on SELECT calls (the rest distributed in other parts). After some trials, I came to this situation: I commented out the INSERT query that took 60% of the time. I was expecting for the total run time to be around 35 minutes, as I have removed 60% of the 90 minutes. But the whole process took the same 90 minutes (doing only SELECTs and nothing else), but each SELECT took longer this time! Everything was running sync, there were no async calls. And there was only one single thread of execution. SELECT and INSERT queries are very simple, and don't have anything special, and they are on different tables, but on the same DB. I tested with both the DB on the application machine, and on a remote network machine. I can't think of any explanation for this, as the Profiler (Application profiler, not SQL Profiler) reported the changes in the method call times, and by removing INSERT statements SELECT statements took longer to run. Can anyone give me some kind of explanation of what could have happened? (there can't be cache / query optimization stuff, because the queries were run in sync, and in a single thread, and it was far from affecting the cache this much) I should note that the bottleneck of the speed was in SQL server, using most of the CPU time.

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  • Zen and the Art of File and Folder Organization

    - by Mark Virtue
    Is your desk a paragon of neatness, or does it look like a paper-bomb has gone off? If you’ve been putting off getting organized because the task is too huge or daunting, or you don’t know where to start, we’ve got 40 tips to get you on the path to zen mastery of your filing system. For all those readers who would like to get their files and folders organized, or, if they’re already organized, better organized—we have compiled a complete guide to getting organized and staying organized, a comprehensive article that will hopefully cover every possible tip you could want. Signs that Your Computer is Poorly Organized If your computer is a mess, you’re probably already aware of it.  But just in case you’re not, here are some tell-tale signs: Your Desktop has over 40 icons on it “My Documents” contains over 300 files and 60 folders, including MP3s and digital photos You use the Windows’ built-in search facility whenever you need to find a file You can’t find programs in the out-of-control list of programs in your Start Menu You save all your Word documents in one folder, all your spreadsheets in a second folder, etc Any given file that you’re looking for may be in any one of four different sets of folders But before we start, here are some quick notes: We’re going to assume you know what files and folders are, and how to create, save, rename, copy and delete them The organization principles described in this article apply equally to all computer systems.  However, the screenshots here will reflect how things look on Windows (usually Windows 7).  We will also mention some useful features of Windows that can help you get organized. Everyone has their own favorite methodology of organizing and filing, and it’s all too easy to get into “My Way is Better than Your Way” arguments.  The reality is that there is no perfect way of getting things organized.  When I wrote this article, I tried to keep a generalist and objective viewpoint.  I consider myself to be unusually well organized (to the point of obsession, truth be told), and I’ve had 25 years experience in collecting and organizing files on computers.  So I’ve got a lot to say on the subject.  But the tips I have described here are only one way of doing it.  Hopefully some of these tips will work for you too, but please don’t read this as any sort of “right” way to do it. At the end of the article we’ll be asking you, the reader, for your own organization tips. Why Bother Organizing At All? For some, the answer to this question is self-evident. And yet, in this era of powerful desktop search software (the search capabilities built into the Windows Vista and Windows 7 Start Menus, and third-party programs like Google Desktop Search), the question does need to be asked, and answered. I have a friend who puts every file he ever creates, receives or downloads into his My Documents folder and doesn’t bother filing them into subfolders at all.  He relies on the search functionality built into his Windows operating system to help him find whatever he’s looking for.  And he always finds it.  He’s a Search Samurai.  For him, filing is a waste of valuable time that could be spent enjoying life! It’s tempting to follow suit.  On the face of it, why would anyone bother to take the time to organize their hard disk when such excellent search software is available?  Well, if all you ever want to do with the files you own is to locate and open them individually (for listening, editing, etc), then there’s no reason to ever bother doing one scrap of organization.  But consider these common tasks that are not achievable with desktop search software: Find files manually.  Often it’s not convenient, speedy or even possible to utilize your desktop search software to find what you want.  It doesn’t work 100% of the time, or you may not even have it installed.  Sometimes its just plain faster to go straight to the file you want, if you know it’s in a particular sub-folder, rather than trawling through hundreds of search results. Find groups of similar files (e.g. all your “work” files, all the photos of your Europe holiday in 2008, all your music videos, all the MP3s from Dark Side of the Moon, all your letters you wrote to your wife, all your tax returns).  Clever naming of the files will only get you so far.  Sometimes it’s the date the file was created that’s important, other times it’s the file format, and other times it’s the purpose of the file.  How do you name a collection of files so that they’re easy to isolate based on any of the above criteria?  Short answer, you can’t. Move files to a new computer.  It’s time to upgrade your computer.  How do you quickly grab all the files that are important to you?  Or you decide to have two computers now – one for home and one for work.  How do you quickly isolate only the work-related files to move them to the work computer? Synchronize files to other computers.  If you have more than one computer, and you need to mirror some of your files onto the other computer (e.g. your music collection), then you need a way to quickly determine which files are to be synced and which are not.  Surely you don’t want to synchronize everything? Choose which files to back up.  If your backup regime calls for multiple backups, or requires speedy backups, then you’ll need to be able to specify which files are to be backed up, and which are not.  This is not possible if they’re all in the same folder. Finally, if you’re simply someone who takes pleasure in being organized, tidy and ordered (me! me!), then you don’t even need a reason.  Being disorganized is simply unthinkable. Tips on Getting Organized Here we present our 40 best tips on how to get organized.  Or, if you’re already organized, to get better organized. Tip #1.  Choose Your Organization System Carefully The reason that most people are not organized is that it takes time.  And the first thing that takes time is deciding upon a system of organization.  This is always a matter of personal preference, and is not something that a geek on a website can tell you.  You should always choose your own system, based on how your own brain is organized (which makes the assumption that your brain is, in fact, organized). We can’t instruct you, but we can make suggestions: You may want to start off with a system based on the users of the computer.  i.e. “My Files”, “My Wife’s Files”, My Son’s Files”, etc.  Inside “My Files”, you might then break it down into “Personal” and “Business”.  You may then realize that there are overlaps.  For example, everyone may want to share access to the music library, or the photos from the school play.  So you may create another folder called “Family”, for the “common” files. You may decide that the highest-level breakdown of your files is based on the “source” of each file.  In other words, who created the files.  You could have “Files created by ME (business or personal)”, “Files created by people I know (family, friends, etc)”, and finally “Files created by the rest of the world (MP3 music files, downloaded or ripped movies or TV shows, software installation files, gorgeous desktop wallpaper images you’ve collected, etc).”  This system happens to be the one I use myself.  See below:  Mark is for files created by meVC is for files created by my company (Virtual Creations)Others is for files created by my friends and familyData is the rest of the worldAlso, Settings is where I store the configuration files and other program data files for my installed software (more on this in tip #34, below). Each folder will present its own particular set of requirements for further sub-organization.  