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  • PHP suddenly failed after IIS update

    - by James Hay
    All my application pools were stopped this morning after I got to work. I can restart them, but when I try to load the website the app pool crashes again. Update: I've looked in the GAC as the error below suggests and it seems that the file is not there. How do I get it back? Update 2: I found a further error in the event log saying The Module name FastCgiModule path C:\WINDOWS\System32\inetsrv\iisfcgi.dll returned an error from registration. The data is the error. So following the information from here http://forums.iis.net/t/1153937.aspx I removed CGI and my sites are working again. This has fixed the initial problem, but now I don't have FastCGI so I'm fairly sure that PHP will no longer be working (I don't have any PHP at the moment to test). Original Post I'm getting this error in the event viewer: IISMANAGER_ERROR_LOADING_PROVIDER_TYPE IIS Manager could not load type 'Web.Management.PHP.PHPProvider, Web.Management.PHP, Version=1.2.0.0, Culture=neutral, PublicKeyToken=8175de49a9aec91d' for module provider 'PHP' that is declared in %windir%\system32\inetsrv\config\administration.config. Verify that the type is correct, and that the assembly that contains the module provider is in the Global Assembly Cache (GAC). Exception:System.IO.FileNotFoundException: Could not load file or assembly 'Web.Management.PHP, Version=1.2.0.0, Culture=neutral, PublicKeyToken=8175de49a9aec91d' or one of its dependencies. The system cannot find the file specified. File name: 'Web.Management.PHP, Version=1.2.0.0, Culture=neutral, PublicKeyToken=8175de49a9aec91d' at System.RuntimeTypeHandle._GetTypeByName(String name, Boolean throwOnError, Boolean ignoreCase, Boolean reflectionOnly, StackCrawlMark& stackMark, Boolean loadTypeFromPartialName) at System.RuntimeTypeHandle.GetTypeByName(String name, Boolean throwOnError, Boolean ignoreCase, Boolean reflectionOnly, StackCrawlMark& stackMark) at System.RuntimeType.PrivateGetType(String typeName, Boolean throwOnError, Boolean ignoreCase, Boolean reflectionOnly, StackCrawlMark& stackMark) at System.Type.GetType(String typeName, Boolean throwOnError) at Microsoft.Web.Management.Server.AdministrationModuleProvider.GetModuleProvider(String userName, String connectionName) WRN: Assembly binding logging is turned OFF. To enable assembly bind failure logging, set the registry value [HKLM\Software\Microsoft\Fusion!EnableLog] (DWORD) to 1. Note: There is some performance penalty associated with assembly bind failure logging. To turn this feature off, remove the registry value [HKLM\Software\Microsoft\Fusion!EnableLog]. Process:InetMgr Connection:CT211511\Administrator Everything was working fine last night when I left work, and since they've done the maintenance it's all broken.

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  • How can you know what is w3wp.exe doing? (or how to diagnose a performance problem)

    - by Daniel Magliola
    I'm having a performance problem in a site we've made, and I'm not exactly sure how to start diagnosing it. The short description is: We have a very small site (http://hearablog.com) with very little traffic, in a crappy dedicated server, CPU is always very high, sometimes it stays at 100% for minutes, and w3wp.exe is taking most of it. A typical scenario is w3wp.exe takes 60%, and SQL Server takes about 30%. Our DB is pretty small too. Long description and more details: The site is hosted in a very crappy server by Cari.Net. From the beginning we had the feeling that the server didn't quite behave correctly, like some things would take just too long, so this could be a configuration problem from the get go. It may also be that we are getting a virtual server while we're supposed to have a dedicated one, although we have no evidence that'd indicate this, except for the fact that the server tends to be quite slow. The server is Windows 2008 Standard 64-bit, with SQL 2008 Express Hardware is a Celeron 2.80 GHz, 1Gb RAM The website is developed in ASP.Net MVC, using Entity Framework for data access. Now, this is pretty crappy hardware, but i've had other servers with these guys, with equivalent (or worse) HW, and performance is much better than this one. That said, the other servers have W2003 and SQL2005, and I'm using ASP.Net "WebForms" 2.0, no MVC, no LINQ, no EF; so I'm not sure whether going to 2008 / the other stuff means a big performance penalty is expected. I'm serving MP3 files (5-20 Mb) regularly, which is a slightly unusual load, maybe that is causing some kind of problems? Would that cause w3wp to use a lot of CPU? Disk usage seems very low. Memory is usually around 90%, but disk usage seems to indicate it's not paging much. I get tons of e-mails every day about SQL timeouts, for queries taking over 30 seconds, although all our queries are pretty straightforward (or should be, but EF may be screwing it up). This is what resource monitor looks like in one of these "sprints" of 100% CPU, in case there's anything useful there. And a snapshot of some performance counters: Now, what confuses me very much is that CPU usage of w3wp is just so high. It shouldn't be doing much really... So my questions are... Is there any way of finding out "what" it is doing? Maybe even profile it? Any performance counters I should be looking at? Is this to be expected given this hardware/software configuration? Is this could be cause by some kind of configuration failure, where would you start looking? Thank you VERY much. Daniel Magliola

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  • In search of a network file system with extended caching to speed up file access

