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  • How can Agile methodologies be adapted to High Volume processing system development?

    - by luckyluke
    I am developing high volume processing systems. Like mathematical models that calculate various parameters based on millions of records, calculated derived fields over milions of records, process huge files having transactions etc... I am well aware of unit testing methodologies and if my code is in C# I have no problem in unit testing it. Problem is I often have code in T-SQL, C# code that is a SQL stored assembly, and SSIS workflow with a good amount of logic (and outcomes etc) or some SAS process. What is the approach YOu use when developing such systems. I usually develop several tests as Stored procedures in a designed schema(TEST) and then automatically run them overnight and check out the results. But this is only for T-SQL. And Continous integration IS hard. But the problem is with testing SSIS packages. How do You test it? What is Your preferred approach for stubbing data into tables (especially if You need a lot data initialization). I have some approach derived over the years but maybe I am just not reading enough articles. So Banking, Telecom, Risk developers out there. How do You test your mission critical apps that process milions of records at end day, month end etc? What frameworks do You use? How do You validate that Your ssis package is Correct (as You develop it)/ How do You achieve continous integration in such an environment (Personally I never got there)? I hope this is not to open-ended question. How do You test Your map-reduce jobs for example (i do not use hadoop but this is quite similar). luke Hope that this is not too open ended

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  • How do I make my character slide down high-angled slopes?

    - by keinabel
    I am currently working on my character's movement in Unity3D. I managed to make him move relatively to the mouse cursor. I set a slope limit of 45°, which does not allow the character to walk up the mountains with higher degrees. But he can still jump them up. How do I manage to make him slide down again when he jumped at places with too high slope? Thanks in advance. edit: Code snippet of my basic movement. using UnityEngine; using System.Collections; public class BasicMovement : MonoBehaviour { private float speed; private float jumpSpeed; private float gravity; private float slopeLimit; private Vector3 moveDirection = Vector3.zero; void Start() { PlayerSettings settings = GetComponent<PlayerSettings>(); speed = settings.GetSpeed(); jumpSpeed = settings.GetJumpSpeed(); gravity = settings.GetGravity(); slopeLimit = settings.GetSlopeLimit(); } void Update() { CharacterController controller = GetComponent<CharacterController>(); controller.slopeLimit = slopeLimit; if (controller.isGrounded) { moveDirection = new Vector3(Input.GetAxis("Horizontal"), 0, Input.GetAxis("Vertical")); moveDirection = transform.TransformDirection(moveDirection); moveDirection *= speed; if (Input.GetButton("Jump")) { moveDirection.y = jumpSpeed; } } moveDirection.y -= gravity * Time.deltaTime; controller.Move(moveDirection * Time.deltaTime); } }

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  • High-level description of how experimental C++ features are developed?

    - by Praxeolitic
    Herb Sutter in a video answers a question about the concepts proposal considered for C++11 and from his remarks it sounds like multiple groups offered prototype implementations but all of them left concerns about slow compile times. The comment surprised me because it suggests that, at least in some cases, the prototypes being developed are not just proofs of concept -- they're even expected to perform. All the work that must take has me curious. For mature languages, especially C++, how are experimental language features developed? Is it much different from developing a compiler that implements a standard? Does a developer have a sense of if it will work and perform or even if it ever could? What are the most time consuming parts and are any parts surprisingly easier than one might expect? The question is not what does the C++ standards committee do, but rather the part that comes before. When an experimental implementation for a proposal is being put together and there aren't any completely solidified rules, how is the sausage made? I'm not a professional compiler developer nor do I expect answers with step by step accounts. I'd like a high-level idea of how this would be done or if there are any general patterns at all. I don't know what to expect from the answers but even if there are no rules to the process and the small number of people who do this just cowboy it and then, for stuff that worked out, write up the "official version" as a proposal, that answer would still be informative.

