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  • Windows 7 explorer crashing trying to read external hard disk

    - by Mario De Schaepmeester
    I have a 1TB Western Digital hard drive which is almost full and last time I tried to plug it into my laptop, I got a Windows dialog saying "this hard drive needs to be formatted". I did not panic because I have experienced things like this before and I know it's often solved by simply re-inserting the drive. Now however, whenever I plug it in and try to browse it in explorer by going to "computer", the explorer process crashes after a while. I simply close explorer since it takes ages trying to read the disk and nothing happens. After searching on the internet, the best thing to do would be a chkdsk. I tried it via properties in explorer (which also took a good 5 minutes to open up), locks up as well, after waiting a couple of minutes it says there's no access to the disk so a chkdsk is not possible... I want to make clear that I always use safe removal before pulling out the USB cable. Last time however, safe removal just would not work and when trying to shut down Windows, the logoff screen just would not disappear (I've waited at least 10 minutes or so) and I powered off the PC by force. This may be the cause of the problems but the disk was still recognised immediately after that. I really don't want to format this thing because it contains C: clones of 3 computers and a lot of other stuff that I don't want to re-copy. What would be the best course of action? Update I got chkdsk working via the command line. I used the /F and /R options. I already got a bunch of lines saying "file record segment X is unreadable" or whatever it is in English, my OS is Dutch. It looks bad... Will chdsk repair these errors?

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  • How do I access an external hard drive plugged into my router?

    - by Shawn
    I am running Ubuntu 11.10 and I own a Netgear N600 Wireless Dual Band Router with a USB port built into it. Naturally, the router came with instructions on how to mount and view this drive with both Windows and Mac, but nothing about Linux. I have an WD Elements 1 TB external HDD that I would like to plug into the router and share across my home network. However, when I plug it in, absolutely nothing happens on my desktop. I checked on two different machines and nothing seems to indicate that the drive has been mounted (or is even seen at all) on either machine. I am fully aware that it may not be possible to do this with a Linux system, but I was hoping someone might have a suggestion. Thanks!

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  • Windows Internet Connection Issue (HELP)

    - by semajjames1399
    I have a windows 8 hp dual booting ubuntu. When i log onto windows i cant get on the internet... But skype and other applications can just now webpages in a browser what so ever (this is on windows 8). But on ubuntu i have no internet issues at all. From what i see right now its only the browsers in windows 8 that cant get the internet, and ive tried all the browsers i had (chrome, ie, firefox) and they cant connect but in the win8 notification area it says im connected. I can even ping via cmd. HELP! Thanks. Whats not working is that i cant get access the internet through the windows 8 broswer.

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  • Ubuntu 11.10 is on external HDD, how to boot (using grub4dos), and which initrd and vmlinuz to use?

    - by user198003
    I installed Ubuntu 11.10 on external HDD. How can I boot it? I used grub4dos before, and it worked with Fedora distributions. Problem I have now is that I don't know which initrd and vmlinuz files to use. Tried with one I have in /boot directory, but booting did not worked... Can you give me some ideas what to try, do i have to use different initrd and vmlinuz, or I can solve this with other solutions. Also, just to mention that boot goes to BusyBox v1.18.4 command prompt. Thank you in advance!

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  • Recovering damaged external hard disk by installing internally

