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  • Why do we get a sudden spike in response times?

    - by Christian Hagelid
    We have an API that is implemented using ServiceStack which is hosted in IIS. While performing load testing of the API we discovered that the response times are good but that they deteriorate rapidly as soon as we hit about 3,500 concurrent users per server. We have two servers and when hitting them with 7,000 users the average response times sit below 500ms for all endpoints. The boxes are behind a load balancer so we get 3,500 concurrents per server. However as soon as we increase the number of total concurrent users we see a significant increase in response times. Increasing the concurrent users to 5,000 per server gives us an average response time per endpoint of around 7 seconds. The memory and CPU on the servers are quite low, both while the response times are good and when after they deteriorate. At peak with 10,000 concurrent users the CPU averages just below 50% and the RAM sits around 3-4 GB out of 16. This leaves us thinking that we are hitting some kind of limit somewhere. The below screenshot shows some key counters in perfmon during a load test with a total of 10,000 concurrent users. The highlighted counter is requests/second. To the right of the screenshot you can see the requests per second graph becoming really erratic. This is the main indicator for slow response times. As soon as we see this pattern we notice slow response times in the load test. How do we go about troubleshooting this performance issue? We are trying to identify if this is a coding issue or a configuration issue. Are there any settings in web.config or IIS that could explain this behaviour? The application pool is running .NET v4.0 and the IIS version is 7.5. The only change we have made from the default settings is to update the application pool Queue Length value from 1,000 to 5,000. We have also added the following config settings to the Aspnet.config file: <system.web> <applicationPool maxConcurrentRequestsPerCPU="5000" maxConcurrentThreadsPerCPU="0" requestQueueLimit="5000" /> </system.web> More details: The purpose of the API is to combine data from various external sources and return as JSON. It is currently using an InMemory cache implementation to cache individual external calls at the data layer. The first request to a resource will fetch all data required and any subsequent requests for the same resource will get results from the cache. We have a 'cache runner' that is implemented as a background process that updates the information in the cache at certain set intervals. We have added locking around the code that fetches data from the external resources. We have also implemented the services to fetch the data from the external sources in an asynchronous fashion so that the endpoint should only be as slow as the slowest external call (unless we have data in the cache of course). This is done using the System.Threading.Tasks.Task class. Could we be hitting a limitation in terms of number of threads available to the process?

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  • Random Hard Freeze of Windows 7 (is Kaspersky to be blamed for this?)

    - by Christian Ivicevic
    The last few weeks I experienced a new strange behavior of my computer. Sometimes Windows 7 just freezes with no real reason at all. While listening to music for example the playback hangs and you can hear a very nasty sound. Neither mouse nor keyboard input is handled and everything is just stuck. Using Ubuntu this does not happen, so I think it is just a matter of driver issues or a Windows 7 bug. Furthermore I am really suspicious about Kaspersky (Internet Security 11) and so I let it perform a complete virus scan while no other app is running. At about 50% it happened again and I needed to restart the computer by holding the power button the bad way... A really weird thing is that playing Skyrim this happened once, however music playback did not stop. Only the framerate dropped to 0 and sometimes for a few seconds I am able to move. Therefore I am really confused as furthermore no bluescreen pops up. Memtest told me that everything seems to be alright... Can anyone explain me which data you need about my hardware and software (and which tools tools to use to gather the informatik) to be able to provide any help on my problem?

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  • How to deploy custom MBean to Tomcat?

