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  • Weird nfs performance: 1 thread better than 8, 8 better than 2!

    - by Joe
    I'm trying to determine the cause of poor nfs performance between two Xen Virtual Machines (client & server) running on the same host. Specifically, the speed at which I can sequentially read a 1GB file on the client is much lower than what would be expected based on the measured network connection speed between the two VMs and the measured speed of reading the file directly on the server. The VMs are running Ubuntu 9.04 and the server is using the nfs-kernel-server package. According to various NFS tuning resources, changing the number of nfsd threads (in my case kernel threads) can affect performance. Usually this advice is framed in terms of increasing the number from the default of 8 on heavily-used servers. What I find in my current configuration: RPCNFSDCOUNT=8: (default): 13.5-30 seconds to cat a 1GB file on the client so 35-80MB/sec RPCNFSDCOUNT=16: 18s to cat the file 60MB/s RPCNFSDCOUNT=1: 8-9 seconds to cat the file (!!?!) 125MB/s RPCNFSDCOUNT=2: 87s to cat the file 12MB/s I should mention that the file I'm exporting is on a RevoDrive SSD mounted on the server using Xen's PCI-passthrough; on the server I can cat the file in under seconds ( 250MB/s). I am dropping caches on the client before each test. I don't really want to leave the server configured with just one thread as I'm guessing that won't work so well when there are multiple clients, but I might be misunderstanding how that works. I have repeated the tests a few times (changing the server config in between) and the results are fairly consistent. So my question is: why is the best performance with 1 thread? A few other things I have tried changing, to little or no effect: increasing the values of /proc/sys/net/ipv4/ipfrag_low_thresh and /proc/sys/net/ipv4/ipfrag_high_thresh to 512K, 1M from the default 192K,256K increasing the value of /proc/sys/net/core/rmem_default and /proc/sys/net/core/rmem_max to 1M from the default of 128K mounting with client options rsize=32768, wsize=32768 From the output of sar -d I understand that the actual read sizes going to the underlying device are rather small (<100 bytes) but this doesn't cause a problem when reading the file locally on the client. The RevoDrive actually exposes two "SATA" devices /dev/sda and /dev/sdb, then dmraid picks up a fakeRAID-0 striped across them which I have mounted to /mnt/ssd and then bind-mounted to /export/ssd. I've done local tests on my file using both locations and see the good performance mentioned above. If answers/comments ask for more details I will add them.

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  • Cannot access boot menu with compaq 8510p

    - by pinouchon
    I have a problem with my HP compaq 8510p laptop: when I start it, the fan starts and the power light is on, but the screen displays nothing. When I insert a bootable hard drive, it activates the hard drive light (meaning that the CD is recognized) but it stops after a few seconds. Same thing with any hard drive: the drive is recognized but does not boot. What I've tried so far: Changing the hard drive or booting with no hard drive (same problem) Plugging anoher display via VGA : no display on the other screen Inserting a windows-7 CD (same problem) Booting only on battery, with battery and power cable, only with power cable (same problem) So it looks like something is preventing the laptop from booting and displaying the boot menu. Do you have experienced something similar with a laptop ? What could be wrong ? The laptop is out of warranty. The system used to be windows-7 x64. Edit: I went to the help desk of my university. A guy took a look (he also tried to plug an external screen) and said that the computer is dead: on the HP laptops eventually the GPU card dies and so does the motherboard because they are linked. He saw this many times, and even if I can fix the problem, the laptop would crash again after a while. Do you have similar experience with HP laptops ? (mine is 4 years old) Edit 2: Believe it or not, my laptop is magically working again. I have no clue about what is going on. Now it is like starting and old car: when you turn it on you secretly hope it will actually start... With that said, I expect my laptop to break again in the near future (its an HP after all) and I will accept an answer or add my own accordingly. Edit 3: As expected, the laptop is down again. This time, sometimes when I power it up, it shuts down automatically after 3 seconds, sometimes not at all. In addition, when it does not shut down on its own, the power button does not work : the only way to shut it down is by unplugging the battery. As before, the screen is black, and only the power and battery lights are on. (the other ones: hard drive and wifi are off). I have tried to plug in another power plug, removing the battery and removing the hard drive without success. I might buy another laptop. I've brought the laptop to a repair shop. The problem is indeed that the graphic card is down. It will be replaced by a new one.

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  • On ESXi, guest machines hang for significant intervals compared to real machines. How can I fix this?

    - by Tarbox
    This is ESXi version 5.0.0. We plan on upgrading to 5.5 eventually. I have four code profiles, two taken on a real, unvirtualized machine, two taken on a virtual machine. Ordering the list of subroutines by time spent in each one, the two real profiles are practically identical. The two virtual profiles are different from each other and from the real profiles: a subset of subroutines are taking a lot more time on the virtual machines, and the subset is different for each run. The two virtual profiles take a similar amount of time, which is 3 times the amount of time the real profiles take. This gross "how long does it take?" result is consistent after hundreds of tests across three different virtual machines on two different host machines -- the virtual machine is just slower. I've only the code profiling on the four, however. Here's the most guilty set of lines: This is the real machine: 8µs $text = '' unless defined $text; 1.48ms foreach ( split( "\n", $text ) ) { This is the first run on the virtual machine: 20.1ms $text = '' unless defined $text; 1.49ms foreach ( split( "\n", $text ) ) { This is the second run on the virtual machine: 6µs $text = '' unless defined $text; 21.9ms foreach ( split( "\n", $text ) ) { My WAG is that the VM is swapping out the thread and then swapping it back in, destroying some level of cache in the process, but these code profiles were taken when the vm in question was the only active vm on the host, so... what? What does that mean? The guest itself is under light load, this is a latency problem for my users rather than throughput. The host is also under a light load, if I knew what resources to assign where, I could do it without worrying about the cost. I've attempted to lock memory, reserve cpu, assign a restrictive affinity, and disable hyperthread sharing. They don't help, it still takes the VM 2-4x the amount of time to do the same thing as the real machine. The host the tests were run on is 6x2.50GHz, Intel Xeon E5-26400 w/ 16gigs of ram. The guest exhibits the same performance under a wide combination of settings. The real machine is 4x2.13GHz, Xeon E5506 w/ 2 gigs of ram. Thank you for all advice.

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  • Mysterious visitor to hidden PHP page

    - by B. VB.
    On my website, I have a "hidden" page that displays a list of the most recent visitors. There exist no links at all to this single PHP page, and, theoretically, only I know of its existence. I check it many times per day to see what new hits I have. However, about once a week, I get a hit from a 208.80.194.* address on this supposedly hidden page (it records hits to itself). The strange thing is this: this mysterious person/bot does not visit any other page on my site. Not the public PHP pages, but only this hidden page that prints the visitors. It's always a single hit, and the HTTP_REFERER is blank. The other data is always some variation of Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; YPC 3.2.0; FunWebProducts; .NET CLR 1.1.4322; SpamBlockerUtility 4.8.4; yplus 5.1.04b) ... but sometimes MSIE 6.0 instead of 7, and various other plug ins. The browser is different every time, as with the lowest-order bits of the address. And it's just that. One hit per week or so, to that one page. Absolutely no other pages are touched by this mysterious vistor. Doing a whois on that IP address showed it's from the new york area, and from the "Websense" ISP. The lowest order 8 bits of their address are always different, but always from 208.80.194.*/8. From most of the computers that I access my website, doing a tracerout to my server does not contain a router anywhere along the way with the IP 208.80.*. So that rules out any kind of HTTP sniffing, I might think. I have NO idea how, why this is happening. Does anyone have any clue, or have seen something as strange as this before? It seems completely benign, but unexplainable and a little creepy. Thanks in advance!