For example, you may decide to organize your music collection into sub-folders based on the artist’s name, while your digital photos might get organized based on the date they were taken.  It can be different for every sub-folder! Another strategy would be based on “currentness”.  Files you have yet to open and look at live in one folder.  Ones that have been looked at but not yet filed live in another place.  Current, active projects live in yet another place.  All other files (your “archive”, if you like) would live in a fourth folder. (And of course, within that last folder you’d need to create a further sub-system based on one of the previous bullet points). Put some thought into this – changing it when it proves incomplete can be a big hassle!  Before you go to the trouble of implementing any system you come up with, examine a wide cross-section of the files you own and see if they will all be able to find a nice logical place to sit within your system. Tip #2.  When You Decide on Your System, Stick to It! There’s nothing more pointless than going to all the trouble of creating a system and filing all your files, and then whenever you create, receive or download a new file, you simply dump it onto your Desktop.  You need to be disciplined – forever!  Every new file you get, spend those extra few seconds to file it where it belongs!  Otherwise, in just a month or two, you’ll be worse off than before – half your files will be organized and half will be disorganized – and you won’t know which is which! Tip #3.  Choose the Root Folder of Your Structure Carefully Every data file (document, photo, music file, etc) that you create, own or is important to you, no matter where it came from, should be found within one single folder, and that one single folder should be located at the root of your C: drive (as a sub-folder of C:\).  In other words, do not base your folder structure in standard folders like “My Documents”.  If you do, then you’re leaving it up to the operating system engineers to decide what folder structure is best for you.  And every operating system has a different system!  In Windows 7 your files are found in C:\Users\YourName, whilst on Windows XP it was C:\Documents and Settings\YourName\My Documents.  In UNIX systems it’s often /home/YourName. These standard default folders tend to fill up with junk files and folders that are not at all important to you.  “My Documents” is the worst offender.  Every second piece of software you install, it seems, likes to create its own folder in the “My Documents” folder.  These folders usually don’t fit within your organizational structure, so don’t use them!  In fact, don’t even use the “My Documents” folder at all.  Allow it to fill up with junk, and then simply ignore it.  It sounds heretical, but: Don’t ever visit your “My Documents” folder!  Remove your icons/links to “My Documents” and replace them with links to the folders you created and you care about! Create your own file system from scratch!  Probably the best place to put it would be on your D: drive – if you have one.  This way, all your files live on one drive, while all the operating system and software component files live on the C: drive – simply and elegantly separated.  The benefits of that are profound.  Not only are there obvious organizational benefits (see tip #10, below), but when it comes to migrate your data to a new computer, you can (sometimes) simply unplug your D: drive and plug it in as the D: drive of your new computer (this implies that the D: drive is actually a separate physical disk, and not a partition on the same disk as C:).  You also get a slight speed improvement (again, only if your C: and D: drives are on separate physical disks). Warning:  From tip #12, below, you will see that it’s actually a good idea to have exactly the same file system structure – including the drive it’s filed on – on all of the computers you own.  So if you decide to use the D: drive as the storage system for your own files, make sure you are able to use the D: drive on all the computers you own.  If you can’t ensure that, then you can still use a clever geeky trick to store your files on the D: drive, but still access them all via the C: drive (see tip #17, below). If you only have one hard disk (C:), then create a dedicated folder that will contain all your files – something like C:\Files.  The name of the folder is not important, but make it a single, brief word. There are several reasons for this: When creating a backup regime, it’s easy to decide what files should be backed up – they’re all in the one folder! If you ever decide to trade in your computer for a new one, you know exactly which files to migrate You will always know where to begin a search for any file If you synchronize files with other computers, it makes your synchronization routines very simple.   It also causes all your shortcuts to continue to work on the other machines (more about this in tip #24, below). Once you’ve decided where your files should go, then put all your files in there – Everything!  Completely disregard the standard, default folders that are created for you by the operating system (“My Music”, “My Pictures”, etc).  In fact, you can actually relocate many of those folders into your own structure (more about that below, in tip #6). The more completely you get all your data files (documents, photos, music, etc) and all your configuration settings into that one folder, then the easier it will be to perform all of the above tasks. Once this has been done, and all your files live in one folder, all the other folders in C:\ can be thought of as “operating system” folders, and therefore of little day-to-day interest for us. Here’s a screenshot of a nicely organized C: drive, where all user files are located within the \Files folder:   Tip #4.  Use Sub-Folders This would be our simplest and most obvious tip.  It almost goes without saying.  Any organizational system you decide upon (see tip #1) will require that you create sub-folders for your files.  Get used to creating folders on a regular basis. Tip #5.  Don’t be Shy About Depth Create as many levels of sub-folders as you need.  Don’t be scared to do so.  Every time you notice an opportunity to group a set of related files into a sub-folder, do so.  Examples might include:  All the MP3s from one music CD, all the photos from one holiday, or all the documents from one client. It’s perfectly okay to put files into a folder called C:\Files\Me\From Others\Services\WestCo Bank\Statements\2009.  That’s only seven levels deep.  Ten levels is not uncommon.  Of course, it’s possible to take this too far.  If you notice yourself creating a sub-folder to hold only one file, then you’ve probably become a little over-zealous.  On the other hand, if you simply create a structure with only two levels (for example C:\Files\Work) then you really haven’t achieved any level of organization at all (unless you own only six files!).  Your “Work” folder will have become a dumping ground, just like your Desktop was, with most likely hundreds of files in it. Tip #6.  Move the Standard User Folders into Your Own Folder Structure Most operating systems, including Windows, create a set of standard folders for each of its users.  These folders then become the default location for files such as documents, music files, digital photos and downloaded Internet files.  In Windows 7, the full list is shown below: Some of these folders you may never use nor care about (for example, the Favorites folder, if you’re not using Internet Explorer as your browser).  Those ones you can leave where they are.  But you may be using some of the other folders to store files that are important to you.  Even if you’re not using them, Windows will still often treat them as the default storage location for many types of files.  When you go to save a standard file type, it can become annoying to be automatically prompted to save it in a folder that’s not part of your own file structure. But there’s a simple solution:  Move the folders you care about into your own folder structure!  If you do, then the next time you go to save a file of the corresponding type, Windows will prompt you to save it in the new, moved location. Moving the folders is easy.  Simply drag-and-drop them to the new location.  Here’s a screenshot of the default My Music folder being moved to my custom personal folder (Mark): Tip #7.  Name Files and Folders Intelligently This is another one that almost goes without saying, but we’ll say it anyway:  Do not allow files to be created that have meaningless names like Document1.doc, or folders called New Folder (2).  