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• downgrading the php version

  - by aadiahg

  I used to upgrade my php from 5.3.5-1ubuntu7.11 to 5.3.18-1~dotdeb.0 I got a lot of problems after the upgrading process . My localhost/phpmyadmin displaying the blank screen. apache2 show me a warning message waiting [Sun Nov 04 12:11:21 2012] [warn] The Alias directive in /etc/apache2/conf.d/phpmyadmin.conf at line 3 will probably never match because it overlaps an earlier Alias. most of CMS cant installed and show me this error Required MySQL version for CMS is 5.x but this server has: mysqlnd 5.0.8-dev the Scripts that has been already installed some of there functions doesn’t work i've googled a lot to fix this problems also i ve googled about downgrading the php version from 5.3.18 to 5.3.x but it doesn’t work with me Can you help please Many thanks

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• Mysql loses its root password

  - by RubyDev

  I am having a strange problem, my mysql loses/resets the root password automatically. By which I mean that it resets it to none. It has happened twice this month. I am worried that it can be a security issue as data is open waiting only for someone trying no password! Here is the version: mysql --version mysql Ver 14.14 Distrib 5.1.56, for redhat-linux-gnu (i386) using readline 5.1 Any help would be appreciated. Update: Output of select user, host, password from mysql.user; how it looks after the password got reset | root | localhost | | root | 127.0.0.1 | | | localhost | | | admin | localhost | ################################# | (I have removed the actual output with #) So all the passwords are blank, except for for another user named 'admin'

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• Restarting nginx backends without losing requests

  - by Oli

  I'm sure it's been asked before in different words but I run several Django sites via uwsgi (emporer mode) behind nginx. It's all a fairly standard configuration but I find that if I restart the central uwsgi process, nginx just bombs out 502s rather than waiting for the socket to become available. I recognise that most of this is probably for a reason but people seeing 502 errors really stings me. It's certainly not something I want a client to see. So... Can I beg nginx to wait/retry backends? Or, Is there anything (other than the obvious) I can do to minimise commercial damage from uwsgi restarts?

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• What happened to the ability to go back in a already-loaded YouTube video?

  - by Chelonian

  For many years, my experience with YouTube had been, consistently and on any computer/browser, that once a section of that video were loaded, or the whole video, if you wanted to see an earlier part of the video again, you could simply click on the loading bar to that area and you would instantly go to that part. More recently (6 months?) this has changed. Now, clicking in an earlier part of the video forces a reload of the whole video (that is, the grey bar goes back to 0) and you have to hope your loading will be fast enough to make waiting to watch it again even worth it. It is a huge regression in usability for me. Is there any way to watch YouTube videos in the "old way"? I use Firefox 17.0.1 at this point and have an updated (I think) Flash, but I'd be willing to try other browsers or versions if it made a difference.

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• all USB "randomly" disconnect and reconnect

  - by teuneboon

  I'm having a weird issue currently: at seemingly random times(although it seems to happen mostly when USB is used a lot, ie downloading + uploading over my WiFi stick or viewing an HD video from my external hard-drive) all my USB devices disconnect and reconnect after a few seconds. This wouldn't be a HUGE problem if I didn't have to rely on my USB for my internet, because now every time this happens my internet, and with it stuff like remote desktop, crashes. I'm running Windows 8 Pro 64 bit with a Gigabyte 990FXA-D3 motherboard. Now the weird thing: I had the same problem with my previous pc, which had a different motherboard(I think it was an Asus M4A785TD-V EVO). I googled a bit and didn't really find anything about this, only found out I could check if something shows up in the Event Viewer, and I get this error there when the USB crashes: "A timeout occurred while waiting for the EHCI host controller Interrupt on Async Advance Doorbell response." If you require any extra information I'm happy to provide it.

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• My laptop (Acer Aspire) doesn't want to start.

  - by Adi87

  I have an Acer Aspire 5520G and recently I had a big problem with it. A couple of days ago I was watching a video on the internet and my laptop froze. I had to shut it down after waiting a couple of minutes and when I wanted to restart it, it acted normally for 2 seconds then it restarts automatically over and over again. I can only shut it down by unplugging it. Nothing appears on screen. I think that it is a hardware problem. If you need further information please leave comment.

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• How to convert ISampleGrabber::BufferCB's buffer to a bitmap

  - by user2509919

  I am trying to use the ISampleGrabberCB::BufferCB to convert the current frame to bitmap using the following code: int ISampleGrabberCB.BufferCB(double sampleTime, IntPtr buffer, int bufferLength) { try { Form1 form1 = new Form1("", "", ""); if (pictureReady == null) { Debug.Assert(bufferLength == Math.Abs(pitch) * videoHeight, "Wrong Buffer Length"); } Debug.Assert(imageBuffer != IntPtr.Zero, "Remove Buffer"); Bitmap bitmapOfCurrentFrame = new Bitmap(width, height, capturePitch, PixelFormat.Format24bppRgb, buffer); MessageBox.Show("Works"); form1.changepicturebox3(bitmapOfCurrentFrame); pictureReady.Set(); } catch (Exception ex) { MessageBox.Show(ex.ToString()); } return 0; } However this does not seem to be working. Additionally it seems to call this function when i press a button which runs the following code: public IntPtr getFrame() { int hr; try { pictureReady.Reset(); } catch (Exception ex) { MessageBox.Show(ex.ToString()); } imageBuffer = Marshal.AllocCoTaskMem(Math.Abs(pitch) * videoHeight); try { gotFrame = true; if (videoControl != null) { hr = videoControl.SetMode(stillPin, VideoControlFlags.Trigger); DsError.ThrowExceptionForHR(hr); } if (!pictureReady.WaitOne(9000, false)) { throw new Exception("Timeout waiting to get picture"); } } catch { Marshal.FreeCoTaskMem(imageBuffer); imageBuffer = IntPtr.Zero; } return imageBuffer; } Once this code is ran I get a message box which shows 'Works' thus meaning my BufferCB must of been called however does not update my picture box with the current image. Is the BufferCB not called after every new frame? If so why do I not recieve the 'Works' message box? Finally is it possible to convert every new frame into a bitmap (this is used for later processing) using BufferCB and if so how? Edited code: int ISampleGrabberCB.BufferCB(double sampleTime, IntPtr buffer, int bufferLength) { Debug.Assert(bufferLength == Math.Abs(pitch) * videoHeight, "Wrong Buffer Length"); Debug.Assert(imageBuffer != IntPtr.Zero, "Remove Buffer"); CopyMemory(imageBuffer, buffer, bufferLength); Decode(buffer); return 0; } public Image Decode(IntPtr imageData) { var bitmap = new Bitmap(width, height, pitch, PixelFormat.Format24bppRgb, imageBuffer); bitmap.RotateFlip(RotateFlipType.RotateNoneFlipY); Form1 form1 = new Form1("", "", ""); form1.changepicturebox3(bitmap); bitmap.Save("C:\\Users\\...\\Desktop\\A2 Project\\barcode.jpg"); return bitmap; } Button code: public void getFrameFromWebcam() { if (iPtr != IntPtr.Zero) { Marshal.FreeCoTaskMem(iPtr); iPtr = IntPtr.Zero; } //Get Image iPtr = sampleGrabberCallBack.getFrame(); Bitmap bitmapOfFrame = new Bitmap(sampleGrabberCallBack.width, sampleGrabberCallBack.height, sampleGrabberCallBack.capturePitch, PixelFormat.Format24bppRgb, iPtr); bitmapOfFrame.RotateFlip(RotateFlipType.RotateNoneFlipY); barcodeReader(bitmapOfFrame); } public IntPtr getFrame() { int hr; try { pictureReady.Reset(); } catch (Exception ex) { MessageBox.Show(ex.ToString()); } imageBuffer = Marshal.AllocCoTaskMem(Math.Abs(pitch) * videoHeight); try { gotFrame = true; if (videoControl != null) { hr = videoControl.SetMode(stillPin, VideoControlFlags.Trigger); DsError.ThrowExceptionForHR(hr); } if (!pictureReady.WaitOne(9000, false)) { throw new Exception("Timeout waiting to get picture"); } } catch { Marshal.FreeCoTaskMem(imageBuffer); imageBuffer = IntPtr.Zero; } return imageBuffer; } I also still need to press the button to run the BufferCB Thanks for reading.