    - by Brecht Machiels
    I'm running a small home server that stores my documents. The disks in this server are in a RAID 1 configuration (using Linux md) and it's also periodically being backup up to an external hard drive to make sure I don't lose them. However, I'm always accessing the files from other computers on the home network using an SMB share, and this results in a considerable speed penalty (especially when connected over WLAN). This is quite annoying when editing large files, such as digital camera RAWs, for example. I've been looking for a solution to this problem. It would have to offer some kind of local caching to speed up the file access. The client would preferably not keep a copy of all data on the server, as it consists of a very large collection of photographs, most of which I will not access frequently. Instead, it should only cache the accessed files and sync the changes back in the background. Ideally, it would also do some smart read-ahead (cache the files that are in the same directory as the currently opened file, for examples), but I suppose that's asking a bit much. Synchronization should be automatic (on file change). Conflicting file changes (at the same time on different clients) are unlikely to happen in my use case, but I would prefer if they are handled properly (notification to the user). I've come across the following options, so far: something similar to Dropbox. iFolder seems to be the only thing that comes close, but its reputation (stability) and requirements put me off. A distributed file system such as OpenAFS. I'm not sure this will speed up file access. It is probably overkill for what I need. Maybe NFS or even Samba offer these possibilities. I read a bit about Windows' Offline Files, but its operation seems limited (at least on Windows XP). As this is just for personal use, I'm not willing to spend a lot of money. A free solution would be preferred. Also, the server needs to run on Linux, and I need a client for at least Windows.

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  • Quantifying the effects of partition mis-alignment

    - by Matt
    I'm experiencing some significant performance issues on an NFS server. I've been reading up a bit on partition alignment, and I think I have my partitions mis-aligned. I can't find anything that tells me how to actually quantify the effects of mis-aligned partitions. Some of the general information I found suggests the performance penalty can be quite high (upwards of 60%) and others say it's negligible. What I want to do is determine if partition alignment is a factor in this server's performance problems or not; and if so, to what degree? So I'll put my info out here, and hopefully the community can confirm if my partitions are indeed mis-aligned, and if so, help me put a number to what the performance cost is. Server is a Dell R510 with dual E5620 CPUs and 8 GB RAM. There are eight 15k 2.5” 600 GB drives (Seagate ST3600057SS) configured in hardware RAID-6 with a single hot spare. RAID controller is a Dell PERC H700 w/512MB cache (Linux sees this as a LSI MegaSAS 9260). OS is CentOS 5.6, home directory partition is ext3, with options “rw,data=journal,usrquota”. I have the HW RAID configured to present two virtual disks to the OS: /dev/sda for the OS (boot, root and swap partitions), and /dev/sdb for a big NFS share: [root@lnxutil1 ~]# parted -s /dev/sda unit s print Model: DELL PERC H700 (scsi) Disk /dev/sda: 134217599s Sector size (logical/physical): 512B/512B Partition Table: msdos Number Start End Size Type File system Flags 1 63s 465884s 465822s primary ext2 boot 2 465885s 134207009s 133741125s primary lvm [root@lnxutil1 ~]# parted -s /dev/sdb unit s print Model: DELL PERC H700 (scsi) Disk /dev/sdb: 5720768639s Sector size (logical/physical): 512B/512B Partition Table: gpt Number Start End Size File system Name Flags 1 34s 5720768606s 5720768573s lvm Edit 1 Using the cfq IO scheduler (default for CentOS 5.6): # cat /sys/block/sd{a,b}/queue/scheduler noop anticipatory deadline [cfq] noop anticipatory deadline [cfq] Chunk size is the same as strip size, right? If so, then 64kB: # /opt/MegaCli -LDInfo -Lall -aALL -NoLog Adapter #0 Number of Virtual Disks: 2 Virtual Disk: 0 (target id: 0) Name:os RAID Level: Primary-6, Secondary-0, RAID Level Qualifier-3 Size:65535MB State: Optimal Stripe Size: 64kB Number Of Drives:7 Span Depth:1 Default Cache Policy: WriteBack, ReadAdaptive, Direct, No Write Cache if Bad BBU Current Cache Policy: WriteThrough, ReadAdaptive, Direct, No Write Cache if Bad BBU Access Policy: Read/Write Disk Cache Policy: Disk's Default Number of Spans: 1 Span: 0 - Number of PDs: 7 ... physical disk info removed for brevity ... Virtual Disk: 1 (target id: 1) Name:share RAID Level: Primary-6, Secondary-0, RAID Level Qualifier-3 Size:2793344MB State: Optimal Stripe Size: 64kB Number Of Drives:7 Span Depth:1 Default Cache Policy: WriteBack, ReadAdaptive, Direct, No Write Cache if Bad BBU Current Cache Policy: WriteThrough, ReadAdaptive, Direct, No Write Cache if Bad BBU Access Policy: Read/Write Disk Cache Policy: Disk's Default Number of Spans: 1 Span: 0 - Number of PDs: 7 If it's not obvious, virtual disk 0 corresponds to /dev/sda, for the OS; virtual disk 1 is /dev/sdb (the exported home directory tree).

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  • Connecting a 2560x1440 display to a laptop?