Take that extra 20 seconds and come up with a meaningful name for the file/folder – one that accurately divulges its contents without repeating the entire contents in the name. Tip #8.  Watch Out for Long Filenames Another way to tell if you have not yet created enough depth to your folder hierarchy is that your files often require really long names.  If you need to call a file Johnson Sales Figures March 2009.xls (which might happen to live in the same folder as Abercrombie Budget Report 2008.xls), then you might want to create some sub-folders so that the first file could be simply called March.xls, and living in the Clients\Johnson\Sales Figures\2009 folder. A well-placed file needs only a brief filename! Tip #9.  Use Shortcuts!  Everywhere! This is probably the single most useful and important tip we can offer.  A shortcut allows a file to be in two places at once. Why would you want that?  Well, the file and folder structure of every popular operating system on the market today is hierarchical.  This means that all objects (files and folders) always live within exactly one parent folder.  It’s a bit like a tree.  A tree has branches (folders) and leaves (files).  Each leaf, and each branch, is supported by exactly one parent branch, all the way back to the root of the tree (which, incidentally, is exactly why C:\ is called the “root folder” of the C: drive). That hard disks are structured this way may seem obvious and even necessary, but it’s only one way of organizing data.  There are others:  Relational databases, for example, organize structured data entirely differently.  The main limitation of hierarchical filing structures is that a file can only ever be in one branch of the tree – in only one folder – at a time.  Why is this a problem?  Well, there are two main reasons why this limitation is a problem for computer users: The “correct” place for a file, according to our organizational rationale, is very often a very inconvenient place for that file to be located.  Just because it’s correctly filed doesn’t mean it’s easy to get to.  Your file may be “correctly” buried six levels deep in your sub-folder structure, but you may need regular and speedy access to this file every day.  You could always move it to a more convenient location, but that would mean that you would need to re-file back to its “correct” location it every time you’d finished working on it.  Most unsatisfactory. A file may simply “belong” in two or more different locations within your file structure.  For example, say you’re an accountant and you have just completed the 2009 tax return for John Smith.  It might make sense to you to call this file 2009 Tax Return.doc and file it under Clients\John Smith.  But it may also be important to you to have the 2009 tax returns from all your clients together in the one place.  So you might also want to call the file John Smith.doc and file it under Tax Returns\2009.  The problem is, in a purely hierarchical filing system, you can’t put it in both places.  Grrrrr! Fortunately, Windows (and most other operating systems) offers a way for you to do exactly that:  It’s called a “shortcut” (also known as an “alias” on Macs and a “symbolic link” on UNIX systems).  Shortcuts allow a file to exist in one place, and an icon that represents the file to be created and put anywhere else you please.  In fact, you can create a dozen such icons and scatter them all over your hard disk.  Double-clicking on one of these icons/shortcuts opens up the original file, just as if you had double-clicked on the original file itself. Consider the following two icons: The one on the left is the actual Word document, while the one on the right is a shortcut that represents the Word document.  Double-clicking on either icon will open the same file.  There are two main visual differences between the icons: The shortcut will have a small arrow in the lower-left-hand corner (on Windows, anyway) The shortcut is allowed to have a name that does not include the file extension (the “.docx” part, in this case) You can delete the shortcut at any time without losing any actual data.  The original is still intact.  All you lose is the ability to get to that data from wherever the shortcut was. So why are shortcuts so great?  Because they allow us to easily overcome the main limitation of hierarchical file systems, and put a file in two (or more) places at the same time.  You will always have files that don’t play nice with your organizational rationale, and can’t be filed in only one place.  They demand to exist in two places.  Shortcuts allow this!  Furthermore, they allow you to collect your most often-opened files and folders together in one spot for convenient access.  The cool part is that the original files stay where they are, safe forever in their perfectly organized location. So your collection of most often-opened files can – and should – become a collection of shortcuts! If you’re still not convinced of the utility of shortcuts, consider the following well-known areas of a typical Windows computer: The Start Menu (and all the programs that live within it) The Quick Launch bar (or the Superbar in Windows 7) The “Favorite folders” area in the top-left corner of the Windows Explorer window (in Windows Vista or Windows 7) Your Internet Explorer Favorites or Firefox Bookmarks Each item in each of these areas is a shortcut!  Each of those areas exist for one purpose only:  For convenience – to provide you with a collection of the files and folders you access most often. It should be easy to see by now that shortcuts are designed for one single purpose:  To make accessing your files more convenient.  Each time you double-click on a shortcut, you are saved the hassle of locating the file (or folder, or program, or drive, or control panel icon) that it represents. Shortcuts allow us to invent a golden rule of file and folder organization: “Only ever have one copy of a file – never have two copies of the same file.  Use a shortcut instead” (this rule doesn’t apply to copies created for backup purposes, of course!) There are also lesser rules, like “don’t move a file into your work area – create a shortcut there instead”, and “any time you find yourself frustrated with how long it takes to locate a file, create a shortcut to it and place that shortcut in a convenient location.” So how to we create these massively useful shortcuts?  There are two main ways: “Copy” the original file or folder (click on it and type Ctrl-C, or right-click on it and select Copy):  Then right-click in an empty area of the destination folder (the place where you want the shortcut to go) and select Paste shortcut: Right-drag (drag with the right mouse button) the file from the source folder to the destination folder.  When you let go of the mouse button at the destination folder, a menu pops up: Select Create shortcuts here. Note that when shortcuts are created, they are often named something like Shortcut to Budget Detail.doc (windows XP) or Budget Detail – Shortcut.doc (Windows 7).   If you don’t like those extra words, you can easily rename the shortcuts after they’re created, or you can configure Windows to never insert the extra words in the first place (see our article on how to do this). And of course, you can create shortcuts to folders too, not just to files! Bottom line: Whenever you have a file that you’d like to access from somewhere else (whether it’s convenience you’re after, or because the file simply belongs in two places), create a shortcut to the original file in the new location. Tip #10.  Separate Application Files from Data Files Any digital organization guru will drum this rule into you.  Application files are the components of the software you’ve installed (e.g. Microsoft Word, Adobe Photoshop or Internet Explorer).  Data files are the files that you’ve created for yourself using that software (e.g. Word Documents, digital photos, emails or playlists). Software gets installed, uninstalled and upgraded all the time.  Hopefully you always have the original installation media (or downloaded set-up file) kept somewhere safe, and can thus reinstall your software at any time.  This means that the software component files are of little importance.  Whereas the files you have created with that software is, by definition, important.  It’s a good rule to always separate unimportant files from important files. So when your software prompts you to save a file you’ve just created, take a moment and check out where it’s suggesting that you save the file.  If it’s suggesting that you save the file into the same folder as the software itself, then definitely don’t follow that suggestion.  File it in your own folder!  In fact, see if you can find the program’s configuration option that determines where files are saved by default (if it has one), and change it. Tip #11.  