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• Using MS Standalone profiler in VS2008 Professional

  - by fishdump

  I am trying to profile my .NET dll while running it from VS unit testing tools but I am having problems. I am using the standalone command-line profiler as VS2008 Professional does not come with an inbuilt profiler. I have an open CMD window and have run the following commands (I instrumented it earlier which is why vsinstr gave the warning that it did): C:\...\BusinessRules\obj\Debug>vsperfclrenv /samplegclife /tracegclife /globalsamplegclife /globaltracegclife Enabling VSPerf Sampling Attach Profiling. Allows to 'attaching' to managed applications. Current Profiling Environment variables are: COR_ENABLE_PROFILING=1 COR_PROFILER={0a56a683-003a-41a1-a0ac-0f94c4913c48} COR_LINE_PROFILING=1 COR_GC_PROFILING=2 C:\...\BusinessRules\obj\Debug>vsinstr BusinessRules.dll Microsoft (R) VSInstr Post-Link Instrumentation 9.0.30729 x86 Copyright (C) Microsoft Corp. All rights reserved. Error VSP1018 : VSInstr does not support processing binaries that are already instrumented. C:\...\BusinessRules\obj\Debug>vsperfcmd /start:trace /output:foo.vsp Microsoft (R) VSPerf Command Version 9.0.30729 x86 Copyright (C) Microsoft Corp. All rights reserved. C:\...\BusinessRules\obj\Debug> I then ran the unit tests that exercised the instrumented code. When the unit tests were complete, I did... C:\...\BusinessRules\obj\Debug>vsperfcmd /shutdown Microsoft (R) VSPerf Command Version 9.0.30729 x86 Copyright (C) Microsoft Corp. All rights reserved. Waiting for process 4836 ( C:\Program Files\Microsoft Visual Studio 9.0\Common7\IDE\vstesthost.exe) to shutdown... It was clearly waiting for VS2008 to close so I closed it... Shutting down the Profile Monitor ------------------------------------------------------------ C:\...\BusinessRules\obj\Debug> All looking good, there was a 3.2mb foo.vsp file in the directory. I next did... C:\...\BusinessRules\obj\Debug>vsperfreport foo.vsp /summary:all Microsoft (R) VSPerf Report Generator, Version 9.0.0.0 Copyright (C) Microsoft Corporation. All rights reserved. VSP2340: Environment variables were not properly set during profiling run and managed symbols may not resolve. Please use vsperfclrenv before profiling. File opened Successfully opened the file. A report file, foo_Header.csv, has been generated. A report file, foo_MarksSummary.csv, has been generated. A report file, foo_ProcessSummary.csv, has been generated. A report file, foo_ThreadSummary.csv, has been generated. Analysis completed A report file, foo_FunctionSummary.csv, has been generated. A report file, foo_CallerCalleeSummary.csv, has been generated. A report file, foo_CallTreeSummary.csv, has been generated. A report file, foo_ModuleSummary.csv, has been generated. C:\...\BusinessRules\obj\Debug> Notice the warning about environment variables and using vsperfclrenv? But I had run it! Maybe I used the wrong switches? I don't know. Anyway, loading the csv files into Excel or using the perfconsole tool gives loads of useful info with useless symbol names: *** Loading commands from: C:\temp\PerfConsole\bin\commands\timebytype.dll *** Adding command: timebytype *** Loading commands from: C:\temp\PerfConsole\bin\commands\partition.dll *** Adding command: partition Welcome to PerfConsole 1.0 (for bugs please email: [email protected]), for help type: ?, for a quickstart type: ?? > load foo.vsp *** Couldn't match to either expected sampled or instrumented profile schema, defaulting to sampled *** Couldn't match to either expected sampled or instrumented profile schema, defaulting to sampled *** Profile loaded from 'foo.vsp' into @foo > > functions @foo >>>>> Function Name Exclusive Inclusive Function Name Module Name -------------------- -------------------- -------------- --------------- 900,798,600,000.00 % 900,798,600,000.00 % 0x0600003F 20397910 14,968,500,000.00 % 44,691,540,000.00 % 0x06000040 14736385 8,101,253,000.00 % 14,836,330,000.00 % 0x06000041 5491345 3,216,315,000.00 % 6,876,929,000.00 % 0x06000042 3924533 <snip> 71,449,430.00 % 71,449,430.00 % 0x0A000074 42572 52,914,200.00 % 52,914,200.00 % 0x0A000073 0 14,791.00 % 13,006,010.00 % 0x0A00007B 0 199,177.00 % 6,082,932.00 % 0x2B000001 5350072 2,420,116.00 % 2,420,116.00 % 0x0A00008A 0 836.00 % 451,888.00 % 0x0A000045 0 9,616.00 % 399,436.00 % 0x0A000039 0 18,202.00 % 298,223.00 % 0x06000046 1479900 I am so close to being able to find the bottlenecks, if only it will give me the function and module names instead of hex numbers! What am I doing wrong? --- Alistair.

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• Odd tcp deadlock under windows

  - by John Robertson

  We are moving large amounts of data on a LAN and it has to happen very rapidly and reliably. Currently we use windows TCP as implemented in C++. Using large (synchronous) sends moves the data much faster than a bunch of smaller (synchronous) sends but will frequently deadlock for large gaps of time (.15 seconds) causing the overall transfer rate to plummet. This deadlock happens in very particular circumstances which makes me believe it should be preventable altogether. More importantly if we don't really know the cause we don't really know it won't happen some time with smaller sends anyway. Can anyone explain this deadlock? Deadlock description (OK, zombie-locked, it isn't dead, but for .15 or so seconds it stops, then starts again) The receiving side sends an ACK. The sending side sends a packet containing the end of a message (push flag is set) The call to socket.recv takes about .15 seconds(!) to return About the time the call returns an ACK is sent by the receiving side The the next packet from the sender is finally sent (why is it waiting? the tcp window is plenty big) The odd thing about (3) is that typically that call doesn't take much time at all and receives exactly the same amount of data. On a 2Ghz machine that's 300 million instructions worth of time. I am assuming the call doesn't (heaven forbid) wait for the received data to be acked before it returns, so the ack must be waiting for the call to return, or both must be delayed by something else. The problem NEVER happens when there is a second packet of data (part of the same message) arriving between 1 and 2. That part very clearly makes it sound like it has to do with the fact that windows TCP will not send back a no-data ACK until either a second packet arrives or a 200ms timer expires. However the delay is less than 200 ms (its more like 150 ms). The third unseemly character (and to my mind the real culprit) is (5). Send is definitely being called well before that .15 seconds is up, but the data NEVER hits the wire before that ack returns. That is the most bizarre part of this deadlock to me. Its not a tcp blockage because the TCP window is plenty big since we set SO_RCVBUF to something like 500*1460 (which is still under a meg). The data is coming in very fast (basically there is a loop spinning out data via send) so the buffer should fill almost immediately. According to msdn the buffer being full and at least one pending send should cause the data to be sent (though in another place it mentions that there various "heuristics" used in deciding when a send hits the wire). Anway, why the sender doesn't actually send more data during that .15 second pause is the most bizarre part to me. The information above was captured on the receiving side via wireshark (except of course the socket.recv return times which were logged in a text file). We tried changing the send buffer to zero and turning off Nagle on the sender (yes, I know Nagle is about not sending small packets - but we tried turning Nagle off in case that was part of the unstated "heuristics" affecting whether the message would be posted to the wire. Technically microsoft's Nagle is that a small packet isn't sent if the buffer is full and there is an outstanding ACK, so it seemed like a possibility).