    - by Christian
    Hi, I'm trying to deploy a custom mbean to a tomcat. This mbean is not part of a webapp. It should be instantiated when tomcat starts. My problem is, I can't find any complete documentation about how to deploy such a mbean. I'm getting different exceptions, depending on my configuration. Has anyone hints, a complete documentation or has implemented a mbean by himself and can post an example? I configured tomcat to read a configuration from his conf directory: <Engine name="Catalina" defaultHost="localhost" mbeansFile="${catalina.base}/conf/mbeans-descriptors.xml"> The content is as follows: <?xml version="1.0"?> <!-- <!DOCTYPE mbeans-descriptors PUBLIC "-//Apache Software Foundation//DTD Model MBeans Configuration File" "http://jakarta.apache.org/commons/dtds/mbeans-descriptors.dtd"> --> <!-- Descriptions of JMX MBeans --> <mbeans-descriptors> <mbean name="Performance" description="Caculate JVM throughput" type="Performance"> <attribute name="throughput" description="calculated throughput (ratio between gc times and uptime of JVM)" type="double" writeable="false"/> </mbean> </mbeans-descriptors> When name in the xml file and class name match, I get this excption: SEVERE: Error creating mbean Performance javax.management.MalformedObjectNameException: Key properties cannot be empty at javax.management.ObjectName.construct(ObjectName.java:467) at javax.management.ObjectName.<init>(ObjectName.java:1403) at org.apache.tomcat.util.modeler.modules.MbeansSource.execute(MbeansSource.java:202) at org.apache.tomcat.util.modeler.modules.MbeansSource.load(MbeansSource.java:137) at org.apache.catalina.core.StandardEngine.readEngineMbeans(StandardEngine.java:517) at org.apache.catalina.core.StandardEngine.init(StandardEngine.java:321) at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:411) at org.apache.catalina.core.StandardService.start(StandardService.java:519) at org.apache.catalina.core.StandardServer.start(StandardServer.java:710) at org.apache.catalina.startup.Catalina.start(Catalina.java:581) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:289) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at org.apache.commons.daemon.support.DaemonLoader.start(DaemonLoader.java:177) When changing the name attribute in the xml file to test.example:type=Performance, I get this exception: SEVERE: Error creating mbean test.example:type=Performance javax.management.NotCompliantMBeanException: MBean class must have public constructor at com.sun.jmx.mbeanserver.Introspector.testCreation(Introspector.java:127) at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.createMBean(DefaultMBeanServerInterceptor.java:284) at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.createMBean(DefaultMBeanServerInterceptor.java:199) at com.sun.jmx.mbeanserver.JmxMBeanServer.createMBean(JmxMBeanServer.java:393) at org.apache.tomcat.util.modeler.modules.MbeansSource.execute(MbeansSource.java:207) at org.apache.tomcat.util.modeler.modules.MbeansSource.load(MbeansSource.java:137) at org.apache.catalina.core.StandardEngine.readEngineMbeans(StandardEngine.java:517) at org.apache.catalina.core.StandardEngine.init(StandardEngine.java:321) at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:411) at org.apache.catalina.core.StandardService.start(StandardService.java:519) at org.apache.catalina.core.StandardServer.start(StandardServer.java:710) at org.apache.catalina.startup.Catalina.start(Catalina.java:581) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:289) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at org.apache.commons.daemon.support.DaemonLoader.start(DaemonLoader.java:177) The documentation from apache is not really helpful, as it just explains a small part. I'm aware of this question but it doesn't help me. The answer I gave worked just for a short time, after that I got some other exceptions. For additional info, the java interface public interface PerformanceMBean { public double getThroughput(); } and implementing class /* some import statements */ public class Performance implements PerformanceMBean { public double getThroughput() { ... } }

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  • Remote Sending of Emails via SMTP/EXIM Issue

    - by Christian Noel
    I have been encountering a problem when sending messages via EXIM. Here is the scenario: I have 2 servers lets just say host1.com = where all my apps and programs are hosted. host2.com = is another server which handles some apps but is also my smtp mail server. whm and cpanel are installed in both hosts as well as exim. right now, messages are being sent out as [email protected] to clients. host1.com uses the [email protected] so that it can send messages outbound as well. here's the problem, after a few hours from a fresh reboot of host1.com, sending messages from host1.com is no longer possible because i encounter an error that states: system/vendor/swift/Swift/Connection/SMTP.php [309]: The SMTP connection failed to start [tls://mail.host2.com]: fsockopen returned Error Number 110 and Error String 'Connection timed out'` also note that this was working fine earlier (like 10 hours ago) but then it suddenly fails. everytime i restart the host1.com then sending messages will work again. i have checked logs and traces but to no avail the only means of fixing this problem is restarting host1.com.

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  • Exchange 2010 OWA with Client Certificates

    - by Christian
    I have enabled Client Certificate Authentication for Exchange 2010 through IIS7 and the users are prompted to choose their User Certificate when they log in, but they are all then presented with the following error message Request Url: https://<domain_name>:443/owa/ User host address: <server_ip_address> OWA version: 14.1.355.2 Exception Exception type: System.NullReferenceException Exception message: Object reference not set to an instance of an object. Call stack Microsoft.Exchange.Clients.Owa.Core.RequestDispatcher.GetUserIdentities(OwaContext owaContext, OwaIdentity& logonIdentity, OwaIdentity& mailboxIdentity, Boolean& isExplicitLogon, Boolean& isAlternateMailbox, ExchangePrincipal& logonExchangePrincipal) Microsoft.Exchange.Clients.Owa.Core.RequestDispatcher.InternalDispatchRequest(OwaContext owaContext) Microsoft.Exchange.Clients.Owa.Core.RequestDispatcher.DispatchRequest(OwaContext owaContext) Microsoft.Exchange.Clients.Owa.Core.OwaRequestEventInspector.OnPostAuthorizeRequest(Object sender, EventArgs e) System.Web.HttpApplication.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) The method I followed to enable Certificate authentiaction was from this post: http://www.miru.ch/2011/04/how-to-enable-certificate-based-authentication-on-exchange-2010/ Any ideas? Google isn't being very helpful

