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  • No apparent reason for high load average

    - by Oz.
    We have several web servers running on Amazon (ec2) c1.xlarge, over Amazon AMI. The servers are duplicates of each other, running the exact same hardware and software. Each server spec is: 7 GB of memory 20 EC2 Compute Units (8 virtual cores with 2.5 EC2 Compute Units each) 1690 GB of instance storage 64-bit platform I/O Performance: High API name: c1.xlarge A couple of weeks ago we have run a yum upgrade on one of the servers. Starting on this upgrade the upgraded server started showing a high load average. Needless to say, we did not update the other servers and we can not do so until we understand the reason for this behavior. The strange thing is that when we compare the servers using top or iostat, we can not find the reason for the high load. Note that we have moved traffic from the "problematic" server to the others, which have made the "problematic" server less crowded in terms of requests, and still his load is higher. Do you have any idea what could it be, or where else can we check? Many thanks for the help! Oz. # # proper server # w command # 00:42:26 up 2 days, 19:54, 2 users, load average: 0.41, 0.48, 0.49 USER TTY FROM LOGIN@ IDLE JCPU PCPU WHAT pts/1 82.80.137.29 00:28 14:05 0.01s 0.01s -bash pts/2 82.80.137.29 00:38 0.00s 0.02s 0.00s w # # proper server # iostat command # Linux 3.2.12-3.2.4.amzn1.x86_64 _x86_64_ (8 CPU) avg-cpu: %user %nice %system %iowait %steal %idle 9.03 0.02 4.26 0.17 0.13 86.39 Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn xvdap1 1.63 1.50 55.00 367236 13444008 xvdfp1 4.41 45.93 70.48 11227226 17228552 xvdfp2 2.61 2.01 59.81 491890 14620104 xvdfp3 8.16 14.47 94.23 3536522 23034376 xvdfp4 0.98 0.79 45.86 192818 11209784 # # problematic server # w command # 00:43:26 up 2 days, 21:52, 2 users, load average: 1.35, 1.10, 1.17 USER TTY FROM LOGIN@ IDLE JCPU PCPU WHAT pts/0 82.80.137.29 00:28 15:04 0.02s 0.02s -bash pts/1 82.80.137.29 00:38 0.00s 0.05s 0.00s w # # problematic server # iostat command # Linux 3.2.20-1.29.6.amzn1.x86_64 _x86_64_ (8 CPU) avg-cpu: %user %nice %system %iowait %steal %idle 7.97 0.04 3.43 0.19 0.07 88.30 Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn xvdap1 2.10 1.49 76.54 374660 19253592 xvdfp1 5.64 40.98 85.92 10308946 21612112 xvdfp2 3.97 4.32 93.18 1087090 23439488 xvdfp3 10.87 30.30 115.14 7622474 28961720 xvdfp4 1.12 0.28 65.54 71034 16487112

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  • nginx proxy pass redirect through load balancer

    - by Brian
    I have several backend webservers that are load-balanced using LVS. These machines have only internal non-routable IPs on them. The load-balancer is the only machine with an external IP. This setup works great. I would like to add another webserver for image serving, but it will not be part of the load-balanced pool. Is it possible to proxy pass from the load-balanced web servers to the image server and have the response redirected to the client? Client--external LB--internal web server--internal image server I've gotten proxy pass working when I remove the LB from the equation, but no luck when trying to use it.

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  • FTP Load Balancer on EC2

    - by inakiabt
    I need an EC2 instance to balance all incoming FTP connections to a list of FTP servers (EC2 instances too). This list will be changed dynamically due to the load of the FTP servers (launch a new FTP server when the FTP servers are overloaded or shutdown a FTP server when the load is low). What you recommend? a FTP proxy? DNS server? Load balancer? Note: The FTP servers must support Passive Mode

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  • Two different page numbers in Word 2007 (one starting at 1, the other at VI)

    - by user1251007
    I have a document (docA) with arabic page numbers in the header. Now docA is part of a thesis which has roman numbers in the footer. So I want to add roman page numbers to docA. This is no problem. But now I want to adjust the numbering of the roman numbers (as the thesis has lets say five pages). This is what I want: arabic page numbers in the header, starting at 1 roman page numbers in the footer, starting at VI I tried this: I choosed 'Page Number', 'Page Number Format' and tried to adjust the starting point. However, this changes both page numbers. How is it possible to have different numbering in the header and in the footer?

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  • nginx proxy pass redirect through load balancer

    - by Brian
    I have several backend webservers that are load-balanced using LVS. These machines have only internal non-routable IPs on them. The load-balancer is the only machine with an external IP. This setup works great. I would like to add another webserver for image serving, but it will not be part of the load-balanced pool. Is it possible to proxy pass from the load-balanced web servers to the image server and have the response redirected to the client? Client--external LB--internal web server--internal image server I've gotten proxy pass working when I remove the LB from the equation, but no luck when trying to use it.

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  • FTP Load Balancer

    - by inakiabt
    I need an EC2 instance to balance all incoming FTP connections to a list of FTP servers (EC2 instances too). This list will be changed dynamically due to the load of the FTP servers (launch a new FTP server when the FTP servers are overloaded or shutdown a FTP server when the load is low). What you recommend? a FTP proxy? DNS server? Load balancer? Note: The FTP servers must support Passive Mode

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  • Load Balancing Linux Web Services and Change Config Without Restart

    - by Eric J.
    What options are available to load balance web service traffic on Linux with the ability to add or remove servers from the server pool without restarting the load balancer? This post: http://serverfault.com/questions/71437/mod-proxy-change-without-restart looks like a very promising way to switch between two servers, but I don't know enough about mod_proxy and mod_rewrite to understand how/if I can use an external file to specify the BalancerMember entries for a section. Are there other open source load balancers that support reconfiguration without restart?

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  • Apache load balancer with https real servers and client certificates

    - by Jack Scheible
    Our network requirements state that ALL network traffic must be encrypted. The network configuration looks like this: ------------ /-- https --> | server 1 | / ------------ |------------| |---------------|/ ------------ | Client | --- https --> | Load Balancer | ---- https --> | server 2 | |------------| |---------------|\ ------------ \ ------------ \-- https --> | server 3 | ------------ And it has to pass client certificates. I've got a config that can do load balancing with in-the-clear real servers: <VirtualHost *:8666> DocumentRoot "/usr/local/apache/ssl_html" ServerName vmbigip1 ServerAdmin [email protected] DirectoryIndex index.html <Proxy *> Order deny,allow Allow from all </Proxy> SSLEngine on SSLProxyEngine On SSLCertificateFile /usr/local/apache/conf/server.crt SSLCertificateKeyFile /usr/local/apache/conf/server.key <Proxy balancer://mycluster> BalancerMember http://1.2.3.1:80 BalancerMember http://1.2.3.2:80 # technically we aren't blocking anyone, but could here Order Deny,Allow Deny from none Allow from all # Load Balancer Settings # A simple Round Robin load balancer. ProxySet lbmethod=byrequests </Proxy> # balancer-manager # This tool is built into the mod_proxy_balancer module allows you # to do simple mods to the balanced group via a gui web interface. <Location /balancer-manager> SetHandler balancer-manager Order deny,allow Allow from all </Location> ProxyRequests Off ProxyPreserveHost On # Point of Balance # Allows you to explicitly name the location in the site to be # balanced, here we will balance "/" or everything in the site. ProxyPass /balancer-manager ! ProxyPass / balancer://mycluster/ stickysession=JSESSIONID </VirtualHost> What I need is for the servers in my load balancer to be BalancerMember https://1.2.3.1:443 BalancerMember https://1.2.3.2:443 But that does not work. I get SSL negotiation errors. Even when I do get that to work, I will need to pass client certificates. Any help would be appreciated.

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  • Load balancers, multiple data centers and url based routing

    - by kunkunur
    There is one data center - dc1. There is a business need to setup another data center - dc2 in another geography and there might be more in the future say dc3. Within the data center dc1: There are two web servers say WS1 and WS2. These two webservers do not share anything currently. There isnt any necessity foreseen to have more webservers within each dc. dc1 also has a local load balancer which has been setup with session stickiness. So if a user say u1 lands on dc1 and if the load balancer decides to route his first request to WS1 then from there on all u1's requests will get routed to WS1. Local load balancer and webservers are invisible to the user. Local load balancer listens to the traffic on a virtual ip which is assigned to the virtual cluster of webservers ws1 and ws2. Virtual ip is the ip to which the host name is resolved to in the DNS. There are no client specific subdomains as of now instead there is a client specific url(context). ex: www.example.com/client1 and www.example.com/client2. Given above when dc2 is onboarded I want to route the traffic between dc1 and dc2 based on the client. The options that I have found so far are. Have client specific subdomains e.g. client1.example.com and client2.example.com and assign each of them with the virtual ip of the data center to which I want to route them. or Assign www.example.com and www1.example.com to first dc i.e. dc1 and assign www2.example.com to dc2. All requests will first get routed to dc1 where WS1 and WS2 will redirect the user to www1.example.com or www2.example.com based on whether the url ends with /client1 or /client2. I need help in the following If I setup a global load balancer between dc1 and dc2 do I have any alternative solutions. That is, can a global load balancer route the traffic based on the url ? Are there drawbacks to subdomain based solutions compared to www1 solution? With www1 solution I am worried that it creates a dependency on dc1 atleast for the first request and the user will see that he is getting redirected to a different url.