    - by nfarshchi
    I had a 1TB Western Digital (My book series) 3.5" USB3. One day, the SATA to USB3 converter board was damaged and has not worked since. I decided to open the cover and use the HDD as an internal HDD. When I attached the HDD to my PC and booted up in Windows, it asked me which type of ????? I want to use "MBR or GBR" (I dont remember the exact question) I chose MBR and Windows gave me a 1TB empty Hard drive. I tried to recover with recover my files and some other recovery programs but no success. Some one told me that you should choosed GBR instead of MBR . How can I do that now? Another guy told me that the SATA to USB3 converter board is coded to save data on HDD and you can not use them internally without losing data, and I should find another SATA to USB3 board (exact same). It is impossible to find because they are not produced any more. Please help me to find a solution to bring back my data. UPDATE I have 1TB WD "Mybook" USB 3. the board that convert sata to usb3 was damaged. so when the HDD was in the box computer did not recognize it. I opened the box and remove HDD to use it internal. after connecting to my PC windows showed me one massage that I had two choice MBR or GPT I choosed MBR one and windows gave me 1TB empty new volume. I tried many recovery software to recover my data but no success. I brought it to one expert recovery company and they told me the converter board (SATA to USB3) make some encryption on data and with out that board you cannot recover any thing. so I bought another empty WD box and put the HDD inside but even after that also there is no file. I tried to recover again in this state but no success. so I have some unanswered question. does this converted boards make any password or encryption? if yes how can I solve it? does using many recovery programs affected my data? any suggestion or solution for bring back my data? I had use recovery programs such as : recover my files , EaseUS data recovery, easy recovery, test disk, Ontrack easy recovery . Note: when I was using test disk it asked me to choose which partition table I want to use. as it was I choose NTFS, does this made any change on data?

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  • SSH very slow when connecting from external [closed]

    - by wnstnsmth
    Possible Duplicate: ssh delay when connecting We have a CentOS server that we use for internal testing purposes, which has sshd enabled. When I (as a developer) am at the company, I use ssh [email protected] to connect to it - and it works flawlessly. Now, in order to work from home, accessing the server via the company's static IP, we set up another port for ssh, 2020. So I execute ssh -p 2020 [email protected] and am immediately granted for a password. After entering the password, it takes up to 30 seconds until I can access the server. Same is with SFTP (i.e. uploading files takes about 30 seconds until it begins to transfer). As you can imagine, if you have to regularly upload files to a webserver via SFTP, this is very tedious. So I looked at similar questions and thus edited the sshd_config file on the server, setting UseDNS to "no" and GSSAPIAuthentication to "no" (this one also in ssh_config on the client) - it did not work.. Please have a look at the -vvv output when externally accessing the server: ssh -p 2020 -vvv [email protected] PasteBin: ssh What could it be? Do you need more info?

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  • Tools to backup an external hard disk

    - by Kaushik Gopal
    Hey people, What's the best method to take an exact copy of my external hard disk? A guru suggested rsync, but I was wondering if there's an easier alternative. I do remember reading somewhere that Acronis also does this. Was looking for your advice on the best option. I'm running Windows. Essentially i have an external HDD which has a lot of stuff synchronized across various pcs. I wish to take a backup of this external Hard disk (ext.HDDs aren't entirely reliable so want to keep a backup of my ext.HDD). Cheers. K

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  • Why does Network-Manager close when it cannot bind to any connection?

    - by Agmenor
    When Network-Manager is not able to bind my Ubuntu to any connection, after a while it closes. The icon in the notification area (or indicator area) disappears, and it does not run any more. For instance this happens when there is really no ethernet network nor wireless one. Nonetheless this is a problem, since I often plug in my ethernet cable long after having booted my computer. As a hack I therefore hit Alt + F2, and type nm-applet. But I am not satisfied with this solution, because I think it is not intuitive enough. Is there a way to keep Network-Manager always running? I have Network-Manager 0.8.1 on Ubuntu 10.10, but this has been so for a long time, at least for one year.

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  • WiFi USB adapter showing the Network ..... but no connection in effect

    - by Idrees
    I have Pentium 4 system 3 GHz, 1 GB RAM ..... (no built-in WiFi) I installed Ubuntu 12.10 on my PC, works fine. It picked all the drivers for audio, video itself. I plugged TP-Link 54Mbps High Gain Wireless USB Adapter (TL-WN422G) ..... (link for the device: http://www.tp-link.com/en/products/details/?model=TL-WN422G) Now what happens is that the WiFi network is detected and shown in the "Network Connections", and it is also connected to it but when I open Firefox it is as if there no internet connection at all.