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• Trying to run Selenium tests using Hudson - "Error: no display specified"

  - by tputkonen

  I'm trying to get Selenium tests to work when they are executed by Hudson, but I have not been successful so far. Hudson is running on Ubuntu, and Selenium is unable to open display. Command I use for launching the build is: mvn clean selenium:xvfb install error log: [INFO] [selenium:xvfb {execution: default-cli}] [INFO] Starting Xvfb... [INFO] Using display: :20 [INFO] Using Xauthority file: /tmp/Xvfb4467650583214148352.Xauthority Deleting: /tmp/Xvfb4467650583214148352.Xauthority xauth: creating new authority file /tmp/Xvfb4467650583214148352.Xauthority Created dir: /var/lib/hudson/jobs/Selenium/workspace/selenium/target/selenium Launching Xvfb Waiting for Xvfb... [INFO] Redirecting output to: /var/lib/hudson/jobs/Selenium/workspace/selenium/target/selenium/xvfb.log Xvfb started ... [INFO] [selenium:start-server {execution: start}] Launching Selenium Server Waiting for Selenium Server... [INFO] Including display properties from: /var/lib/hudson/jobs/Selenium/workspace/selenium/target/selenium/display.properties [INFO] Redirecting output to: /var/lib/hudson/jobs/Selenium/workspace/selenium/target/selenium/server.log [INFO] User extensions: /var/lib/hudson/jobs/Selenium/workspace/selenium/target/selenium/user-extensions.js Selenium Server started [INFO] [selenium:selenese {execution: run-selenium}] [INFO] Results will go to: /var/lib/hudson/jobs/Selenium/workspace/selenium/target/results-firefox-suite.html ... <~30 seconds pause> ... Error: no display specified ... pom.xml: <groupId>org.codehaus.mojo</groupId> <artifactId>selenium-maven-plugin</artifactId> <version>1.0.1</version> <executions> <execution> <id>start</id> <phase>pre-integration-test</phase> <goals> <goal>start-server</goal> </goals> <configuration> <logOutput>true</logOutput> <background>true</background> <port>5123</port> </configuration> </execution> <execution> <id>run-selenium</id> <phase>integration-test</phase> <goals> <goal>selenese</goal> </goals> </execution> <execution> <id>stop</id> <phase>post-integration-test</phase> <goals> <goal>stop-server</goal> </goals> </execution> </executions> <configuration> <browser>*firefox</browser> <suite>src/test/selenium/suite.html</suite> <startURL>http://localhost:${env.port}</startURL> </configuration> I've also tried to get it working by adding execution for xvfb, but also it failed.

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• SQL Server 2005 Blocking Problem (ASYNC_NETWORK_IO)

  - by ivankolo

  I am responsible for a third-party application (no access to source) running on IIS and SQL Server 2005 (500 concurrent users, 1TB data, 8 IIS servers). We have recently started to see significant blocking on the database (after months of running this application in production with no problems). This occurs at random intervals during the day, approximately every 30 minutes, and affects between 20 and 100 sessions each time. All of the sessions eventually hit the application time out and the sessions abort. The problem disappears and then gradually re-emerges. The SPID responsible for the blocking always has the following features: WAIT TYPE = ASYNC_NETWORK_IO The SQL being run is “(@claimid varchar(15))SELECT claimid, enrollid, status, orgclaimid, resubclaimid, primaryclaimid FROM claim WHERE primaryclaimid = @claimid AND primaryclaimid < claimid)”. This is relatively innocuous SQL that should only return one or two records, not a large dataset. NO OTHER SQL statements have been implicated in the blocking, only this SQL statement. This is parameterized SQL for which an execution plan is cached in sys.dm_exec_cached_plans. This SPID has an object-level S lock on the claim table, so all UPDATEs/INSERTs to the claim table are also blocked. HOST ID varies. Different web servers are responsible for the blocking sessions. E.g., sometimes we trace back to web server 1, sometimes web server 2. When we trace back to the web server implicated in the blocking, we see the following: There is always some sort of application related error in the Event Log on the web server, linked to the Host ID and Host Process ID from the SQL Session. The error messages vary, usually some sort of SystemOutofMemory. (These error messages seem to be similar to error messages that we have seen in the past without such dramatic consequences. We think was happening before, but didn’t lead to blocking. Why now?) No known problems with the network adapters on either the web servers or the SQL server. (In any event the record set returned by the offending query would be small.) Things ruled out: Indexes are regularly defragmented. Statistics regularly updated. Increased sample size of statistics on claim.primaryclaimid. Forced recompilation of the cached execution plan. Created a compound index with primaryclaimid, claimid. No networking problems. No known issues on the web server. No changes to application software on web servers. We hypothesize that the chain of events goes something like this: Web server process submits SQL above. SQL server executes the SQL, during which it acquires a lock on the claim table. Web server process gets an error and dies. SQL server session is hung waiting for the web server process to read the data set. SQL Server sessions that need to get X locks on parts of the claim table (anyone processing claims) are blocked by the lock on the claim table and remain blocked until they all hit the application time out. Any suggestions for troubleshooting while waiting for the vendor's assistance would be most welcome. Is there a way to force SQL Server to lock at the row/page level for this particular SQL statement only? Is there a way to set a threshold on ASYNC_NETWORK_IO waits only?

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• Perl IO modules possibly causing issues in Net::DNS module

  - by Rich

  Hi! I’m porting some software that I wrote for a White Russian OpenWRT system to a new Kamikaze 8.09.1 OpenWRT system but I am having some serious issues that I’m hoping you can help me with. Old system Linux kernel 2.4.34 MIPSEL arch Perl 5.8.7 Net::DNS 0.48 IO 1.21 IO::Socket 1.28 IO::Socket::INET 1.28 New system Linux kernel 2.6.26.8 MIPS arch Perl 5.10.0 Net::DNS 0.66 IO 1.23_01 IO::Socket 1.30_01 IO::Socket::INET 1.31 First, let me provide some background information… I am trying to resolve my server (clearprobe.winbeam.com) from within my Perl program and see the following if I enable debugging in Net::DNS: resolve: Server 'clearprobe-ddns.winbeam.com' ;; query(clearprobe-ddns.winbeam.com) ;; setting up an AF_INET() family type UDP socket ;; send_udp(192.168.88.1:53) ;; send_udp(4.2.2.2:53) ;; send_udp(192.168.88.1:53) ;; send_udp(4.2.2.2:53) resolve: res->errorstring: query timed out Both of these servers resolve clearprobe.winbeam.com fine from the command line: root@cwb-2-11:~# echo “nameserver 192.168.88.1” > /etc/resolv.conf root@cwb-2-11:~# nslookup clearprobe-ddns.winbeam.com Server: 192.168.88.1 Address 1: 192.168.88.1 router Name: clearprobe-ddns.winbeam.com Address 1: 64.13.48.40 64-13-48-40.war.clearwire-dns.net root@cwb-2-11:~# echo “nameserver 4.2.2.2” > /etc/resolv.conf root@cwb-2-11:~# nslookup clearprobe-ddns.winbeam.com Server: 4.2.2.2 Address 1: 4.2.2.2 vnsc-bak.sys.gtei.net Name: clearprobe-ddns.winbeam.com Address 1: 64.13.48.40 64-13-48-40.war.clearwire-dns.net Using Perl’s call to the C gethostbyaddr() function works fine, but I need to do another lookup later in the software which requires that I specify the nameserver (clearprobe-ddns.winbeam.com is the authority for my internal DNS zone), hence my Net::DNS requirement. Now, here is the IO module-specific information: What I am seeing is that the reply is coming back from the nameserver (confirmed via tcpdump – I can send the captures if you’d like), but the UDP packets are sitting in the process’s UDP receive queue pending reception by Net::DNS (the approx 1752 bytes per response stay queued waiting for $sel-can_read()): root@cwb-2-11:~# netstat -una Active Internet connections (servers and established) Proto Recv-Q Send-Q Local Address Foreign Address State udp 1752 0 0.0.0.0:52680 0.0.0.0:* root@cwb-2-11:~# netstat -una Active Internet connections (servers and established) Proto Recv-Q Send-Q Local Address Foreign Address State udp 5256 0 0.0.0.0:52680 0.0.0.0:* If I force $sock[AF_INET]-recv($buf, $self-_packetsz) around line 803 of /usr/lib/perl5/5.10/Net/DNS/Resolver/Base.pm, instead of waiting for IO::Select’s can_read() function ( @ready = $sel-can_read($timeout)) to populate @ready, the response is received and processed. Any idea what could be causing this issue? In a possibly related matter, I noticed in another script that the following code fails in the same manner (network responses stay in the process’s TCP receive queue) with the new system: $sock = new IO::Socket::INET( PeerAddr => "$server", PeerPort => 37, Proto => 'tcp', Timeout => 5 ); Whereas the following code works: $sock = new IO::Socket::INET( PeerAddr => "$server", PeerPort => 37, Proto => 'tcp' ); I have looked through the NET::DNS code and don’t see a timeout passed for the UDP sockets, so I am not sure if that this is related or not. Please let me know if I can provide you with any further information in order to help diagnose this issue. Thanks! -Rich