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  • Low FPS in some games, but hardware not fully used

    - by Mario De Schaepmeester
    I just did a little funny experiment in the game/sim "Train Simulator 2013". I normally have good FPS in it (around 30) at full settings. What I did was make a really, really long train so that the calculations the sim needed to make were enormous (the sim is quite realistic, it takes all things into account like speed/acceleration, G-forces, comfort levels, possible wheel slip and many more, and most of those things on each carriage seperately). This resulted in only 14FPS as reported by the game, but it felt more like 8FPS or so. I have a Logitech G15 keyboard which has an LCD, and it allows me to monitor CPU/RAM and video card load on it. The strange thing is, all CPU cores were busy, but the total load was only about 60% maximum at all times. The video card was only on 30% load (possibly an important note, the memory was full, which is however not unusual for the game in question). The RAM had plenty of room and there weren't many operations as it didn't grow or shrink much. I just have the feeling that the game would run smoother if it used more of my hardware power. Why is it not doing so? I had the same in another game, The Elder Scrolls: Morrowind when using more than 100 mods (that all use scripting) and a few high res texture mods, + a full-on graphics improvement program. The engine is very old (2003), and so I thought this might be the cause (not being optimised for multithreading). I had thought of possible causes, like: The operating system doesn't let the games use all the resources. It doesn't make use of multi-threading appropriately. To eliminate the former, I tried a CPU stress tool and that got 100% CPU juice as I let it run, so the OS is not the problem. I gave its thread the "higher" priority though. My actual question In both games, I did things the engine was not really built to do or support. Can those games' framerate be limited cause of their own engine not being able to cope? What is the real reason and more importantly, can I help it? And in any case, could something actually be wrong with my hardware? It's all reasonably new, a couple of months, and I (almost) never experience any other trouble. Modern and much more demanding games work absolutely fine. Specs CPU: AMD Phenom II 965 X4 @ 3.4gHz RAM: 8GB of DDR3 RAM Video: MSI GTX560 (nVidia chip) with 1GB of GDDR5 memory OS: Windows 7 Ultimate 64 bit Nothing overclocked.

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  • How to store data on a machine whose power gets cut at random

    - by Sevas
    I have a virtual machine (Debian) running on a physical machine host. The virtual machine acts as a buffer for data that it frequently receives over the local network (the period for this data is 0.5s, so a fairly high throughput). Any data received is stored on the virtual machine and repeatedly forwarded to an external server over UDP. Once the external server acknowledges (over UDP) that it has received a data packet, the original data is deleted from the virtual machine and not sent to the external server again. The internet connection that connects the VM and the external server is unreliable, meaning it could be down for days at a time. The physical machine that hosts the VM gets its power cut several times per day at random. There is no way to tell when this is about to happen and it is not possible to add a UPS, a battery, or a similar solution to the system. Originally, the data was stored on a file-based HSQLDB database on the virtual machine. However, the frequent power cuts eventually cause the database script file to become corrupted (not at the file system level, i.e. it is readable, but HSQLDB can't make sense of it), which leads to my question: How should data be stored in an environment where power cuts can and do happen frequently? One option I can think of is using flat files, saving each packet of data as a file on the file system. This way if a file is corrupted due to loss of power, it can be ignored and the rest of the data remains intact. This poses a few issues however, mainly related to the amount of data likely being stored on the virtual machine. At 0.5s between each piece of data, 1,728,000 files will be generated in 10 days. This at least means using a file system with an increased number of inodes to store this data (the current file system setup ran out of inodes at ~250,000 messages and 30% disk space used). Also, it is hard (not impossible) to manage. Are there any other options? Are there database engines that run on Debian that would not get corrupted by power cuts? Also, what file system should be used for this? ext3 is what is used at the moment. The software that runs on the virtual machine is written using Java 6, so hopefully the solution would not be incompatible.

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  • Pushing Large Files to 500+ Computers [closed]

    - by WMIF
    I work with a team to manage 500-600 rented Windows 7 computers for an annual conference. We have a large amount of data that needs to be synced to these computers, up to 1 TiB. The computers are divided into rooms and connected through unmanaged gigabit switches. We prepare these computers ahead of time with the Windows installation and configuration, plus any files that we have available to us before we send the base image in for replication by the rental company. Every year, we have presenters approach on site with up to gigs of data that need to be pushed to the room that they will be presenting in. Sometimes they only have a few files that are small sizes, such as a slide PDF, but can sometimes be much larger 5 GiB. Our current strategy for pushing these files is using batch scripts and RoboCopy. For the large pushes, we actually use a BitTorrent client to generate a torrent file, and then we use the batch-RoboCopy to push the torrent into a folder on the remote machines that is being monitored by an installed BT client. Often times, this data needs to be pushed immediately with a small time window. We have several machines in a control room that are identical to the machines on the floor that we use for these pushes. We occasionally have a need to execute a program on the remote machines, and we currently use batch and PSexec to handle this task. We would love to be able to respond to these last minute pushes with "sorry, your own fault", but it won't happen. The BT method has allowed us to have a much faster response time, but the whole batch process can get messy when there are multiple jobs being pushed. We use Enterprise Ghost for other processes, and it doesn't work well in this large of scale, plus it is really quite expensive for a once-a-year task like this. EDIT: There is a hard requirement that the remote machines on the floor are running Windows. The control machines do not have a hard OS requirement. I would really like to stay away from Multicast because of complications with upstream routers. Is Multicast or BitTorrent the better way to go on this? Is there another protocol that might work better?

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  • Server to server replication and CPU and 32k\ corrupt doc

    - by nick wall
    Summary: if database contains a doc with 32K issue or corrupt, on server to server replication it causes marked increase in CPU in nserver.exe task, which effectively causes our server(s) to slow right down. We have a 5 server cluster (1 "hub" and 4 HTTP servers accessed via reverse proxy and SSO for load balancing and redundancy). All are physically located next to each other on network, they don't have dedicated network\ ports for cluster or replication. I realise IBM recommendation is dedicated port for cluster. Cluster queues are in tolerance and under heavy application user load, i.e. the maximum number of documents are being created, edited, deleted, the replication times between servers are negligible. Normally, all is well. Of the servers in the cluster, 1 is considered the "hub", and imitates a PUSH-PULL replication with it's cluster mates every 60mins, so that the replication load is taken by the hub and not cluster mates. The problem we have: every now and then we get a slow replication time from the hub to a cluster mate, sometimes up to 30mins. This maxes out the nserver.exe task on the "cluster mate" which causes it to respond to http requests very slowly. In the past, we have found that if a corrupt document is in the DB, it can have this affect, but on those occasions, the server log will show the corrupt doc noteId, we run fixup, all well. But we are not now seeing any record of corrupt docs. What we have noticed is if a doc with the 32K issue is present, the same thing can happen. Our only solution in that case is to run a : fixup mydb.nsf -V, which shows it is purging a 32K doc. Luckily we run a reverse proxy, so we can shut HTTP servers down without users noticing, but users do notice when a server has the problem! Has anyone else seen this occur? I have set up DDM event handlers for many of the replication events. I have set the replication time out limit to 5 mins (the max we usually see under full user load is 0.1min), to prevent it rep'ing for 30mins as before. This ia a temporary work around. Does anyone know of a DDM event to trap the 32K issue? we could at least then send alert. Regarding 32K issue: this prob needs another thread, but we are finding this relatively hard to find the source of the issue as the 32K event is fairly rare. Our app is fairly complex, interacting with various other external web services, with 2 way data transfer. But if we do encounter a 32K doc, we can't look at field properties, so we can't work out which field has issue which would give us a clue as to which process is culprit. As above, we run a fixup -V. Any help\ comments on this would be gratefully received.