    - by tjollans
    Having read Jeff Atwood's blog post on Korean 27" IPS LCDs, I've been wondering to what extent these are useful in a notebook + large display situation. I own a Lenovo Thinkpad Edge E320 with 2nd gen. integrated Intel graphics. According to the spec from Intel, this should support HDMI version 1.4, and, using DisplayPort, resolutions up to 2560x1600. HDMI version 1.4 supports resolutions up to 4096×2160, however, according to c't (German), the HDMI interface used with Intel chips only supports 1920x1200. The same goes for the DVI output - dual-link DVI-D, apparently, is not supported by Intel. It would appear that my laptop cannot digitally drive this kind of resolution. Now what about other laptops? According to the article in c't above, AMD's integrated graphics chips have the same limitation as Intel's. NVIDIA graphics cards, apparently, only offer resolutions up to 1900x1200 over HDMI out of the box, but it's possible, when using Linux at least, to trick the driver into enabling higher resolutions. Is this still true? What's the situation on Windows and OSX? I found no information on whether discrete AMD chips support ultra-high resolutions over HDMI. Owners of laptops with (Mini) DisplayPort / Thunderbolt won't have any issues with displays this large, but if you're planning to go for a display with dual-link DVI-D input only (like the Korean ones), you're going to need an adapter, which will set you back something like €70-€100 (since the protocols are incompatible). The big question mark in this equation is VGA: a lot of laptops have it, and I don't see any reason to think this resolution is not supported by the hardware (an oft-quoted figure appears to be 2048x1536@75Hz, so 2560x1440@60Hz should be possible, right?), but are the drivers likely to cause problems? Perhaps more critically, you'd need a VGA to dual-link DVI-D adapter that converts analog to digital signals. Do these exist? How good are they? How expensive are they? Is there a performance penalty involved? Please correct me if I'm wrong on any points. In summary, what are the requirements on a laptop to drive an external LCD at 2560x1440, in particular one that supports dual-link DVI-D only, and what tools and adapters can be used to lower the bar?

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  • Suggestions for splitting server roles amongst Hyper-V virtual servers / RAID6 or RAID10? / AppAssure

    - by Anon
    We have 2 Hyper-V hosts at present running 1 virtual server that was converted from a physical box running all roles. My plan is to split the roles over various virtual machines, upgrading to the latest software versions as I go, and use the backup server as a standby in case the main server fails. AppAssure backup software has a feature called Virtual Standby, so the VHD's can be ready to be fired up on the backup server if necessary. Off-site backups will be done via external USB drive for now. I'm just seeking some input/suggestions into how I'm planning to split the roles out amongst various virtual servers. Also, I'm curious how to setup the storage on the servers. We do not have any NAS's, SAN'S or any budget for this. What would the best RAID level be to use? I'm thinking either RAID6 (which is currently used) however I'm concerned about the write speeds, or RAID10 but again I'm worried that I can only lose 1 drive (from the same mirror) as opposed to any 2 with RAID6. I realise I have a hot swap for this, but what if a further drive fails during a rebuild? Is the write penalty of RAID6 worth the extra reliability over RAID10? Or will it be too slow with all the roles I am planning, therefore RAID10 is my only real option? The reason for the needed redundancy is I am the only technician and I'm not always on-site. Options I've considered: 1) 5 drives in RAID6 set, 200gb for host OS, rest for VM storage. 1 drive for hot swap - this is how it is currently setup 2) 4 drives in RAID10 set, 200gb for host OS, rest for VM storage. 2 drives for hot swap 3) 4 drives in RAID10 set for VM storage, 2 drives in RAID1 set for host OS. No drives for hot swap - While this is probably the best option with the amount of drives I have, I don't like the idea of having no hot swap 4) 3 drives in RAID6 set for VM storage, 2 drives in RAID1 set for host OS. 1 drive for hot swap All options give us enough storage capacity for our files, etc. We don't have any budget for extra drives or extra hot swap HD chassis for the servers. We have about 70 clients and about 150 users. MAIN SERVER Intel Xeon 5520 @ 2.27 GHz (2 processors) 16GB RAM 6 x 1TB Seagate Barracuda ES.2 Enterprise SATA drives Intel SRCSATAWB RAID controller Virtual machine workload using Hyper-V on Windows Server 2008 R2: DC01 - Active Directory Domain Controller / DNS server / Global catalog - 1GB RAM DC02 - Active Directory Domain Controller / DNS server / Global catalog - 1GB RAM Member Server - DHCP server, File server, Print server - 1GB RAM SCCM Member Server - 4GB RAM Third Party Software Member Server - A/V server, Ticketing software, etc - 4GB RAM Exchange 2007 - 4GB RAM - however we are probably migrating to a hosted solution, therefore freeing up resources BACKUP SERVER Intel Xeon E5410 @ 2.33GHz (2 processors) 16GB RAM 6 x 2TB WD RE4 SATA drives Intel SRCSASRB RAID controller Virtual machine workload using Hyper-V on Windows Server 2008 R2: AppAssure backup software - 8GB RAM

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  • Troubleshooting Application Timeouts in SQL Server