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  • Establishing connection from java to access 2010 64bit

    - by user993250
    after going through several tutorials and blog posts, i have unsuccessfully tried to set up a connection from java to a microsoft access database. my system specifications are win 7 [64 bit] odbcad32.ese [64 bit] access 2010 [64 bit] jre6 [64 bit] the code that i wrote for establishing a connection public Connection makeConn() throws ClassNotFoundException, SQLException { Class.forName("sun.jdbc.odbc.JdbcOdbcDriver"); conn = DriverManager.getConnection("jdbc:odbc:Driver={Microsoft Access Driver (*.mdb)};DBQ=C:\\Users\\ARIFAH\\Desktop\\sampleDb.mdb"); return conn; } in the data source [odbc]---[located at path %windir%\system32\odbcad32.exe] i performed the following task USER DNS TAB ADD-Microsoft Access Driver (*.mdb, *.accdb ) [file ACEODBC.dll] -Finish Data Source Name: TestDriver ; Description: test driver for access 2010 64 bit ; DataBase-select -browse: C:\Users\ARIFAH\Desktop\sampleDb.mdb - ok apply ok now when i try to run my application, this is the error that i m getting, java.sql.SQLException: [Microsoft][ODBC Microsoft Access Driver] Could not find file '(unknown)'. at sun.jdbc.odbc.JdbcOdbc.createSQLException(Unknown Source) at sun.jdbc.odbc.JdbcOdbc.standardError(Unknown Source) at sun.jdbc.odbc.JdbcOdbc.SQLDriverConnect(Unknown Source) at sun.jdbc.odbc.JdbcOdbcConnection.initialize(Unknown Source) at sun.jdbc.odbc.JdbcOdbcDriver.connect(Unknown Source) at java.sql.DriverManager.getConnection(Unknown Source) at java.sql.DriverManager.getConnection(Unknown Source) at dataBase.connection.makeConn(connection.java:22) at newmodulewizrd.ui.App.<init>(App.java:32) at archetypedcomponent.commands.newModuleHandler.execute(newModuleHandler.java:39) at org.eclipse.ui.internal.handlers.HandlerProxy.execute(HandlerProxy.java:294) at org.eclipse.core.commands.Command.executeWithChecks(Command.java:476) at org.eclipse.core.commands.ParameterizedCommand.executeWithChecks(ParameterizedCommand.java:508) at org.eclipse.ui.internal.handlers.HandlerService.executeCommand(HandlerService.java:169) at org.eclipse.ui.internal.handlers.SlaveHandlerService.executeCommand(SlaveHandlerService.java:241) at org.eclipse.ui.internal.handlers.SlaveHandlerService.executeCommand(SlaveHandlerService.java:241) at org.eclipse.ui.menus.CommandContributionItem.handleWidgetSelection(CommandContributionItem.java:770) at org.eclipse.ui.menus.CommandContributionItem.access$10(CommandContributionItem.java:756) at org.eclipse.ui.menus.CommandContributionItem$5.handleEvent(CommandContributionItem.java:746) at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84) at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1003) at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:3910) at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3503) at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2405) at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2369) at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2221) at org.eclipse.ui.internal.Workbench$5.run(Workbench.java:500) at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332) at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:493) at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149) at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:113) at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:194) at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:110) at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:79) at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:368) at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:179) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at java.lang.reflect.Method.invoke(Unknown Source) at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:559) at org.eclipse.equinox.launcher.Main.basicRun(Main.java:514) at org.eclipse.equinox.launcher.Main.run(Main.java:1311) at org.eclipse.equinox.launcher.Main.main(Main.java:1287) *can somebody help with it??? *

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  • DriverManager always returns my custom driver regardless of the connection URL