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  • Float table to bottom of page in Word 2007

    - by Christian W
    Is it possible to float a table to the bottom of a page in Word 2007? I am making a template for revisable documents for work (specs, routines etc) and I want the front page to contain the document title, and a table of revisions. I want to float this table to the bottom of the page. So as I add rows to it, it grows upwards towards the title (which is at top of page, and not middle.) Is this possible?

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  • Ubuntu 10.10 strange USB file Permissions

    - by Christian Hubinger
    Hi, I'm developing a cross-plattform application that is delivered an run dirctly form an USB stick. As FAT32 ist the only FS working well for this (rw on windos/linux/mac) we use it as the FS for the stick. My Problem is that from Ubuntu 10.4 - 10.10 something changed at mounting the stick is mounted with files: rw-rw-r directories: rwxrwxr-x and (that is really strange) the Win32 Version of the application app.exe: rwxrwxr-x I tried for quit a while to find out where this is configured but could not find it - simple udev rule with MODE="0777" simpyl gets ignored. Any kind of idea help is very, very welcome, as not being able to find a solution for this is a real show stopper. thanks in advance and kind regards, Chris

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  • mysql settings - using the available resources

    - by Christian Payne
    I've got a lot of processing work I need to run on a mysql server. I've installed mysql 5.1.45-community on a Win 2007 64bit. Its running on a xenon, 3ghz 6 processors with 8 gig ram. It doesn't seem to matter what queries I run (or the number I run at the same time), when I look in task manager, I'll see one processor is out at 100%. The other 5 are idol. Memory is static at 1.54 gig. When I installed mysql, I used the wizard and selected the default "server" (not workstation) option. I feel like I should be getting more bang for my buck. Is there something else I should be monitoring or something I should change to use the other system resources???

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  • Available Instance types for marketplace ami's

    - by Christian
    I based my autoscaling AMI's on the Turnkey Linux nginx AMI from the marketplace. I am now unable to select any of the newer generation instance types; for instance, my autoscaling uses m3.large type but I'd really like it to use the c3.xlarge type but every time I try to create a c3.xlarge instance with my AMI I get errors; The instance configuration for this AWS Marketplace product is not supported. My question is; Can I override this? I'm not using TKL support or any of their services, just the AMI. If I can't override it, do I have any other options besides creating a brand new AMI from scratch to use?

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  • No Editor in Directory Utility

    - by Christian Macht
    I'm on OSX 10.6.8 and would like to enable the root user. I found Apple's KB article, however this point Click the lock in the Directory Utility window. Enter an administrator account name and password, then click OK. Choose Enable Root User from the Edit menu. is not possible, because there is no "Edit Menu" Icon! I'm logged in as admin, but I only see "Services" and "Search Policy". Repeat, I do not see the "Editor", it's just not there. What gives? How it should be: Directory Utility

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  • Hanging page loads every n loads

    - by Christian
    Hi Guys I recently moved my site to a new server (Apache 2, PHP5, MySQL5). The site is an Invision based forum. Every few posts / topics it just hangs. The data has been written because if you stop and reload, the post / thread is there. I thought it was a write issue initially, but nope. So, the data is written but the page load never completes. It doesn't leave the page where the data has been input. Whats the best way to trouble shoot this issue? The only thing I have done recently is reduce my MySQL timeouts, but I can't see that being an issue as the values are still big enough and there are no mentions of timeouts in the MySQL log. (For the record there is nothing in PHP's error log either) Thanks in advance!