Organize Files Based on Purpose, Not on File Type If you have, for example a folder called Work\Clients\Johnson, and within that folder you have two sub-folders, Word Documents and Spreadsheets (in other words, you’re separating “.doc” files from “.xls” files), then chances are that you’re not optimally organized.  It makes little sense to organize your files based on the program that created them.  Instead, create your sub-folders based on the purpose of the file.  For example, it would make more sense to create sub-folders called Correspondence and Financials.  It may well be that all the files in a given sub-folder are of the same file-type, but this should be more of a coincidence and less of a design feature of your organization system. Tip #12.  Maintain the Same Folder Structure on All Your Computers In other words, whatever organizational system you create, apply it to every computer that you can.  There are several benefits to this: There’s less to remember.  No matter where you are, you always know where to look for your files If you copy or synchronize files from one computer to another, then setting up the synchronization job becomes very simple Shortcuts can be copied or moved from one computer to another with ease (assuming the original files are also copied/moved).  There’s no need to find the target of the shortcut all over again on the second computer Ditto for linked files (e.g Word documents that link to data in a separate Excel file), playlists, and any files that reference the exact file locations of other files. This applies even to the drive that your files are stored on.  If your files are stored on C: on one computer, make sure they’re stored on C: on all your computers.  Otherwise all your shortcuts, playlists and linked files will stop working! Tip #13.  Create an “Inbox” Folder Create yourself a folder where you store all files that you’re currently working on, or that you haven’t gotten around to filing yet.  You can think of this folder as your “to-do” list.  You can call it “Inbox” (making it the same metaphor as your email system), or “Work”, or “To-Do”, or “Scratch”, or whatever name makes sense to you.  It doesn’t matter what you call it – just make sure you have one! Once you have finished working on a file, you then move it from the “Inbox” to its correct location within your organizational structure. You may want to use your Desktop as this “Inbox” folder.  Rightly or wrongly, most people do.  It’s not a bad place to put such files, but be careful:  If you do decide that your Desktop represents your “to-do” list, then make sure that no other files find their way there.  In other words, make sure that your “Inbox”, wherever it is, Desktop or otherwise, is kept free of junk – stray files that don’t belong there. So where should you put this folder, which, almost by definition, lives outside the structure of the rest of your filing system?  Well, first and foremost, it has to be somewhere handy.  This will be one of your most-visited folders, so convenience is key.  Putting it on the Desktop is a great option – especially if you don’t have any other folders on your Desktop:  the folder then becomes supremely easy to find in Windows Explorer: You would then create shortcuts to this folder in convenient spots all over your computer (“Favorite Links”, “Quick Launch”, etc). Tip #14.  Ensure You have Only One “Inbox” Folder Once you’ve created your “Inbox” folder, don’t use any other folder location as your “to-do list”.  Throw every incoming or created file into the Inbox folder as you create/receive it.  This keeps the rest of your computer pristine and free of randomly created or downloaded junk.  The last thing you want to be doing is checking multiple folders to see all your current tasks and projects.  Gather them all together into one folder. Here are some tips to help ensure you only have one Inbox: Set the default “save” location of all your programs to this folder. Set the default “download” location for your browser to this folder. If this folder is not your desktop (recommended) then also see if you can make a point of not putting “to-do” files on your desktop.  This keeps your desktop uncluttered and Zen-like: (the Inbox folder is in the bottom-right corner) Tip #15.  Be Vigilant about Clearing Your “Inbox” Folder This is one of the keys to staying organized.  If you let your “Inbox” overflow (i.e. allow there to be more than, say, 30 files or folders in there), then you’re probably going to start feeling like you’re overwhelmed:  You’re not keeping up with your to-do list.  Once your Inbox gets beyond a certain point (around 30 files, studies have shown), then you’ll simply start to avoid it.  You may continue to put files in there, but you’ll be scared to look at it, fearing the “out of control” feeling that all overworked, chaotic or just plain disorganized people regularly feel. So, here’s what you can do: Visit your Inbox/to-do folder regularly (at least five times per day). Scan the folder regularly for files that you have completed working on and are ready for filing.  File them immediately. Make it a source of pride to keep the number of files in this folder as small as possible.  If you value peace of mind, then make the emptiness of this folder one of your highest (computer) priorities If you know that a particular file has been in the folder for more than, say, six weeks, then admit that you’re not actually going to get around to processing it, and move it to its final resting place. Tip #16.  File Everything Immediately, and Use Shortcuts for Your Active Projects As soon as you create, receive or download a new file, store it away in its “correct” folder immediately.  Then, whenever you need to work on it (possibly straight away), create a shortcut to it in your “Inbox” (“to-do”) folder or your desktop.  That way, all your files are always in their “correct” locations, yet you still have immediate, convenient access to your current, active files.  When you finish working on a file, simply delete the shortcut. Ideally, your “Inbox” folder – and your Desktop – should contain no actual files or folders.  They should simply contain shortcuts. Tip #17.  Use Directory Symbolic Links (or Junctions) to Maintain One Unified Folder Structure Using this tip, we can get around a potential hiccup that we can run into when creating our organizational structure – the issue of having more than one drive on our computer (C:, D:, etc).  We might have files we need to store on the D: drive for space reasons, and yet want to base our organized folder structure on the C: drive (or vice-versa). Your chosen organizational structure may dictate that all your files must be accessed from the C: drive (for example, the root folder of all your files may be something like C:\Files).  And yet you may still have a D: drive and wish to take advantage of the hundreds of spare Gigabytes that it offers.  Did you know that it’s actually possible to store your files on the D: drive and yet access them as if they were on the C: drive?  And no, we’re not talking about shortcuts here (although the concept is very similar). By using the shell command mklink, you can essentially take a folder that lives on one drive and create an alias for it on a different drive (you can do lots more than that with mklink – for a full rundown on this programs capabilities, see our dedicated article).  These aliases are called directory symbolic links (and used to be known as junctions).  You can think of them as “virtual” folders.  They function exactly like regular folders, except they’re physically located somewhere else. For example, you may decide that your entire D: drive contains your complete organizational file structure, but that you need to reference all those files as if they were on the C: drive, under C:\Files.  If that was the case you could create C:\Files as a directory symbolic link – a link to D:, as follows: mklink /d c:\files d:\ Or it may be that the only files you wish to store on the D: drive are your movie collection.  You could locate all your movie files in the root of your D: drive, and then link it to C:\Files\Media\Movies, as follows: mklink /d c:\files\media\movies d:\ (Needless to say, you must run these commands from a command prompt – click the Start button, type cmd and press Enter) Tip #18. Customize Your Folder Icons This is not strictly speaking an organizational tip, but having unique icons for each folder does allow you to more quickly visually identify which folder is which, and thus saves you time when you’re finding files.  An example is below (from my folder that contains all files downloaded from the Internet): To learn how to change your folder icons, please refer to our dedicated article on the subject. Tip #19.  