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  • Load testing nginx inside AWS

    - by andy
    I'm trying to load test nginx running on AWS. I need to try to optimise it to handle 1Gbps of inbound traffic. Currently I've got it to peak at 85Mbit/s by running nginx on an m1.large with 4 other machines hitting it by using ab with -i (for head requests) -k (keepalives) -r (ignore failed requests) -n 500000 -c 20000. I'm struggling to generate more than 85 Mbit/s traffic from 4 machines, yet when I do scp a large file I get nearly 0.25Gbit/s of traffic going over the network. Are there any tools or approaches that I could use to load test nginx that might generate more load? I'm only interested in inbound traffic, so perhaps a DoS tool could help if it chucks away responses? I'm hitting a very small (40 byte) static asset, and have peaked at handling 50K concurrent connections and getting 25k reqs/s when just using a single load generator machine.

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  • What other ways can I load balance EC2 servers without using Elastic Load Balancing?

    - by undefined
    I have a web application that consists of a web server managed by a web hosting firm, a set of EC2 instances in amazons cloud and a MySQL database (hosted on the webserver). MySQL is behind a firewall and is set to allow access from Localhost and from a single IP address which is an Amazon Elastic IP address that is attached to the EC2 instance I have been running up to now. The problem is that I want to look at my scaling up and load balancing strategy for my EC2 instance. To this end I have been investigating the Elastic Load Balancers and Autoscaling tools that Amazon provides and have managed to set this up fine but for one thing - connecting to the MySQL database running on my webserver. I realised (thanks to answers on Serverfault) that I needed to check firewall settings and add the IP address for the load balancer, however Elastic Load Balancers provide you with a DNS name, not an IP address and infact the IP addresses change over time so this will not work. I have been told by the company hosting the database that the way the firewall works is to look up the IP address of the DNS name and store the IP rather than the DNS name. so basically this will not work and the only way to allow access would be to open up the SQL port to allow access from anyone! Is this a viable idea? Should I look at moving my database into the cloud? Is there another firewall that the server company can use? Should I find another way of load balancing (if so what?) tricky one eh? any help appreciated!

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  • Jquery / PHP - pre-loading next page before navigating to it.

    - by Tim
    Hey all Using jQuery, is there a way to prevent going to the next page until the animation has finished AND the next page has completely loaded (including images)? The code below works but it is a bit clunky. You can see what I am trying to achieve here: http://bit.ly/aOeYgE The first three or so pages work. But when you click to go to the homepage a few times (after it's cached) you will see that it jumps, and the animation isn't very smooth. As you can see with the code below, the height is immediately set to 0, then when the page has loaded the height is set to 500px. When users navigate to a new page, the height should go back to 0, the next page content should load, and then upon loading the new window, the first bit of code will run again to set the width back to 500px. $(".content-center").css({"height": "0px"}); $(window).load(function() { if($('.content-center').is(':not(:animated)')) { $('.content-center').animate({height: "500px"}, 450); } }); $("a").click(function(event){ $(".content-center").animate({height: "0px"}, 500); if($('.content-center').is(':not(:animated)')) { navigate($(this).attr('href')); event.preventDefault(); } }); If anyone has any suggestions or alternative ideas to this code then it would be hugely appreciated. Many thanks Tim

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  • Squid on windows loadbalancing only to one server

    - by Martin L.
    After thousands of googles and trying days i cant get the load balancer/failover in squid on windows to work. Iam using squid 2.7. My webservers are 2 single NIC lighttpd and one dual nic lighttpd. server1 in this example is running squid on port 80 and lighttpd on port 8080 (just to test) Requirements: All 3 webservers running lighttpd should be balanced two option for load balancing: Best would be if server1 is busy server2 takes over, if server2 is busy server3 takes over, etc.. Round robin style evenly distributed load. Eg server1 takes first call, server2 second etc.. All requests should be treated the same way (no url rewriting or so on) Sent host headers have to be redirected to every server as http host header, speaking of "server1", "server1.company.internal" and "10.211.1.1". My approach: acl all src all acl manager proto cache_object http_port 80 accel defaultsite=server1.company.internal vhost #reverse proxy entries cache_peer 10.211.2.1 parent 8080 0 no-query originserver round-robin login=PASS name=server1_nic1 cache_peer 10.211.1.2 parent 80 0 no-query originserver round-robin login=PASS name=server2_nic1 cache_peer 10.211.2.3 parent 8080 0 no-query originserver round-robin login=PASS name=server3_nic1 cache_peer 10.211.2.4 parent 8080 0 no-query originserver round-robin login=PASS name=server3_nic2 #decl of names of squid host acl registered_name_hostdomain dstdomain server1.company.internal acl registered_name_host dstdomain server1 #ip of squid host acl registered_name_ip dstdomain 10.211.2.1 # access: redirects the correct squid hostname http_access allow registered_name_hostdomain http_access allow registered_name_host http_access allow registered_name_ip http_access deny all cache_peer_access server1_nic1 allow registered_name_hostdomain cache_peer_access server1_nic1 allow registered_name_host cache_peer_access server1_nic1 allow registered_name_ip cache_peer_access server2_nic1 allow registered_name_hostdomain cache_peer_access server2_nic1 allow registered_name_host cache_peer_access server2_nic1 allow registered_name_ip cache_peer_access server3_nic1 allow registered_name_hostdomain cache_peer_access server3_nic1 allow registered_name_host cache_peer_access server3_nic1 allow registered_name_ip cache_peer_access server3_nic2 allow registered_name_hostdomain cache_peer_access server3_nic2 allow registered_name_host cache_peer_access server3_nic2 allow registered_name_ip cache_peer_access server1_nic1 deny all cache_peer_access server2_nic1 deny all cache_peer_access server3_nic1 deny all cache_peer_access server3_nic2 deny all never_direct allow all Problems: Load balancer does not load balance other than to first server. Only if the first server is killed in any way the second will take over. I have seen the others working at some point, but definitely not as the intended load balancing described above. If the cache_peer_access is not defined sometimes the wrong hostname is sent to the backend webserver and this always depends on the defaultsite= parameter. Probably because the host header on the request to squid is not set and its replaced by defaultsite. Leaving out defaultsite didnt solve the problem. The only workaround i found for this is the current approach with cache_peer_access. Questions: Does the cache_peer_access influence the round-robin? Is there a better workaround to pass the host header to the backed webservers? Which parameters do increase the speed of load balancing or does anyone have a better approach? -Martin

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  • Updating a SharePoint master page via a solution (WSP)