    - by JGB146
    I am writing a driver to act as a wrapper around two separate MySQL connections (to distributed databases). Basically, the goal is to enable interaction with my driver for all applications instead of requiring the application to sort out which database holds the desired data. Most of the code for this is in place, but I'm having a problem in that when I attempt to create connections via the MySQL Driver, the DriverManager is returning an instance of my driver instead of the MySQL Driver. I'd appreciate any tips on what could be causing this and what could be done to fix it! Below is a few relevant snippets of code. I can provide more, but there's a lot, so I'd need to know what else you want to see. First, from MyDriver.java: public MyDriver() throws SQLException { DriverManager.registerDriver(this); } public Connection connect(String url, Properties info) throws SQLException { try { return new MyConnection(info); } catch (Exception e) { return null; } } public boolean acceptsURL(String url) throws SQLException { if (url.contains("jdbc:jgb://")) { return true; } return false; } It is my understanding that this acceptsURL function will dictate whether or not the DriverManager deems my driver a suitable fit for a given URL. Hence it should only be passing connections from my driver if the URL contains "jdbc:jgb://" right? Here's code from MyConnection.java: Connection c1 = null; Connection c2 = null; /** *Constructors */ public DDBSConnection (Properties info) throws SQLException, Exception { info.list(System.out); //included for testing Class.forName("com.mysql.jdbc.Driver").newInstance(); String url1 = "jdbc:mysql://server1.com/jgb"; String url2 = "jdbc:mysql://server2.com/jgb"; this.c1 = DriverManager.getConnection( url1, info.getProperty("username"), info.getProperty("password")); this.c2 = DriverManager.getConnection( url2, info.getProperty("username"), info.getProperty("password")); } And this tells me two things. First, the info.list() call confirms that the correct user and password are being sent. Second, because we enter an infinite loop, we see that the DriverManager is providing new instances of my connection as matches for the mysql URLs instead of the desired mysql driver/connection. FWIW, I have separately tested implementations that go straight to the mysql driver using this exact syntax (al beit only one at a time), and was able to successfully interact with each database individually from a test application outside of my driver.

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  • Accessing different connection strings at runtime in ASP.NET MVC 1

    - by Neil T.
    I'm trying to implement integration testing in my ASP.NET MVC 1.0 solution. The technologies in use are LINQ-to-SQL, NUnit and WatiN. I recently discovered a pattern that will allow me to create a testing version of the database on the fly without modifying the development version of the database. I needed this behavior in order to run my user interface tests in WatiN that may modify the database. The plan is to modify the connection string in the Web.config file, and pass that new connection string to the DataContext constructor. This way, I don't have to add routes or modify my URLs in order to perform the integration testing. I've set up the project so that the test setup can modify the connection string to point to the test database when the tests are running. The connection string is stored in web.config. The problem I'm having is that when I try to run the tests, I get a NullReferenceException when trying to access the HTTPContext. From everything that I have read so far, the HTTPContext is only available within the context of a controller. Here is the code for the property that is supposed to give me the reference to the Web.config file: private System.Configuration.Configuration WebConfig { get { ExeConfigurationFileMap fileMap = new ExeConfigurationFileMap(); // NullReferenceException occurs on this line. fileMap.ExeConfigFilename = HttpContext.Current.Server.MapPath("~\\web.config"); System.Configuration.Configuration config = ConfigurationManager.OpenMappedExeConfiguration(fileMap, ConfigurationUserLevel.None); return config; } } Is there something that I am missing in order to make this work? Is there a better way to accomplish what I'm trying to achieve? UPDATE: I decided to abandon the modification of Web.config in lieu of a "request-scoped DataContext" pattern that I found here. From the looks of it, I believe it should give me the results I'm looking for. However, during the TextFixtureSetUp, I try to create a new copy of the database for testing purposes, and it fails silently. When I get to the tests, the repository still uses the production database connection string to load data.