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  • Undelivered Mail Returned to Sender

    - by Alex
    When sending to [email protected] via PHP mail() function, I receive mails. When sending emails from external machines, I receive the following (e.g., sending from [email protected]. [mail.ru is Russian gmail]): This is the mail system at host fallback2.mail.ru. I'm sorry to have to inform you that your message could not be delivered to one or more recipients. It's attached below. For further assistance, please send mail to <postmaster> If you do so, please include this problem report. You can delete your own text from the attached returned message. The mail system <[email protected]>: lost connection with mail.mydomain.com[xxx.xxx.xxx.xxx] while receiving the initial server greeting Reporting-MTA: dns; fallback2.mail.ru X-mPOP-Fallback_MX-Queue-ID: D8C19F2411F1 X-mPOP-Fallback_MX-Sender: rfc822; [email protected] Arrival-Date: Tue, 29 Oct 2013 10:09:21 +0400 (MSK) Final-Recipient: rfc822; [email protected] Original-Recipient: rfc822;[email protected] Action: failed Status: 4.4.2 Diagnostic-Code: X-mPOP-Fallback_MX; lost connection with mail.tld.com[xxx.xxx.xxx.xxx] while receiving the initial server greeting Here is my postfix main.cf: command_directory = /usr/sbin daemon_directory = /usr/libexec/postfix data_directory = /var/lib/postfix myhostname = mail.mydomain.com mydomain = mydomain.com myorigin = mydomain.com inet_interfaces = all inet_protocols = all unknown_local_recipient_reject_code = 550 in_flow_delay = 1s alias_maps = hash:/etc/aliases alias_database = hash:/etc/aliases mail_name = mydomain.com daemon debug_peer_level = 2 debugger_command = PATH=/bin:/usr/bin:/usr/local/bin:/usr/X11R6/bin ddd $daemon_directory/$process_name $process_id & sleep 5 sendmail_path = /usr/sbin/sendmail.postfix newaliases_path = /usr/bin/newaliases.postfix mailq_path = /usr/bin/mailq.postfix setgid_group = postdrop html_directory = no manpage_directory = /usr/share/man sample_directory = /usr/share/doc/postfix-2.6.6/samples readme_directory = /usr/share/doc/postfix-2.6.6/README_FILES bounce_queue_lifetime = 4h maximal_queue_lifetime = 4h delay_warning_time = 1h strict_rfc821_envelopes = yes show_user_unknown_table_name = no allow_percent_hack = no swap_bangpath = no smtpd_delay_reject = yes smtpd_error_sleep_time = 20 smtpd_soft_error_limit = 1 smtpd_hard_error_limit = 3 smtpd_junk_command_limit = 2 mydestination = mydomain.com, localhost.localdomain, localhost smtpd_client_restrictions = permit_inet_interfaces smtpd_recipient_limit = 100 virtual_alias_domains = mydomain.com virtual_alias_maps = hash:/etc/postfix/virtual smtpd_sasl_type = dovecot smtpd_sasl_path = private/auth smtpd_sasl_auth_enable = yes smtpd_relay_restrictions = permit_mynetworks, permit_sasl_authenticated, reject_unauth_destination Why emails from external server are not being delivered? Thank you! Update In a log, the following lines appear a lot of times Oct 30 10:48:29 mydomain postfix/smtpd[16216]: connect from fallback5.mail.ru[94.100.176.59] Oct 30 10:48:29 mydomain postfix/smtpd[16216]: warning: SASL: Connect to private/auth failed: Connection refused Oct 30 10:48:29 mydomain postfix/smtpd[16216]: fatal: no SASL authentication mechanisms It appears I have to configure SASL? I would understand if I would like to send emails from postfix, but why do I need it to receive emails?

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  • MySQL performance over a (local) network much slower than I would expect

    - by user15241
    MySQL queries in my production environment are taking much longer than I would expect them too. The site in question is a fairly large Drupal site, with many modules installed. The webserver (Nginx) and database server (mysql) are hosted on separated machines, connected by a 100mbps LAN connection (hosted by Rackspace). I have the exact same site running on my laptop for development. Obviously, on my laptop, the webserver and database server are on the same box. Here are the results of my database query times: Production: Executed 291 queries in 320.33 milliseconds. (homepage) Executed 517 queries in 999.81 milliseconds. (content page) Development: Executed 316 queries in 46.28 milliseconds. (homepage) Executed 586 queries in 79.09 milliseconds. (content page) As can clearly be seen from these results, the time involved with querying the MySQL database is much shorter on my laptop, where the MySQL server is running on the same database as the web server. Why is this?! One factor must be the network latency. On average, a round trip from from the webserver to the database server takes 0.16ms (shown by ping). That must be added to every singe MySQL query. So, taking the content page example above, where there are 517 queries executed. Network latency alone will add 82ms to the total query time. However, that doesn't account for the difference I am seeing (79ms on my laptop vs 999ms on the production boxes). What other factors should I be looking at? I had thought about upgrading the NIC to a gigabit connection, but clearly there is something else involved. I have run the MySQL performance tuning script from http://www.day32.com/MySQL/ and it tells me that my database server is configured well (better than my laptop apparently). The only problem reported is "Of 4394 temp tables, 48% were created on disk". This is true in both environments and in the production environment I have even tried increasing max_heap_table_size and Current tmp_table_size to 1GB, with no change (I think this is because I have some BLOB and TEXT columns).

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  • Why is my concurrency capacity so low for my web app on a LAMP EC2 instance?

    - by AMF
    I come from a web developer background and have been humming along building my PHP app, using the CakePHP framework. The problem arose when I began the ab (Apache Bench) testing on the Amazon EC2 instance in which the app resides. I'm getting pretty horrendous average page load times, even though I'm running a c1.medium instance (2 cores, 2GB RAM), and I think I'm doing everything right. I would run: ab -n 200 -c 20 http://localhost/heavy-but-view-cached-page.php Here are the results: Concurrency Level: 20 Time taken for tests: 48.197 seconds Complete requests: 200 Failed requests: 0 Write errors: 0 Total transferred: 392111200 bytes HTML transferred: 392047600 bytes Requests per second: 4.15 [#/sec] (mean) Time per request: 4819.723 [ms] (mean) Time per request: 240.986 [ms] (mean, across all concurrent requests) Transfer rate: 7944.88 [Kbytes/sec] received While the ab test is running, I run VMStat, which shows that Swap stays at 0, CPU is constantly at 80-100% (although I'm not sure I can trust this on a VM), RAM utilization ramps up to about 1.6G (leaving 400M free). Load goes up to about 8 and site slows to a crawl. Here's what I think I'm doing right on the code side: In Chrome browser uncached pages typically load in 800-1000ms, and cached pages load in 300-500ms. Not stunning, but not terrible either. Thanks to view caching, there might be at most one DB query per page-load to write session data. So we can rule out a DB bottleneck. I have APC on. I am using Memcached to serve the view cache and other site caches. xhprof code profiler shows that cached pages take up 10MB-40MB in memory and 100ms - 1000ms in wall time. Pages that would be the worst offenders would look something like this in xhprof: Total Incl. Wall Time (microsec): 330,143 microsecs Total Incl. CPU (microsecs): 320,019 microsecs Total Incl. MemUse (bytes): 36,786,192 bytes Total Incl. PeakMemUse (bytes): 46,667,008 bytes Number of Function Calls: 5,195 My Apache config: KeepAlive On MaxKeepAliveRequests 100 KeepAliveTimeout 3 <IfModule mpm_prefork_module> StartServers 5 MinSpareServers 5 MaxSpareServers 10 MaxClients 120 MaxRequestsPerChild 1000 </IfModule> Is there something wrong with the server? Some gotcha with the EC2? Or is it my code? Some obvious setting I should look into? Too many DNS lookups? What am I missing? I really want to get to 1,000 concurrency capacity, but at this rate, it ain't gonna happen.