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  • How to Achieve Real-Time Data Protection and Availabilty....For Real

    - by JoeMeeks
    There is a class of business and mission critical applications where downtime or data loss have substantial negative impact on revenue, customer service, reputation, cost, etc. Because the Oracle Database is used extensively to provide reliable performance and availability for this class of application, it also provides an integrated set of capabilities for real-time data protection and availability. Active Data Guard, depicted in the figure below, is the cornerstone for accomplishing these objectives because it provides the absolute best real-time data protection and availability for the Oracle Database. This is a bold statement, but it is supported by the facts. It isn’t so much that alternative solutions are bad, it’s just that their architectures prevent them from achieving the same levels of data protection, availability, simplicity, and asset utilization provided by Active Data Guard. Let’s explore further. Backups are the most popular method used to protect data and are an essential best practice for every database. Not surprisingly, Oracle Recovery Manager (RMAN) is one of the most commonly used features of the Oracle Database. But comparing Active Data Guard to backups is like comparing apples to motorcycles. Active Data Guard uses a hot (open read-only), synchronized copy of the production database to provide real-time data protection and HA. In contrast, a restore from backup takes time and often has many moving parts - people, processes, software and systems – that can create a level of uncertainty during an outage that critical applications can’t afford. This is why backups play a secondary role for your most critical databases by complementing real-time solutions that can provide both data protection and availability. Before Data Guard, enterprises used storage remote-mirroring for real-time data protection and availability. Remote-mirroring is a sophisticated storage technology promoted as a generic infrastructure solution that makes a simple promise – whatever is written to a primary volume will also be written to the mirrored volume at a remote site. Keeping this promise is also what causes data loss and downtime when the data written to primary volumes is corrupt – the same corruption is faithfully mirrored to the remote volume making both copies unusable. This happens because remote-mirroring is a generic process. It has no  intrinsic knowledge of Oracle data structures to enable advanced protection, nor can it perform independent Oracle validation BEFORE changes are applied to the remote copy. There is also nothing to prevent human error (e.g. a storage admin accidentally deleting critical files) from also impacting the remote mirrored copy. Remote-mirroring tricks users by creating a false impression that there are two separate copies of the Oracle Database. In truth; while remote-mirroring maintains two copies of the data on different volumes, both are part of a single closely coupled system. Not only will remote-mirroring propagate corruptions and administrative errors, but the changes applied to the mirrored volume are a result of the same Oracle code path that applied the change to the source volume. There is no isolation, either from a storage mirroring perspective or from an Oracle software perspective.  Bottom line, storage remote-mirroring lacks both the smarts and isolation level necessary to provide true data protection. Active Data Guard offers much more than storage remote-mirroring when your objective is protecting your enterprise from downtime and data loss. Like remote-mirroring, an Active Data Guard replica is an exact block for block copy of the primary. Unlike remote-mirroring, an Active Data Guard replica is NOT a tightly coupled copy of the source volumes - it is a completely independent Oracle Database. Active Data Guard’s inherent knowledge of Oracle data block and redo structures enables a separate Oracle Database using a different Oracle code path than the primary to use the full complement of Oracle data validation methods before changes are applied to the synchronized copy. These include: physical check sum, logical intra-block checking, lost write validation, and automatic block repair. The figure below illustrates the stark difference between the knowledge that remote-mirroring can discern from an Oracle data block and what Active Data Guard can discern. An Active Data Guard standby also provides a range of additional services enabled by the fact that it is a running Oracle Database - not just a mirrored copy of data files. An Active Data Guard standby database can be open read-only while it is synchronizing with the primary. This enables read-only workloads to be offloaded from the primary system and run on the active standby - boosting performance by utilizing all assets. An Active Data Guard standby can also be used to implement many types of system and database maintenance in rolling fashion. Maintenance and upgrades are first implemented on the standby while production runs unaffected at the primary. After the primary and standby are synchronized and all changes have been validated, the production workload is quickly switched to the standby. The only downtime is the time required for user connections to transfer from one system to the next. These capabilities further expand the expectations of availability offered by a data protection solution beyond what is possible to do using storage remote-mirroring. So don’t be fooled by appearances.  Storage remote-mirroring and Active Data Guard replication may look similar on the surface - but the devil is in the details. Only Active Data Guard has the smarts, the isolation, and the simplicity, to provide the best data protection and availability for the Oracle Database. Stay tuned for future blog posts that dive into the many differences between storage remote-mirroring and Active Data Guard along the dimensions of data protection, data availability, cost, asset utilization and return on investment. For additional information on Active Data Guard, see: Active Data Guard Technical White Paper Active Data Guard vs Storage Remote-Mirroring Active Data Guard Home Page on the Oracle Technology Network

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  • question about mergesort