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  • Synchronize Dreamweaver over an SSH tunnel using an SFTP connection

    - by Aeo
    Maybe... Just maybe... I'm asking too much here. Maybe I'm even barking up the wrong tree. I'm looking to essentially have Dreamweaver establish an SSH tunnel to one machine, and then use that connection to synchronize a site that is on another machine entirely. Now for some details: We've got two connections here at work. We've got our office connection for day to day business, and then we've got some fancy connection hosting our web servers upstairs. For the most part they've been mutually exclusive until recently. We had been establishing an SFTP connection to synchronize our web sites by going out over the office connection to the web and coming back in over the fancy connection to our servers upstairs. Recently -ish, we established a LAN connection to one of our servers that makes a pleasant change in VNC connection quality. Thanks to Vinagre, this makes it really easy to connect to any of our servers over this LAN connection via SSH tunnel for VNC. However, in spite of that new addition of a LAN connection, we still synchronize over the 'net. Out the office connection and in on the fancy one upstairs. I'm looking to change this. I'd like to get Dreamweaver to first tunnel over our LAN connection to the servers, and then go from there to whatever connection it needs to. Am I asking too much? The current set up: Dreamweaver is installed on Windows XP which is running within VirtualBox on top of Ubuntu 10.10. The network connection for VirtualBox is currently made in NAT mode, but could easily be switched to a Bridged Connection should it need be. The LAN connection is to 1 of 5 servers running CentOS 5.

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  • vb6 ADODB connection string to sql server 2008

    - by phill
    I recently migrated a database from sql server 2005 to 2008 on windows server 2008. Clients connect fine from their XP machines and so does the SQL Management Studio 2008. I have also tested a remote connection using LINQPad which worked fine. However on my VB6 app, the connection string seems to give me problems. Any ideas what I'm doing wrong? Dim strUserName As String Dim strPassword As String Dim sProc As String sProc = "Class_clsAdoFnx_Initialize" Me.DatabaseName = "db_app" 'Connect to SQL Server strUserName = "admin" strPassword = "mudslinger" Set cSQLConn = New ADODB.Connection '**Original connection String 'cSQLConn.CommandTimeout = 0 'cSQLConn.ConnectionString = " PROVIDER=SQLOLEDB" & _ ' ";SERVER=NET-BRAIN" & _ ' ";UID=" & strUserName & _ ' ";PWD=" & strPassword & _ ' ";DATABASE=" & Me.DatabaseName '***First attempt, no dice 'cSQLConn.ConnectionString = "Provider=sqloledb;" & _ ' "Data Source=NET-BRAIN;" & _ ' "Initial Catalog=DB_APP;" & _ ' "User Id=admin;" & _ ' "Password=mudslinger" 'cSQLConn.Open '***3rd attempt, no dice cSQLConn.Open "Provider=sqloledb;" & _ "Data Source=NET-BRAIN;" & _ "Initial Catalog=db_app;" & _ "User Id=admin;" & _ "Password=mudslinger", "admin", "mudslinger" thanks in advance.

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  • ADODB Connection String: Workgroup Information file is Missing?

    - by Mohgeroth
    I have a few data sources in access that I need to connect to programatically to do things with behind the scenes and keep visibility away from users. Said datasource has a password 'pass' as I'm going to call it here. Using this connection method I get an error attempting to use the open method Dim conn as ADODB.Connection Set ROBBERS.conn = New ADODB.Connection conn.open "Provider=Microsoft.Jet.OLEDB.4.0;" _ & "Data Source=\\pep-home\projects\billing\autobilling\DPBilling2.mdb;" _ & "Jet OLEDB:Database Password=pass;", "admin", "pass" "Cannot start your application. The workgroup information file is missing or opened exclusively by another user." Due to planning to move into 2007, we are not using nor have ever used a workgroup identification file through access. The database password on the data source was set through the Set Databa Password which had to be done on an exclusive open. Ive spent a good while changing around my connection options, where to put the passwords etc and either cannot find the right format, or (why I'm asking here) I think there may be some other unknown that I must setup to do this. Anyone out there got some useful information?