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  • Windows 7 UAC (user access control) is being disabled on every reboot

    - by Christian Thamer
    To put it simply, I noticed UAC was disabled so I enabled it. I was prompted to reboot the computer for the changes to take effect. Upon my reboot I checked the settings again as I hadn't disabled UAC in the first place. It was again set to off (never notify). For the heck of it I repeated the process a couple of more times. Same result each time. I have Microsoft Security Essentials running a full scan nightly so I should be protected from viruses. I also did an on demand scan with the online tool at www.antivirus.com. Nothing was found. Other than the fact that UAC is being disabled on each reboot I have no other reason to suspect a virus. So my question is does anyone have insight into if this is a possible problem with a virus or other malware changing my UAC settings on each boot or is it possibly a problem with Windows and UAC itself? If it is malware are there suggestions for other products outside of the ones I have used to detect and remove it.

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  • Enabling login logging in Ubuntu 9.10

    - by Sopa Christian
    On a Ubuntu 9.10 system: $ uname -a Linux ionut-laptop 2.6.31-14-generic #48-Ubuntu SMP Fri Oct 16 14:04:26 UTC 2009 i686 GNU/Linux the files /var/log/wtmp and /var/log/btmp are empty: $ ls -la /var/log/?tmp -rw-rw---- 1 root utmp 0 2010-04-10 16:54 /var/log/btmp -rw-rw-r-- 1 root utmp 0 2010-04-10 16:54 /var/log/wtmp Because of this, the last(1) command is not working. What to do?

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  • apt-get install phpmyadmin on debian doesn't install /etc/phpmyadmin/apache.conf

    - by Christian Nikkanen
    I'm trying to install phpmyadmin on my webserver, using this guide: http://www.howtoforge.com/ubuntu_debian_lamp_server I did that once, and it worked like a dream, but I hated the looks of phpmyadmin (maybe the oldest layout ever) and decided to delete it, and didn't know that deleting is done with apt-get remove phpmyadmin and did in phpmyadmin directory rm * and thought that it's done. However, as I can't find the debian build of phpmyadmin anywhere, I want to install it again, but when I add Include /etc/phpmyadmin/apache.conf to /etc/apache2/apache2.conf, and restart apache, it give's me this error: apache2: Syntax error on line 73 of /etc/apache2/apache2.conf: Could not open configuration file /etc/phpmyadmin/apache.conf: No such file or directory Action 'configtest' failed. The Apache error log may have more information. failed! No matter how I try, I always get this error, and phpmyadmin isn't there.

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  • Resolving a BSOD/CPU/GPU issue...

    - by Christian Sciberras
    Hello all, I'm getting a BSOD / system crash (sometimes the PC just quits without a BSOD). Hardware Specifications cpu: i7 920 2666MHz / 8 cores (not OCed afaik) mobo: Asus P6T SE ram: 2x Corsair CM3X2G1333C9 (64bit DDR3 667MHz) gfx: ATI Radeon HD 5970 1GB (XFX HD5970 BE) os: Windows 7 Ultimate 64 bit (legit) All bios, firmware and drivers are all up to date (as of today). Symptoms Sometimes the PC runs smoothly, sometimes I get this BSOD. The BSOD always happens when I'm doing something related to graphics, such as viewing a video or playing a game. I get to know about the imminent BSOD ~10 seconds earlier; the PC starts freezing occasionally but increasing in frequency and length of lag (I noticed processor usage in creased from Process Monitor). I've tweaked BIOS settings occasionally but afaik, it was in vain. A day or so ago, I reset it to factory settings. BSOD contents The computer has rebooted from a bugcheck. The bugcheck was: 0x00000101 (0x0000000000000019, 0x0000000000000000, 0xfffff88001f35180, 0x0000000000000004). 15-12-2010 A fatal hardware error has occurred. Reported by component: Processor Core Error Source: Machine Check Exception Error Type: Internal Timer Error Processor ID: 4 23-12-2010 A fatal hardware error has occurred. Reported by component: Processor Core Error Source: Machine Check Exception Error Type: Internal Timer Error Processor ID: 2 Important The interesting thing is that although the event log (and BSOD screen) blame a "secondary processor", Windows Action Center sometimes blamed the GFX driver (for the same error). Also It is interesting to note that after hibernating my PC, I always get the BSOD.

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  • How can I simulate blocking RTMP over port 80 on Windows?