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  • Architectural advice - web camera remote access

    - by Alan Hollis
    I'm looking for architectural advice. I have a client who I've built a website for which essentially allows users to view their web cameras remotely. The current flow of data is as follows: User opens page to view web camera image. Javascript script polls url on server ( appended with unique timestamp ) every 1000ms Ftp connection is enabled for the cameras ftp user. Web camera opens ftp connection to server. Web camera begins taking photos. Web camera sends photo to ftp server. On image url request: Server reads latest image on hard drive uploaded via ftp for camera. Server deleted any older images from the server. This is working okay at the moment for a small amount of users/cameras ( about 10 users and around the same amount of cameras), but we're starting to worrying about the scalability of this approach. My original plan was instead of having the files read from the server, the web server would open up an ftp connection to the web server and read the latest images directly from there meaning we should have been able to scale horizontally fairly easily. But ftp connection establishment times were too slow ( mainly due to the fact that PHP out of the ox is unable to persist ftp connections ) and so we abandoned this approach and went straight for reading from the hard drive. The firmware provider for the cameras state they're able to build a http client which instead of using ftp to upload the image could post the image to a web server. This seems plausible enough to me, but I'm looking for some architectural advice. My current thought is a simple Nginx/PHP/Redis stack. Web camera issues post requests of latest image to Nginx/PHP and the latest image for that camera is stored in Redis. The clients can then pull the latest image from Redis which should be extremely quick as the images will always be stored in memory. The data flow would then become: User opens page to view web camera image. Javascript script polls url on server ( appended with unique timestamp ) every 1000ms Camera is sent an http request to start posting images to a provided url Web camera begins taking photos. Web camera sends post requests to server as fast as it can On image url request: Server reads latest image from redis Server tells redis to delete later image My questions are: Are there any greater overheads of transferring images via HTTP instead of FTP? Is there a simple way to calculate how many potential cameras we could have streaming at once? Is there any way to prevent potentially DOS'ing our own servers due to web camera requests? Is Redis a good solution to this problem? Should I abandon PHP/Ngix combination and go for something else? Is this proposed solution actually any good? Will adding HTTPs to the mix cause posting the image to become too slow? Thanks in advance Alan

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  • mdadm raid1 fails to resync

    - by JuanD
    Hello, I'm trying to solve this problem I'm having with an mdadm raid1. I have an ubuntu 9.04 server running on a software 2-drive raid1 with mdadm. Yesterday, one of the drives failed, and so I replaced it with a brand new drive of the same size. I removed the faulty drive, copied the partition from the remaining good drive to the new drive and then added it to the raid. It re-synced and the system worked fine, until the drive that hadn't failed, was also labeled failed. Now I had the raid running solely on the new drive. So I purchased another drive and repeated the procedure above. So now I had 2 brand new drives and the raid was syncing. However, after a few minutes I checked /proc/mdstat and the raid was no longer syncing. mdadm --detail /dev/md1 shows: (sdb is the first new drive, and sdc is the second new drive) root@dola:/home/jjaramillo# mdadm --detail /dev/md1 /dev/md1: Version : 00.90 Creation Time : Sat Dec 20 00:42:05 2008 Raid Level : raid1 Array Size : 974711680 (929.56 GiB 998.10 GB) Used Dev Size : 974711680 (929.56 GiB 998.10 GB) Raid Devices : 2 Total Devices : 2 Preferred Minor : 1 Persistence : Superblock is persistent Update Time : Wed Jun 2 10:09:35 2010 State : clean, degraded Active Devices : 1 Working Devices : 2 Failed Devices : 0 Spare Devices : 1 UUID : bba497c6:5029ba0b:bfa4f887:c0dc8f3d Events : 0.5395594 Number Major Minor RaidDevice State 2 8 35 0 spare rebuilding /dev/sdc3 1 8 19 1 active sync /dev/sdb3 I've tried removing and re-adding the drive a few times, but the same thing happens. The raid fails to resync. I've looked at /var/log/messages, and found the following: Jun 2 07:57:36 dola kernel: [35708.917337] sd 5:0:0:0: [sdb] Unhandled sense code Jun 2 07:57:36 dola kernel: [35708.917339] sd 5:0:0:0: [sdb] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE Jun 2 07:57:36 dola kernel: [35708.917342] sd 5:0:0:0: [sdb] Sense Key : Medium Error [current] [descriptor] Jun 2 07:57:36 dola kernel: [35708.917346] Descriptor sense data with sense descriptors (in hex): Jun 2 07:57:36 dola kernel: [35708.917348] 72 03 11 04 00 00 00 0c 00 0a 80 00 00 00 00 00 Jun 2 07:57:36 dola kernel: [35708.917357] 00 43 9e 47 Jun 2 07:57:36 dola kernel: [35708.917360] sd 5:0:0:0: [sdb] Add. Sense: Unrecovered read error - auto reallocate failed So it looks like there's some kind of error on sdb (the first new drive). My question is, what would be the best approach to get the raid up and running again? I've thought about dd'ing the /dev/md1 to a blank hard drive, then re-doing the raid from scratch and loading the data back, but there could be an easier solution.. Any help would be appreciated.

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  • windows 7 virtual wireless adapter keeps going to sleep

    - by conners
    Just a quick question that I can't see mentioned anywhere online. I have a Windows 7 box configured like these guys recommend http://www.itgeekdiary.com/windows-7-as-an-wi-fi-access-point/ simply so that I can have my Windows 7 box as a wifi access point or a wifi emitter. It's also called a Microsoft Virtual WiFi Miniport Adapter. But it powers off and shuts down automatically and stops working. Basically everything works as intended and then - well -it will stopped working when I am not at the Windows 7 PC for a long time. The problem seems to be that every time my PC goes to "power save / sleep" and in the morning the Windows 7 machine "wakes" but blooming heck the wifi has stopped and you have to power cycle the PC (which is very uncool). When I power Cycle I have to do the following as administrator C:\Windows\System32\netsh.exe wlan start hostednetwork I then tried a gazllion things involving services and power management and eventually discovered that if I run the following commands as administrator it will be ok (for a bit) but every 3rd ot 4th time I try this "trick" it simply fails. the trick that seems to work 3 out of 4 times (i.e. "most" of the time) C:\Windows\System32\netsh.exe wlan stop hostednetwork C:\Windows\System32\netsh.exe wlan start hostednetwork But why does this only work "some" of the time? What else I did by myself: on every manage adapter properties (that relates to the wifi) I right clicked [configure] [power management] /disabled/ "allow the computer to power off to save power" <- this made no difference Also (and this is a bit annoying) there is no system tray app/GUI for the Microsoft Virtual WiFi Miniport Adapter output signal ... none... so (lame as it sounds) the ONLY way I can check if it's on is to physically go to another device and SCAN.. lame so my question can probably be solved by any of the following: a) can I stop Windows 7 sleeping this wifi when the machine sleeps b) can I force Windows to force wake this process on wake? if so how? c) what is the service / process REALLY called and how do I restart it if it crashes d) how can I flush the wifi properly rather power cycle the host machine e) anyone have a link to an program or app that can sit in the system tray that shows windows 7 wifi hotspot emission status (on/off/etc etc) Since I am a programmer I can easily write a vbs script / windows exe to fix this (and I will share this solution) and the gui problem if I can work out the actual service that is running that netsh stops/starts

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  • Switching efficiently between windows, not apps, in OS X

    - by Vultan
    Previous questions have asked "how can I efficiently switch between windows, not applications, in OS X"? (Switching windows on OS X, Switch between windows on Mac OS X? and others). The most recommended suggestions seem to be: Use some combo of cmd-tab and cmd-~. Use Expose, and possibly Spaces Use Witch I spent the money on Witch, and have been using it for a few weeks; it's ok, but it is sometimes slow to respond, sometimes buggy on window order, crashes my system if I disable and re-enable it too many times, and doesn't work properly with X11 apps. The built-in cmd-tab and cmd-~ are ok, but still bring an entire application to the forefront. I find a very common workflow I use is to bounce back and forth between two windows (for example, a browser window and a Thunderbird email in progress), when both apps (the browser and email software) have multiple windows open. I can use Cmd-Tab to get back and forth between apps, but whenever I switch to an app, ALL windows from that app pop up. That suddenly fills my screen with irrelevant data and windows, and often drops those other windows in front of the single window from the other app that I was using and would conveniently like to keep viewing even though it isn't in focus. Expose seems to be the preferred "OS X natural way," but I can't seem to get myself to use it efficiently. I hit F9, and see 10 windows; I then need to squint, try to find the window I want, then use the mouse or the cursor keys to navigate to the one I want. Given the number of power users who say they use Expose, I must be missing the boat here. My goal is not to make this a repeat of previous questions. I'm not asking "what are my alternatives?" (unless I've missed one above!) Rather, I'm asking: what are you, OS X power users, actually doing to handle the use case I described above? Another common use case for me is having multiple Excel spreadsheets open and multiple browser windows open, and I'm rapidly switching back and forth between one spreadsheet in particular and one browser window. Every time I Cmd-Tab, all spreadsheets or all browser windows appear: I don't want to see the ones I'm not working with, and they tend to hide the windows from the alternative app that I don't have in focus but I'd like to at least eyeball. Can you describe what your workflow is like, and how you rapidly and thoughtlessly switch between windows from apps that have multiple windows open?