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  • Create 2 connection pools using c3p0 in Jetty

    - by Mike
    Hello, I'm trying to set up a maven web project that runs Jetty. In this project, I need 2 JNDIs... my plan is to configure 2 connection pools using c3p0 in Jetty. So, I created WEB-INF/jetty-env.xml, and I have the following:- <Configure class="org.mortbay.jetty.webapp.WebAppContext"> <New id="ds1" class="org.mortbay.jetty.plus.naming.Resource"> <Arg>jdbc/ds1</Arg> <Arg> <New class="com.mchange.v2.c3p0.ComboPooledDataSource"> // ... JTDS to SQL Server - omitted for brevity </New> </Arg> </New> <New id="ds2" class="org.mortbay.jetty.plus.naming.Resource"> <Arg>jdbc/ds2</Arg> <Arg> <New class="com.mchange.v2.c3p0.ComboPooledDataSource"> // ... JTDS to Sybase - omitted for brevity </New> </Arg> </New> </Configure> When I run jetty, I get this exception:- May 14, 2010 1:16:56 PM com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource getPoolManager INFO: Initializing c3p0 pool... com.mchange.v2.c3p0.ComboPooledDataSource [ acquireIncrement -> ... ... ... Exception in thread "com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#0" java.lang.LinkageError: net.sourceforge.jtds.jdbc.DefaultProperties at java.lang.ClassLoader.defineClassImpl(Native Method) at java.lang.ClassLoader.defineClass(ClassLoader.java:258) It seems to me that I can't create 2 connection pools using c3p0. If I remove either one of the connection pool, it worked. What am I doing wrong? How do I create 2 connection pools in Jetty? Thanks much.

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  • How do you cancel an external git diff?

    - by v2k
    I've got vim setup as my external diff tool: [diff] external = git_diff_wrapper !/bin/sh vimdiff "$2" "$5" Say I have 300 files that have been modified; via bash, I type "git diff". It launches 300 vimdiffs sequentially, how do I abort it?

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  • Blocking on DBCP connection pool (open and close connnection). Is database connection pooling in OpenEJB pluggable?

    - by topchef
    We use OpenEJB on Tomcat (used to run on JBoss, Weblogic, etc.). While running load tests we experience significant performance problems with handling JMS messages (queues). Problem was localized to blocking on database connection pool getting or releasing connection to the pool. Blocking prevented concurrent MDB instances (threads) from running hence performance suffered 10-fold and worse. The same code used to run on application servers (with their respective connection pool implementations) with no blocking at all. Example of thread blocked: Name: JMS Resource Adapter-worker-23 State: BLOCKED on org.apache.commons.pool.impl.GenericObjectPool@1ea6b4a owned by: JMS Resource Adapter-worker-19 Total blocked: 18,426 Total waited: 0 Stack trace: org.apache.commons.pool.impl.GenericObjectPool.returnObject(GenericObjectPool.java:916) org.apache.commons.dbcp.PoolableConnection.close(PoolableConnection.java:91) - locked org.apache.commons.dbcp.PoolableConnection@1bcba8 org.apache.commons.dbcp.managed.ManagedConnection.close(ManagedConnection.java:147) com.xxxxx.persistence.DbHelper.closeConnection(DbHelper.java:290) .... Couple of questions. I am almost certain that some transactional attributes and properties contribute to this blocking, but MDBs are defined as non-transactional (we use both annotations and ejb-jar.xml). Some EJBs do use container-managed transactions though (and we can observe blocking there as well). Are there any DBCP configurations that may fix blocking? Is DBCP connection pool implementation replaceable in OpenEJB? How easy (difficult) to replace it with another library? Just in case this is how we define data source in OpenEJB (openejb.xml): <Resource id="MyDataSource" type="DataSource"> JdbcDriver oracle.jdbc.driver.OracleDriver JdbcUrl ${oracle.jdbc} UserName ${oracle.user} Password ${oracle.password} JtaManaged true InitialSize 5 MaxActive 30 ValidationQuery SELECT 1 FROM DUAL TestOnBorrow true </Resource>

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  • Dealing with external processes