    - by Tara Kizer
    I recently received the following email from a blog reader: "We are having an OLTP database instance, using SQL Server 2005 with little to moderate traffic (10-20 requests/min). There are also bulk imports that occur at regular intervals in this DB and the import duration ranges between 10secs to 1 min, depending on the data size. Intermittently (2-3 times in a week), we face an issue, where queries get timed out (default of 30 secs set in application). On analyzing, we found two stored procedures, having queries with multiple table joins inside them of taking a long time (5-10 mins) in getting executed, when ideally the execution duration ranges between 5-10 secs. Execution plan of the same displayed Clustered Index Scan happening instead of Clustered Index Seek. All required Indexes are found to be present and Index fragmentation is also minimal as we Rebuild Indexes regularly alongwith Updating Statistics. With no other alternate options occuring to us, we restarted SQL server and thereafter the performance was back on track. But sometimes it was still giving timeout errors for some hits and so we also restarted IIS and that stopped the problem as of now." Rather than respond directly to the blog reader, I thought it would be more interesting to share my thoughts on this issue in a blog. There are a few things that I can think of that could cause abnormal timeouts: Blocking Bad plan in cache Outdated statistics Hardware bottleneck To determine if blocking is the issue, we can easily run sp_who/sp_who2 or a query directly on sysprocesses (select * from master..sysprocesses where blocking <> 0).  If blocking is present and consistent, then you'll need to determine whether or not to kill the parent blocking process.  Killing a process will cause the transaction to rollback, so you need to proceed with caution.  Killing the parent blocking process is only a temporary solution, so you'll need to do more thorough analysis to figure out why the blocking was present.  You should look into missing indexes and perhaps consider changing the database's isolation level to READ_COMMITTED_SNAPSHOT. The blog reader mentions that the execution plan shows a clustered index scan when a clustered index seek is normal for the stored procedure.  A clustered index scan might have been chosen either because that is what is in cache already or because of out of date statistics.  The blog reader mentions that bulk imports occur at regular intervals, so outdated statistics is definitely something that could cause this issue.  The blog reader may need to update statistics after imports are done if the imports are changing a lot of data (greater than 10%).  If the statistics are good, then the query optimizer might have chosen to scan rather than seek in a previous execution because the scan was determined to be less costly due to the value of an input parameter.  If this parameter value is rare, then its execution plan in cache is what we call a bad plan.  You want the best plan in cache for the most frequent parameter values.  If a bad plan is a recurring problem on your system, then you should consider rewriting the stored procedure.  You might want to break up the code into multiple stored procedures so that each can have a different execution plan in cache. To remove a bad plan from cache, you can recompile the stored procedure.  An alternative method is to run DBCC FREEPROCACHE which drops the procedure cache.  It is better to recompile stored procedures rather than dropping the procedure cache as dropping the procedure cache affects all plans in cache rather than just the ones that were bad, so there will be a temporary performance penalty until the plans are loaded into cache again. To determine if there is a hardware bottleneck occurring such as slow I/O or high CPU utilization, you will need to run Performance Monitor on the database server.  Hopefully you already have a baseline of the server so you know what is normal and what is not.  Be on the lookout for I/O requests taking longer than 12 milliseconds and CPU utilization over 90%.  The servers that I support typically are under 30% CPU utilization, but your baseline could be higher and be within a normal range. If restarting the SQL Server service fixes the problem, then the problem was most likely due to blocking or a bad plan in the procedure cache.  Rather than restarting the SQL Server service, which causes downtime, the blog reader should instead analyze the above mentioned things.  Proceed with caution when restarting the SQL Server service as all transactions that have not completed will be rolled back at startup.  This crash recovery process could take longer than normal if there was a long-running transaction running when the service was stopped.  Until the crash recovery process is completed on the database, it is unavailable to your applications. If restarting IIS fixes the problem, then the problem might not have been inside SQL Server.  Prior to taking this step, you should do analysis of the above mentioned things. If you can think of other reasons why the blog reader is facing this issue a few times a week, I'd love to hear your thoughts via a blog comment.

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  • Messaging Systems – Handshaking, Reconciliation and Tracking for Data Transparency