    - by Christian Nunciato
    It seems like this should be so simple, but since this isn't my area of expertise, I'm having a hell of a time figuring out how to do it. Basically, I have a Flash app and I'm connecting to a Flash Media Server to stream some content. The URL I'm using to do this, for example, looks like this: rtmp://someserver.com/some/path/mp3:somefile Everything works -- but that's sort of the problem. When I'm trying to do is simulate my users attempting to play back my media under more restrictive conditions than the ones I have here (i.e., none) -- namely being stuck behind firewalls or proxy servers that block access to RTMP streams. Flash, according to Adobe, is equipped to handle proxy servers and firewalls automatically, like so (from the docs): When you do not specify a port number in an RTMP address, Flash will attempt to connect to port 1935. If it fails it will then try to connect to port 443; if that fails, it will try port 80. [And if that fails, it will attempt to connect via RTMPT (i.e., HTTP tunneling) on port 80.] So no coding is required to access ports 1935, 443, or port 80 if you do not specify a port in the RTMP address. The problem I'm having is setting up a reliable environment in which to test that this behavior actually happens. I'm on a Windows machine, for example, so with Windows Firewall, I can block certain ports and protocols (1935, 443), but I don't want to block port 80, because the final fallback protocol (RTMPT) is supposed to run on port 80, and Windows Firewall only gives me enough granularity (as far as I know, anyway) to block "all outbound TCP traffic to remote port 80" -- that is, I can't, apparently, block "all outbound RTMP traffic to port 80" while leaving RTMPT traffic to port 80 unaffected. My understanding thus far is that I'll probably need to set up a proxy server to do this. Is this correct? Or is there a simpler way (on Win 7, at least) to filter out RTMP to 1935, RTMP to 443, RTMP to 80, but still allow RTMPT to 80 (where all four hostnames are identical)? And if I do have to set up a proxy server, what's the simplest way to go on Windows? I've set up WinProxy, which seems a bit janky but apparently works -- but then what I can't figure out is how to tell Windows to force all TCP traffic (including RTMP, RTMPT and HTTO) through this proxy server so I can turn around and reject the requests for RTMP. Any help would be hugely appreciated. This isn't my realm of expertise and I've alreasdy spent more time on it than I probably should. :)

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  • Alternatives for heapdumps creation with higher performance than jmap?

    - by Christian
    Hi, I have to create heapdumps, which works nice with jmap. My problem is, that jmap takes very long to create the heapdump file. Especially when the heap is getting bigger ( 1GB) it is taking too long. One situation as example: When the server gets into trouble with the heapspace, I want to restart it automatically and create a heapdump before the restart. This works, but takes too long to write the heapdump. This way the server is down for too long. The heapdump creation takes longer than one hour. I know about -XX:+HeapDumpOnOutOfMemoryError, but most of the time I can find the memory problem before the exception is thrown by the jvm. Is there an alternative to jmap which writes the heapdumps faster? A special solution for the example above would also be appreciated. This question is a mix between programming and system-administration, but I think I'm at the right place here.

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  • Regular issue with keys on temp tables

    - by Christian
    We run a large forum with lots of reads and writes, particularly to the posts and topics tables which are both innodb. Last week I started doing 12 hourly backups with innobackupex because mysqldump just takes forever (7+ million rows in posts table.) It seems that something doesn't like these backups because I have a recurring problem every other day. The symptoms; The front page of the site starts throwing errors The logs start showing errors like Error: 126 - Incorrect key file for table '/tmp/mysql/#sql_4e87_14.MYI'; try to repair it The /tmp/ dir fills up and we start getting Error: 1030 - Got error 28 from storage engine in the logs. The only way to fix is to optimize table on each of the posts and topics tables. I'm trying all I can to stop MySQL using disks for temp tables, but I'd have more problems than this if it used all my memory also. My my.cnf is here; https://gist.github.com/cbiggins/0aa26f6defb7a14541d7 The box has 32GB memory and I don't come near that usually. Currently at 15GB use. Thanks in advance. Update 1: Despite the conf looking like there is replication, there isn't. This is a stand alone instance.

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  • I need something substantial to do [on hold]

    - by Christian Delapena
    I'm a 19 year old computer geek who was recently exposed to Linux. I know quite a bit of it now and would like to do something substantial with it. I've visited websites like openhatch where you can get started on opensource projects but I'm more interested in something Linux-specific like hosting a website or tracking some important operation. Maybe running a script that will give me data on something important. I don't know. I'm essentially bored and I want to put my knowledge and love of Linux to good use. Someone please point me in the right direction.

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  • Sending output to both bluetooth headset and normal speakers - Windows 7

    - by Christian Mann
    Hey, I have a bluetooth "headset" (it's more like a speaker with a microphone on it, but it registers as a headset) and I want to play music through it. I also want to play the same music through the "normal" speakers on the laptop. Is this possible? If so, is it possible to play two different streams on each speaker? Say if I wanted to DJ a party or something, I'd want to hear the upcoming song and mix it before sending it live.

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