Tidy Your Start Menu The Windows Start Menu is usually one of the messiest parts of any Windows computer.  Every program you install seems to adopt a completely different approach to placing icons in this menu.  Some simply put a single program icon.  Others create a folder based on the name of the software.  And others create a folder based on the name of the software manufacturer.  It’s chaos, and can make it hard to find the software you want to run. Thankfully we can avoid this chaos with useful operating system features like Quick Launch, the Superbar or pinned start menu items. Even so, it would make a lot of sense to get into the guts of the Start Menu itself and give it a good once-over.  All you really need to decide is how you’re going to organize your applications.  A structure based on the purpose of the application is an obvious candidate.  Below is an example of one such structure: In this structure, Utilities means software whose job it is to keep the computer itself running smoothly (configuration tools, backup software, Zip programs, etc).  Applications refers to any productivity software that doesn’t fit under the headings Multimedia, Graphics, Internet, etc. In case you’re not aware, every icon in your Start Menu is a shortcut and can be manipulated like any other shortcut (copied, moved, deleted, etc). With the Windows Start Menu (all version of Windows), Microsoft has decided that there be two parallel folder structures to store your Start Menu shortcuts.  One for you (the logged-in user of the computer) and one for all users of the computer.  Having two parallel structures can often be redundant:  If you are the only user of the computer, then having two parallel structures is totally redundant.  Even if you have several users that regularly log into the computer, most of your installed software will need to be made available to all users, and should thus be moved out of the “just you” version of the Start Menu and into the “all users” area. To take control of your Start Menu, so you can start organizing it, you’ll need to know how to access the actual folders and shortcut files that make up the Start Menu (both versions of it).  To find these folders and files, click the Start button and then right-click on the All Programs text (Windows XP users should right-click on the Start button itself): The Open option refers to the “just you” version of the Start Menu, while the Open All Users option refers to the “all users” version.  Click on the one you want to organize. A Windows Explorer window then opens with your chosen version of the Start Menu selected.  From there it’s easy.  Double-click on the Programs folder and you’ll see all your folders and shortcuts.  Now you can delete/rename/move until it’s just the way you want it. Note:  When you’re reorganizing your Start Menu, you may want to have two Explorer windows open at the same time – one showing the “just you” version and one showing the “all users” version.  You can drag-and-drop between the windows. Tip #20.  Keep Your Start Menu Tidy Once you have a perfectly organized Start Menu, try to be a little vigilant about keeping it that way.  Every time you install a new piece of software, the icons that get created will almost certainly violate your organizational structure. So to keep your Start Menu pristine and organized, make sure you do the following whenever you install a new piece of software: Check whether the software was installed into the “just you” area of the Start Menu, or the “all users” area, and then move it to the correct area. Remove all the unnecessary icons (like the “Read me” icon, the “Help” icon (you can always open the help from within the software itself when it’s running), the “Uninstall” icon, the link(s)to the manufacturer’s website, etc) Rename the main icon(s) of the software to something brief that makes sense to you.  For example, you might like to rename Microsoft Office Word 2010 to simply Word Move the icon(s) into the correct folder based on your Start Menu organizational structure And don’t forget:  when you uninstall a piece of software, the software’s uninstall routine is no longer going to be able to remove the software’s icon from the Start Menu (because you moved and/or renamed it), so you’ll need to remove that icon manually. Tip #21.  Tidy C:\ The root of your C: drive (C:\) is a common dumping ground for files and folders – both by the users of your computer and by the software that you install on your computer.  It can become a mess. There’s almost no software these days that requires itself to be installed in C:\.  99% of the time it can and should be installed into C:\Program Files.  And as for your own files, well, it’s clear that they can (and almost always should) be stored somewhere else. In an ideal world, your C:\ folder should look like this (on Windows 7): Note that there are some system files and folders in C:\ that are usually and deliberately “hidden” (such as the Windows virtual memory file pagefile.sys, the boot loader file bootmgr, and the System Volume Information folder).  Hiding these files and folders is a good idea, as they need to stay where they are and are almost never needed to be opened or even seen by you, the user.  Hiding them prevents you from accidentally messing with them, and enhances your sense of order and well-being when you look at your C: drive folder. Tip #22.  Tidy Your Desktop The Desktop is probably the most abused part of a Windows computer (from an organization point of view).  It usually serves as a dumping ground for all incoming files, as well as holding icons to oft-used applications, plus some regularly opened files and folders.  It often ends up becoming an uncontrolled mess.  See if you can avoid this.  Here’s why… Application icons (Word, Internet Explorer, etc) are often found on the Desktop, but it’s unlikely that this is the optimum place for them.  The “Quick Launch” bar (or the Superbar in Windows 7) is always visible and so represents a perfect location to put your icons.  You’ll only be able to see the icons on your Desktop when all your programs are minimized.  It might be time to get your application icons off your desktop… You may have decided that the Inbox/To-do folder on your computer (see tip #13, above) should be your Desktop.  If so, then enough said.  Simply be vigilant about clearing it and preventing it from being polluted by junk files (see tip #15, above).  On the other hand, if your Desktop is not acting as your “Inbox” folder, then there’s no reason for it to have any data files or folders on it at all, except perhaps a couple of shortcuts to often-opened files and folders (either ongoing or current projects).  Everything else should be moved to your “Inbox” folder. In an ideal world, it might look like this: Tip #23.  Move Permanent Items on Your Desktop Away from the Top-Left Corner When files/folders are dragged onto your desktop in a Windows Explorer window, or when shortcuts are created on your Desktop from Internet Explorer, those icons are always placed in the top-left corner – or as close as they can get.  If you have other files, folders or shortcuts that you keep on the Desktop permanently, then it’s a good idea to separate these permanent icons from the transient ones, so that you can quickly identify which ones the transients are.  An easy way to do this is to move all your permanent icons to the right-hand side of your Desktop.  That should keep them separated from incoming items. Tip #24.  Synchronize If you have more than one computer, you’ll almost certainly want to share files between them.  If the computers are permanently attached to the same local network, then there’s no need to store multiple copies of any one file or folder – shortcuts will suffice.  However, if the computers are not always on the same network, then you will at some point need to copy files between them.  For files that need to permanently live on both computers, the ideal way to do this is to synchronize the files, as opposed to simply copying them. We only have room here to write a brief summary of synchronization, not a full article.  In short, there are several different types of synchronization: Where the contents of one folder are accessible anywhere, such as with Dropbox Where the contents of any number of folders are accessible anywhere, such as with Windows Live Mesh Where any files or folders from anywhere on your computer are synchronized with exactly one other computer, such as with the Windows “Briefcase”, Microsoft SyncToy, or (much more powerful, yet still free) SyncBack from 2BrightSparks.  This only works when both computers are on the same local network, at least temporarily. A great advantage of synchronization solutions is that once you’ve got it configured the way you want it, then the sync process happens automatically, every time.  