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• How to generate a Program template by generating an abstract class

  - by Byron-Lim Timothy Steffan

  i have the following problem. The 1st step is to implement a program, which follows a specific protocol on startup. Therefore, functions as onInit, onConfigRequest, etc. will be necessary. (These are triggered e.g. by incoming message on a TCP Port) My goal is to generate a class for example abstract one, which has abstract functions as onInit(), etc. A programmer should just inherit from this base class and should merely override these abstract functions of the base class. The rest as of the protocol e.g. should be simply handled in the background (using the code of the base class) and should not need to appear in the programmers code. What is the correct design strategy for such tasks? and how do I deal with, that the static main method is not inheritable? What are the key-tags for this problem? (I have problem searching for a solution since I lack clear statements on this problem) Goal is to create some sort of library/class, which - included in ones code - results in executables following the protocol. EDIT (new explanation): Okay let me try to explain more detailled: In this case programs should be clients within a client server architecture. We have a client server connection via TCP/IP. Each program needs to follow a specific protocol upon program start: As soon as my program starts and gets connected to the server it will receive an Init Message (TcpClient), when this happens it should trigger the function onInit(). (Should this be implemented by an event system?) After onInit() a acknowledgement message should be sent to the server. Afterwards there are some other steps as e.g. a config message from the server which triggers an onConfig and so on. Let's concentrate on the onInit function. The idea is, that onInit (and onConfig and so on) should be the only functions the programmer should edit while the overall protocol messaging is hidden for him. Therefore, I thought using an abstract class with the abstract methods onInit(), onConfig() in it should be the right thing. The static Main class I would like to hide, since within it e.g. there will be some part which connects to the tcp port, which reacts on the Init Message and which will call the onInit function. 2 problems here: 1. the static main class cant be inherited, isn it? 2. I cannot call abstract functions from the main class in the abstract master class. Let me give an Pseudo-example for my ideas: public abstract class MasterClass { static void Main(string[] args){ 1. open TCP connection 2. waiting for Init Message from server 3. onInit(); 4. Send Acknowledgement, that Init Routine has ended successfully 5. waiting for Config message from server 6..... } public abstract void onInit(); public abstract void onConfig(); } I hope you get the idea now! The programmer should afterwards inherit from this masterclass and merely need to edit the functions onInit and so on. Is this way possible? How? What else do you recommend for solving this? EDIT: The strategy ideo provided below is a good one! Check out my comment on that.

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• Unnecessary Java context switches

  - by Paul Morrison

  I have a network of Java Threads (Flow-Based Programming) communicating via fixed-capacity channels - running under WindowsXP. What we expected, based on our experience with "green" threads (non-preemptive), would be that threads would switch context less often (thus reducing CPU time) if the channels were made bigger. However, we found that increasing channel size does not make any difference to the run time. What seems to be happening is that Java decides to switch threads even though channels aren't full or empty (i.e. even though a thread doesn't have to suspend), which costs CPU time for no apparent advantage. Also changing Thread priorities doesn't make any observable difference. My question is whether there is some way of persuading Java not to make unnecessary context switches, but hold off switching until it is really necessary to switch threads - is there some way of changing Java's dispatching logic? Or is it reacting to something I didn't pay attention to?! Or are there other asynchronism mechanisms, e.g. Thread factories, Runnable(s), maybe even daemons (!). The answer appears to be non-obvious, as so far none of my correspondents has come up with an answer (including most recently two CS profs). Or maybe I'm missing something that's so obvious that people can't imagine my not knowing it... I've added the send and receive code here - not very elegant, but it seems to work...;-) In case you are wondering, I thought the goLock logic in 'send' might be causing the problem, but removing it temporarily didn't make any difference. I have added the code for send and receive... public synchronized Packet receive() { if (isDrained()) { return null; } while (isEmpty()) { try { wait(); } catch (InterruptedException e) { close(); return null; } if (isDrained()) { return null; } } if (isDrained()) { return null; } if (isFull()) { notifyAll(); // notify other components waiting to send } Packet packet = array[receivePtr]; array[receivePtr] = null; receivePtr = (receivePtr + 1) % array.length; //notifyAll(); // only needed if it was full usedSlots--; packet.setOwner(receiver); if (null == packet.getContent()) { traceFuncs("Received null packet"); } else { traceFuncs("Received: " + packet.toString()); } return packet; } synchronized boolean send(final Packet packet, final OutputPort op) { sender = op.sender; if (isClosed()) { return false; } while (isFull()) { try { wait(); } catch (InterruptedException e) { indicateOneSenderClosed(); return false; } sender = op.sender; } if (isClosed()) { return false; } try { receiver.goLock.lockInterruptibly(); } catch (InterruptedException ex) { return false; } try { packet.clearOwner(); array[sendPtr] = packet; sendPtr = (sendPtr + 1) % array.length; usedSlots++; // move this to here if (receiver.getStatus() == StatusValues.DORMANT || receiver.getStatus() == StatusValues.NOT_STARTED) { receiver.activate(); // start or wake up if necessary } else { notifyAll(); // notify receiver // other components waiting to send to this connection may also get // notified, // but this is handled by while statement } sender = null; Component.network.active = true; } finally { receiver.goLock.unlock(); } return true; }

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• C socket: problem with connect() and/or accept() between clients. 111: Connection refused