    - by Ahsan Alam
    As many corporations build business partnerships with other organizations, the need to share information becomes necessary. Large amount of data sharing using snail mail, email and/or fax are quickly becoming a thing of the past. More and more organizations are relying heavily on Ftp and/or Web Service to exchange data. Corporations apply wide range of technologies and techniques based on available resources and data transfer needs. Sometimes, it involves simple home-grown applications. Other times, large investments are made on products like BizTalk, TIBCO etc. Complexity of information management also varies significantly from one organizations to another. Some may deal with handful of simple steps to process and manage shared data; whereas others may rely on fairly complex processes with heavy interaction with internal and external systems in order to serve the business needs. It is not surprising that many of these systems end up becoming black boxes over a period of time. Consequently, people and business start to rely more and more on developers and support personnel just to extract simple information adding to the loss of productivity. One of the most important factor in any business is transparency to data irrespective of technology preferences and the complexity of business processes. Not knowing the state of data could become very costly to the business. Being involved in messaging systems for some time now, I have heard the same type of questions over and over again. Did we transmit messages successfully? Did we get responses back? What is the expected turn-around-time? Did the system experience any errors? When one company transmits data to one or more company, it may invoke a set of processes that could complete in matter of seconds, or it could days. As data travels from one organizations to another, the uncertainty grows, and the longer it takes to track uncertain state of the data the costlier it gets for the business, So, in every business scenario, it's extremely important to be aware of the state of the data.   Architects of messaging systems can take several steps to aid with data transparency. Some forms of data handshaking and reconciliation mechanism as well as extensive data tracking can be incorporated into the system to provide clear visibility to the data. What do I mean by handshaking and reconciliation? Some might consider these to be a single concept; however, I like to consider them in two unique categories. Handshaking serves as message receipts or acknowledgment. When one transmits messages to another, the receiver must acknowledge each message by sending immediate responses for each transaction. Whenever we use Web Services, handshaking is often achieved utilizing request/reply pattern. Similarly, if Ftp is used, a receiver can acknowledge by dropping messages for the sender as soon as the files are picked up. These forms of handshaking or acknowledgment informs the message sender and receiver that a successful transaction has occurred. I have mentioned earlier that it could take anywhere from a few seconds to a number of days before shared data is completely processed. In addition, whenever a batched transaction is used, processing time for each data element inside the batch could also vary significantly. So, in order to successfully manage data processing, reconciliation becomes extremely important; otherwise it may result into data loss or in some cases hefty penalty. Reconciliation can be done in many ways. Partner organizations can share and compare ad hoc reports to achieve reconciliation. On the other hand, partners can agree on some type of systematic reconciliation messages. Systems within responsible parties can trigger messages to partners as soon as the data process completes.   Next step in the data transparency is extensive data tracking. Some products such as BizTalk and TIBCO provide built-in functionality for data tracking; however, built-in functionality may not always be adequate. Sometimes additional tracking system (or databases) needs to be built in order monitor all types of data flow including, message transactions, handshaking, reconciliation, system errors and many more. If these types of data are captured, then these can be presented to business users in any forms or fashion. When business users are empowered with such information, then the reliance on developers and support teams decreases dramatically.   In today's collaborative world of information sharing, data transparency is key to the success of every business. The state of business data will constantly change. However, when people have easier access to various states of data, it allows them to make better and quicker decisions. Therefore, I feel that data handshaking, reconciliation and tracking is very important aspect of messaging systems.

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  • jqGrid - dynamically load different drop down values for different rows depending on another column value