Click a button (or schedule it to happen automatically) and all your files are automagically put where they’re supposed to be. If you maintain the same file and folder structure on both computers, then you can also sync files depend upon the correct location of other files, like shortcuts, playlists and office documents that link to other office documents, and the synchronized files still work on the other computer! Tip #25.  Hide Files You Never Need to See If you have your files well organized, you will often be able to tell if a file is out of place just by glancing at the contents of a folder (for example, it should be pretty obvious if you look in a folder that contains all the MP3s from one music CD and see a Word document in there).  This is a good thing – it allows you to determine if there are files out of place with a quick glance.  Yet sometimes there are files in a folder that seem out of place but actually need to be there, such as the “folder art” JPEGs in music folders, and various files in the root of the C: drive.  If such files never need to be opened by you, then a good idea is to simply hide them.  Then, the next time you glance at the folder, you won’t have to remember whether that file was supposed to be there or not, because you won’t see it at all! To hide a file, simply right-click on it and choose Properties: Then simply tick the Hidden tick-box:   Tip #26.  Keep Every Setup File These days most software is downloaded from the Internet.  Whenever you download a piece of software, keep it.  You’ll never know when you need to reinstall the software. Further, keep with it an Internet shortcut that links back to the website where you originally downloaded it, in case you ever need to check for updates. See tip #33 below for a full description of the excellence of organizing your setup files. Tip #27.  Try to Minimize the Number of Folders that Contain Both Files and Sub-folders Some of the folders in your organizational structure will contain only files.  Others will contain only sub-folders.  And you will also have some folders that contain both files and sub-folders.  You will notice slight improvements in how long it takes you to locate a file if you try to avoid this third type of folder.  It’s not always possible, of course – you’ll always have some of these folders, but see if you can avoid it. One way of doing this is to take all the leftover files that didn’t end up getting stored in a sub-folder and create a special “Miscellaneous” or “Other” folder for them. Tip #28.  Starting a Filename with an Underscore Brings it to the Top of a List Further to the previous tip, if you name that “Miscellaneous” or “Other” folder in such a way that its name begins with an underscore “_”, then it will appear at the top of the list of files/folders. The screenshot below is an example of this.  Each folder in the list contains a set of digital photos.  The folder at the top of the list, _Misc, contains random photos that didn’t deserve their own dedicated folder: Tip #29.  Clean Up those CD-ROMs and (shudder!) Floppy Disks Have you got a pile of CD-ROMs stacked on a shelf of your office?  Old photos, or files you archived off onto CD-ROM (or even worse, floppy disks!) because you didn’t have enough disk space at the time?  In the meantime have you upgraded your computer and now have 500 Gigabytes of space you don’t know what to do with?  If so, isn’t it time you tidied up that stack of disks and filed them into your gorgeous new folder structure? So what are you waiting for?  Bite the bullet, copy them all back onto your computer, file them in their appropriate folders, and then back the whole lot up onto a shiny new 1000Gig external hard drive! Useful Folders to Create This next section suggests some useful folders that you might want to create within your folder structure.  I’ve personally found them to be indispensable. The first three are all about convenience – handy folders to create and then put somewhere that you can always access instantly.  For each one, it’s not so important where the actual folder is located, but it’s very important where you put the shortcut(s) to the folder.  You might want to locate the shortcuts: On your Desktop In your “Quick Launch” area (or pinned to your Windows 7 Superbar) In your Windows Explorer “Favorite Links” area Tip #30.  Create an “Inbox” (“To-Do”) Folder This has already been mentioned in depth (see tip #13), but we wanted to reiterate its importance here.  This folder contains all the recently created, received or downloaded files that you have not yet had a chance to file away properly, and it also may contain files that you have yet to process.  In effect, it becomes a sort of “to-do list”.  It doesn’t have to be called “Inbox” – you can call it whatever you want. Tip #31.  Create a Folder where Your Current Projects are Collected Rather than going hunting for them all the time, or dumping them all on your desktop, create a special folder where you put links (or work folders) for each of the projects you’re currently working on. You can locate this folder in your “Inbox” folder, on your desktop, or anywhere at all – just so long as there’s a way of getting to it quickly, such as putting a link to it in Windows Explorer’s “Favorite Links” area: Tip #32.  Create a Folder for Files and Folders that You Regularly Open You will always have a few files that you open regularly, whether it be a spreadsheet of your current accounts, or a favorite playlist.  These are not necessarily “current projects”, rather they’re simply files that you always find yourself opening.  Typically such files would be located on your desktop (or even better, shortcuts to those files).  Why not collect all such shortcuts together and put them in their own special folder? As with the “Current Projects” folder (above), you would want to locate that folder somewhere convenient.  Below is an example of a folder called “Quick links”, with about seven files (shortcuts) in it, that is accessible through the Windows Quick Launch bar: See tip #37 below for a full explanation of the power of the Quick Launch bar. Tip #33.  Create a “Set-ups” Folder A typical computer has dozens of applications installed on it.  For each piece of software, there are often many different pieces of information you need to keep track of, including: The original installation setup file(s).  This can be anything from a simple 100Kb setup.exe file you downloaded from a website, all the way up to a 4Gig ISO file that you copied from a DVD-ROM that you purchased. The home page of the software manufacturer (in case you need to look up something on their support pages, their forum or their online help) The page containing the download link for your actual file (in case you need to re-download it, or download an upgraded version) The serial number Your proof-of-purchase documentation Any other template files, plug-ins, themes, etc that also need to get installed For each piece of software, it’s a great idea to gather all of these files together and put them in a single folder.  The folder can be the name of the software (plus possibly a very brief description of what it’s for – in case you can’t remember what the software does based in its name).  Then you would gather all of these folders together into one place, and call it something like “Software” or “Setups”. If you have enough of these folders (I have several hundred, being a geek, collected over 20 years), then you may want to further categorize them.  My own categorization structure is based on “platform” (operating system): The last seven folders each represents one platform/operating system, while _Operating Systems contains set-up files for installing the operating systems themselves.  _Hardware contains ROMs for hardware I own, such as routers. Within the Windows folder (above), you can see the beginnings of the vast library of software I’ve compiled over the years: An example of a typical application folder looks like this: Tip #34.  Have a “Settings” Folder We all know that our documents are important.  So are our photos and music files.  We save all of these files into folders, and then locate them afterwards and double-click on them to open them.  But there are many files that are important to us that can’t be saved into folders, and then searched for and double-clicked later on.  These files certainly contain important information that we need, but are often created internally by an application, and saved wherever that application feels is appropriate. A good example of this is the “PST” file that Outlook creates for us and uses to store all our emails, contacts, appointments and so forth.  Another example would be the collection of Bookmarks that Firefox stores on your behalf. And yet another example would be the customized settings and configuration files of our all our software.  