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  • TrueCrypt partition will no longer mount

    - by sparkyuiop
    I am hoping for some advice to help me out of my situation, with luck. I have a computer running Windows 7 Ultimate x64 with 3 hard disks installed. On my 2TB hard disk 2 (non-system disk) I have 4 partitions. One is for music, another for video, a downloads partition and a 500GB RAW Truecrypt encrypted partition / volume that I had setup to mount with 4 photographs used as keyfiles. The 4 photographs are located in my 'Documents' partition which is one of four partitions on my 1.5TB hard disk 1 (non-system disk) When I setup the disk encryption I did not (I'm 99% sure) create a password, I only used the 4 photograph keyfiles to mount the volume. Recently my 1TB hard disk 0 (system / boot) started to fail so I decided to replace it. I was going to clone the old disk to a new disk but decided that a fresh installation would be more beneficial. Once I had transferred all the required 'User Data' from my old hard disk 0 (C: disk) I discarded it. I reinstalled Truecrypt, pointed to the partition, selected my 4 keyfiles photographs and I mounted my encrypted volume with no issues. In fact I mounted it several times after re-installing Windows and after reboots. Now all of a sudden when I try and mount it I get the message "incorrect keyfile(s) and/or password or not a Truecrypt volume". Now I am not sure why this happened as I do not recall exactly what I did between last mounting the volume successfully and it not mounting. Here are some of the possible things I may have done to cause it to stop working but I am at a loss as to where to start to try and resolve the problem. 1. I had swapped the drive letters to a preferred order. 2. I possibly swapped the physical SATA connectors on the mainboard. 3. I enabled 'Hot Plugging' for the two non-system hard disk SATA ports and the DVD SATA port in the BIOS. I have tried changing the encrypted partition drive letter as suggested in another post but this does not help. On my old system the encrypted drive was drive "X". I have about tried it with all the other free drive letters but alas nothing changes. I do not recall what drive letter was allocated to the encrypted partition before I changed them all. I have not tried to change the letter back to what it possibly was to start with as I am happy with the current layout. I will try this is anyone thinks it would be worthwhile though. I do hope I have managed to convey my situation in an understandable manner and live in hope someone could help me recover years of personal files. Thank you very much for taking the time to read my post and for any suggestions you may offer. Regards Phillip Thorne (UK) Anyone???

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  • Windows 7 booting and startup repair issues

    - by aardvark
    I have a MSI FR720 laptop with Windows 7 and Lubuntu partions. For quite a while (6 months or so) I've been having issues booting from my hard drive, it'd take me between 5 minutes and several hours for me to be able to have it recognize the hard drive as a bootable device. I did several disk checks on it, and my hard drive seems in perfect condition, and the fact that booting would usually only work after removing the hard drive and trying to reset it in its slot or lightly shaking it makes me think it had something to do with the connection in the hard drive slot as opposed to the hard drive itself. I was having particular issues with it detecting the hard drive today so I decided to try booting it from an external hard drive dock. It detected it first try and so far has had no problems finding the bootable partitions on my hard drive. When I selected my Windows 7 partition from the boot menu it said that it hadn't been shut down properly last time and needed startup repair. I've done this several times over the last 6 months, so this is hardly unusual. I do startup repair, it fails, and then I try to do a system restore. The system restore also failed, and it says that no files were changed. I restart and try it again. However, this time when I get to the startup repair it's not detecting a Windows OS. I tried clicking next and doing a startup repair but the repair is always failing. If I ignore the startup repair option and instead select "Launch windows normally" it will get to the windows animation, stop halfway through and then crash into a BSoD. I can't read the error on the screen because it immediately switches to back and tries to restart. This is my first time asking a question like this online, so let me know if I need to provide any extra information and I'll do my best to give it I tried using diskpart to find the list of partitions and see if one's labelled as an active partition, but it says that no disk were detected. I can run Lubuntu just fine. I can also see all of my Windows 7 files from it EDIT: The startup repair diagnosis and repair log is this: -- Number of repair attempts: 1 Session details System Disk = Windows directory = AutoChk Run = 0 Number of root causes = 1 Test Performed: Name: Check for updates Result: Completed successfully. Error code = 0x0 Time taken = 15ms Test Performed: Name: System disk test Result: Completed successfully. Error code = 0x0 Time taken = 31ms Root cause found. If a hard disk is installed, it is not responding. -- Any chance that this is a result of me doing this through an external dock through a USB drive?

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  • Windows 7 immediately disconnects a USB drive

    - by Daniel Saner
    I am having a problem with Windows 7 x64 consistently disconnecting one specific USB mass storage drive immediately after it is connected. The drive in question is a Cowon C2 digital music player which works in standard mass storage controller mode (i.e. no device-specific drivers needed/available). When I connect the player, Windows plays the "USB connect" sound and the device appears (under its correct name) in the device manager, but it never appears as a drive. The player itself displays "USB Connected" for a split-second before reporting that it has been disconnected again. Since the player, by design, reboots after it has been disconnected, Windows plays the "USB disconnect" sound before restarting the whole cycle once the player has powered back on. I am connecting the player through an Intel X79 Chipset motherboard (Gigabyte GA-X79-UD3) to Windows 7 Pro 64-bit. The player used to work fine the first few times I connected it, showing up as an external drive; it only recently stopped working. It is not a problem with the player, since it works fine when connected to another computer, even such running the exact same operating system. It is also not a problem with the USB controller, since the issue is the same on both the Intel USB 2.0 and the Fresco Logic FL1009 USB 3.0 controller ports. I have also not had the problem with any other drive so far. Among the things I have tried so far: Disabling USB legacy mode in BIOS Disabling energy-saving power down for all USB controllers in Windows' device manager Removing and reinstalling Windows' USB mass storage driver Removing and reinstalling Intel and Fresco Logic USB controller driver Restoring the player to factory defaults None of these made a difference. Again, the player used to work fine on the exact same system just days ago; I didn't install any new hardware or drivers on it since then. I would be very grateful for any hints on what else to try. Edit: Here is another new hint; I found out that when I connect the drive before booting Windows, it is available in Windows Explorer as it should, and does not automatically disconnect. If I remove and reconnect it though, the infinite connect/disconnect-loop starts anew.

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  • How can I minimize the amount my router slows down my Internet connection speed?

    - by Lord Torgamus
    Background I'm working with what I assume is a pretty common Internet setup: a cable modem, a wireless router and a few Internet-connected devices. Lately, I've started being more demanding on my Internet connection, and noticed that using my router slows down my download speeds considerably. I just kind of dealt with it until Zune Marketplace on the Xbox 360 told me that a movie was going to take well over ten hours to download, and I just didn't want to wait that long. Good little scientist that I am, I tried to reduce the problem down to one variable. The test As a control, I turned off all the devices in the house that use wireless Internet, and unplugged all the wired devices except for the Xbox. I also power-cycled both the modem and the router. I then tried to download the movie again, and was told that it would still take over ten hours. Next, I unplugged the router, and connected the Xbox directly to the modem. The movie downloaded in just over one hour. As far as I can tell, this means that my ISP, other cable users near me, the remote servers, anything wireless-related and my machines' disk speeds can't be at fault. A similar experiment that replaced the Xbox with a wired laptop produced similar results. To me, this says "the router is responsible for things taking around ten times longer to download." My question I'd still prefer to use the router for a few reasons: it's a pain to connect and disconnect everything every time there's a big file to download direct connection to the modem isn't good for security only one machine can be connected directly to the modem at a time What can I do to have fast connection speeds while still using the router? I don't mind turning other machines off, as long as I don't have to mess with power and ethernet cables. EDIT : After asking this followup question and then this one, I installed dd-wrt on my router, and I seem to be getting higher and more consistent speeds. Perhaps more importantly, my memory use is fairly constant. I know this isn't an answer — which is why I'm not posting it as an answer — but it is how I resolved the situation, and hopefully it'll be helpful for someone.