  - by Fantastic Fourier

  Hello ladies and gents, I'm having a bit of problem with accept(). I have a multiple clients and one server. The clients can connect and communicate just fine with server. But at one point, I need some clients to be directly connected to each other and I'm having a bit of difficulty there. The clients have bunch of threads going on, where one of them is handle_connection() and it has a while(1), looping forever to listen() and accept() whatever incoming connections. Whenever a client tries to connect() to other client, connect() returns an error, 111: Connection Refused. I know I have the right IP address and right port (I have specified a port just for between-client connections). The client that is waiting for connection doesn't notice anything, no new connection, nada. I copied some parts of the code, in hopes that someone can point out what I'm doing wrong. Thanks for any inputs! This is all client side code. void * handle_connections(void * arg) is a thread that loops forever to accept() any incoming connections. My server has a very similar thang going on and it works very well. (not sure why it doesn't work here..) This is the part of client that is waiting for a new incoming connection. int handle_request(void * arg, struct message * msg) is called at one point during program and tries to connect to a client that is specified in struct message * msg which includes struct sockaddr_in with IP address and port number and whatever. #define SERVER_PORT 10000 #define CLIENT_PORT 3456 #define MAX_CONNECTION 20 #define MAX_MSG 50 void * handle_connections(void * arg) { struct fd_info * info; struct sockaddr_in client_address; struct timeval timeout; fd_set readset, copyset; bzero((char * ) &client_address, sizeof(client_address)); // copy zeroes into string client_address.sin_family = AF_INET; client_address.sin_addr.s_addr = htonl(INADDR_ANY); client_address.sin_port = htons(CLIENT_PORT); sockfd = socket(AF_INET, SOCK_STREAM, 0); rv = listen(sockfd,MAX_CONNECTION); while(1) { new_sockfd = accept(sockfd, (struct sockaddr *) &client_address, &client_addr_len); //blocks if (new_sockfd < 0) { printf("C: ERROR accept() %i: %s \n", errno, strerror(errno)); sleep(2); } else { printf("C: accepted\n"); FD_SET(new_sockfd, &readset); // sets bit for new_sockfd to list of sockets to watch out for if (maxfd < new_sockfd) maxfd = new_sockfd; if (minfd > new_sockfd) minfd = new_sockfd; } //end if else (new_sockfd) } // end of the forever while loop } int handle_request(void * arg, struct message * msg) { char * cname, gname, payload; char * command[3]; int i, rv, sockfd, client_addr_len; struct sockaddr_in client_address; struct fd_info * info; info = (struct fd_info *) arg; sockfd = info->sock_fd; sockfd = socket(AF_INET, SOCK_STREAM, 0); if (sockfd == -1) { printf("HR: ERROR socket() %i: %s \n", errno, strerror(errno)); break; } else if (sockfd > 0) { printf("HR: new socks is %i \n", sockfd); printf("HR: sin_family is %i: %i\n", msg->peer.client_address.sin_family, msg->peer.client_address.sin_port); //************************************************************* //this is the part that returns error 111: Connection refused!!! //************************************************************* rv = connect(sockfd, (struct sockaddr *) &msg->peer.client_address, sizeof(struct sockaddr)); if (rv == -1) { printf("HR: ERROR: connect() %i: %s \n", errno, strerror(errno)); printf("HR: at %li \n", msg->peer.client_address.sin_addr.s_addr); break; } else if (rv > 0) { info->max_fd = sockfd; printf("HR: connected successfully!! \n"); } } }

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• Windows Form hangs when running threads

  - by Benjamin Ortuzar

  JI have written a .NET C# Windows Form app in Visual Studio 2008 that uses a Semaphore to run multiple jobs as threads when the Start button is pressed. It’s experiencing an issue where the Form goes into a comma after being run for 40 minutes or more. The log files indicate that the current jobs complete, it picks a new job from the list, and there it hangs. I have noticed that the Windows Form becomes unresponsive when this happens. The form is running in its own thread. This is a sample of the code I am using: protected void ProcessJobsWithStatus (Status status) { int maxJobThreads = Convert.ToInt32(ConfigurationManager.AppSettings["MaxJobThreads"]); Semaphore semaphore = new Semaphore(maxJobThreads, maxJobThreads); // Available=3; Capacity=3 int threadTimeOut = Convert.ToInt32(ConfigurationManager.AppSettings["ThreadSemaphoreWait"]);//in Seconds //gets a list of jobs from a DB Query. List<Job> jobList = jobQueue.GetJobsWithStatus(status); //we need to create a list of threads to check if they all have stopped. List<Thread> threadList = new List<Thread>(); if (jobList.Count > 0) { foreach (Job job in jobList) { logger.DebugFormat("Waiting green light for JobId: [{0}]", job.JobId.ToString()); if (!semaphore.WaitOne(threadTimeOut * 1000)) { logger.ErrorFormat("Semaphore Timeout. A thread did NOT complete in time[{0} seconds]. JobId: [{1}] will start", threadTimeOut, job.JobId.ToString()); } logger.DebugFormat("Acquired green light for JobId: [{0}]", job.JobId.ToString()); // Only N threads can get here at once job.semaphore = semaphore; ThreadStart threadStart = new ThreadStart(job.Process); Thread thread = new Thread(threadStart); thread.Name = job.JobId.ToString(); threadList.Add(thread); thread.Start(); } logger.Info("Waiting for all threads to complete"); //check that all threads have completed. foreach (Thread thread in threadList) { logger.DebugFormat("About to join thread(jobId): {0}", thread.Name); if (!thread.Join(threadTimeOut * 1000)) { logger.ErrorFormat("Thread did NOT complete in time[{0} seconds]. JobId: [{1}]", threadTimeOut, thread.Name); } else { logger.DebugFormat("Thread did complete in time. JobId: [{0}]", thread.Name); } } } logger.InfoFormat("Finished Processing Jobs in Queue with status [{0}]...", status); } //form methods private void button1_Click(object sender, EventArgs e) { buttonStop.Enabled = true; buttonStart.Enabled = false; ThreadStart threadStart = new ThreadStart(DoWork); workerThread = new Thread(threadStart); serviceStarted = true; workerThread.Start(); } private void DoWork() { EmailAlert emailAlert = new EmailAlert (); // start an endless loop; loop will abort only when "serviceStarted" flag = false while (serviceStarted) { emailAlert.ProcessJobsWithStatus(0); // yield if (serviceStarted) { Thread.Sleep(new TimeSpan(0, 0, 1)); } } // time to end the thread Thread.CurrentThread.Abort(); } //job.process() public void Process() { try { //sets the status, DateTimeStarted, and the processId this.UpdateStatus(Status.InProgress); //do something logger.Debug("Updating Status to [Completed]"); //hits, status,DateFinished this.UpdateStatus(Status.Completed); } catch (Exception e) { logger.Error("Exception: " + e.Message); this.UpdateStatus(Status.Error); } finally { logger.Debug("Relasing semaphore"); semaphore.Release(); } I have tried to log what I can into a file to detect where the problem is happening, but so far I haven't been able to identify where this happens. Losing control of the Windows Form makes me think that this has nothing to do with processing the jobs. Any ideas?

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• Trying to packetize TCP with non-blocking IO is hard! Am I doing something wrong?

  - by Ricket

  Oh how I wish TCP was packet-based like UDP is! But alas, that's not the case, so I'm trying to implement my own packet layer. Here's the chain of events so far (ignoring writing packets) Oh, and my Packets are very simply structured: two unsigned bytes for length, and then byte[length] data. (I can't imagine if they were any more complex, I'd be up to my ears in if statements!) Server is in an infinite loop, accepting connections and adding them to a list of Connections. PacketGatherer (another thread) uses a Selector to figure out which Connection.SocketChannels are ready for reading. It loops over the results and tells each Connection to read(). Each Connection has a partial IncomingPacket and a list of Packets which have been fully read and are waiting to be processed. On read(): Tell the partial IncomingPacket to read more data. (IncomingPacket.readData below) If it's done reading (IncomingPacket.complete()), make a Packet from it and stick the Packet into the list waiting to be processed and then replace it with a new IncomingPacket. There are a couple problems with this. First, only one packet is being read at a time. If the IncomingPacket needs only one more byte, then only one byte is read this pass. This can of course be fixed with a loop but it starts to get sorta complicated and I wonder if there is a better overall way. Second, the logic in IncomingPacket is a little bit crazy, to be able to read the two bytes for the length and then read the actual data. Here is the code, boiled down for quick & easy reading: int readBytes; // number of total bytes read so far byte length1, length2; // each byte in an unsigned short int (see getLength()) public int getLength() { // will be inaccurate if readBytes < 2 return (int)(length1 << 8 | length2); } public void readData(SocketChannel c) { if (readBytes < 2) { // we don't yet know the length of the actual data ByteBuffer lengthBuffer = ByteBuffer.allocate(2 - readBytes); numBytesRead = c.read(lengthBuffer); if(readBytes == 0) { if(numBytesRead >= 1) length1 = lengthBuffer.get(); if(numBytesRead == 2) length2 = lengthBuffer.get(); } else if(readBytes == 1) { if(numBytesRead == 1) length2 = lengthBuffer.get(); } readBytes += numBytesRead; } if(readBytes >= 2) { // then we know we have the entire length variable // lazily-instantiate data buffers based on getLength() // read into data buffers, increment readBytes // (does not read more than the amount of this packet, so it does not // need to handle overflow into the next packet's data) } } public boolean complete() { return (readBytes > 2 && readBytes == getLength()+2); } Basically I need feedback on my code. Please suggest any improvements. Even overhauling my entire system would be okay, if you have suggestions for how better to implement the whole thing. Book recommendations are welcome too; I love books. I just get the feeling that something isn't quite right.