    - by Jesse Aldridge
    I've been working on a gui app that needs to manage external processes. Working with external processes leads to a lot of issues that can make a programmer's life difficult. I feel like maintenence on this app is taking an unacceptably long time. I've been trying to list the things that make working with external processes difficult so that I can come up with ways of mitigating the pain. This kind of turned into a rant which I thought I'd post here in order to get some feedback and to provide some guidance to anybody thinking about sailing into these very murky waters. Here's what I've got so far: Output from the child can get mixed up with output from the parent. This can make both outputs misleading and hard to read. It can be hard to tell what came from where. It becomes harder to figure out what's going on when things are asynchronous. Here's a contrived example: import textwrap, os, time from subprocess import Popen test_path = 'test_file.py' with open(test_path, 'w') as file: file.write(textwrap.dedent(''' import time for i in range(3): print 'Hello %i' % i time.sleep(1)''')) proc = Popen('python -B "%s"' % test_path) for i in range(3): print 'Hello %i' % i time.sleep(1) os.remove(test_path) I guess I could have the child process write its output to a file. But it can be annoying to have to open up a file every time I want to see the result of a print statement. If I have code for the child process I could add a label, something like print 'child: Hello %i', but it can be annoying to do that for every print. And it adds some noise to the output. And of course I can't do it if I don't have access to the code. I could manually manage the process output. But then you open up a huge can of worms with threads and polling and stuff like that. A simple solution is to treat processes like synchronous functions, that is, no further code executes until the process completes. In other words, make the process block. But that doesn't work if you're building a gui app. Which brings me to the next problem... Blocking processes cause the gui to become unresponsive. import textwrap, sys, os from subprocess import Popen from PyQt4.QtGui import * from PyQt4.QtCore import * test_path = 'test_file.py' with open(test_path, 'w') as file: file.write(textwrap.dedent(''' import time for i in range(3): print 'Hello %i' % i time.sleep(1)''')) app = QApplication(sys.argv) button = QPushButton('Launch process') def launch_proc(): # Can't move the window until process completes proc = Popen('python -B "%s"' % test_path) proc.communicate() button.connect(button, SIGNAL('clicked()'), launch_proc) button.show() app.exec_() os.remove(test_path) Qt provides a process wrapper of its own called QProcess which can help with this. You can connect functions to signals to capture output relatively easily. This is what I'm currently using. But I'm finding that all these signals behave suspiciously like goto statements and can lead to spaghetti code. I think I want to get sort-of blocking behavior by having the 'finished' signal from QProcess call a function containing all the code that comes after the process call. I think that should work but I'm still a bit fuzzy on the details... Stack traces get interrupted when you go from the child process back to the parent process. If a normal function screws up, you get a nice complete stack trace with filenames and line numbers. If a subprocess screws up, you'll be lucky if you get any output at all. You end up having to do a lot more detective work everytime something goes wrong. Speaking of which, output has a way of disappearing when dealing external processes. Like if you run something via the windows 'cmd' command, the console will pop up, execute the code, and then disappear before you have a chance to see the output. You have to pass the /k flag to make it stick around. Similar issues seem to crop up all the time. I suppose both problems 3 and 4 have the same root cause: no exception handling. Exception handling is meant to be used with functions, it doesn't work with processes. Maybe there's some way to get something like exception handling for processes? I guess that's what stderr is for? But dealing with two different streams can be annoying in itself. Maybe I should look into this more... Processes can hang and stick around in the background without you realizing it. So you end up yelling at your computer cuz it's going so slow until you finally bring up your task manager and see 30 instances of the same process hanging out in the background. Also, hanging background processes can interefere with other instances of the process in various fun ways, such as causing permissions errors by holding a handle to a file or someting like that. It seems like an easy solution to this would be to have the parent process kill the child process on exit if the child process didn't close itself. But if the parent process crashes, cleanup code might not get called and the child can be left hanging. Also, if the parent waits for the child to complete, and the child is in an infinite loop or something, you can end up with two hanging processes. This problem can tie in to problem 2 for extra fun, causing your gui to stop responding entirely and force you to kill everything with the task manager. F***ing quotes Parameters often need to be passed to processes. This is a headache in itself. Especially if you're dealing with file paths. Say... 'C:/My Documents/whatever/'. If you don't have quotes, the string will often be split at the space and interpreted as two arguments. If you need nested quotes you can use ' and ". But if you need to use more than two layers of quotes, you have to do some nasty escaping, for example: "cmd /k 'python \'path 1\' \'path 2\''". A good solution to this problem is passing parameters as a list rather than as a single string. Subprocess allows you to do this. Can't easily return data from a subprocess. You can use stdout of course. But what if you want to throw a print in there for debugging purposes? That's gonna screw up the parent if it's expecting output formatted a certain way. In functions you can print one string and return another and everything works just fine. Obscure command-line flags and a crappy terminal based help system. These are problems I often run into when using os level apps. Like the /k flag I mentioned, for holding a cmd window open, who's idea was that? Unix apps don't tend to be much friendlier in this regard. Hopefully you can use google or StackOverflow to find the answer you need. But if not, you've got a lot of boring reading and frusterating trial and error to do. External factors. This one's kind of fuzzy. But when you leave the relatively sheltered harbor of your own scripts to deal with external processes you find yourself having to deal with the "outside world" to a much greater extent. And that's a scary place. All sorts of things can go wrong. Just to give a random example: the cwd in which a process is run can modify it's behavior. There are probably other issues, but those are the ones I've written down so far. Any other snags you'd like to add? Any suggestions for dealing with these problems?