    - by Renso
    Goal: As we all know the jqGrid examples in the demo and the Wiki always refer to static values for drop down boxes. This of course is a personal preference but in dynamic design these values should be populated from the database/xml file, etc, ideally JSON formatted. Can you do this in jqGrid, yes, but with some custom coding which we will briefly show below (refer to some of my other blog entries for a more detailed discussion on this topic). What you CANNOT do in jqGrid, referrign here up and to version 3.8.x, is to load different drop down values for different rows in the jqGrid. Well, not without some trickery, which is what this discussion is about. Issue: Of course the issue is that jqGrid has been designed for high performance and thus I have no issue with them loading a  reference to a single drop down values list for every column. This way if you have 500 rows or one, each row only refers to a single list for that particuolar column. Nice! SO how easy would it be to simply traverse the grid once loaded on gridComplete or loadComplete and simply load the select tag's options from scratch, via ajax, from memory variable, hard coded etc? Impossible! Since their is no embedded SELECT tag within each cell containing the drop down values (remeber it only has a reference to that list in memory), all you will see when you inspect the cell prior to clicking on it, or even before and on beforeEditCell, is an empty <TD></TD>. When trying to load that list via a click event on that cell will temporarily load the list but jqGrid's last internal callback event will remove it and replace it with the old one, and you are back to square one. Solution: Yes, after spending a few hours on this found a solution to the problem that does not require any updates to jqGrid source code, thank GOD! Before we get into the coding details, the solution here can of course be customized to suite your specific needs, this one loads the entire drop down list that would be needed across all rows once into global variable. I then parse this object that contains all the properties I need to filter the rows depending on which ones I want the user to see based off of another cell value in that row. This only happens when clicking the cell, so no performance penalty. You may of course to load it via ajax when the user clicks the cell, but I found it more effecient to load the entire list as part of jqGrid's normal editoptions: { multiple: false, value: listingStatus } colModel options which again keeps only a reference to the sinlge list, no duplciation. Lets get into the meat and potatoes of it.         var acctId = $('#Id').val();         var data = $.ajax({ url: $('#ajaxGetAllMaterialsTrackingLookupDataUrl').val(), data: { accountId: acctId }, dataType: 'json', async: false, success: function(data, result) { if (!result) alert('Failure to retrieve the Alert related lookup data.'); } }).responseText;         var lookupData = eval('(' + data + ')');         var listingCategory = lookupData.ListingCategory;         var listingStatus = lookupData.ListingStatus;         var catList = '{';         $(lookupData.ListingCategory).each(function() {             catList += this.Id + ':"' + this.Name + '",';         });         catList += '}';         var lastsel;         var ignoreAlert = true;         $(item)         .jqGrid({             url: listURL,             postData: '',             datatype: "local",             colNames: ['Id', 'Name', 'Commission<br />Rep', 'Business<br />Group', 'Order<br />Date', 'Edit', 'TBD', 'Month', 'Year', 'Week', 'Product', 'Product<br />Type', 'Online/<br />Magazine', 'Materials', 'Special<br />Placement', 'Logo', 'Image', 'Text', 'Contact<br />Info', 'Everthing<br />In', 'Category', 'Status'],             colModel: [                 { name: 'Id', index: 'Id', hidden: true, hidedlg: true },                 { name: 'AccountName', index: 'AccountName', align: "left", resizable: true, search: true, width: 100 },                 { name: 'OnlineName', index: 'OnlineName', align: 'left', sortable: false, width: 80 },                 { name: 'ListingCategoryName', index: 'ListingCategoryName', width: 85, editable: true, hidden: false, edittype: "select", editoptions: { multiple: false, value: eval('(' + catList + ')') }, editrules: { required: false }, formatoptions: { disabled: false} }             ],             jsonReader: {                 root: "List",                 page: "CurrentPage",                 total: "TotalPages",                 records: "TotalRecords",                 userdata: "Errors",                 repeatitems: false,                 id: "0"             },             rowNum: $rows,             rowList: [10, 20, 50, 200, 500, 1000, 2000],             imgpath: jQueryImageRoot,             pager: $(item + 'Pager'),             shrinkToFit: true,             width: 1455,             recordtext: 'Traffic lines',             sortname: 'OrderDate',             viewrecords: true,             sortorder: "asc",             altRows: true,             cellEdit: true,             cellsubmit: "remote",             cellurl: editURL + '?rows=' + $rows + '&page=1',             loadComplete: function() {               },             gridComplete: function() {             },             loadError: function(xhr, st, err) {             },             afterEditCell: function(rowid, cellname, value, iRow, iCol) {                 var select = $(item).find('td.edit-cell select');                 $(item).find('td.edit-cell select option').each(function() {                     var option = $(this);                     var optionId = $(this).val();                     $(lookupData.ListingCategory).each(function() {                         if (this.Id == optionId) {                                                       if (this.OnlineName != $(item).getCell(rowid, 'OnlineName')) {                                 option.remove();                                 return false;                             }                         }                     });                 });             },             search: true,             searchdata: {},             caption: "List of all Traffic lines",             editurl: editURL + '?rows=' + $rows + '&page=1',             hiddengrid: hideGrid   Here is the JSON data returned via the ajax call during the jqGrid function call above (NOTE it must be { async: false}: {"ListingCategory":[{"Id":29,"Name":"Document Imaging & Management","OnlineName":"RF Globalnet"} ,{"Id":1,"Name":"Ancillary Department Hardware","OnlineName":"Healthcare Technology Online"} ,{"Id":2,"Name":"Asset Tracking","OnlineName":"Healthcare Technology Online"} ,{"Id":3,"Name":"Asset Tracking","OnlineName":"Healthcare Technology Online"} ,{"Id":4,"Name":"Asset Tracking","OnlineName":"Healthcare Technology Online"} ,{"Id":5,"Name":"Document Imaging & Management","OnlineName":"Healthcare Technology Online"} ,{"Id":6,"Name":"Document Imaging & Management","OnlineName":"Healthcare Technology Online"} ,{"Id":7,"Name":"EMR/EHR Software","OnlineName":"Healthcare Technology Online"}]} I only need the Id and Name for the drop down list, but the third column in the JSON object is important, it is the only that I match up with the OnlineName in the jqGrid column, and then in the loop during afterEditCell simply remove the ones I don't want the user to see. That's it!

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  • Could not load file or assembly 'System.Web.Ajax, Version=3.0.31106.0

    - by Jonesy
    HI folks, I have a .net application (vb.net) and I'm using the ajax control toolkit. It works fine on my production machine but when I upload it to the host (fasthosts) i get this error: Could not load file or assembly 'System.Web.Ajax, Version=3.0.31106.0, Culture=neutral, PublicKeyToken=28f01b0e84b6d53e' or one of its dependencies. The module was expected to contain an assembly manifest. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.BadImageFormatException: Could not load file or assembly 'System.Web.Ajax, Version=3.0.31106.0, Culture=neutral, PublicKeyToken=28f01b0e84b6d53e' or one of its dependencies. The module was expected to contain an assembly manifest. Source Error: An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below. Assembly Load Trace: The following information can be helpful to determine why the assembly 'System.Web.Ajax, Version=3.0.31106.0, Culture=neutral, PublicKeyToken=28f01b0e84b6d53e' could not be loaded. WRN: Assembly binding logging is turned OFF. To enable assembly bind failure logging, set the registry value [HKLM\Software\Microsoft\Fusion!EnableLog] (DWORD) to 1. Note: There is some performance penalty associated with assembly bind failure logging. To turn this feature off, remove the registry value [HKLM\Software\Microsoft\Fusion!EnableLog]. Stack Trace: [BadImageFormatException: Could not load file or assembly 'System.Web.Ajax, Version=3.0.31106.0, Culture=neutral, PublicKeyToken=28f01b0e84b6d53e' or one of its dependencies. The module was expected to contain an assembly manifest.] AjaxControlToolkit.ToolkitScriptManager.ApplyAssembly(ScriptReference script, Boolean isComposite) +0 AjaxControlToolkit.ToolkitScriptManager.OnResolveScriptReference(ScriptReferenceEventArgs e) +167 System.Web.UI.ScriptManager.RegisterScripts() +191 System.Web.UI.ScriptManager.OnPagePreRenderComplete(Object sender, EventArgs e) +113 System.Web.UI.Page.OnPreRenderComplete(EventArgs e) +8698462 System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1029 Here is my web.conf file. Its very simple: <system.web> <customErrors mode="Off"/> <compilation debug="true"> <assemblies> <add assembly="System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/> <add assembly="System.Web.Extensions.Design, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/> <add assembly="System.Design, Version=2.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A"/> <add assembly="System.Windows.Forms, Version=2.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/></assemblies></compilation></system.web> Does anyone know whats up? -- Billy