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• Use of select or multithread for almost 80 or more clients?

  - by Tushar Goel

  I am working on one project in which i need to read from 80 or more clients and then write their o/p into a file continuously and then read these new data for another task. My question is what should i use select or multithreading? Also I tried to use multi threading using read/fgets and write/fputs call but as they are blocking calls and one operation can be performed at one time so it is not feasible. Any idea is much appreciated. update 1: I have tried to implement the same using condition variable. I able to achieve this but it is writing and reading one at a time.When another client tried to write then it cannot able to write unless i quit from the 1st thread. I do not understand this. This should work now. What mistake i am doing? Update 2: Thanks all .. I am able to succeeded to get this model implemented using mutex condition variable. updated Code is as below: **header file******* char *mailbox ; pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER ; pthread_cond_t writer = PTHREAD_COND_INITIALIZER; int main(int argc,char *argv[]) { pthread_t t1 , t2; pthread_attr_t attr; int fd, sock , *newfd; struct sockaddr_in cliaddr; socklen_t clilen; void *read_file(); void *update_file(); //making a server socket if((fd=make_server(atoi(argv[1])))==-1) oops("Unable to make server",1) //detaching threads pthread_attr_init(&attr); pthread_attr_setdetachstate(&attr,PTHREAD_CREATE_DETACHED); ///opening thread for reading pthread_create(&t2,&attr,read_file,NULL); while(1) { clilen = sizeof(cliaddr); //accepting request sock=accept(fd,(struct sockaddr *)&cliaddr,&clilen); //error comparison against failire of request and INT if(sock==-1 && errno != EINTR) oops("accept",2) else if ( sock ==-1 && errno == EINTR) oops("Pressed INT",3) newfd = (int *)malloc(sizeof(int)); *newfd = sock; //creating thread per request pthread_create(&t1,&attr,update_file,(void *)newfd); } free(newfd); return 0; } void *read_file(void *m) { pthread_mutex_lock(&lock); while(1) { printf("Waiting for lock.\n"); pthread_cond_wait(&writer,&lock); printf("I am reading here.\n"); printf("%s",mailbox); mailbox = NULL ; pthread_cond_signal(&writer); } } void *update_file(int *m) { int sock = *m; int fs ; int nread; char buffer[BUFSIZ] ; if((fs=open("database.txt",O_RDWR))==-1) oops("Unable to open file",4) while(1) { pthread_mutex_lock(&lock); write(1,"Waiting to get writer lock.\n",29); if(mailbox != NULL) pthread_cond_wait(&writer,&lock); lseek(fs,0,SEEK_END); printf("Reading from socket.\n"); nread=read(sock,buffer,BUFSIZ); printf("Writing in file.\n"); write(fs,buffer,nread); mailbox = buffer ; pthread_cond_signal(&writer); pthread_mutex_unlock(&lock); } close(fs); }

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• SQL SERVER – 2011 – Wait Type – Day 25 of 28

  - by pinaldave

  Since the beginning of the series, I have been getting the following question again and again: “What are the changes in SQL Server 2011 – Denali with respect to Wait Types?” SQL Server 2011 – Denali is yet to be released, and making statements on the subject will be inappropriate. Denali CTP1 has been released so I suggest that all of you download the same and experiment on it. I quickly compared the wait stats of SQL Server 2008 R2 and Denali (CTP1) and found the following changes: Wait Types Exists in SQL Server 2008 R2 and Not Exists in SQL Server 2011 “Denali” SOS_RESERVEDMEMBLOCKLIST SOS_LOCALALLOCATORLIST QUERY_WAIT_ERRHDL_SERVICE QUERY_ERRHDL_SERVICE_DONE XE_PACKAGE_LOCK_BACKOFF Wait Types Exists in SQL Server 2011 and Not Exists in SQL Server 2008 SLEEP_MASTERMDREADY SOS_MEMORY_TOPLEVELBLOCKALLOCATOR SOS_PHYS_PAGE_CACHE FILESTREAM_WORKITEM_QUEUE FILESTREAM_FILE_OBJECT FILESTREAM_FCB FILESTREAM_CACHE XE_CALLBACK_LIST PWAIT_MD_RELATION_CACHE PWAIT_MD_SERVER_CACHE PWAIT_MD_LOGIN_STATS DISPATCHER_PRIORITY_QUEUE_SEMAPHORE FT_PROPERTYLIST_CACHE SECURITY_KEYRING_RWLOCK BROKER_TRANSMISSION_WORK BROKER_TRANSMISSION_OBJECT BROKER_TRANSMISSION_TABLE BROKER_DISPATCHER BROKER_FORWARDER UCS_MANAGER UCS_TRANSPORT UCS_MEMORY_NOTIFICATION UCS_ENDPOINT_CHANGE UCS_TRANSPORT_STREAM_CHANGE QUERY_TASK_ENQUEUE_MUTEX DBCC_SCALE_OUT_EXPR_CACHE PWAIT_ALL_COMPONENTS_INITIALIZED PREEMPTIVE_SP_SERVER_DIAGNOSTICS SP_SERVER_DIAGNOSTICS_SLEEP SP_SERVER_DIAGNOSTICS_INIT_MUTEX AM_INDBUILD_ALLOCATION QRY_PARALLEL_THREAD_MUTEX FT_MASTER_MERGE_COORDINATOR PWAIT_RESOURCE_SEMAPHORE_FT_PARALLEL_QUERY_SYNC REDO_THREAD_PENDING_WORK REDO_THREAD_SYNC COUNTRECOVERYMGR HADR_DB_COMMAND HADR_TRANSPORT_SESSION HADR_CLUSAPI_CALL PWAIT_HADR_CHANGE_NOTIFIER_TERMINATION_SYNC PWAIT_HADR_ACTION_COMPLETED PWAIT_HADR_OFFLINE_COMPLETED PWAIT_HADR_ONLINE_COMPLETED PWAIT_HADR_FORCEFAILOVER_COMPLETED PWAIT_HADR_WORKITEM_COMPLETED HADR_WORK_POOL HADR_WORK_QUEUE HADR_LOGCAPTURE_SYNC LOGPOOL_CACHESIZE LOGPOOL_FREEPOOLS LOGPOOL_REPLACEMENTSET LOGPOOL_CONSUMERSET LOGPOOL_MGRSET LOGPOOL_CONSUMER LOGPOOLREFCOUNTEDOBJECT_REFDONE HADR_SYNC_COMMIT HADR_AG_MUTEX PWAIT_SECURITY_CACHE_INVALIDATION PWAIT_HADR_SERVER_READY_CONNECTIONS HADR_FILESTREAM_MANAGER HADR_FILESTREAM_BLOCK_FLUSH HADR_FILESTREAM_IOMGR XDES_HISTORY XDES_SNAPSHOT HADR_FILESTREAM_IOMGR_IOCOMPLETION UCS_SESSION_REGISTRATION ENABLE_EMPTY_VERSIONING HADR_DB_OP_START_SYNC HADR_DB_OP_COMPLETION_SYNC HADR_LOGPROGRESS_SYNC HADR_TRANSPORT_DBRLIST HADR_FAILOVER_PARTNER XDESTSVERMGR GHOSTCLEANUPSYNCMGR HADR_AR_UNLOAD_COMPLETED HADR_PARTNER_SYNC HADR_DBSTATECHANGE_SYNC We already know that Wait Types and Wait Stats are going to be the next big thing in the next version of SQL Server. So now I am eagerly waiting to dig deeper in the wait stats. Read all the post in the Wait Types and Queue series. Note: The information presented here is from my experience and there is no way that I claim it to be accurate. I suggest reading Book OnLine for further clarification. All the discussion of Wait Stats in this blog is generic and varies from system to system. It is recommended that you test this on a development server before implementing it to a production server. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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• Error while installing vmware tools v8.8.2 in Ubuntu 12.04 beta