    - by davit-datuashvili
    i have write code on mergesort here is code public class mergesort{ public static int a[]; public static void merges(int work[],int low,int high){ if (low==high) return ; else{ int mid=(low+high)/2; merges(work,low,mid); merges(work,mid+1,high); merge(work,low,mid+1,high); } } public static void main(String[]args){ int a[]=new int[]{64,21,33,70,12,85,44,99,36,108}; merges(a,0,a.length-1); for (int i=0;i<a.length;i++){ System.out.println(a[i]); } } public static void merge(int work[],int low,int high,int upper){ int j=0; int l=low; int mid=high-1; int n=upper-l+1; while(low<=mid && high<=upper) if ( a[low]<a[high]) work[j++]=a[low++]; else work[j++]=a[high++]; while(low<=mid) work[j++]=a[low++]; while(high<=upper) work[j++]=a[high++]; for (j=0;j<n;j++) a[l+j]=work[j]; } } but it does nort work after compile this code here is mistake java.lang.NullPointerException at mergesort.merge(mergesort.java:45) at mergesort.merges(mergesort.java:12) at mergesort.merges(mergesort.java:10) at mergesort.merges(mergesort.java:10) at mergesort.merges(mergesort.java:10) at mergesort.main(mergesort.java:27)

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  • apache2 + mod_fastcgi + suexec + php5.2 = unstable on high load...

    - by redguy..pl
    I am hosting several (~30) different sites on one server with apache2+fastcgi+suexec+php5. Sites have different loads and different execution times of their scripts (some of them process request for 5-7 seconds, some <1sek). Sometimes when single site receives very high load (all php instances of this site are created and used) - whole apache server hangs. Apache (worker mpm) creates new processes up to the upper limit. It looks like it is starting to queue ALL new request for EVERY site, not only the one that has high load and quickly achieves process limits... restart of apache solves the problem... config: FastCgiConfig -singleThreshold 1 -multiThreshold 10 -listen-queue-depth 30 -maxProcesses 80 -maxClassProcesses 12 -idle-timeout 30 -pass-header HTTP_AUTHORIZATION -pass-header If-Modified-Since -pass-header If-None-Match (earlier have default -listen-queue-depth = 100, but it didn't change anything...) Any suggestions? Another question - how is implemented this listen queue? is it one queue for whole apache, or unique queue for every defined php apllication (suexec site)? I would like to achieve something like this: when one site receives high load and its queue is full - server bounces next request, but only for this one site.. Other sites should work properly...

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  • Very high-pitched noise when computer does something intense?

    - by Starkers
    "Intense" is the best word I can use to describe it because I'm not sure what it is, whether it's RAM, GPU or CPU. If I pan the camera in unity: A high pitched noise issues from the computer. The picosecond I start panning the sound starts. Stops the picosecond I stop panning. If I start an infinite loop: 2.0.0p247 :016 > x = 1 => 1 2.0.0p247 :017 > while x < 2 do 2.0.0p247 :018 > puts 'huzzah!' 2.0.0p247 :019?> end huzzah! huzzah! huzzah! An identical high pitched noise can be heard. I don't think it's the GPU due to this simple experiment. Or any monitor-weirdness (although the sound does sound like one of those old CRT monitors if you're old enough to be young when those things were about) The CPU? Or maybe my SSD? It's my first SSD and the first time I've heard this noise. Should I be worried? Regardless, what's causing this sound? I can't think what would cause such high frequency vibrations. I built the PC myself. Not enough heat paste on the CPU? Too much? Just no idea what's going on. Info: CPU Type QuadCore Intel Core i5-3570K, 3800 MHz (38 x 100) Motherboard Name Asus Maximus V Extreme Flash Memory Type Samsung 21nm TLC NAND Video Adapter Asus HD7770

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  • BackupExec Hyper-V availability (within BackupExec 2010 or seperate?)

    - by blade
    Hi, I have downloaded the trial of Symantec BackupExec 2010 but I am a little confused: The agent for Hyper-V is available and for sale ($1800 or something), but the trial of BackupExec tells me i can install the agents I need from the installer. Can I install a full version of BackupExec, providing I have the license, but also install a full version of the Hyper-V agent? Or do I have to download/buy this seperately? Is a trial version available for the agents? As is probably obvious from this thread, I am a bit confused about the business model of this product. Please clarify. Thanks

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  • How to make a server check it's own availability on the web?