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  • "ResolveAssemblyReference" task fails and System.BadImageFormatException, but assembly isn't used an

    - by bdwakefield
    I am getting an error about the assembly "C:\Ora10g\bin\Zip.exe". The trouble is this solution does NOT use anything in Oracle at all. I could not find a single reference to 10g anywhere in the project. I inherited this from another person who left our group. He never had this issue. Another member of my team said he got this before but reinstalling the client portion of 10g fixed it. No such luck there. I even tried using WinGrep to search the entire solution folder for "Ora10g" but it wasn't there. Any ideas? I can't build this solution until I can figure out how to get rid of this false reference to Oracle. VS 2005 solution. Contains a couple WinForm apps, a couple class libraries, and a web service. The error occurs in the main class library project. Here is the error message: Error 1 The "ResolveAssemblyReference" task failed unexpectedly. System.BadImageFormatException: Could not load file or assembly 'C:\Ora10g\bin\Zip.exe' or one of its dependencies. The module was expected to contain an assembly manifest. File name: 'C:\Ora10g\bin\Zip.exe' at System.Reflection.AssemblyName.nGetFileInformation(String s) at System.Reflection.AssemblyName.GetAssemblyName(String assemblyFile) at Microsoft.Build.Shared.AssemblyNameExtension.GetAssemblyNameEx(String path) at Microsoft.Build.Tasks.SystemState.GetAssemblyName(String path) at Microsoft.Build.Tasks.Resolver.FileMatchesAssemblyName(AssemblyNameExtension assemblyName, Boolean isPrimaryProjectReference, Boolean wantSpecificVersion, Boolean allowMismatchBetweenFusionNameAndFileName, String pathToCandidateAssembly, ResolutionSearchLocation searchLocation) at Microsoft.Build.Tasks.Resolver.ResolveAsFile(String fullPath, AssemblyNameExtension assemblyName, Boolean isPrimaryProjectReference, Boolean wantSpecificVersion, Boolean allowMismatchBetweenFusionNameAndFileName, ArrayList assembliesConsideredAndRejected) at Microsoft.Build.Tasks.Resolver.ResolveFromDirectory(AssemblyNameExtension assemblyName, Boolean isPrimaryProjectReference, Boolean wantSpecificVersion, String[] executableExtensions, String directory, ArrayList assembliesConsideredAndRejected) at Microsoft.Build.Tasks.AssemblyFoldersResolver.Resolve(AssemblyNameExtension assemblyName, String rawFileNameCandidate, Boolean isPrimaryProjectReference, Boolean wantSpecificVersion, String[] executableExtensions, String hintPath, String assemblyFolderKey, ArrayList assembliesConsideredAndRejected, String& foundPath, Boolean& userRequestedSpecificFile) at Microsoft.Build.Tasks.AssemblyResolution.ResolveReference(IEnumerable`1 jaggedResolvers, AssemblyNameExtension assemblyName, String rawFileNameCandidate, Boolean isPrimaryProjectReference, Boolean wantSpecificVersion, String[] executableExtensions, String hintPath, String assemblyFolderKey, ArrayList assembliesConsideredAndRejected, String& resolvedSearchPath, Boolean& userRequestedSpecificFile) at Microsoft.Build.Tasks.ReferenceTable.ResolveReference(AssemblyNameExtension assemblyName, String rawFileNameCandidate, Reference reference) at Microsoft.Build.Tasks.ReferenceTable.ResolveAssemblyFilenames() at Microsoft.Build.Tasks.ReferenceTable.ComputeClosure() at Microsoft.Build.Tasks.ReferenceTable.ComputeClosure(DependentAssembly[] remappedAssembliesValue, ITaskItem[] referenceAssemblyFiles, ITaskItem[] referenceAssemblyNames, ArrayList exceptions) at Microsoft.Build.Tasks.ResolveAssemblyReference.Execute(FileExists fileExists, DirectoryExists directoryExists, GetDirectories getDirectories, GetAssemblyName getAssemblyName, GetAssemblyMetadata getAssemblyMetadata, GetRegistrySubKeyNames getRegistrySubKeyNames, GetRegistrySubKeyDefaultValue getRegistrySubKeyDefaultValue, GetLastWriteTime getLastWriteTime) at Microsoft.Build.Tasks.ResolveAssemblyReference.Execute() at Microsoft.Build.BuildEngine.TaskEngine.ExecuteTask(ExecutionMode howToExecuteTask, Hashtable projectItemsAvailableToTask, BuildPropertyGroup projectPropertiesAvailableToTask, Boolean& taskClassWasFound) WRN: Assembly binding logging is turned OFF. To enable assembly bind failure logging, set the registry value [HKLM\Software\Microsoft\Fusion!EnableLog] (DWORD) to 1. Note: There is some performance penalty associated with assembly bind failure logging. To turn this feature off, remove the registry value [HKLM\Software\Microsoft\Fusion!EnableLog].