    - by Kelly Jones
    In my last blog post, I wrote how to deploy a SharePoint theme using Features and a solution package.  As promised in that post, here is how to update an already deployed master page. There are several ways to update a master page in SharePoint.  You could upload a new version to the master page gallery, or you could upload a new master page to the gallery, and then set the site to use this new page.  Manually uploading your master page to the master page gallery might be the best option, depending on your environment.  For my client, I did these steps in code, which is what they preferred. (Image courtesy of: http://www.joiningdots.net/blog/2007/08/sharepoint-and-quick-launch.html ) Before you decide which method you need to use, take a look at your existing pages.  Are they using the SharePoint dynamic token or the static token for the master page reference?  The wha, huh? SO, there are four ways to tell an .aspx page hosted in SharePoint which master page it should use: “~masterurl/default.master” – tells the page to use the default.master property of the site “~masterurl/custom.master” – tells the page to use the custom.master property of the site “~site/default.master” – tells the page to use the file named “default.master” in the site’s master page gallery “~sitecollection/default.master” – tells the page to use the file named “default.master” in the site collection’s master page gallery For more information about these tokens, take a look at this article on MSDN. Once you determine which token your existing pages are pointed to, then you know which file you need to update.  So, if the ~masterurl tokens are used, then you upload a new master page, either replacing the existing one or adding another one to the gallery.  If you’ve uploaded a new file with a new name, you’ll just need to set it as the master page either through the UI (MOSS only) or through code (MOSS or WSS Feature receiver code – or using SharePoint Designer). If the ~site or ~sitecollection tokens were used, then you’re limited to either replacing the existing master page, or editing all of your existing pages to point to another master page.  In most cases, it probably makes sense to just replace the master page. For my project, I’m working with WSS and the existing pages are set to the ~sitecollection token.  Based on this, I decided to just upload a new version of the existing master page (and not modify the dozens of existing pages). Also, since my client prefers Features and solutions, I created a master page Feature and a corresponding Feature Receiver.  For information on creating the elements and feature files, check out this post: http://sharepointmagazine.net/technical/development/deploying-the-master-page . This works fine, unless you are overwriting an existing master page, which was my case.  You’ll run into errors because the master page file needs to be checked out, replaced, and then checked in.  I wrote code in my Feature Activated event handler to accomplish these steps. Here are the steps necessary in code: Get the file name from the elements file of the Feature Check out the file from the master page gallery Upload the file to the master page gallery Check in the file to the master page gallery Here’s the code in my Feature Receiver: 1: public override void FeatureActivated(SPFeatureReceiverProperties properties) 2: { 3: try 4: { 5:   6: SPElementDefinitionCollection col = properties.Definition.GetElementDefinitions(System.Globalization.CultureInfo.CurrentCulture); 7:   8: using (SPWeb curweb = GetCurWeb(properties)) 9: { 10: foreach (SPElementDefinition ele in col) 11: { 12: if (string.Compare(ele.ElementType, "Module", true) == 0) 13: { 14: // <Module Name="DefaultMasterPage" List="116" Url="_catalogs/masterpage" RootWebOnly="FALSE"> 15: // <File Url="myMaster.master" Type="GhostableInLibrary" IgnoreIfAlreadyExists="TRUE" 16: // Path="MasterPages/myMaster.master" /> 17: // </Module> 18: string Url = ele.XmlDefinition.Attributes["Url"].Value; 19: foreach (System.Xml.XmlNode file in ele.XmlDefinition.ChildNodes) 20: { 21: string Url2 = file.Attributes["Url"].Value; 22: string Path = file.Attributes["Path"].Value; 23: string fileType = file.Attributes["Type"].Value; 24:   25: if (string.Compare(fileType, "GhostableInLibrary", true) == 0) 26: { 27: //Check out file in document library 28: SPFile existingFile = curweb.GetFile(Url + "/" + Url2); 29:   30: if (existingFile != null) 31: { 32: if (existingFile.CheckOutStatus != SPFile.SPCheckOutStatus.None) 33: { 34: throw new Exception("The master page file is already checked out. Please make sure the master page file is checked in, before activating this feature."); 35: } 36: else 37: { 38: existingFile.CheckOut(); 39: existingFile.Update(); 40: } 41: } 42:   43: //Upload file to document library 44: string filePath = System.IO.Path.Combine(properties.Definition.RootDirectory, Path); 45: string fileName = System.IO.Path.GetFileName(filePath); 46: char slash = Convert.ToChar("/"); 47: string[] folders = existingFile.ParentFolder.Url.Split(slash); 48:   49: if (folders.Length > 2) 50: { 51: Logger.logMessage("More than two folders were detected in the library path for the master page. Only two are supported.", 52: Logger.LogEntryType.Information); //custom logging component 53: } 54:   55: SPFolder myLibrary = curweb.Folders[folders[0]].SubFolders[folders[1]]; 56:   57: FileStream fs = File.OpenRead(filePath); 58:   59: SPFile newFile = myLibrary.Files.Add(fileName, fs, true); 60:   61: myLibrary.Update(); 62: newFile.CheckIn("Updated by Feature", SPCheckinType.MajorCheckIn); 63: newFile.Update(); 64: } 65: } 66: } 67: } 68: } 69: } 70: catch (Exception ex) 71: { 72: string msg = "Error occurred during feature activation"; 73: Logger.logException(ex, msg, ""); 74: } 75:   76: } 77:   78: /// <summary> 79: /// Using a Feature's properties, get a reference to the Current Web 80: /// </summary> 81: /// <param name="properties"></param> 82: public SPWeb GetCurWeb(SPFeatureReceiverProperties properties) 83: { 84: SPWeb curweb; 85:   86: //Check if the parent of the web is a site or a web 87: if (properties != null && properties.Feature.Parent.GetType().ToString() == "Microsoft.SharePoint.SPWeb") 88: { 89:   90: //Get web from parent 91: curweb = (SPWeb)properties.Feature.Parent; 92: 93: } 94: else 95: { 96: //Get web from Site 97: using (SPSite cursite = (SPSite)properties.Feature.Parent) 98: { 99: curweb = (SPWeb)cursite.OpenWeb(); 100: } 101: } 102:   103: return curweb; 104: } This did the trick.  It allowed me to update my existing master page, through an easily repeatable process (which is great when you are working with more than one environment and what to do things like TEST it!).  I did run into what I would classify as a strange issue with one of my subsites, but that’s the topic for another blog post.

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  • How to make a legacy system time-zone sensitive?

    - by Jerry Dodge
    I need to implement time zones in a very large and old Delphi system, where there's a central SQL Server database and possibly hundreds of client installations around the world in different time zones. The application already interacts with the database by only using the date/time of the database server. So, all the time stamps saved in both the database and on the client machines are the date/time of the database server when it happened, never the time of the client machine. So, when a client is about to display the date/time of something (such as a transaction) which is coming from this database, it needs to show the date/time converted to the local time zone. This is where I get lost. I would naturally assume there should be something in SQL to recognize the time zone and convert a DateTime field dynamically. I'm not sure if such a thing exists though. If so, that would be perfect, but if not, I need to figure out another way. This Delphi system (multiple projects) utilizes the SQL Server database using ADO components, VCL data-aware controls, and QuickReports (using data sources). So, there's many places where the data goes directly from the database query to rendering on the screen, without any code to actually put this data on the screen. In the end, I need to know when and how should I get the properly converted time? What is the proper way to ensure that I handle Dates and Times correctly in a legacy application?

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  • West Wind WebSurge - an easy way to Load Test Web Applications