    - by Javawag
    Hi all, Just a quick question – my server is running at my house serving www pages at www.javawag.com. The problem is that my home internet connection keeps dropping randomly - for about 10 mins at a time. This is only an intermittent problem and will go away soon I hope. However, my server doesn't recover properly - when the connection comes back, I can still access it at 192.168.0.8 (locally) without any issue, but at www.javawag.com there's no reply! (Just an aside - my home internet connection is dynamic ISP, the domain www.javawag.com points to javawag.dyndns.org which in turn points to my IP, updated every minute by ddclient on the server) Is there some way for the server to check if it's accessible from the outside world periodically, and if not restart Apache/reboot? Oh, and if I reboot the problem fixes itself also! Javawag

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  • AWS: Should my EC2 and RDS instances be in the same Availability Zone?

    - by DOOManiac
    I just noticed that all of our EC2 instances are in zone us-west-2b, but our Multi-AZ RDS instance is in us-west-2a. Performance-wise everything seems to be okay, and it will be a hassle to "move" the instances to one place since you have to stop and re-create them all. However if either of the two zones goes down when we will have some downtime; if everything is in one zone then at least we have a higher chance of not being in the zone that has downtime... Is this something worth fixing, or am I over-thinking it? (I was about to purchase some EC2 Reserved Instances, which are tied to specific AZs, so I wanted to make sure before going through with it) Thanks!

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  • Apache conf for high trafic CMS with backend users?

    - by Annan
    I'm in the situation where a website is going to have a high number of web users and a few backend webmasters. Webmasters will upload images (+other high mem tasks) and this bumps up the memory allocation of the httpd child processes to 100-150mb. In order to stop swapping I'm currently setting MaxClients in httpd.conf to 20. However this lowers maximum simultaneous requests. Will this be a problem when the website goes live? What is the best configuration? Info: Drupal 6, PHP 5, Apache 2.2 (Prefork atm) I'm thinking about Worker MPM, two apache instances or low MaxRequestsPerChild.

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  • How to make a server check it's own availability on the web?

    - by Javawag
    Hi all, Just a quick question – my server is running at my house serving www pages at www.javawag.com. The problem is that my home internet connection keeps dropping randomly - for about 10 mins at a time. This is only an intermittent problem and will go away soon I hope. However, my server doesn't recover properly - when the connection comes back, I can still access it at 192.168.0.8 (locally) without any issue, but at www.javawag.com there's no reply! (Just an aside - my home internet connection is dynamic ISP, the domain www.javawag.com points to javawag.dyndns.org which in turn points to my IP, updated every minute by ddclient on the server) Is there some way for the server to check if it's accessible from the outside world periodically, and if not restart Apache/reboot? Oh, and if I reboot the problem fixes itself also! Javawag

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  • Why is RAM usage so high on an idle server? [duplicate]

    - by DeeDee
    This question already has an answer here: Why is Linux reporting “free” memory strangely? 2 answers I'm investigating a server used for scientific data analysis. It's running RHEL 6.4 It has almost 200GB of RAM. It's been running very slowly for users via SSH, and after some poking around I quickly noticed that the RAM usage was sky-high. What's odd is that even in an idle state it's still using a ton of RAM: I also looked via htop and I can't see that any running process is using more than 0.1% of the RAM. So I wonder what's going on? Right now the only user-initiated process running is an rsync between two NFS-mounted shares. I tried rebooting the server and it was much more responsive for a few minutes, but then memory usage shot up again. Is there any way I can pinpoint why memory usage is so high?

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  • sensors reporting weird temperatures