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  • Connection Pool Strategy: Good, Bad or Ugly?

    - by Drew
    I'm in charge of developing and maintaining a group of Web Applications that are centered around similar data. The architecture I decided on at the time was that each application would have their own database and web-root application. Each application maintains a connection pool to its own database and a central database for shared data (logins, etc.) A co-worker has been positing that this strategy will not scale because having so many different connection pools will not be scalable and that we should refactor the database so that all of the different applications use a single central database and that any modifications that may be unique to a system will need to be reflected from that one database and then use a single pool powered by Tomcat. He has posited that there is a lot of "meta data" that goes back and forth across the network to maintain a connection pool. My understanding is that with proper tuning to use only as many connections as necessary across the different pools (low volume apps getting less connections, high volume apps getting more, etc.) that the number of pools doesn't matter compared to the number of connections or more formally that the difference in overhead required to maintain 3 pools of 10 connections is negligible compared to 1 pool of 30 connections. The reasoning behind initially breaking the systems into a one-app-one-database design was that there are likely going to be differences between the apps and that each system could make modifications on the schema as needed. Similarly, it eliminated the possibility of system data bleeding through to other apps. Unfortunately there is not strong leadership in the company to make a hard decision. Although my co-worker is backing up his worries only with vagueness, I want to make sure I understand the ramifications of multiple small databases/connections versus one large database/connection pool.

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  • Perl: reference to subroutine in external .pm file

    - by Pmarcoen
    I'm having some trouble figuring out how to make a reference to a subroutine in an external .pm file. Right now, I'm doing this : External file package settingsGeneral; sub printScreen { print $_[0]; } Main use settingsGeneral; my $printScreen = settingsGeneral::printScreen; &$printScreen("test"); but this result into an error: Can't use string ("1") as a subroutine ref while "strict refs" in use

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  • External XML using AS3.0

    - by vishnubhatla
    Hi, How can i load external xml file in Action Script 3.0, I have seen a tutorial http://webdeginer.blogspot.com/2010/06/external-xml-loading.html, is it right or I have to see any more tutorials. Thanks, K Swamy Vishnubhatla, webdeginer.blogspot.com.

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  • Setup a git external for remote repo

    - by Tom
    I'd create a repo which pulls in a remote repo, let's say I'd like to setup jQuery as a submodule for example git://github.com/jquery/jquery.git What would be the process of creating a repo with jQuery as a submodule and adding my own external as a remote repo. Also once this is setup, if I push / pull to my own remote, will the external remain intact?

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