    - by Rick Strahl
    A few months ago on a project the subject of load testing came up. We were having some serious issues with a Web application that would start spewing SQL lock errors under somewhat heavy load. These sort of errors can be tough to catch, precisely because they only occur under load and not during typical development testing. To replicate this error more reliably we needed to put a load on the application and run it for a while before these SQL errors would flare up. It’s been a while since I’d looked at load testing tools, so I spent a bit of time looking at different tools and frankly didn’t really find anything that was a good fit. A lot of tools were either a pain to use, didn’t have the basic features I needed, or are extravagantly expensive. In  the end I got frustrated enough to build an initially small custom load test solution that then morphed into a more generic library, then gained a console front end and eventually turned into a full blown Web load testing tool that is now called West Wind WebSurge. I got seriously frustrated looking for tools every time I needed some quick and dirty load testing for an application. If my aim is to just put an application under heavy enough load to find a scalability problem in code, or to simply try and push an application to its limits on the hardware it’s running I shouldn’t have to have to struggle to set up tests. It should be easy enough to get going in a few minutes, so that the testing can be set up quickly so that it can be done on a regular basis without a lot of hassle. And that was the goal when I started to build out my initial custom load tester into a more widely usable tool. If you’re in a hurry and you want to check it out, you can find more information and download links here: West Wind WebSurge Product Page Walk through Video Download link (zip) Install from Chocolatey Source on GitHub For a more detailed discussion of the why’s and how’s and some background continue reading. How did I get here? When I started out on this path, I wasn’t planning on building a tool like this myself – but I got frustrated enough looking at what’s out there to think that I can do better than what’s available for the most common simple load testing scenarios. When we ran into the SQL lock problems I mentioned, I started looking around what’s available for Web load testing solutions that would work for our whole team which consisted of a few developers and a couple of IT guys both of which needed to be able to run the tests. It had been a while since I looked at tools and I figured that by now there should be some good solutions out there, but as it turns out I didn’t really find anything that fit our relatively simple needs without costing an arm and a leg… I spent the better part of a day installing and trying various load testing tools and to be frank most of them were either terrible at what they do, incredibly unfriendly to use, used some terminology I couldn’t even parse, or were extremely expensive (and I mean in the ‘sell your liver’ range of expensive). Pick your poison. There are also a number of online solutions for load testing and they actually looked more promising, but those wouldn’t work well for our scenario as the application is running inside of a private VPN with no outside access into the VPN. Most of those online solutions also ended up being very pricey as well – presumably because of the bandwidth required to test over the open Web can be enormous. When I asked around on Twitter what people were using– I got mostly… crickets. Several people mentioned Visual Studio Load Test, and most other suggestions pointed to online solutions. I did get a bunch of responses though with people asking to let them know what I found – apparently I’m not alone when it comes to finding load testing tools that are effective and easy to use. As to Visual Studio, the higher end skus of Visual Studio and the test edition include a Web load testing tool, which is quite powerful, but there are a number of issues with that: First it’s tied to Visual Studio so it’s not very portable – you need a VS install. I also find the test setup and terminology used by the VS test runner extremely confusing. Heck, it’s complicated enough that there’s even a Pluralsight course on using the Visual Studio Web test from Steve Smith. And of course you need to have one of the high end Visual Studio Skus, and those are mucho Dinero ($$$) – just for the load testing that’s rarely an option. Some of the tools are ultra extensive and let you run analysis tools on the target serves which is useful, but in most cases – just plain overkill and only distracts from what I tend to be ultimately interested in: Reproducing problems that occur at high load, and finding the upper limits and ‘what if’ scenarios as load is ramped up increasingly against a site. Yes it’s useful to have Web app instrumentation, but often that’s not what you’re interested in. I still fondly remember early days of Web testing when Microsoft had the WAST (Web Application Stress Tool) tool, which was rather simple – and also somewhat limited – but easily allowed you to create stress tests very quickly. It had some serious limitations (mainly that it didn’t work with SSL),  but the idea behind it was excellent: Create tests quickly and easily and provide a decent engine to run it locally with minimal setup. You could get set up and run tests within a few minutes. Unfortunately, that tool died a quiet death as so many of Microsoft’s tools that probably were built by an intern and then abandoned, even though there was a lot of potential and it was actually fairly widely used. Eventually the tools was no longer downloadable and now it simply doesn’t work anymore on higher end hardware. West Wind Web Surge – Making Load Testing Quick and Easy So I ended up creating West Wind WebSurge out of rebellious frustration… The goal of WebSurge is to make it drop dead simple to create load tests. It’s super easy to capture sessions either using the built in capture tool (big props to Eric Lawrence, Telerik and FiddlerCore which made that piece a snap), using the full version of Fiddler and exporting sessions, or by manually or programmatically creating text files based on plain HTTP headers to create requests. I’ve been using this tool for 4 months now on a regular basis on various projects as a reality check for performance and scalability and it’s worked extremely well for finding small performance issues. I also use it regularly as a simple URL tester, as it allows me to quickly enter a URL plus headers and content and test that URL and its results along with the ability to easily save one or more of those URLs. A few weeks back I made a walk through video that goes over most of the features of WebSurge in some detail: Note that the UI has slightly changed since then, so there are some UI improvements. Most notably the test results screen has been updated recently to a different layout and to provide more information about each URL in a session at a glance. The video and the main WebSurge site has a lot of info of basic operations. For the rest of this post I’ll talk about a few deeper aspects that may be of interest while also giving a glance at how WebSurge works. Session Capturing As you would expect, WebSurge works with Sessions of Urls that are played back under load. Here’s what the main Session View looks like: You can create session entries manually by individually adding URLs to test (on the Request tab on the right) and saving them, or you can capture output from Web Browsers, Windows Desktop applications that call services, your own applications using the built in Capture tool. With this tool you can capture anything HTTP -SSL requests and content from Web pages, AJAX calls, SOAP or REST services – again anything that uses Windows or .NET HTTP APIs. Behind the scenes the capture tool uses FiddlerCore so basically anything you can capture with Fiddler you can also capture with Web Surge Session capture tool. Alternately you can actually use Fiddler as well, and then export the captured Fiddler trace to a file, which can then be imported into WebSurge. This is a nice way to let somebody capture session without having to actually install WebSurge or for your customers to provide an exact playback scenario for a given set of URLs that cause a problem perhaps. Note that not all applications work with Fiddler’s proxy unless you configure a proxy. For example, .NET Web applications that make HTTP calls usually don’t show up in Fiddler by default. For those .NET applications you can explicitly override proxy settings to capture those requests to service calls. The capture tool also has handy optional filters that allow you to filter by domain, to help block out noise that you typically don’t want to include in your requests. For example, if your pages include links to CDNs, or Google Analytics or social links you typically don’t want to include those in your load test, so by capturing just from a specific domain you are guaranteed content from only that one domain. Additionally you can provide url filters in the configuration file – filters allow to provide filter strings that if contained in a url will cause requests to be ignored. Again this is useful if you don’t filter by domain but you want to filter out things like static image, css and script files etc. Often you’re not interested in the load characteristics of these static and usually cached resources as they just add noise to tests and often skew the overall url performance results. In my testing I tend to care only about my dynamic requests. SSL Captures require Fiddler Note, that in order to capture SSL requests you’ll have to install the Fiddler’s SSL certificate. The easiest way to do this is to install Fiddler and use its SSL configuration options to get the certificate into the local certificate store. There’s a document on the Telerik site that provides the exact steps to get SSL captures to work with Fiddler and therefore with WebSurge. Session Storage A group of URLs entered or captured make up a Session. Sessions can be saved and restored easily as they use a very simple text format that simply stored on disk. The format is slightly customized HTTP header traces separated by a separator line. The headers are standard HTTP headers except that the full URL instead of just the domain relative path is stored as part of the 1st HTTP header line for easier parsing. Because it’s just text and uses the same format that Fiddler uses for exports, it’s super easy to create Sessions by hand manually or under program control writing out to a simple text file. You can see what this format looks like in the Capture window figure above – the raw captured format is also what’s stored to disk and what WebSurge parses from. The only ‘custom’ part of these headers is that 1st line contains the full URL instead of the domain relative path and Host: header. The rest of each header are just plain standard HTTP headers with each individual URL isolated by a separator line. The format used here also uses what Fiddler produces for exports, so it’s easy to exchange or view data either in Fiddler or WebSurge. Urls can also be edited interactively so you can modify the headers easily as well: Again – it’s just plain HTTP headers so anything you can do with HTTP can be added here. Use it for single URL Testing Incidentally I’ve also found this form as an excellent way to test and replay individual URLs for simple non-load testing purposes. Because you can capture a single or many URLs and store them on disk, this also provides a nice HTTP playground where you can record URLs with their headers, and fire them one at a time or as a session and see results immediately. It’s actually an easy way for REST presentations and I find the simple UI flow actually easier than using Fiddler natively. Finally you can save one or more URLs as a session for later retrieval. I’m using this more and more for simple URL checks. Overriding Cookies and Domains Speaking of HTTP headers – you can also overwrite cookies used as part of the options. One thing that happens with modern Web applications is that you have session cookies in use for authorization. These cookies tend to expire at some point which would invalidate a test. Using the Options dialog you can actually override the cookie: which replaces the cookie for all requests with the cookie value specified here. You can capture a valid cookie from a manual HTTP request in your browser and then paste into the cookie field, to replace the existing Cookie with the new one that is now valid. Likewise you can easily replace the domain so if you captured urls on west-wind.com and now you want to test on localhost you can do that easily easily as well. You could even do something like capture on store.west-wind.com and then test on localhost/store which would also work. Running Load Tests Once you’ve created a Session you can specify the length of the test in seconds, and specify the number of simultaneous threads to run each session on. Sessions run through each of the URLs in the session sequentially by default. One option in the options list above is that you can also randomize the URLs so each thread runs requests in a different order. This avoids bunching up URLs initially when tests start as all threads run the same requests simultaneously which can sometimes skew the results of the first few minutes of a test. While sessions run some progress information is displayed: By default there’s a live view of requests displayed in a Console-like window. On the bottom of the window there’s a running total summary that displays where you’re at in the test, how many requests have been processed and what the requests per second count is currently for all requests. Note that for tests that run over a thousand requests a second it’s a good idea to turn off the console display. While the console display is nice to see that something is happening and also gives you slight idea what’s happening with actual requests, once a lot of requests are processed, this UI updating actually adds a lot of CPU overhead to the application which may cause the actual load generated to be reduced. If you are running a 1000 requests a second there’s not much to see anyway as requests roll by way too fast to see individual lines anyway. If you look on the options panel, there is a NoProgressEvents option that disables the console display. Note that the summary display is still updated approximately once a second so you can always tell that the test is still running. Test Results When the test is done you get a simple Results display: On the right you get an overall summary as well as breakdown by each URL in the session. Both success and failures are highlighted so it’s easy to see what’s breaking in your load test. The report can be printed or you can also open the HTML document in your default Web Browser for printing to PDF or saving the HTML document to disk. The list on the right shows you a partial list of the URLs that were fired so you can look in detail at the request and response data. The list can be filtered by success and failure requests. Each list is partial only (at the moment) and limited to a max of 1000 items in order to render reasonably quickly. Each item in the list can be clicked to see the full request and response data: This particularly useful for errors so you can quickly see and copy what request data was used and in the case of a GET request you can also just click the link to quickly jump to the page. For non-GET requests you can find the URL in the Session list, and use the context menu to Test the URL as configured including any HTTP content data to send. You get to see the full HTTP request and response as well as a link in the Request header to go visit the actual page. Not so useful for a POST as above, but definitely useful for GET requests. Finally you can also get a few charts. The most useful one is probably the Request per Second chart which can be accessed from the Charts menu or shortcut. Here’s what it looks like:   Results can also be exported to JSON, XML and HTML. Keep in mind that these files can get very large rather quickly though, so exports can end up taking a while to complete. Command Line Interface WebSurge runs with a small core load engine and this engine is plugged into the front end application I’ve shown so far. There’s also a command line interface available to run WebSurge from the Windows command prompt. Using the command line you can run tests for either an individual URL (similar to AB.exe for example) or a full Session file. By default when it runs WebSurgeCli shows progress every second showing total request count, failures and the requests per second for the entire test. A silent option can turn off this progress display and display only the results. The command line interface can be useful for build integration which allows checking for failures perhaps or hitting a specific requests per second count etc. It’s also nice to use this as quick and dirty URL test facility similar to the way you’d use Apache Bench (ab.exe). Unlike ab.exe though, WebSurgeCli supports SSL and makes it much easier to create multi-URL tests using either manual editing or the WebSurge UI. Current Status Currently West Wind WebSurge is still in Beta status. I’m still adding small new features and tweaking the UI in an attempt to make it as easy and self-explanatory as possible to run. Documentation for the UI and specialty features is also still a work in progress. I plan on open-sourcing this product, but it won’t be free. There’s a free version available that provides a limited number of threads and request URLs to run. A relatively low cost license  removes the thread and request limitations. Pricing info can be found on the Web site – there’s an introductory price which is $99 at the moment which I think is reasonable compared to most other for pay solutions out there that are exorbitant by comparison… The reason code is not available yet is – well, the UI portion of the app is a bit embarrassing in its current monolithic state. The UI started as a very simple interface originally that later got a lot more complex – yeah, that never happens, right? Unless there’s a lot of interest I don’t foresee re-writing the UI entirely (which would be ideal), but in the meantime at least some cleanup is required before I dare to publish it :-). The code will likely be released with version 1.0. I’m very interested in feedback. Do you think this could be useful to you and provide value over other tools you may or may not have used before? I hope so – it already has provided a ton of value for me and the work I do that made the development worthwhile at this point. You can leave a comment below, or for more extensive discussions you can post a message on the West Wind Message Board in the WebSurge section Microsoft MVPs and Insiders get a free License If you’re a Microsoft MVP or a Microsoft Insider you can get a full license for free. Send me a link to your current, official Microsoft profile and I’ll send you a not-for resale license. Send any messages to [email protected]. Resources For more info on WebSurge and to download it to try it out, use the following links. West Wind WebSurge Home Download West Wind WebSurge Getting Started with West Wind WebSurge Video© Rick Strahl, West Wind Technologies, 2005-2014Posted in ASP.NET   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • Start Time & Calculated Column Wonkiness in a SharePoint Event Calendar