  - by Dipen Patel

  I just upgraded to Ubuntu 12.04 from 11.10 using update manager. I use it as virtual machine on VMWare Player 4.xx. As usual I installed vmware tools to enable full screen mode and shared folder functionality. But while installing I got an error while building modules for shared folder and fast networking utilities for vmware tools. Error is ============================================== /tmp/vmware-root/modules/vmhgfs-only/fsutil.c: In function ‘HgfsChangeFileAttributes’: /tmp/vmware-root/modules/vmhgfs-only/fsutil.c:610:4: error: assignment of read-only member ‘i_nlink’ make[2]: *** [/tmp/vmware-root/modules/vmhgfs-only/fsutil.o] Error 1 make[2]: *** Waiting for unfinished jobs.... /tmp/vmware-root/modules/vmhgfs-only/file.c:128:4: warning: initialization from incompatible pointer type [enabled by default] /tmp/vmware-root/modules/vmhgfs-only/file.c:128:4: warning: (near initialization for ‘HgfsFileFileOperations.fsync’) [enabled by default] /tmp/vmware-root/modules/vmhgfs-only/tcp.c:53:30: error: expected ‘)’ before numeric constant /tmp/vmware-root/modules/vmhgfs-only/tcp.c:56:25: error: expected ‘)’ before ‘int’ /tmp/vmware-root/modules/vmhgfs-only/tcp.c:59:33: error: expected ‘)’ before ‘int’ make[2]: *** [/tmp/vmware-root/modules/vmhgfs-only/tcp.o] Error 1 make[1]: *** [_module_/tmp/vmware-root/modules/vmhgfs-only] Error 2 make[1]: Leaving directory `/usr/src/linux-headers-3.2.0-22-generic' make: *** [vmhgfs.ko] Error 2 make: Leaving directory `/tmp/vmware-root/modules/vmhgfs-only' The filesystem driver (vmhgfs module) is used only for the shared folder feature. The rest of the software provided by VMware Tools is designed to work independently of this feature. Let me know if anyone has encountered and solved this problem. Regards, Dipen Patel

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• Password Security: Short and Complex versus ‘Short or Lengthy’ and Less Complex

  - by Akemi Iwaya

  Creating secure passwords for our online accounts is a necessary evil due to the huge increase in database and account hacking that occurs these days. The problem though is that no two companies have a similar policy for complex and secure password creation, then factor in the continued creation of insecure passwords or multi-site use of the same password and trouble is just waiting to happen. Ars Technica decided to take a look at multiple password types, how users fared with them, and how well those password types held up to cracking attempts in their latest study. The password types that Ars Technica looked at were comprehensive8, basic8, and basic16. The comprehensive type required a variety of upper-case, lower-case, digits, and symbols with no dictionary words allowed. The only restriction on the two basic types was the number of characters used. Which type do you think was easier for users to adopt and did better in the two password cracking tests? You can learn more about how well users did with the three password types and the results of the tests by visiting the article linked below. What are your thoughts on the matter? Are shorter, more complex passwords better or worse than using short or long, but less complex passwords? What methods do you feel work best since most passwords are limited to approximately 16 characters in length? Perhaps you use a service like LastPass or keep a dedicated list/notebook to manage your passwords. Let us know in the comments!    

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• SQL SERVER – The Difference between Dual Core vs. Core 2 Duo

  - by pinaldave

  I have decided that I would not write on this subject until I have received a total of 25 questions on this subject. Here are a few questions from the list: Questions: What is the difference between Dual Core and Core 2 Duo? Which one is recommended for SQL Server: Core 2 Duo or Dual Core? Can I upgrade my Dual Core to Core 2 Duo? If Dual Core has 2 CPUs, how many CPUs does Core 2 Duo have? Is it true that Core 2 Duo and Dual Core meant the same thing? Well, let us see the answer. Optimistically, I would be directing everybody to this blog post if I receive a question of the same kind sometime in the future. To verify the information that I provide, visit Intel’s site. For additional information regarding the subject, visit Wikipedia. My Answer: Any computer that has two CPUs or two “cores“ is known as Dual Core. Core Duo is a brand name of Intel for Dual Core. Core 2 Duo is simply a higher version of Core Duo. (e.g. for Pentium brand, it`s like Pentium I, Pentium II, etc.) The computer I am using now has Core 2 Duo. Intel has launched a new brand, which they call i3, i5, and i7.  Here, the numbers are not related to the number of cores; rather, they show the range of the CPU. I3 is of low range and i7 is of high range. Feel free to add more details by adding valuable comments here. And if you still want to ask why I created this blog post, well, I mentioned that I was waiting for 25 questions threshold to hit, before I write about this subject which I didn`t really plan to write about. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority News, T SQL, Technology

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• SQL SERVER – A Puzzle – Illusion – Confusion – April Fools’ Day

  - by pinaldave

  Today is April 1st and just like every other year, I like to bring something interesting and light for the day. Atleast there should be days in every one’s life when they should feel easy. Here is a quick puzzle for you and I believe it will make you feel extremely smart if you can figure out the result behind the same. Run following in SQL Server Management Studio and observe the output: SELECT 30.0/(-2.0)/5.0; SELECT 30.0/-2.0/5.0; Here are few questions for you: 1) What will be the result of above two queries? 2) Why? If you think you can figure out the result without executing them – I encourage you to execute BOTH of them in SSMS and see if they give you same result or different result. Well, now I am waiting for your answer here – why? I often post similar things on my facebook page http://facebook.com/SQLAuth – you are welcome to play with me there. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Puzzle, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• MVP Summit 2011 summary and thoughts: The &ldquo;I hope I don&rsquo;t cross a line and lose my MVP status&rdquo; post