Granted, most Windows programs store their configuration in the Registry, but there are still many programs that use configuration files to store their settings. Imagine if you lost all of the above files!  And yet, when people are backing up their computers, they typically only back up the files they know about – those that are stored in the “My Documents” folder, etc.  If they had a hard disk failure or their computer was lost or stolen, their backup files would not include some of the most vital files they owned.  Also, when migrating to a new computer, it’s vital to ensure that these files make the journey. It can be a very useful idea to create yourself a folder to store all your “settings” – files that are important to you but which you never actually search for by name and double-click on to open them.  Otherwise, next time you go to set up a new computer just the way you want it, you’ll need to spend hours recreating the configuration of your previous computer! So how to we get our important files into this folder?  Well, we have a few options: Some programs (such as Outlook and its PST files) allow you to place these files wherever you want.  If you delve into the program’s options, you will find a setting somewhere that controls the location of the important settings files (or “personal storage” – PST – when it comes to Outlook) Some programs do not allow you to change such locations in any easy way, but if you get into the Registry, you can sometimes find a registry key that refers to the location of the file(s).  Simply move the file into your Settings folder and adjust the registry key to refer to the new location. Some programs stubbornly refuse to allow their settings files to be placed anywhere other then where they stipulate.  When faced with programs like these, you have three choices:  (1) You can ignore those files, (2) You can copy the files into your Settings folder (let’s face it – settings don’t change very often), or (3) you can use synchronization software, such as the Windows Briefcase, to make synchronized copies of all your files in your Settings folder.  All you then have to do is to remember to run your sync software periodically (perhaps just before you run your backup software!). There are some other things you may decide to locate inside this new “Settings” folder: Exports of registry keys (from the many applications that store their configurations in the Registry).  This is useful for backup purposes or for migrating to a new computer Notes you’ve made about all the specific customizations you have made to a particular piece of software (so that you’ll know how to do it all again on your next computer) Shortcuts to webpages that detail how to tweak certain aspects of your operating system or applications so they are just the way you like them (such as how to remove the words “Shortcut to” from the beginning of newly created shortcuts).  In other words, you’d want to create shortcuts to half the pages on the How-To Geek website! Here’s an example of a “Settings” folder: Windows Features that Help with Organization This section details some of the features of Microsoft Windows that are a boon to anyone hoping to stay optimally organized. Tip #35.  Use the “Favorite Links” Area to Access Oft-Used Folders Once you’ve created your great new filing system, work out which folders you access most regularly, or which serve as great starting points for locating the rest of the files in your folder structure, and then put links to those folders in your “Favorite Links” area of the left-hand side of the Windows Explorer window (simply called “Favorites” in Windows 7):   Some ideas for folders you might want to add there include: Your “Inbox” folder (or whatever you’ve called it) – most important! The base of your filing structure (e.g. C:\Files) A folder containing shortcuts to often-accessed folders on other computers around the network (shown above as Network Folders) A folder containing shortcuts to your current projects (unless that folder is in your “Inbox” folder) Getting folders into this area is very simple – just locate the folder you’re interested in and drag it there! Tip #36.  Customize the Places Bar in the File/Open and File/Save Boxes Consider the screenshot below: The highlighted icons (collectively known as the “Places Bar”) can be customized to refer to any folder location you want, allowing instant access to any part of your organizational structure. Note:  These File/Open and File/Save boxes have been superseded by new versions that use the Windows Vista/Windows 7 “Favorite Links”, but the older versions (shown above) are still used by a surprisingly large number of applications. The easiest way to customize these icons is to use the Group Policy Editor, but not everyone has access to this program.  If you do, open it up and navigate to: User Configuration > Administrative Templates > Windows Components > Windows Explorer > Common Open File Dialog If you don’t have access to the Group Policy Editor, then you’ll need to get into the Registry.  Navigate to: HKEY_CURRENT_USER \ Software \ Microsoft  \ Windows \ CurrentVersion \ Policies \ comdlg32 \ Placesbar It should then be easy to make the desired changes.  Log off and log on again to allow the changes to take effect. Tip #37.  Use the Quick Launch Bar as a Application and File Launcher That Quick Launch bar (to the right of the Start button) is a lot more useful than people give it credit for.  Most people simply have half a dozen icons in it, and use it to start just those programs.  But it can actually be used to instantly access just about anything in your filing system: For complete instructions on how to set this up, visit our dedicated article on this topic. Tip #38.  Put a Shortcut to Windows Explorer into Your Quick Launch Bar This is only necessary in Windows Vista and Windows XP.  The Microsoft boffins finally got wise and added it to the Windows 7 Superbar by default. Windows Explorer – the program used for managing your files and folders – is one of the most useful programs in Windows.  Anyone who considers themselves serious about being organized needs instant access to this program at any time.  A great place to create a shortcut to this program is in the Windows XP and Windows Vista “Quick Launch” bar: To get it there, locate it in your Start Menu (usually under “Accessories”) and then right-drag it down into your Quick Launch bar (and create a copy). Tip #39.  Customize the Starting Folder for Your Windows 7 Explorer Superbar Icon If you’re on Windows 7, your Superbar will include a Windows Explorer icon.  Clicking on the icon will launch Windows Explorer (of course), and will start you off in your “Libraries” folder.  Libraries may be fine as a starting point, but if you have created yourself an “Inbox” folder, then it would probably make more sense to start off in this folder every time you launch Windows Explorer. To change this default/starting folder location, then first right-click the Explorer icon in the Superbar, and then right-click Properties:Then, in Target field of the Windows Explorer Properties box that appears, type %windir%\explorer.exe followed by the path of the folder you wish to start in.  For example: %windir%\explorer.exe C:\Files If that folder happened to be on the Desktop (and called, say, “Inbox”), then you would use the following cleverness: %windir%\explorer.exe shell:desktop\Inbox Then click OK and test it out. Tip #40.  Ummmmm…. No, that’s it.  I can’t think of another one.  That’s all of the tips I can come up with.  I only created this one because 40 is such a nice round number… Case Study – An Organized PC To finish off the article, I have included a few screenshots of my (main) computer (running Vista).  The aim here is twofold: To give you a sense of what it looks like when the above, sometimes abstract, tips are applied to a real-life computer, and To offer some ideas about folders and structure that you may want to steal to use on your own PC. Let’s start with the C: drive itself.  Very minimal.  All my files are contained within C:\Files.  