    - by _zekeMouseOver
    I was creating some custom rollups on some of our event calendars and came across a very odd bug when trying to grab only the date component of the built-in Start Time field. One's first inclination will be to create a calculated column and give it the formula... =[Start Time]... and then assign its output type to be "Date Only." This works well until a user adds an All Day Event. For reasons unexplainable, the All Day Event flag causes your =[Start Time] to display the date minus one day. Here is an example of this in action:  Start Date and Time, Duration, Start Date Value and Start Day are all calculated fields. Notice how the Start Date and Time (=[Start Time]) is reporting 6:00PM of the previous day. The Start Date Value (=[Start Time] - Output Type: Number) confirms this (.75 = 6:00 PM.) Curiously enough, the Duration (=[End Time]-[Start Time]) is properly reporting the duration between 12:00AM and 11:59PM. Why? I don't know. Perhaps it's somehow bound to the regional settings on the site, but I'm not interested in changing a global site setting for the sake of one calculated field.With this information at our disposal, our calculated column to display the date part of the start date needs to be modified to add one day to the [Start Time] field if an All Day Event is selected. To determine this, we use the Duration above to assume the item is an all-day event and change our formula to be:=IF(TEXT(([End Time]-[Start Time])-TRUNC(([End Time]-[Start Time]),0),"0.000000000")="0.999305556",[Start Time] + 1, [Start Time])This will work, but what happens when the user de-selects the "All Day Event" checkbox? The duration stays the same, but all other values begin reporting the correct time: Since our formula above is strictly based on an expected duration, it will add one to the correct date, causing the date 5/11/2010 to appear. Notice though that the raw value of the start time (in this case) is a non-fractional number (40,308) whereas the all-day event was being represented as 6:00 PM (.75) of the previous day. We can use this to add one more nested branch of logic to our calculation:=IF(TEXT(([End Time]-[Start Time])-TRUNC(([End Time]-[Start Time]),0),"0.000000000")="0.999305556",IF([Start Time]=ROUND([Start Time],0),[Start Time],[Start Time]+1),[Start Time]) I feel somewhat... dirty about having to resort to this kind of calculation in what SHOULD have been a simple =[Start Time] to extract the date part of the Start Time field, but there you have it. Make sure to shower extra longer after having used it.

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  • Using HTML 5 SessionState to save rendered Page Content