    - by Felix
    lm-sensors is reporting weird temps for me: $ sensors coretemp-isa-0000 Adapter: ISA adapter Core 0: +38.0°C (high = +72.0°C, crit = +100.0°C) coretemp-isa-0001 Adapter: ISA adapter Core 1: +35.0°C (high = +72.0°C, crit = +100.0°C) coretemp-isa-0002 Adapter: ISA adapter Core 2: +32.0°C (high = +72.0°C, crit = +100.0°C) coretemp-isa-0003 Adapter: ISA adapter Core 3: +42.0°C (high = +72.0°C, crit = +100.0°C) w83627dhg-isa-0290 Adapter: ISA adapter Vcore: +1.10 V (min = +0.00 V, max = +1.74 V) in1: +1.62 V (min = +0.06 V, max = +0.17 V) ALARM AVCC: +3.34 V (min = +2.98 V, max = +3.63 V) VCC: +3.34 V (min = +2.98 V, max = +3.63 V) in4: +1.83 V (min = +1.30 V, max = +1.15 V) ALARM in5: +1.26 V (min = +0.83 V, max = +1.03 V) ALARM in6: +0.11 V (min = +1.22 V, max = +0.56 V) ALARM 3VSB: +3.30 V (min = +2.98 V, max = +3.63 V) Vbat: +3.18 V (min = +2.70 V, max = +3.30 V) fan1: 0 RPM (min = 0 RPM, div = 128) ALARM fan2: 1117 RPM (min = 860 RPM, div = 8) fan3: 0 RPM (min = 10546 RPM, div = 128) ALARM fan4: 0 RPM (min = 10546 RPM, div = 128) ALARM fan5: 0 RPM (min = 10546 RPM, div = 128) ALARM temp1: +88.0°C (high = +20.0°C, hyst = +4.0°C) ALARM sensor = diode temp2: +25.0°C (high = +80.0°C, hyst = +75.0°C) sensor = diode temp3: +121.5°C (high = +80.0°C, hyst = +75.0°C) ALARM sensor = thermistor cpu0_vid: +2.050 V Please note temp3. How can I know what temp3 is, and why it is so high? The system is really stable (which I guess it wouldn't be at those temps). Also, note the really decent core temps, which suggest a healthy system as well. My guess is that the readout is wrong. On another computer it reported temperatures below 0 degrees centigrade, which was not possible, considering the environment temperature of ~22-24. Is this some known bug/issue? Should I try some Windows programs (like CPU-Z) and see they give similar results?

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  • What's going on with my server? High load, lots of idle CPU time, low disk utilization