I’ll confine the rest of the case study to this folder: That folder contains the following: Mark: My personal files VC: My business (Virtual Creations, Australia) Others contains files created by friends and family Data contains files from the rest of the world (can be thought of as “public” files, usually downloaded from the Net) Settings is described above in tip #34 The Data folder contains the following sub-folders: Audio:  Radio plays, audio books, podcasts, etc Development:  Programmer and developer resources, sample source code, etc (see below) Humour:  Jokes, funnies (those emails that we all receive) Movies:  Downloaded and ripped movies (all legal, of course!), their scripts, DVD covers, etc. Music:  (see below) Setups:  Installation files for software (explained in full in tip #33) System:  (see below) TV:  Downloaded TV shows Writings:  Books, instruction manuals, etc (see below) The Music folder contains the following sub-folders: Album covers:  JPEG scans Guitar tabs:  Text files of guitar sheet music Lists:  e.g. “Top 1000 songs of all time” Lyrics:  Text files MIDI:  Electronic music files MP3 (representing 99% of the Music folder):  MP3s, either ripped from CDs or downloaded, sorted by artist/album name Music Video:  Video clips Sheet Music:  usually PDFs The Data\Writings folder contains the following sub-folders: (all pretty self-explanatory) The Data\Development folder contains the following sub-folders: Again, all pretty self-explanatory (if you’re a geek) The Data\System folder contains the following sub-folders: These are usually themes, plug-ins and other downloadable program-specific resources. The Mark folder contains the following sub-folders: From Others:  Usually letters that other people (friends, family, etc) have written to me For Others:  Letters and other things I have created for other people Green Book:  None of your business Playlists:  M3U files that I have compiled of my favorite songs (plus one M3U playlist file for every album I own) Writing:  Fiction, philosophy and other musings of mine Mark Docs:  Shortcut to C:\Users\Mark Settings:  Shortcut to C:\Files\Settings\Mark The Others folder contains the following sub-folders: The VC (Virtual Creations, my business – I develop websites) folder contains the following sub-folders: And again, all of those are pretty self-explanatory. Conclusion These tips have saved my sanity and helped keep me a productive geek, but what about you? What tips and tricks do you have to keep your files organized?  Please share them with us in the comments.  Come on, don’t be shy… Similar Articles Productive Geek Tips Fix For When Windows Explorer in Vista Stops Showing File NamesWhy Did Windows Vista’s Music Folder Icon Turn Yellow?Print or Create a Text File List of the Contents in a Directory the Easy WayCustomize the Windows 7 or Vista Send To MenuAdd Copy To / Move To on Windows 7 or Vista Right-Click Menu TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips Acronis Online Backup DVDFab 6 Revo Uninstaller Pro Registry Mechanic 9 for Windows Track Daily Goals With 42Goals Video Toolbox is a Superb Online Video Editor Fun with 47 charts and graphs Tomorrow is Mother’s Day Check the Average Speed of YouTube Videos You’ve Watched OutlookStatView Scans and Displays General Usage Statistics

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  • Parallelism in .NET – Part 10, Cancellation in PLINQ and the Parallel class

    - by Reed
    Many routines are parallelized because they are long running processes.  When writing an algorithm that will run for a long period of time, its typically a good practice to allow that routine to be cancelled.  I previously discussed terminating a parallel loop from within, but have not demonstrated how a routine can be cancelled from the caller’s perspective.  Cancellation in PLINQ and the Task Parallel Library is handled through a new, unified cooperative cancellation model introduced with .NET 4.0. Cancellation in .NET 4 is based around a new, lightweight struct called CancellationToken.  A CancellationToken is a small, thread-safe value type which is generated via a CancellationTokenSource.  There are many goals which led to this design.  For our purposes, we will focus on a couple of specific design decisions: Cancellation is cooperative.  A calling method can request a cancellation, but it’s up to the processing routine to terminate – it is not forced. Cancellation is consistent.  A single method call requests a cancellation on every copied CancellationToken in the routine. Let’s begin by looking at how we can cancel a PLINQ query.  Supposed we wanted to provide the option to cancel our query from Part 6: double min = collection .AsParallel() .Min(item => item.PerformComputation()); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } We would rewrite this to allow for cancellation by adding a call to ParallelEnumerable.WithCancellation as follows: var cts = new CancellationTokenSource(); // Pass cts here to a routine that could, // in parallel, request a cancellation try { double min = collection .AsParallel() .WithCancellation(cts.Token) .Min(item => item.PerformComputation()); } catch (OperationCanceledException e) { // Query was cancelled before it finished } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Here, if the user calls cts.Cancel() before the PLINQ query completes, the query will stop processing, and an OperationCanceledException will be raised.  Be aware, however, that cancellation will not be instantaneous.  When cts.Cancel() is called, the query will only stop after the current item.PerformComputation() elements all finish processing.  cts.Cancel() will prevent PLINQ from scheduling a new task for a new element, but will not stop items which are currently being processed.  This goes back to the first goal I mentioned – Cancellation is cooperative.  Here, we’re requesting the cancellation, but it’s up to PLINQ to terminate. If we wanted to allow cancellation to occur within our routine, we would need to change our routine to accept a CancellationToken, and modify it to handle this specific case: public void PerformComputation(CancellationToken token) { for (int i=0; i<this.iterations; ++i) { // Add a check to see if we've been canceled // If a cancel was requested, we'll throw here token.ThrowIfCancellationRequested(); // Do our processing now this.RunIteration(i); } } With this overload of PerformComputation, each internal iteration checks to see if a cancellation request was made, and will throw an OperationCanceledException at that point, instead of waiting until the method returns.  This is good, since it allows us, as developers, to plan for cancellation, and terminate our routine in a clean, safe state. This is handled by changing our PLINQ query to: try { double min = collection .AsParallel() .WithCancellation(cts.Token) .Min(item => item.PerformComputation(cts.Token)); } catch (OperationCanceledException e) { // Query was cancelled before it finished } PLINQ is very good about handling this exception, as well.  There is a very good chance that multiple items will raise this exception, since the entire purpose of PLINQ is to have multiple items be processed concurrently.  PLINQ will take all of the OperationCanceledException instances raised within these methods, and merge them into a single OperationCanceledException in the call stack.  This is done internally because we added the call to ParallelEnumerable.WithCancellation. If, however, a different exception is raised by any of the elements, the OperationCanceledException as well as the other Exception will be merged into a single AggregateException. The Task Parallel Library uses the same cancellation model, as well.  Here, we supply our CancellationToken as part of the configuration.  The ParallelOptions class contains a property for the CancellationToken.  This allows us to cancel a Parallel.For or Parallel.ForEach routine in a very similar manner to our PLINQ query.  As an example, we could rewrite our Parallel.ForEach loop from Part 2 to support cancellation by changing it to: try { var cts = new CancellationTokenSource(); var options = new ParallelOptions() { CancellationToken = cts.Token }; Parallel.ForEach(customers, options, customer => { // Run some process that takes some time... DateTime lastContact = theStore.GetLastContact(customer); TimeSpan timeSinceContact = DateTime.Now - lastContact; // Check for cancellation here options.CancellationToken.ThrowIfCancellationRequested(); // If it's been more than two weeks, send an email, and update... if (timeSinceContact.Days > 14) { theStore.EmailCustomer(customer); customer.LastEmailContact = DateTime.Now; } }); } catch (OperationCanceledException e) { // The loop was cancelled } Notice that here we use the same approach taken in PLINQ.  The Task Parallel Library will automatically handle our cancellation in the same manner as PLINQ, providing a clean, unified model for cancellation of any parallel routine.  The TPL performs the same aggregation of the cancellation exceptions as PLINQ, as well, which is why a single exception handler for OperationCanceledException will cleanly handle this scenario.  This works because we’re using the same CancellationToken provided in the ParallelOptions.  If a different exception was thrown by one thread, or a CancellationToken from a different CancellationTokenSource was used to raise our exception, we would instead receive all of our individual exceptions merged into one AggregateException.

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