    - by Rick Strahl
    HTML 5 SessionState and LocalStorage are very useful and super easy to use to manage client side state. For building rich client side or SPA style applications it's a vital feature to be able to cache user data as well as HTML content in order to swap pages in and out of the browser's DOM. What might not be so obvious is that you can also use the sessionState and localStorage objects even in classic server rendered HTML applications to provide caching features between pages. These APIs have been around for a long time and are supported by most relatively modern browsers and even all the way back to IE8, so you can use them safely in your Web applications. SessionState and LocalStorage are easy The APIs that make up sessionState and localStorage are very simple. Both object feature the same API interface which  is a simple, string based key value store that has getItem, setItem, removeitem, clear and  key methods. The objects are also pseudo array objects and so can be iterated like an array with  a length property and you have array indexers to set and get values with. Basic usage  for storing and retrieval looks like this (using sessionStorage, but the syntax is the same for localStorage - just switch the objects):// set var lastAccess = new Date().getTime(); if (sessionStorage) sessionStorage.setItem("myapp_time", lastAccess.toString()); // retrieve in another page or on a refresh var time = null; if (sessionStorage) time = sessionStorage.getItem("myapp_time"); if (time) time = new Date(time * 1); else time = new Date(); sessionState stores data that is browser session specific and that has a liftetime of the active browser session or window. Shut down the browser or tab and the storage goes away. localStorage uses the same API interface, but the lifetime of the data is permanently stored in the browsers storage area until deleted via code or by clearing out browser cookies (not the cache). Both sessionStorage and localStorage space is limited. The spec is ambiguous about this - supposedly sessionStorage should allow for unlimited size, but it appears that most WebKit browsers support only 2.5mb for either object. This means you have to be careful what you store especially since other applications might be running on the same domain and also use the storage mechanisms. That said 2.5mb worth of character data is quite a bit and would go a long way. The easiest way to get a feel for how sessionState and localStorage work is to look at a simple example. You can go check out the following example online in Plunker: http://plnkr.co/edit/0ICotzkoPjHaWa70GlRZ?p=preview which looks like this: Plunker is an online HTML/JavaScript editor that lets you write and run Javascript code and similar to JsFiddle, but a bit cleaner to work in IMHO (thanks to John Papa for turning me on to it). The sample has two text boxes with counts that update session/local storage every time you click the related button. The counts are 'cached' in Session and Local storage. The point of these examples is that both counters survive full page reloads, and the LocalStorage counter survives a complete browser shutdown and restart. Go ahead and try it out by clicking the Reload button after updating both counters and then shutting down the browser completely and going back to the same URL (with the same browser). What you should see is that reloads leave both counters intact at the counted values, while a browser restart will leave only the local storage counter intact. The code to deal with the SessionStorage (and LocalStorage not shown here) in the example is isolated into a couple of wrapper methods to simplify the code: function getSessionCount() { var count = 0; if (sessionStorage) { var count = sessionStorage.getItem("ss_count"); count = !count ? 0 : count * 1; } $("#txtSession").val(count); return count; } function setSessionCount(count) { if (sessionStorage) sessionStorage.setItem("ss_count", count.toString()); } These two functions essentially load and store a session counter value. The two key methods used here are: sessionStorage.getItem(key); sessionStorage.setItem(key,stringVal); Note that the value given to setItem and return by getItem has to be a string. If you pass another type you get an error. Don't let that limit you though - you can easily enough store JSON data in a variable so it's quite possible to pass complex objects and store them into a single sessionStorage value:var user = { name: "Rick", id="ricks", level=8 } sessionStorage.setItem("app_user",JSON.stringify(user)); to retrieve it:var user = sessionStorage.getItem("app_user"); if (user) user = JSON.parse(user); Simple! If you're using the Chrome Developer Tools (F12) you can also check out the session and local storage state on the Resource tab:   You can also use this tool to refresh or remove entries from storage. What we just looked at is a purely client side implementation where a couple of counters are stored. For rich client centric AJAX applications sessionStorage and localStorage provide a very nice and simple API to store application state while the application is running. But you can also use these storage mechanisms to manage server centric HTML applications when you combine server rendering with some JavaScript to perform client side data caching. You can both store some state information and data on the client (ie. store a JSON object and carry it forth between server rendered HTML requests) or you can use it for good old HTTP based caching where some rendered HTML is saved and then restored later. Let's look at the latter with a real life example. Why do I need Client-side Page Caching for Server Rendered HTML? I don't know about you, but in a lot of my existing server driven applications I have lists that display a fair amount of data. Typically these lists contain links to then drill down into more specific data either for viewing or editing. You can then click on a link and go off to a detail page that provides more concise content. So far so good. But now you're done with the detail page and need to get back to the list, so you click on a 'bread crumbs trail' or an application level 'back to list' button and… …you end up back at the top of the list - the scroll position, the current selection in some cases even filters conditions - all gone with the wind. You've left behind the state of the list and are starting from scratch in your browsing of the list from the top. Not cool! Sound familiar? This a pretty common scenario with server rendered HTML content where it's so common to display lists to drill into, only to lose state in the process of returning back to the original list. Look at just about any traditional forums application, or even StackOverFlow to see what I mean here. Scroll down a bit to look at a post or entry, drill in then use the bread crumbs or tab to go back… In some cases returning to the top of a list is not a big deal. On StackOverFlow that sort of works because content is turning around so quickly you probably want to actually look at the top posts. Not always though - if you're browsing through a list of search topics you're interested in and drill in there's no way back to that position. Essentially anytime you're actively browsing the items in the list, that's when state becomes important and if it's not handled the user experience can be really disrupting. Content Caching If you're building client centric SPA style applications this is a fairly easy to solve problem - you tend to render the list once and then update the page content to overlay the detail content, only hiding the list temporarily until it's used again later. It's relatively easy to accomplish this simply by hiding content on the page and later making it visible again. But if you use server rendered content, hanging on to all the detail like filters, selections and scroll position is not quite as easy. Or is it??? This is where sessionStorage comes in handy. What if we just save the rendered content of a previous page, and then restore it when we return to this page based on a special flag that tells us to use the cached version? Let's see how we can do this. A real World Use Case Recently my local ISP asked me to help out with updating an ancient classifieds application. They had a very busy, local classifieds app that was originally an ASP classic application. The old app was - wait for it: frames based - and even though I lobbied against it, the decision was made to keep the frames based layout to allow rapid browsing of the hundreds of posts that are made on a daily basis. The primary reason they wanted this was precisely for the ability to quickly browse content item by item. While I personally hate working with Frames, I have to admit that the UI actually works well with the frames layout as long as you're running on a large desktop screen. You can check out the frames based desktop site here: http://classifieds.gorge.net/ However when I rebuilt the app I also added a secondary view that doesn't use frames. The main reason for this of course was for mobile displays which work horribly with frames. So there's a somewhat mobile friendly interface to the interface, which ditches the frames and uses some responsive design tweaking for mobile capable operation: http://classifeds.gorge.net/mobile  (or browse the base url with your browser width under 800px)   Here's what the mobile, non-frames view looks like:   As you can see this means that the list of classifieds posts now is a list and there's a separate page for drilling down into the item. And of course… originally we ran into that usability issue I mentioned earlier where the browse, view detail, go back to the list cycle resulted in lost list state. Originally in mobile mode you scrolled through the list, found an item to look at and drilled in to display the item detail. Then you clicked back to the list and BAM - you've lost your place. Because there are so many items added on a daily basis the full list is never fully loaded, but rather there's a "Load Additional Listings"  entry at the button. Not only did we originally lose our place when coming back to the list, but any 'additionally loaded' items are no longer there because the list was now rendering  as if it was the first page hit. The additional listings, and any filters, the selection of an item all were lost. Major Suckage! Using Client SessionStorage to cache Server Rendered Content To work around this problem I decided to cache the rendered page content from the list in SessionStorage. Anytime the list renders or is updated with Load Additional Listings, the page HTML is cached and stored in Session Storage. Any back links from the detail page or the login or write entry forms then point back to the list page with a back=true query string parameter. If the server side sees this parameter it doesn't render the part of the page that is cached. Instead the client side code retrieves the data from the sessionState cache and simply inserts it into the page. It sounds pretty simple, and the overall the process is really easy, but there are a few gotchas that I'll discuss in a minute. But first let's look at the implementation. Let's start with the server side here because that'll give a quick idea of the doc structure. As I mentioned the server renders data from an ASP.NET MVC view. On the list page when returning to the list page from the display page (or a host of other pages) looks like this: https://classifieds.gorge.net/list?back=True The query string value is a flag, that indicates whether the server should render the HTML. Here's what the top level MVC Razor view for the list page looks like:@model MessageListViewModel @{ ViewBag.Title = "Classified Listing"; bool isBack = !string.IsNullOrEmpty(Request.QueryString["back"]); } <form method="post" action="@Url.Action("list")"> <div id="SizingContainer"> @if (!isBack) { @Html.Partial("List_CommandBar_Partial", Model) <div id="PostItemContainer" class="scrollbox" xstyle="-webkit-overflow-scrolling: touch;"> @Html.Partial("List_Items_Partial", Model) @if (Model.RequireLoadEntry) { <div class="postitem loadpostitems" style="padding: 15px;"> <div id="LoadProgress" class="smallprogressright"></div> <div class="control-progress"> Load additional listings... </div> </div> } </div> } </div> </form> As you can see the query string triggers a conditional block that if set is simply not rendered. The content inside of #SizingContainer basically holds  the entire page's HTML sans the headers and scripts, but including the filter options and menu at the top. In this case this makes good sense - in other situations the fact that the menu or filter options might be dynamically updated might make you only cache the list rather than essentially the entire page. In this particular instance all of the content works and produces the proper result as both the list along with any filter conditions in the form inputs are restored. Ok, let's move on to the client. On the client there are two page level functions that deal with saving and restoring state. Like the counter example I showed earlier, I like to wrap the logic to save and restore values from sessionState into a separate function because they are almost always used in several places.page.saveData = function(id) { if (!sessionStorage) return; var data = { id: id, scroll: $("#PostItemContainer").scrollTop(), html: $("#SizingContainer").html() }; sessionStorage.setItem("list_html",JSON.stringify(data)); }; page.restoreData = function() { if (!sessionStorage) return; var data = sessionStorage.getItem("list_html"); if (!data) return null; return JSON.parse(data); }; The data that is saved is an object which contains an ID which is the selected element when the user clicks and a scroll position. These two values are used to reset the scroll position when the data is used from the cache. Finally the html from the #SizingContainer element is stored, which makes for the bulk of the document's HTML. In this application the HTML captured could be a substantial bit of data. If you recall, I mentioned that the server side code renders a small chunk of data initially and then gets more data if the user reads through the first 50 or so items. The rest of the items retrieved can be rather sizable. Other than the JSON deserialization that's Ok. Since I'm using SessionStorage the storage space has no immediate limits. Next is the core logic to handle saving and restoring the page state. At first though this would seem pretty simple, and in some cases it might be, but as the following code demonstrates there are a few gotchas to watch out for. Here's the relevant code I use to save and restore:$( function() { … var isBack = getUrlEncodedKey("back", location.href); if (isBack) { // remove the back key from URL setUrlEncodedKey("back", "", location.href); var data = page.restoreData(); // restore from sessionState if (!data) { // no data - force redisplay of the server side default list window.location = "list"; return; } $("#SizingContainer").html(data.html); var el = $(".postitem[data-id=" + data.id + "]"); $(".postitem").removeClass("highlight"); el.addClass("highlight"); $("#PostItemContainer").scrollTop(data.scroll); setTimeout(function() { el.removeClass("highlight"); }, 2500); } else if (window.noFrames) page.saveData(null); // save when page loads $("#SizingContainer").on("click", ".postitem", function() { var id = $(this).attr("data-id"); if (!id) return true; if (window.noFrames) page.saveData(id); var contentFrame = window.parent.frames["Content"]; if (contentFrame) contentFrame.location.href = "show/" + id; else window.location.href = "show/" + id; return false; }); … The code starts out by checking for the back query string flag which triggers restoring from the client cache. If cached the cached data structure is read from sessionStorage. It's important here to check if data was returned. If the user had back=true on the querystring but there is no cached data, he likely bookmarked this page or otherwise shut down the browser and came back to this URL. In that case the server didn't render any detail and we have no cached data, so all we can do is redirect to the original default list view using window.location. If we continued the page would render no data - so make sure to always check the cache retrieval result. Always! If there is data the it's loaded and the data.html data is restored back into the document by simply injecting the HTML back into the document's #SizingContainer element:$("#SizingContainer").html(data.html); It's that simple and it's quite quick even with a fully loaded list of additional items and on a phone. The actual HTML data is stored to the cache on every page load initially and then again when the user clicks on an element to navigate to a particular listing. The former ensures that the client cache always has something in it, and the latter updates with additional information for the selected element. For the click handling I use a data-id attribute on the list item (.postitem) in the list and retrieve the id from that. That id is then used to navigate to the actual entry as well as storing that Id value in the saved cached data. The id is used to reset the selection by searching for the data-id value in the restored elements. The overall process of this save/restore process is pretty straight forward and it doesn't require a bunch of code, yet it yields a huge improvement in the usability of the site on mobile devices (or anybody who uses the non-frames view). Some things to watch out for As easy as it conceptually seems to simply store and retrieve cached content, you have to be quite aware what type of content you are caching. The code above is all that's specific to cache/restore cycle and it works, but it took a few tweaks to the rest of the script code and server code to make it all work. There were a few gotchas that weren't immediately obvious. Here are a few things to pay attention to: Event Handling Logic Timing of manipulating DOM events Inline Script Code Bookmarking to the Cache Url when no cache exists Do you have inline script code in your HTML? That script code isn't going to run if you restore from cache and simply assign or it may not run at the time you think it would normally in the DOM rendering cycle. JavaScript Event Hookups The biggest issue I ran into with this approach almost immediately is that originally I had various static event handlers hooked up to various UI elements that are now cached. If you have an event handler like:$("#btnSearch").click( function() {…}); that works fine when the page loads with server rendered HTML, but that code breaks when you now load the HTML from cache. Why? Because the elements you're trying to hook those events to may not actually be there - yet. Luckily there's an easy workaround for this by using deferred events. With jQuery you can use the .on() event handler instead:$("#SelectionContainer").on("click","#btnSearch", function() {…}); which monitors a parent element for the events and checks for the inner selector elements to handle events on. This effectively defers to runtime event binding, so as more items are added to the document bindings still work. For any cached content use deferred events. Timing of manipulating DOM Elements Along the same lines make sure that your DOM manipulation code follows the code that loads the cached content into the page so that you don't manipulate DOM elements that don't exist just yet. Ideally you'll want to check for the condition to restore cached content towards the top of your script code, but that can be tricky if you have components or other logic that might not all run in a straight line. Inline Script Code Here's another small problem I ran into: I use a DateTime Picker widget I built a while back that relies on the jQuery date time picker. I also created a helper function that allows keyboard date navigation into it that uses JavaScript logic. Because MVC's limited 'object model' the only way to embed widget content into the page is through inline script. This code broken when I inserted the cached HTML into the page because the script code was not available when the component actually got injected into the page. As the last bullet - it's a matter of timing. There's no good work around for this - in my case I pulled out the jQuery date picker and relied on native <input type="date" /> logic instead - a better choice these days anyway, especially since this view is meant to be primarily to serve mobile devices which actually support date input through the browser (unlike desktop browsers of which only WebKit seems to support it). Bookmarking Cached Urls When you cache HTML content you have to make a decision whether you cache on the client and also not render that same content on the server. In the Classifieds app I didn't render server side content so if the user comes to the page with back=True and there is no cached content I have to a have a Plan B. Typically this happens when somebody ends up bookmarking the back URL. The easiest and safest solution for this scenario is to ALWAYS check the cache result to make sure it exists and if not have a safe URL to go back to - in this case to the plain uncached list URL which amounts to effectively redirecting. This seems really obvious in hindsight, but it's easy to overlook and not see a problem until much later, when it's not obvious at all why the page is not rendering anything. Don't use <body> to replace Content Since we're practically replacing all the HTML in the page it may seem tempting to simply replace the HTML content of the <body> tag. Don't. The body tag usually contains key things that should stay in the page and be there when it loads. Specifically script tags and elements and possibly other embedded content. It's best to create a top level DOM element specifically as a placeholder container for your cached content and wrap just around the actual content you want to replace. In the app above the #SizingContainer is that container. Other Approaches The approach I've used for this application is kind of specific to the existing server rendered application we're running and so it's just one approach you can take with caching. However for server rendered content caching this is a pattern I've used in a few apps to retrofit some client caching into list displays. In this application I took the path of least resistance to the existing server rendering logic. Here are a few other ways that come to mind: Using Partial HTML Rendering via AJAXInstead of rendering the page initially on the server, the page would load empty and the client would render the UI by retrieving the respective HTML and embedding it into the page from a Partial View. This effectively makes the initial rendering and the cached rendering logic identical and removes the server having to decide whether this request needs to be rendered or not (ie. not checking for a back=true switch). All the logic related to caching is made on the client in this case. Using JSON Data and Client RenderingThe hardcore client option is to do the whole UI SPA style and pull data from the server and then use client rendering or databinding to pull the data down and render using templates or client side databinding with knockout/angular et al. As with the Partial Rendering approach the advantage is that there's no difference in the logic between pulling the data from cache or rendering from scratch other than the initial check for the cache request. Of course if the app is a  full on SPA app, then caching may not be required even - the list could just stay in memory and be hidden and reactivated. I'm sure there are a number of other ways this can be handled as well especially using  AJAX. AJAX rendering might simplify the logic, but it also complicates search engine optimization since there's no content loaded initially. So there are always tradeoffs and it's important to look at all angles before deciding on any sort of caching solution in general. State of the Session SessionState and LocalStorage are easy to use in client code and can be integrated even with server centric applications to provide nice caching features of content and data. In this post I've shown a very specific scenario of storing HTML content for the purpose of remembering list view data and state and making the browsing experience for lists a bit more friendly, especially if there's dynamically loaded content involved. If you haven't played with sessionStorage or localStorage I encourage you to give it a try. There's a lot of cool stuff that you can do with this beyond the specific scenario I've covered here… Resources Overview of localStorage (also applies to sessionStorage) Web Storage Compatibility Modernizr Test Suite© Rick Strahl, West Wind Technologies, 2005-2013Posted in JavaScript  HTML5  ASP.NET  MVC   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • Ubuntu Server 12.04 CPU Load