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  • CSS issue with elements spanning columns

    - by bigFoot
    Hi folks. Overview: I'm trying to create a relatively simple page layout detailed below and running into problems no matter how I try to approach it. Concept: - A standard-size-block layout. I'll quote unit widths: each content block is 240px square with 5px of margin around it. - A left column of fixed width of 1 unit (245px - 1 block + margin to left). No problems here. - A right column of variable width to fill the remaining space. No problems here either. - In the left column, a number of 1unit x 1unit blocks fixed down the column. Also some blank space at the top - again, not a problem. - In the right column: a number of free-floating blocks of standard unit-sizes which float around and fill the space given to them by the browser window. No problems here. - Lastly, a single element, 2 units wide, which sits half in the left column and half in the right column, and which the blocks in the right column still float around. Here be dragons. Please see here for a diagram: http://is.gd/bPUGI Problem: No matter how I approach this, it goes wrong. Below is code for my existing attempt at a solution. My current problem is that the 1x1 blocks on the right do not respect the 2x1 block, and as a result half of the 2x1 block is overwritten by a 1x1 block in the right-hand column. I'm aware that this is almost certainly an issue with position: absolute taking things out of flow. However, can't really find a way round that which doesn't just throw up another problem instead. Code: <html> <head> <title>wat</title> <style type="text/css"> body { background: #ccc; color: #000; padding: 0px 5px 5px 0px; margin: 0px; } #leftcol { width: 245px; margin-top: 490px; position: absolute; } #rightcol { left: 245px; position: absolute; } #bigblock { float: left; position: relative; margin-top: -240px; background: red; } .cblock { margin: 5px 0px 0px 5px; float: left; overflow: hidden; display: block; background: #fff; } .w1 { width: 240px; } .w2 { width: 485px; } .l1 { height: 240px; } </head> <body> <div class="cblock w2 l1" id="bigblock"> <h1>DRAGONS</h1> <p>Here be they</p> </div> <div id="leftcol"> <div class="cblock w1 l1"> <h1>Left 1</h1> <p>1x1 block</p> </div> </div> <div id="rightcol"> <div class="cblock w1 l1"> <h1>Right 1</h1> <p>1x1 block</p> </div> <div class="cblock w1 l1"> <h1>Right 2</h1> <p>1x1 block</p> </div> <div class="cblock w1 l1"> <h1>Right 3</h1> <p>1x1 block</p> </div> <div class="cblock w1 l1"> <h1>Right 4</h1> <p>1x1 block</p> </div> <div class="cblock w1 l1"> <h1>Right 5</h1> <p>1x1 block</p> </div> <div class="cblock w1 l1"> <h1>Right 6</h1> <p>1x1 block</p> </div> <div class="cblock w1 l1"> <h1>Right 7</h1> <p>1x1 block</p> </div> </div> </body> </html> Constraints: One final note that I need cross-browser compatibility, though I'm more than happy to enforce this with JS if necessary. That said, if a CSS-only solution exists, I'd be extremely happy. Thanks in advance!

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  • What does a Software Developer actually do?

    - by chobo2
    Hi I am graduating from my Computer Science degree in a few weeks from now!! I started to look for my first job. For the last couple years I gotten really into web programming(Asp.net). My first choice would be to get a junior asp.net MVC developer but I don't any companies in my area use MVC yet or if they do they are not hiring. So my second choice would be a junior asp.net Webforms developer. My other choices after that would be forms applications, mobile applications using .Net and C#. As you can see I am looking for something with .Net. I spent the last couple years doing .Net projects for school, on my free time and love the Language and it would pain me right now to switch to something like php. So now I found a posting in my area for an Entry Software Developer. I like the fact that they are using .net and that it is entry job(I never worked in this industry and never had more then like a tutoring job so I want to for like intermediate jobs). Posting Are you looking for an exciting challenge within a dynamic, people-oriented culture where you can launch your technical career? Company Name Inc. is a technology consulting company, located in Canada, that designs, develops, and delivers real-time interactive applications accessed via the Internet as well as back-end tools to support these applications. Company Name provides a combination of out-of-the-box and customized solutions to an expanding list of partners and customers. POSITION SUMMARY As a member of our team, the successful candidate will be responsible for helping us increase the quality and stability of our software systems by working jointly and directly with both the Software Development teams and the QA Team. The primary mission of this role will be to substantially enhance our test automation suite. The incumbent will design and program automated tests (unit, integration, system, stress and load) in Visual Studio using C# and will develop sound processes that help us identify and resolve defects as early as possible. The successful incumbent will help us improve and enhance system functionality, reliability, performance and scalability. This role is specifically designed for an eager, bright, new graduate who is looking for a stepping stone into a software engineering role. We promote from within and invite new graduates to apply for this important position - which may lead to new opportunities. We also offer a generous professional development plan to help you on your way. You will be a key part of a team of experts that is responsible for improving the quality of our software by: • Designing, writing, and executing test plans and programmatic tests in Visual Studio using C# and NUnit for functional testing of our code, new features, regression, and performance test procedures. • Working with the engineers to design and build the stress and load testing framework which emulates tens and even hundreds of thousands of concurrent users via a distributed network interfacing with our Load Testing Lab. • Interfacing with both the Development Team and the QA Team to ensure risks are identified and managed. • Mentoring and leading the QA Team in programmatic test automation technologies and tools. MUST HAVE SKILLS / QUALIFICATIONS: • Diploma or higher Degree in Computer Science, or equivalent formal training. • Fundamental C# programming skills. • Knowledge of Internet technologies and Microsoft Windows platforms. • Knowledge of PC hardware. • Excellent communication skills (both oral and written). • Self-starter who takes initiative, requires minimal supervision, can handle multiple simultaneous tasks. • Detail-oriented, able to concentrate, and work quickly. • Proven diagnostic, analytical, and problem solving skills. NICE TO HAVE SKILLS: • Exposure to Visual Studio Team System or Visual Studio Test Edition. • Exposure in C# using NUnit. • Exposure to NUnit, HTTPUnit, and other automation tool suites. • Exposure to Performance/Stress/Load Testing. • Good understanding of relational databases (MS SQL Server). • Familiar with video and online multi-player games. As part of our team you will have the opportunity to work with a supportive team of experts, drive your own success, and ride the wave as we continually expand our team of experts. If you are interested in this opportunity, please send your resume to [email protected] with “Entry Level Software Developer” in the subject line. So that is the posting. To me it sounds like it is QA job. I don't have anything against QA jobs but alot of them seems to be your just clicking buttons and running scripts. Is this what a typical software developer does? Like I am so on the fence to apply for this job. On one side I am not sure how much programming I would be doing. Like I want to be at least half the time programming otherwise my skills will never improve since I will never be programming in teams and stuff. At the same time I have no experience in the industry so on the other side I am thinking just go for it and then maybe a year later try to get a full programming job(provided that I got the job). Yet if I am not programming in that job then that experience will not help me for the next job I find as I will be back a square one.

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  • Scala n00b: Critique my code