  - by George Clingerman

  I've been wanting to write this post summarizing my thoughts about the MVP summit but have been dragging my feet since it's a very difficult one to write. However seeing Andy (http://forums.create.msdn.com/forums/t/77625.aspx) and Catalin (http://www.catalinzima.com/2011/03/mvp-summit-2011/) and Chris (http://geekswithblogs.net/cwilliams/archive/2011/03/07/144229.aspx) post about it has encouraged me to finally take the plunge. I'm going to have to write carefully though because I'm going to be dancing around a ton of NDA mine fields as well as having to walk the tight-rope of not sending the wrong message or having people read too much into what I'm saying. I want to note that most of what I'm about to say is just based on my observations, they're not thoughts that Microsoft has asked me to pass along and they're not things I heard Microsoft say. It's just me sharing what I think after going to the MVP summit. Let's start off with a short imaginary question and answer session.     Has the App Hub forums and XBLIG management been rather poor by Microsoft? Yes.     Do I think we're going to see changes to that overnight? No.     Will it continue to look bad from the outside? Somewhat. Confusing right? Well that's kind of how things are right now. Lots of confusion. XNA is doing AWESOME. Like, really, really awesome. As a result of that awesomeness, XNA is on three major platforms: Xbox 360, WP7 and PC. This means that internally Microsoft is really excited and invested in the technology. That's fantastic for XNA and really should show you the future the framework has. It's here to stay. So why are Xbox LIVE Indie Game developers feeling so much pain? The ironic thing is that pain is being caused by the success of XNA. When XNA was just a small thing, there was more freedom and more focus. It was just us and them. We were an only child. Now our family has grown and everyone has and wants some time with XNA. This gets XNA pulled in all directions and as it moves onto new platforms, it plays catch up trying to get those platforms up to speed to where Xbox LIVE Indie Games has grown. Forums, documentation, educational content. They all need to be there because Xbox LIVE Indie Games has all of that and more. Along with the catch up in features/documentation/awesomeness there's the catch up that the people on the team have to play. New platforms and new areas of development mean new players and those new guys don't have the history of being around from the beginning. This leads to a lack of understanding at times just how important some things are because they seem so small and insignificant (Rich Text defaulting for new forum profiles would be one things that jumps to mind). If you're not aware that the forums have become more than just a basic Q&A, if you're not aware that they're a central hub to a very active community, then you don't understand why that small change should be prioritized over something else. New people have to get caught up and figure out how to make a framework and central forum site work for everyone it's now serving. So yeah, a lot of our pain this last year has been simply that XNA is doing well and XBLIG is doing well so the focus was shifted to catch other things up. It hurts when a parent seems to not have any time for you and they're spending some much time with your new baby brother. Growing pains. All families and in our case our product family experience it to some degree. I think as WP7 matures we'll see the team figuring out how to give everyone the right amount of attention. While we're talking about some of our growing pains, it is also important to note (although not really an excuse) that the Xbox LIVE Arcade developers complain about many of the same things that we do. If you paid attention to talks and information coming out of GDC 2011, most of the the XBLA guys were saying things that sounded eerily similar to what the XBLIG developers are saying (Scott Nichols from GayGamer.net noticed http://twitter.com/#!/NaviFairyGG/status/43540379206811650). Does this mean we should just accept the status quo since we're being treated exactly the same? No way. However it DOES show that the way we're being treated is no indication of the stability and future of the platform, it's just Microsoft dropping the communication ball on two playing fields. We're not alone and we're not even being treated worse. Not great, but also in a weird way a very good sign. Now on to a few tidbits I think I CAN share from the summit (I'm really crossing my fingers I'm not stepping over some NDA line I shouldn't be). First, I discovered that the XBLIG user base is bigger than I personally had originally estimated. I won't give the exact numbers (although we did beg Microsoft to release some of these numbers so maybe someday?) but it was much larger than my original guestimates and I was pleasantly surprised. Maybe some of you guys had the right number when you were guessing, but I know that mine was much too low. And even MORE importantly the number of users/shoppers is growing at a steady pace as well. Our market is growing! That was fantastic news and really something that I had to share. On to the community manager discussion. It was mentioned. I was mentioned. I blushed. Nothing more to report there than the blush in my cheeks was a light crimson color. If I ever see a job description posted for that position I have a resume waiting in the wings. I can't deny that I think that would be my dream job... ...so after I finished blushing, the MVPs did make it very, very clear that the communication has to improve. Community manager or not the single biggest pain point with the Xbox LIVE Indie Game community has been a lack of communication. I have seen dramatic improvement in the team responding to MVPs and I'm even seeing more communication from them on the forums so I'm hoping that's a long term change. I really think they understood the issue, the problem remains how to open that communication channel in a way that was sustainable. I think they'll get it figured out and hopefully that's sooner rather than later. During the summit, you may have seen me tweeting about how I was "that guy" (http://twitter.com/#!/clingermangw/status/42740432471470081). You also may have noticed that Andy and Catalin both mentioned me in their summit write ups. I may have come on a bit strong while I was there...went a little out of character for myself. I've been agitated for a while with the way things have been and I've been listening to you guys and hearing you guys be agitated. I'm also watching some really awesome indie game developers looking elsewhere and leaving the platform. Some of them we might not have been able to keep even with changes, but others are only leaving because of perceptions and lack of communication from Microsoft. And that pisses me off. And I let Microsoft know that I was pissed off. You made your list and I took that list and verbalized it. I verbalized the hell out of it. [It was actually mentioned that I'm a lot nicer on the forums and in email than I am in person...I felt bad about that, but I couldn't stay silent]. Hopefully it did something guys, I really did try hard to get the message across. Along with my agitation, I also brought some pride. I mentioned several things in person to the team that I was particularly proud of. From people in the community that are doing an awesome job, to the re-launch of XboxIndies that was going on that week and even gamers like Steven Hurdle (http://writingsofmassdeduction.com/) who have purchased one XBLIG every day for over 100 days now. The community is freaking rocking it and I made sure to highlight that. So in conclusion, I'd just like to say hang in there (you know, like that picture of the cat). If you've been worried about investing in Xbox LIVE Indie Games because you think it's on shaky ground. It's not. Dream Build Play being about the Xbox 360 should have helped a little to point that out. The team is really scrambling around trying to figure things out and make improvements all around. There’s quite a few new gals and guys and it's going to take them time to catch up and there are a lot of constantly shifting priorities. We all have one toy, one team and we're fighting for time with it. It's also time for the community to continue spreading our wings and going out on our own more often. The Indie Game Winter Uprising was a fantastic example of that. We took things into our own hands and it got noticed and Microsoft got behind it. They do every time we stand up and do something (look at how many Microsoft employees tweeted, wrote about the re-launch of XboxIndies.com or the support I've gotten from them for my weekly XNA Notes). XNA is here to stay, it's time for us to stop being scared of that and figure out how to make our own games the successes they should be. There's definitely a list of things that need to be fixed, things that should be improved and I think we should definitely keep vocal about that with Microsoft. Keep it short, focused and prioritized. There's also a lot of things we can do ourselves while we're waiting on them to fix and change things. Lots of ways we can compensate for particular weaknesses in the channel. The kind of stuff that we can step up and do ourselves. Do it on our own, you know, the way Indies always do. And I'm really looking forward to watching us do just that.

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• SQL SERVER – Difference Between ROLLBACK IMMEDIATE and WITH NO_WAIT during ALTER DATABASE

  - by pinaldave

  Today, we are going to discuss about something very simple, but quite commonly confused two options of ALTER DATABASE. The first one is ALTER DATABASE …ROLLBACK IMMEDIATE and the second one is WITH NO_WAIT. Many people think they are the same or are not sure of the difference between these two options. Before we continue our explaination, let us go through the explanation given by Book On Line. ROLLBACK AFTER integer [SECONDS] | ROLLBACK IMMEDIATE Specifies whether to roll back after a specified number of seconds or immediately. NO_WAIT Specifies that if the requested database state or option change cannot complete immediately without waiting for transactions to commit or roll back on their own, then the request will fail. If you have understood the difference by now, there is no need to proceed further. If you are still confused, continue with the rest of the post. There is one big difference between ROLLBACK and NO_WAIT. In case incomplete Transaction ALTER DATABASE … ROLLBACK rollbacks those incomplete transaction immediately, where as ALTER DATABASE … NO_WAIT will terminate and rollback the transaction of ALTER DATABASE … NO_WAIT itself. I think it can be clearly explained with the help of the following images. Option 1: ALTER DATABASE … ROLLBACK Connection 1 – Simulating some operation using WAITFOR DELAY WAITFOR DELAY '1:00:00' Connection 2 ALTER DATABASE TestDb SET SINGLE_USER WITH ROLLBACK IMMEDIATE; Option 2: ALTER DATABASE … NO_WAIT Connection 1 – Simulating some operation using WAITFOR DELAY WAITFOR DELAY '1:00:00' Connection 2 ALTER DATABASE TestDb SET SINGLE_USER WITH NO_WAIT; Let me know if this example was simple enough. Reference : Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Documentation, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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