    - by Jonathan
    I run a web site and send a legitimate opt-in, daily email newsletter to subscribers. Both the web hosting and email sending are done by the same machine. I have about 100,000 subscribers who have opted in to my daily email newsletter. My PHP script did a pretty good job sending mail to all of them until fairly recently, but as the list has grown I can't keep up. When I run top, I have very high load--usually at least 6 or 7, sometimes as high as 15--even though I only have two CPUs. However, when I run sar, my CPU is idle an average of about 30% of the time. So, it seems I'm not CPU bound. When I run iostat, it seems as though I'm not disk bound because my %util for each device is very low (no more than 5%). Given that I don't seem to be CPU bound or disk bound, why is top reporting such high load? Additionally, since I don't seem to be CPU bound or disk bound, why is my email sending script not able to keep up? Here's what I see when running top: top - 11:33:28 up 74 days, 18:49, 2 users, load average: 7.65, 8.79, 8.28 Tasks: 168 total, 5 running, 162 sleeping, 0 stopped, 1 zombie Cpu(s): 38.9%us, 58.6%sy, 0.8%ni, 0.0%id, 0.7%wa, 0.2%hi, 0.8%si, 0.0%st Mem: 3083012k total, 2144436k used, 938576k free, 281136k buffers Swap: 2048248k total, 39164k used, 2009084k free, 1470412k cached Here's what I see when running iostat -mx: avg-cpu: %user %nice %system %iowait %steal %idle 34.80 1.20 55.24 0.37 0.00 8.38 Device: rrqm/s wrqm/s r/s w/s rMB/s wMB/s avgrq-sz avgqu-sz await svctm %util sda 0.19 71.70 1.59 29.45 0.02 0.07 5.90 0.55 17.82 1.16 3.59 sda1 0.00 0.00 0.00 0.00 0.00 0.00 7.10 0.00 13.80 13.72 0.00 sda2 0.05 50.45 1.13 24.57 0.01 0.29 24.25 0.35 13.43 1.15 2.97 sda3 0.05 10.17 0.20 2.33 0.01 0.05 43.75 0.05 20.96 2.45 0.62 sda4 0.00 0.00 0.00 0.00 0.00 0.00 2.00 0.00 70.50 70.50 0.00 sda5 0.07 0.22 0.03 0.07 0.00 0.00 32.84 0.08 856.19 8.03 0.08 sda6 0.02 5.45 0.03 0.72 0.00 0.02 67.55 0.02 26.72 5.26 0.39 sda7 0.00 1.56 0.00 0.42 0.00 0.01 38.04 0.00 8.88 5.84 0.24 sda8 0.01 3.84 0.20 1.35 0.00 0.02 28.55 0.05 31.90 4.08 0.63 Here's what I see when running sar: 09:40:02 AM CPU %user %nice %system %iowait %steal %idle 09:50:01 AM all 30.59 1.01 49.80 0.23 0.00 18.37 10:00:08 AM all 31.73 0.92 51.66 0.13 0.00 15.55 10:10:06 AM all 30.43 0.99 48.94 0.26 0.00 19.38 10:20:01 AM all 29.58 1.00 47.76 0.25 0.00 21.42 10:30:01 AM all 29.37 1.02 47.30 0.18 0.00 22.13 10:40:06 AM all 32.50 1.01 52.94 0.16 0.00 13.39 10:50:01 AM all 30.49 1.00 49.59 0.15 0.00 18.77 11:00:01 AM all 29.43 0.99 47.71 0.17 0.00 21.71 11:10:07 AM all 30.26 0.93 49.48 0.83 0.00 18.50 11:20:02 AM all 29.83 0.81 48.51 1.32 0.00 19.52 11:30:06 AM all 31.18 0.88 51.33 1.15 0.00 15.47 Average: all 26.21 1.15 42.62 0.48 0.00 29.54 Here are the top handful of processes listed at the particular time I happened to run top -c: PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 8180 mysql 16 0 57448 19m 2948 S 26.6 0.7 4702:26 /usr/sbin/mysqld --basedir=/ --datadir=/var/lib/mysql --user=mysql --pid-file=/var/lib/mysql/bristno.pid --skip-external-locking 26956 brristno 17 0 0 0 0 Z 8.0 0.0 0:00.24 [php] <defunct> 26958 brristno 17 0 94408 43m 37m R 5.0 1.4 0:00.15 /usr/bin/php /home/brristno/public_html/dbv.php 22852 nobody 16 0 9628 2900 1524 S 0.7 0.1 0:00.17 /usr/local/apache/bin/httpd -k start -DSSL 8591 brristno 34 19 96896 13m 6652 S 0.3 0.4 0:29.82 /usr/local/bin/php /home/brristno/bin/mailer.php 1qwqyb6 i0gbor 24469 nobody 16 0 9628 2880 1508 S 0.3 0.1 0:00.08 /usr/local/apache/bin/httpd -k start -DSSL 25495 nobody 15 0 9628 2876 1500 S 0.3 0.1 0:00.06 /usr/local/apache/bin/httpd -k start -DSSL 26149 nobody 15 0 9628 2864 1504 S 0.3 0.1 0:00.04 /usr/local/apache/bin/httpd -k start -DSSL

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  • Open source C# projects that have high code quality?

    - by Simucal
    Question: What are some open source C# projects I can download that implement many best-practices and have a relatively high code quality? Please accompany your answer with some of the reasons you consider the code is of high quality. Suggestions so far: SharpDevelop NHibernate Boo Rhino Mocks Mono Paint.NET - Not Open Source ASP.NET MVC Framework .Net Framework Source Code The Weekly Source Code (Scott Hanselman's Series) Microsoft's Pattern and Practices

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  • High Apache CPU usage, but low nginx - Configured correctly?

    - by Buckers
    We've just moved a website of ours over to a brand new high-spec Linux server (1x Intel Xeon E3-1230 v2 @ 3.30GHz, 8GB DDR3 ECC, 2x 128GB SATA SSD RAID1). The server has been configured to use nginx but we're not sure if its working correctly. The site always loads very fast to us (http://www.onedirection.net), but Plesk often sends us reports that the Apache CPU usage percentage reaches high leves, yet when we look at the nginx percentage it's always very low. We've come from a Windows background so are very new to Linux, but shouldn't nginx run INSTEAD of apache? Here's a screenshot from Plesk showing the CPU usage: http://www.pixelkicks.co.uk/_download/plesk.JPG The website gets around 20,000 visitors per day, and we use W3 Total Cache to get it running as fast as possible. MySQL has been optimised well. Memory usage is only running at 2GB of the 8GB. Does this look right? How can we tell that nginx is doing most of the work? Thanks, Chris.

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  • What would you suggest as a high school first language?