    - by Peter
    G'day everyone, I'm a Scala n00b (but am experienced with other languages) and am learning the language as I find time - very much enjoying it so far! Usually when learning a new language the first thing I do is implement Conway's Game of Life, since it's just complex enough to give a good sense of the language, but small enough in scope to be able to whip up in a couple of hours (most of which is spent wrestling with syntax). Anyhoo, having gone through this exercise with Scala I was hoping the Scala gurus out there might take a look at the code I've ended up with and provide feedback on it. I'm after anything - algorithmic improvements (particularly concurrent solutions!), stylistic improvements, alternative APIs or language constructs, disgust at the length of my function names - whatever feedback you've got, I'm keen to hear it! You should be able to run the following script via "scala GameOfLife.scala" - by default it will run a 20x20 board with a single glider on it - please feel free to experiment. // CONWAY'S GAME OF LIFE (SCALA) abstract class GameOfLifeBoard(val aliveCells : Set[Tuple2[Int, Int]]) { // Executes a "time tick" - returns a new board containing the next generation def tick : GameOfLifeBoard // Is the board empty? def empty : Boolean = aliveCells.size == 0 // Is the given cell alive? protected def alive(cell : Tuple2[Int, Int]) : Boolean = aliveCells contains cell // Is the given cell dead? protected def dead(cell : Tuple2[Int, Int]) : Boolean = !alive(cell) } class InfiniteGameOfLifeBoard(aliveCells : Set[Tuple2[Int, Int]]) extends GameOfLifeBoard(aliveCells) { // Executes a "time tick" - returns a new board containing the next generation override def tick : GameOfLifeBoard = new InfiniteGameOfLifeBoard(nextGeneration) // The next generation of this board protected def nextGeneration : Set[Tuple2[Int, Int]] = aliveCells flatMap neighbours filter shouldCellLiveInNextGeneration // Should the given cell should live in the next generation? protected def shouldCellLiveInNextGeneration(cell : Tuple2[Int, Int]) : Boolean = (alive(cell) && (numberOfAliveNeighbours(cell) == 2 || numberOfAliveNeighbours(cell) == 3)) || (dead(cell) && numberOfAliveNeighbours(cell) == 3) // The number of alive neighbours for the given cell protected def numberOfAliveNeighbours(cell : Tuple2[Int, Int]) : Int = aliveNeighbours(cell) size // Returns the alive neighbours for the given cell protected def aliveNeighbours(cell : Tuple2[Int, Int]) : Set[Tuple2[Int, Int]] = aliveCells intersect neighbours(cell) // Returns all neighbours (whether dead or alive) for the given cell protected def neighbours(cell : Tuple2[Int, Int]) : Set[Tuple2[Int, Int]] = Set((cell._1-1, cell._2-1), (cell._1, cell._2-1), (cell._1+1, cell._2-1), (cell._1-1, cell._2), (cell._1+1, cell._2), (cell._1-1, cell._2+1), (cell._1, cell._2+1), (cell._1+1, cell._2+1)) // Information on where the currently live cells are protected def xVals = aliveCells map { cell => cell._1 } protected def xMin = (xVals reduceLeft (_ min _)) - 1 protected def xMax = (xVals reduceLeft (_ max _)) + 1 protected def xRange = xMin until xMax + 1 protected def yVals = aliveCells map { cell => cell._2 } protected def yMin = (yVals reduceLeft (_ min _)) - 1 protected def yMax = (yVals reduceLeft (_ max _)) + 1 protected def yRange = yMin until yMax + 1 // Returns a simple graphical representation of this board override def toString : String = { var result = "" for (y <- yRange) { for (x <- xRange) { if (alive (x,y)) result += "# " else result += ". " } result += "\n" } result } // Equality stuff override def equals(other : Any) : Boolean = { other match { case that : InfiniteGameOfLifeBoard => (that canEqual this) && that.aliveCells == this.aliveCells case _ => false } } def canEqual(other : Any) : Boolean = other.isInstanceOf[InfiniteGameOfLifeBoard] override def hashCode = aliveCells.hashCode } class FiniteGameOfLifeBoard(val boardWidth : Int, val boardHeight : Int, aliveCells : Set[Tuple2[Int, Int]]) extends InfiniteGameOfLifeBoard(aliveCells) { override def tick : GameOfLifeBoard = new FiniteGameOfLifeBoard(boardWidth, boardHeight, nextGeneration) // Determines the coordinates of all of the neighbours of the given cell override protected def neighbours(cell : Tuple2[Int, Int]) : Set[Tuple2[Int, Int]] = super.neighbours(cell) filter { cell => cell._1 >= 0 && cell._1 < boardWidth && cell._2 >= 0 && cell._2 < boardHeight } // Information on where the currently live cells are override protected def xRange = 0 until boardWidth override protected def yRange = 0 until boardHeight // Equality stuff override def equals(other : Any) : Boolean = { other match { case that : FiniteGameOfLifeBoard => (that canEqual this) && that.boardWidth == this.boardWidth && that.boardHeight == this.boardHeight && that.aliveCells == this.aliveCells case _ => false } } override def canEqual(other : Any) : Boolean = other.isInstanceOf[FiniteGameOfLifeBoard] override def hashCode : Int = { 41 * ( 41 * ( 41 + super.hashCode ) + boardHeight.hashCode ) + boardWidth.hashCode } } class GameOfLife(initialBoard: GameOfLifeBoard) { // Run the game of life until the board is empty or the exact same board is seen twice // Important note: this method does NOT necessarily terminate!! def go : Unit = { var currentBoard = initialBoard var previousBoards = List[GameOfLifeBoard]() while (!currentBoard.empty && !(previousBoards contains currentBoard)) { print(27.toChar + "[2J") // ANSI: clear screen print(27.toChar + "[;H") // ANSI: move cursor to top left corner of screen println(currentBoard.toString) Thread.sleep(75) // Warning: unbounded list concatenation can result in OutOfMemoryExceptions ####TODO: replace with LRU bounded list previousBoards = List(currentBoard) ::: previousBoards currentBoard = currentBoard tick } // Print the final board print(27.toChar + "[2J") // ANSI: clear screen print(27.toChar + "[;H") // ANSI: move cursor to top left corner of screen println(currentBoard.toString) } } // Script starts here val simple = Set((1,1)) val square = Set((4,4), (4,5), (5,4), (5,5)) val glider = Set((2,1), (3,2), (1,3), (2,3), (3,3)) val initialBoard = glider (new GameOfLife(new FiniteGameOfLifeBoard(20, 20, initialBoard))).go //(new GameOfLife(new InfiniteGameOfLifeBoard(initialBoard))).go // COPYRIGHT PETER MONKS 2010 Thanks! Peter

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  • Repeated Squaring - Matrix Multiplication using NEWMAT

    - by Dinakar Kulkarni
    I'm trying to use the repeated squaring algorithm (using recursion) to perform matrix exponentiation. I've included header files from the NEWMAT library instead of using arrays. The original matrix has elements in the range (-5,5), all numbers being of type float. # include "C:\User\newmat10\newmat.h" # include "C:\User\newmat10\newmatio.h" # include "C:\User\newmat10\newmatap.h" # include <iostream> # include <time.h> # include <ctime> # include <cstdlib> # include <iomanip> using namespace std; Matrix repeated_squaring(Matrix A, int exponent, int n) //Recursive function { A(n,n); IdentityMatrix I(n); if (exponent == 0) //Matrix raised to zero returns an Identity Matrix return I; else { if ( exponent%2 == 1 ) // if exponent is odd return (A * repeated_squaring (A*A, (exponent-1)/2, n)); else //if exponent is even return (A * repeated_squaring( A*A, exponent/2, n)); } } Matrix direct_squaring(Matrix B, int k, int no) //Brute Force Multiplication { B(no,no); Matrix C = B; for (int i = 1; i <= k; i++) C = B*C; return C; } //----Creating a matrix with elements b/w (-5,5)---- float unifRandom() { int a = -5; int b = 5; float temp = (float)((b-a)*( rand()/RAND_MAX) + a); return temp; } Matrix initialize_mat(Matrix H, int ord) { H(ord,ord); for (int y = 1; y <= ord; y++) for(int z = 1; z<= ord; z++) H(y,z) = unifRandom(); return(H); } //--------------------------------------------------- void main() { int exponent, dimension; cout<<"Insert exponent:"<<endl; cin>>exponent; cout<< "Insert dimension:"<<endl; cin>>dimension; cout<<"The number of rows/columns in the square matrix is: "<<dimension<<endl; cout<<"The exponent is: "<<exponent<<endl; Matrix A(dimension,dimension),B(dimension,dimension); Matrix C(dimension,dimension),D(dimension,dimension); B= initialize_mat(A,dimension); cout<<"Initial Matrix: "<<endl; cout<<setw(5)<<setprecision(2)<<B<<endl; //----------------------------------------------------------------------------- cout<<"Repeated Squaring Result: "<<endl; clock_t time_before1 = clock(); C = repeated_squaring (B, exponent , dimension); cout<< setw(5) <<setprecision(2) <<C; clock_t time_after1 = clock(); float diff1 = ((float) time_after1 - (float) time_before1); cout << "It took " << diff1/CLOCKS_PER_SEC << " seconds to complete" << endl<<endl; //--------------------------------------------------------------------------------- cout<<"Direct Squaring Result:"<<endl; clock_t time_before2 = clock(); D = direct_squaring (B, exponent , dimension); cout<<setw(5)<<setprecision(2)<<D; clock_t time_after2 = clock(); float diff2 = ((float) time_after2 - (float) time_before2); cout << "It took " << diff2/CLOCKS_PER_SEC << " seconds to complete" << endl<<endl; } I face the following problems: The random number generator returns only "-5" as each element in the output. The Matrix multiplication yield different results with brute force multiplication and using the repeated squaring algorithm. I'm timing the execution time of my code to compare the times taken by brute force multiplication and by repeated squaring. Could someone please find out what's wrong with the recursion and with the matrix initialization? NOTE: While compiling this program, make sure you've imported the NEWMAT library. Thanks in advance!