    - by zertux
    I have a Server (2x Hexa-Core Xeon E5649 2.53GHz w/HT with 32GB RAM and 20000 GB Bandwidth) running Ubuntu Server 12.04 LTS. The server runs LAMP and serves one website only, the estimated number of users is to be ~ 15,000 at the same time. At the moment i have around 2000 users online each of them runs 50 MySQL queries (small values mostly select and insert) from the beginning until the end of the session. Server CPU Load is high at this number of connections while the RAM usage is almost 1GB out of 32GB its worth mentioning that the server was running very fast with no problems at all but am concerned about the load average. http://s12.postimage.org/z7hi6mz3h/photo.png top - 03:02:43 up 9 min, 2 users, load average: 50.83, 30.14, 12.83 Tasks: 432 total, 1 running, 430 sleeping, 0 stopped, 1 zombie Cpu(s): 0.1%us, 0.2%sy, 0.0%ni, 66.5%id, 33.1%wa, 0.0%hi, 0.0%si, 0.0%st Mem: 32939992k total, 3111604k used, 29828388k free, 84108k buffers Swap: 2048280k total, 0k used, 2048280k free, 1621640k cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 2860 root 20 0 25820 2288 1420 S 3 0.0 0:11.18 htop 1182 root 20 0 0 0 0 D 2 0.0 0:01.46 kjournald 1935 mysql 20 0 12.3g 161m 7924 S 1 0.5 102:31.45 mysqld 11 root 20 0 0 0 0 S 0 0.0 0:00.38 kworker/0:1 1822 www-data 20 0 247m 25m 4188 D 0 0.1 0:01.81 apache2 2920 www-data 20 0 0 0 0 Z 0 0.0 0:01.20 apache2 <defunct> 2942 www-data 20 0 247m 23m 3056 D 0 0.1 0:00.20 apache2 3516 www-data 20 0 247m 23m 3028 D 0 0.1 0:00.06 apache2 3521 www-data 20 0 247m 23m 3020 D 0 0.1 0:00.09 apache2 3664 www-data 20 0 247m 23m 3132 D 0 0.1 0:00.09 apache2 3674 www-data 20 0 247m 23m 3252 D 0 0.1 0:00.06 apache2 3713 www-data 20 0 247m 23m 3040 D 0 0.1 0:00.09 apache2 1 root 20 0 24328 2284 1344 S 0 0.0 0:03.09 init 2 root 20 0 0 0 0 S 0 0.0 0:00.00 kthreadd 3 root 20 0 0 0 0 S 0 0.0 0:00.01 ksoftirqd/0 6 root RT 0 0 0 0 S 0 0.0 0:00.00 migration/0 7 root RT 0 0 0 0 S 0 0.0 0:00.00 watchdog/0 8 root RT 0 0 0 0 S 0 0.0 0:00.00 migration/1 9 root 20 0 0 0 0 S 0 0.0 0:00.00 kworker/1:0 root@server:~/codes# vmstat 1 procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu---- r b swpd free buff cache si so bi bo in cs us sy id wa 19 0 0 29684012 86112 1689844 0 0 19 590 254 231 48 0 47 5 23 0 0 29704812 86128 1697672 0 0 4 320 11100 8121 77 1 22 0 33 0 0 29671044 86156 1705308 0 0 0 5440 13190 9140 95 1 4 0 33 3 0 29670088 86160 1706288 0 0 0 32932 12275 7297 99 0 1 0 35 0 0 29693456 86188 1710724 0 0 4 676 12701 7867 98 1 1 0 ^C I have not changed any of the default configurations that comes with Ubuntu. Is this load normal for such powerful server ? is there any optimization i can make to Apache/MySQL to minimize the load ? What do you recommend ?