    - by ldigas
    Edit by OA: After reading some answers I'll just update the question a little. At first I put it a little bluntly, but some of those gave me some good arguments which have to be taken into consideration while making a stand on this one. (these are mostly picked up from comments and answers below). A few things to take into account: to many pupils this is a first programming language - at this stage most of them have trouble grasping a difference between data types, variable passing, ... and whatnot, less alone pointers and similar 'low level stuff' :) they will all have to pass this to get into next grade (well, big majority of them anyway) not all of them have computers at home, not all of them are willing to learn this, less alone interested in - so the concepts have to be taught on a finite time scale in school hours (as well as practice on computers) free literature is a bonus - the teacher will make some scripts and handaways, but still ... I wouldn't like to bear the parents with the burden of buying expensive literature (also, english is not a native language here ... and although they are all learning it, their ability to read it fluently is somewhat questionable) somebody gave an argument - "a language which does not get in the way of ideas" - good one accessibility on different platforms in not expecially important at this point - although most of the suggested ones are available on win as well as linux - not many macs in this part of europe (their prices are sky high for anything but specialised usage) I will check what are the licencing issues on ms express editions about using it massively in high schools for purposes like this - if someone has any info about this, please, do not be shy with it :) A friend of mine, informatics teacher - in EU it comes as something as junior cs teacher, in a local high school asked me what I thought about what should be the first language pupils should be taught? It is a technical school (a little more oriented towards mathematics than the gymnasium, but not computer oriented totally). So I'm asking you - what do you think should be the first language pupils are exposed to in highschool? They have been teaching Pascal so far, but she's not sure that's a good course. She thought about switching to C (which I resented; considering not all pupils have interests in programming, to start with, and should be taught something higher level since they are just gripping the idea of a loop and such ... for a start), I suggested python or ruby (preferably py since it handles all paradigms). What is your opinion on this one? I looked, but didn't find a similar question on SO, so if there is one, please just point me towards it. Edit: The assumption is that none of the pupils have been exposed to any programming in junior school. See also: What is the best way to teach young kids some basic programming concepts? Best ways to teach a beginner to program How and when do you teach a kid to code What is the easiest language to start with? High School Programming

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  • How do I lower the hardware volume? (volume too high)

    - by Zom-B
    I have a 4yo Dell laptop with Windows XP Pro (modern ones unfortunately don't have a physical volume knob), and lately I'm using my Apple earphones, because they have much better low frequency response than my $10 earphones. They also have the side effect of being much louder. To give an indication of my agony, for most tasks (movie, music, games) I have my main volume at 3 ticks: drag to 0 with the mouse and press the up key 3 times (the handle does not even raise 1 pixel) and my wave volume at 50%. I notice that when I do this, I have a lot of digital noise, because I'm using just a tiny fraction of the 16-bit space. If I drag the Wave slider down until I barely hear the audio, it becomes really distorted and noisy, indicating that this is digital volume (in the DirectSound driver or something) and not hardware volume. I experimented in Audition. When I make a tone of 1000Hz at -50db, (all windows volumes at max) the volume is just below my pain threshold. When I zoom in to see how high the sample values reach, I see that just 8 of the 16 bits are used (about -100 ~ 100). When I generate such tone at -80db (minimum I can specify) then I can still clearly hear the tone, although really noisy. When I zoom in, I see that just 3 out of 16 bits are used. I created a squarewave tone that is just 1 bit high, and I can still hear it! For most uses, this is not a big problem (audiophiles will disagree!), as I just have more noise than usual (about the same as old 8 bit hardware), but I'm also in the process of programming a hearing test program, in which case this problem is a death blow as the test subjects will even hear tones at the bottom of the theoretical range (lowering the windows volume is futile, see above) (I cannot update drivers, as Dell has discontinued XP support for my model)

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  • Anyone have real world experience with Rackspace Cloud Sites at high scale?

    - by Allara
    I have a pure web service application layer using .NET. I was originally planning to use Amazon EC2, but rolling my own autoscaling procedures is a bit intimidating, and the scaling isn't very granular from a cost perspective. If the app is successful, we could be looking at relatively high scale (millions of requests per month). The app uses Amazon SimpleDB as the database layer. As a test, I have the app running successfully in Rackspace Cloud Sites. Performance seems to be equal to (if not better than) a standard EC2 instance, even with the added latency of the SimpleDB requests travelling to the Rackspace network. However, testing at this stage is at a very low scale. My question is this: has anyone had real-world experience running a high scale application on Rackspace Cloud Sites? Moreover, once you pass the "included" 10,000 compute cycles per month, does the overall cost seem to be lower than rolling lots of EC2 instances? My assumption would be that with completely smooth scaling (i.e. only adding compute resources as needed), the cost could be lower on average. However, their stated goal of calibrating 10,000 CCs as a single 1.2 Ghz CPU seems on average to be much more expensive than EC2. I like the idea of no-touch scaling, but is it too good to be true?