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  • javascript robot

    - by sarah
    hey guys! I need help making this robot game in javascript (notepad++) please HELP! I'm really confused by the functions <html> <head><title>Robot Invasion 2199</title></head> <body style="text-align:center" onload="newGame();"> <h2>Robot Invasion 2199</h2> <div style="text-align:center; background:white; margin-right: auto; margin-left:auto;"> <div style=""> <div style="width: auto; border:solid thin red; text-align:center; margin:10px auto 10px auto; padding:1ex 0ex;font-family: monospace" id="scene"></pre> </div> <div><span id="status"></span></div> <form style="text-align:center"> PUT THE CONTROL PANEL HERE!!! </form> </div> <script type="text/javascript"> // GENERAL SUGGESTIONS ABOUT WRITING THIS PROGRAM: // You should test your program before you've finished writing all of the // functions. The newGame, startLevel, and update functions should be your // first priority since they're all involved in displaying the initial state // of the game board. // // Next, work on putting together the control panel for the game so that you // can begin to interact with it. Your next goal should be to get the move // function working so that everything else can be testable. Note that all nine // of the movement buttons (including the pass button) should call the move // function when they are clicked, just with different parameters. // // All the remaining functions can be completed in pretty much any order, and // you'll see the game gradually improve as you write the functions. // // Just remember to keep your cool when writing this program. There are a // bunch of functions to write, but as long as you stay focused on the function // you're writing, each individual part is not that hard. // These variables specify the number of rows and columns in the game board. // Use these variables instead of hard coding the number of rows and columns // in your loops, etc. // i.e. Write: // for(i = 0; i < NUM_ROWS; i++) ... // not: // for(i = 0; i < 15; i++) ... var NUM_ROWS = 15; var NUM_COLS = 25; // Scene is arguably the most important variable in this whole program. It // should be set up as a two-dimensional array (with NUM_ROWS rows and // NUM_COLS columns). This represents the game board, with the scene[i][j] // representing what's in row i, column j. In particular, the entries should // be: // // "." for empty space // "R" for a robot // "S" for a scrap pile // "H" for the hero var scene; // These variables represent the row and column of the hero's location, // respectively. These are more of a conveniece so you don't have to search // for the "H" in the scene array when you need to know where the hero is. var heroRow; var heroCol; // These variables keep track of various aspects of the gameplay. // score is just the number of robots destroyed. // screwdrivers is the number of sonic screwdriver charges left. // fastTeleports is the number of fast teleports remaining. // level is the current level number. // Be sure to reset all of these when a new game starts, and update them at the // appropriate times. var score; var screwdrivers; var fastTeleports; var level; // This function should use a sonic screwdriver if there are still charges // left. The sonic screwdriver turns any robot that is in one of the eight // squares immediately adjacent to the hero into scrap. If there are no charges // left, then this function should instead pop up a dialog box with the message // "Out of sonic screwdrivers!". As with any function that alters the game's // state, this function should call the update function when it has finished. // // Your "Sonic Screwdriver" button should call this function directly. function screwdriver() { // WRITE THIS FUNCTION } // This function should move the hero to a randomly selected location if there // are still fast teleports left. This function MUST NOT move the hero on to // a square that is already occupied by a robot or a scrap pile, although it // can move the hero next to a robot. The number of fast teleports should also // be decreased by one. If there are no fast teleports left, this function // should just pop up a message box saying so. As with any function that alters // the game's state, this function should call the update function when it has // finished. // // HINT: Have a loop that keeps trying random spots until a valid one is found. // HINT: Use the validPosition function to tell if a spot is valid // // Your "Fast Teleport" button s

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  • Setting marker title in Google Maps API 3 using jQuery

    - by bateman_ap
    Hi, I am having a couple of problems with Google Maps and jQuery. Wondered if anyone can help with the smaller of the two problems and hopefully it will help me to fixing the bigger one. I am using the below code to populate a google map, basically it uses generated HTML to populate the maps in the form: <div class="item mapSearch" id="map52.48228_-1.9026:800"> <div class="box-prise"><p>(0.62km away)</p><div class="btn-book-now"> <a href="/venue/800.htm">BOOK NOW</a> </div> </div><img src="http://media.toptable.com/images/thumb/13152.jpg" alt="Metro Bar and Grill" width="60" height="60" /> <div class="info"> <h2><a href="/venue/800.htm">Metro Bar and Grill</a></h2> <p class="address">73 Cornwall Street, Birmingham, B3 2DF</p><strong class="proposal">2 courses £14.50</strong> <dl> <dt>Diner Rating: </dt> <dd>7.8</dd> </dl></div></div> <div class="item mapSearch" id="map52.4754_-1.8999:3195"> <div class="box-prise"><p>(0.97km away)</p><div class="btn-book-now"> <a href="/venue/3195.htm">BOOK NOW</a> </div> </div><img src="http://media.toptable.com/images/thumb/34998.jpg" alt="Filini Restaurant - Birmingham" width="60" height="60" /> <div class="info"> <h2><a href="/venue/3195.htm">Filini Restaurant - Birmingham</a></h2> <p class="address">Radisson Blu Hotel, 12 Holloway Circus, Queensway, Birmingham, B1 1BT</p><strong class="proposal">2 for 1: main courses </strong> <dl> <dt>Diner Rating: </dt> <dd>7.8</dd> </dl></div></div> <div class="item mapSearch" id="map52.47775_-1.90619:10657"> <div class="box-prise"><p>(1.05km away)</p><div class="btn-book-now"> <a href="/venue/10657.htm">BOOK NOW</a> </div> </div><img src="http://media.toptable.com/images/thumb/34963.jpg" alt="B1 " width="60" height="60" /> <div class="info"> <h2><a href="/venue/10657.htm">B1 </a></h2> <p class="address">Central Square , Birmingham, B1 1HH</p><strong class="proposal">25% off food</strong> <dl> <dt>Diner Rating: </dt> <dd>7.9</dd> </dl></div></div> The JavaScript loops though all the divs with class mapSearch and uses this to plot markers using the div ID to get the lat/lon and ID of the venue: var locations = $(".mapSearch"); for (var i=0;i<locations.length;i++) { var id = locations[i].id; if (id) { var jsLonLat = id.substring(3).split(":")[0]; var jsId = id.substring(3).split(":")[1]; var jsLat = jsLonLat.split("_")[0]; var jsLon = jsLonLat.split("_")[1]; var jsName = $("h2").text(); var jsAddress = $("p.address").text(); var latlng = new google.maps.LatLng(jsLat,jsLon); var marker = new google.maps.Marker({ position: latlng, map:map, icon: greenRestaurantImage, title: jsName }); google.maps.event.addListener(marker, 'click', function() { //Check to see if info window already exists if (!infowindow) { //if doesn't exist then create a empty InfoWindow object infowindow = new google.maps.InfoWindow(); } //Set the content of InfoWindow infowindow.setContent(jsAddress); //Tie the InfoWindow to the market infowindow.open(map,marker); }); bounds.extend(latlng); map.fitBounds(bounds); } } The markers all plot OK on the map, however I am having probs with the infoWindow bit. I want to display info about each venue when clicked, however using my code above it just puts all info in one box when clicked, not individually. Hoping it is a simple fix! Hoping once I fix this I can work out a way to get the info window displaying if I hover over the div in the html.

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