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  • Plesk Postfix Mail Server 9.5.4 very heavy load, 1000s of processes

    - by Eugene van der Merwe
    Our Plesk Linux Ubuntu 64-bit mail server has extremely high load and we don't know how to isolate it. The load was okay will two weeks ago but in the last two weeks it's seriously deteriorated. The mail server has been running for years and we have had sporadic performance issues. Normally we reduce the load by turning off all SPAM checks until the problem is sorted (which sometimes resolves itself). Currently we have turned of real time block lists, SPF checking and we have attempted to turn off SpamAssassin. No matter what we do the SpamAssassin check box stays ticked in the GUI. Out of desperation we have done /etc/init.d/psa-spamassassin stop. For years we haven't been able to do SpamAssassin because it kills the server. We would like to use it but performance is more important for now. We cannot turn off Greylisting. The moment we turn off Greylisting our help desk is inandated with calls. Out of desperation we investigated truncating the Greylisting database which is now 2.5 GB big but we abandoned this after noticing turning of Greylisting doesn't improve the performance at all. We have no anti-virus. It's just more load and Dr. Web never really worked that well for us. But we'll try that if it will make a difference. We have implemented Postfix Anvil. This seems to have made the situation worse so we disabled it. We’re not sure if this is the case. Our current mail server is configured to forward all SMTP to a relay server. We did so to reduce the load. This helped a lot because outgoing queues are generally empty. We are running in an Expand configuration. The mail server has about 12 000 accounts of which maybe half are active. We have read through this document: http://www.postfix.org/STRESS_README.html but there are too many settings and we don’t know which ones to choose. Please assist urgently. We need advice on how to fix this problem before all our clients abandon is. The only clue we have is that there are 100s of these processes: 30 13205 1 0 13:18 ? 00:00:00 /usr/lib/plesk-9.0/postfix-queue 127.0.0.1 10027 before-queue 30 13207 1 0 11:38 ? 00:00:00 /usr/lib/plesk-9.0/postfix-queue 127.0.0.1 10027 before-queue 30 13208 1 0 13:18 ? 00:00:00 /usr/lib/plesk-9.0/postfix-queue 127.0.0.1 10026 before-remote 30 13209 1 0 11:38 ? 00:00:00 /usr/lib/plesk-9.0/postfix-queue 127.0.0.1 10026 before-remote 30 13213 1 0 13:18 ? 00:00:00 /usr/lib/plesk-9.0/postfix-queue 127.0.0.1 10027 before-queue

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  • I need help in inno setup custom page

    - by vinutavishal
    in inno setup i hav created a custom page with following code and has 3 text boxes now i want to validate that text box on custom form next button click if in text.text='2121212' something text is entered by user then only next button enabled pls help any one its urgent [CustomMessages] CustomForm_Caption=CustomForm Caption CustomForm_Description=CustomForm Description CustomForm_Label1_Caption0=College Name: CustomForm_Label2_Caption0=Product Type: CustomForm_Label3_Caption0=Product ID: [Code] var Label1: TLabel; Label2: TLabel; Label3: TLabel; Edit1: TEdit; Edit2: TEdit; Edit3: TEdit; Edit4: TEdit; Edit5: TEdit; Edit6: TEdit; { CustomForm_Activate } procedure CustomForm_Activate(Page: TWizardPage); begin // enter code here... end; { CustomForm_ShouldSkipPage } function CustomForm_ShouldSkipPage(Page: TWizardPage): Boolean; begin Result := False; end; { CustomForm_BackButtonClick } function CustomForm_BackButtonClick(Page: TWizardPage): Boolean; begin Result := True; end; { CustomForm_NextkButtonClick } function CustomForm_NextButtonClick(Page: TWizardPage): Boolean; begin RegWriteStringValue(HKEY_LOCAL_MACHINE, 'Software\SGS2.2\CS', 'College Name', Edit1.Text); RegWriteStringValue(HKEY_LOCAL_MACHINE, 'Software\SGS2.2\CS', 'Product Type', Edit2.Text); RegWriteStringValue(HKEY_LOCAL_MACHINE, 'Software\SGS2.2\CS', 'Product ID', Edit3.Text); Result := True; end; { CustomForm_CancelButtonClick } procedure CustomForm_CancelButtonClick(Page: TWizardPage; var Cancel, Confirm: Boolean); begin // enter code here... end; { CustomForm_CreatePage } function CustomForm_CreatePage(PreviousPageId: Integer): Integer; var Page: TWizardPage; begin Page := CreateCustomPage( PreviousPageId, ExpandConstant('{cm:CustomForm_Caption}'), ExpandConstant('{cm:CustomForm_Description}') ); { Label1 } Label1 := TLabel.Create(Page); with Label1 do begin Parent := Page.Surface; Caption := ExpandConstant('{cm:CustomForm_Label1_Caption0}'); Left := ScaleX(16); Top := ScaleY(24); Width := ScaleX(70); Height := ScaleY(13); end; { Label2 } Label2 := TLabel.Create(Page); with Label2 do begin Parent := Page.Surface; Caption := ExpandConstant('{cm:CustomForm_Label2_Caption0}'); Left := ScaleX(17); Top := ScaleY(56); Width := ScaleX(70); Height := ScaleY(13); end; { Label3 } Label3 := TLabel.Create(Page); with Label3 do begin Parent := Page.Surface; Caption := ExpandConstant('{cm:CustomForm_Label3_Caption0}'); Left := ScaleX(17); Top := ScaleY(88); Width := ScaleX(70); Height := ScaleY(13); end; { Edit1 } Edit1 := TEdit.Create(Page); with Edit1 do begin Parent := Page.Surface; Left := ScaleX(115); Top := ScaleY(24); Width := ScaleX(273); Height := ScaleY(21); TabOrder := 0; end; { Edit2 } Edit2 := TEdit.Create(Page); with Edit2 do begin Parent := Page.Surface; Left := ScaleX(115); Top := ScaleY(56); Width := ScaleX(273); Height := ScaleY(21); TabOrder := 1; end; { Edit3 } Edit3 := TEdit.Create(Page); with Edit3 do begin Parent := Page.Surface; Left := ScaleX(115); Top := ScaleY(88); Width := ScaleX(273); Height := ScaleY(21); TabOrder := 2; end; with Page do begin OnActivate := @CustomForm_Activate; OnShouldSkipPage := @CustomForm_ShouldSkipPage; OnBackButtonClick := @CustomForm_BackButtonClick; OnNextButtonClick := @CustomForm_NextButtonClick; OnCancelButtonClick := @CustomForm_CancelButtonClick; end; Result := Page.ID; end; { CustomForm_InitializeWizard } procedure InitializeWizard(); begin CustomForm_CreatePage(wpWelcome); end;

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  • SSI includes not working on Debian with Apache

    - by Mike
    I'm trying to get SSI to work on Debian running Apache, however the .shtml files are not being parsed. From a PHP file with phpinfo() I can see that the following show up in the loaded modules section: mod_mime_xattr mod_mime mod_mime_magic In /etc/apache2/mods-enabled/mime.conf I have (among other things): AddType text/html .shtml AddOutputFilter INCLUDES .shtml In /etc/apache2/sites-enabled/domain.com.conf (for the virtual host in question) I have: <Directory /home/username/public_html> Options +Includes allow from all AllowOverride All </Directory> and for good measure, I added the following as well: <Directory /> Options +Includes </directory> In the user's .htaccess file, I tried adding: Options +Includes AddType text/html shtml AddHandler server-parsed shtml Nothing seems to work. How can I even debug this? Edit: Here is the output of ls /etc/apache2/mods-enabled/ in case this helps actions.conf dav_svn.load proxy_balancer.load actions.load deflate.conf proxy.conf alias.conf deflate.load proxy_connect.load alias.load dir.conf proxy_http.load auth_basic.load dir.load proxy.load auth_digest.load env.load python.load authn_file.load fcgid.conf reqtimeout.conf authz_default.load fcgid.load reqtimeout.load authz_groupfile.load mime.conf rewrite.load authz_host.load mime.load ruby.load authz_user.load mime_magic.conf setenvif.conf autoindex.conf mime_magic.load setenvif.load autoindex.load mime-xattr.load ssl.conf cgi.load negotiation.conf ssl.load dav_fs.conf negotiation.load status.conf dav_fs.load php5.conf status.load dav.load php5.load suexec.load dav_svn.conf proxy_balancer.conf

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