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  • High CPU usage compared to WinXP. Common aps and actions use 100% CPU cycles

    - by Jopower
    I'm running Lubunto 14.04.1 LTS. PC is a 2004 HP ze4200 laptop: 1.8 ghz Celeron M with 1 gb RAM and 80 gb drive. Was running fine on WinXP SP3 and I cleaned the drive off to test Lubuntu 14 LTS. No anti-virus is installed yet. I enabled the CPU resource monitor to see how various programs drag the OS. Using Firefox 31 online right now, I see doing basic functions like openning a new tab and scrolling down a page are using 100% CPU time, ocassionally for 10-30 seconds. In fact some pretty basic aps like Leafnote hit 100% for a second. Wordpad never did that. Lubuntu Software Center locks things up at 100% for 10 seconds. Just typing here shows a 60-80% spike every character. Running the mouse around the screen for 10 seconds results in a sustained 100% load during that time. Right now, if I let the PC rest just idling Firefox and not doing anything with it, CPU use bounces from 20-40% all by itself. WinXP idles at 2-10% and it's considered not good for it to be above 20%... something odd must be happening. Sure, XP will give similar higher CPU cycles with program use, but it's not locking and slogging like this. Lubuntu is supposed to be a light OS and by memory usage it is and I'm happy since this is an old PC maxed for memory upgrades. However, being used to doing some tuning and wary of abnormalities going on in the background, the CPU use indicates things going on that I want to know about and perhaps apply a tweek or two. Recommendations are appreciated. And this 300 point "new tags" restriction bites!

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  • Why should we use low level languages if a high level one like python can do almost everything? [closed]

    - by killown
    I know python is not suitable for things like microcontrolers, make drivers etc, but besides that, you can do everything using python, companys get stuck with speed optimizations for real hard time system but does forget other factors which one you can just upgrade your hardware for speed proposes in order to get your python program fit in it, if you think how much cust can the company have to maintain a system written in C, the comparison is like that: for example: 10 programmers to mantain a system written in c and just one programmer to mantain a system written in python, with python you can buy some better hardware to fit your python program, I think that low level languages tend to get more cost, since programmers aren't so cheaply than a hardware upgrade, then, this is my point, why should a system be written in c instead of python?

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  • The Calmest IT Guy in the World

    - by Markus Weber
    Unplanned outages and downtime still result not only in major productivity losses, but also major financial losses. Along the same lines, if zero planned downtime and zero data loss are key to your IT environment and your business requirements, planning for those becomes very important, all while balancing between performance, high availability, and cost. Oracle Database High Availability technologies will help you achieve these mission-critical goals, and are reflected in Oracle's best practices offerings of the Maximum Availability Architecture, or MAA. We created three neat, short videos showcasing some typical use cases, and highlighting three important components (amongst many more) of MAA: Oracle Real Application Clusters (RAC) Oracle Active Data Guard Oracle Flashback Technologies Make sure to watch those videos here, and learn about challenges, and solutions, around High Availability database environments from a recent Independent Oracle Users Group (IOUG) survey. 

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  • Can throwing the iPhone high in the air launch my app or trigger desired function in iOS 7 or later

    - by aMother
    My app is an emergency app. It will be used by people in emergency and disasters. It's possible that they got stuck in situations where they just don't have the time to enter or draw their password, launch the appp and push a button. Is it possible that ask the OS to launch the app if user throw their iphone up in the air or shake it vigrously or something else. PS: I think it's possible with the accelerometer.

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  • how to write high quality GUI software with qt?

    - by Opetmar
    I want to write a project using QT library, so after learning the library and mastering it how should I start, what other libraries or things that I should learn? are there any other tools that will help me during the development or tools well help the end user to install the software and using it? What are the things that I should be aware? what are the things that I should avoid so it can run efficiently?

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