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  • Error in facebook.dll facebooksdk

    - by Surendar Radhakrishnan
    I got the web application working with facebooksdk and when i deployed it...it is running fine for sometime and it is throwing the error like this... Server Error in '/' Application. Could not load file or assembly 'Facebook, Version=4.1.1.0, Culture=neutral, PublicKeyToken=58cb4f2111d1e6de' or one of its dependencies. Access is denied. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.IO.FileLoadException: Could not load file or assembly 'Facebook, Version=4.1.1.0, Culture=neutral, PublicKeyToken=58cb4f2111d1e6de' or one of its dependencies. Access is denied. Source Error: An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below. Assembly Load Trace: The following information can be helpful to determine why the assembly 'Facebook, Version=4.1.1.0, Culture=neutral, PublicKeyToken=58cb4f2111d1e6de' could not be loaded. WRN: Assembly binding logging is turned OFF. To enable assembly bind failure logging, set the registry value [HKLM\Software\Microsoft\Fusion!EnableLog] (DWORD) to 1. Note: There is some performance penalty associated with assembly bind failure logging. To turn this feature off, remove the registry value [HKLM\Software\Microsoft\Fusion!EnableLog]. Stack Trace: [FileLoadException: Could not load file or assembly 'Facebook, Version=4.1.1.0, Culture=neutral, PublicKeyToken=58cb4f2111d1e6de' or one of its dependencies. Access is denied.] Secured_Login.FacebookVerification() +0 System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e) +25 System.Web.UI.Control.LoadRecursive() +71 System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +3048 Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.1 i got this method in pageload protected void Page_Load(object sender, EventArgs e) { FacebookVerification(); } protected void FacebookVerification() { try { FacebookApp fbApp = new FacebookApp(); if (fbApp.Session != null) { dynamic myinfo = fbApp.Get("me"); String firstname = myinfo.first_name; String lastname = myinfo.last_name; lblFBStatus.Text = "you signed in as " + firstname + " " + lastname ; } else { lblFBStatus.Text = "Please sign in with facebook"; } } catch (Exception) { throw; } }

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  • Could not load file or assembly 'Base' or one of its dependencies. Access is denied

    - by starcorn
    I have deployed one web project into Azure emulator. And I get this error saying that Could not load file or assembly Base. The thing is that this web project, got dependencies to another project in the same solution. I have added that dependency into the reference list of my web project. And if I run this web application without using the azure emulator it will run fine. But I will get error when I try to run it on the azure emulator. At first glance I thought that I maybe need to add the other project as role also. But it couldn't be that. Anyone know what the problem might be? I hope I got enough data for you to look into. My solution structure looks like following Solution Base WebAPI WebAPI.Azure And it is the WebAPI that has a dependency to the Base project Here's the Assembly load trace WRN: Assembly binding logging is turned OFF. To enable assembly bind failure logging, set the registry value [HKLM\Software\Microsoft\Fusion!EnableLog] (DWORD) to 1. Note: There is some performance penalty associated with assembly bind failure logging. To turn this feature off, remove the registry value [HKLM\Software\Microsoft\Fusion!EnableLog]. And stack trace [FileLoadException: Could not load file or assembly 'Base' or one of its dependencies. Access is denied.] System.Reflection.RuntimeAssembly._nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, RuntimeAssembly locationHint, StackCrawlMark& stackMark, Boolean throwOnFileNotFound, Boolean forIntrospection, Boolean suppressSecurityChecks) +0 System.Reflection.RuntimeAssembly.InternalLoadAssemblyName(AssemblyName assemblyRef, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection, Boolean suppressSecurityChecks) +567 System.Reflection.RuntimeAssembly.InternalLoad(String assemblyString, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection) +192 System.Reflection.Assembly.Load(String assemblyString) +35 System.Web.Configuration.CompilationSection.LoadAssemblyHelper(String assemblyName, Boolean starDirective) +123 [ConfigurationErrorsException: Could not load file or assembly 'Base' or one of its dependencies. Access is denied.] System.Web.Configuration.CompilationSection.LoadAssemblyHelper(String assemblyName, Boolean starDirective) +11568160 System.Web.Configuration.CompilationSection.LoadAllAssembliesFromAppDomainBinDirectory() +485 System.Web.Configuration.AssemblyInfo.get_AssemblyInternal() +79 System.Web.Compilation.BuildManager.GetReferencedAssemblies(CompilationSection compConfig) +337 System.Web.Compilation.BuildManager.CallPreStartInitMethods() +280 System.Web.Hosting.HostingEnvironment.Initialize(ApplicationManager appManager, IApplicationHost appHost, IConfigMapPathFactory configMapPathFactory, HostingEnvironmentParameters hostingParameters, PolicyLevel policyLevel, Exception appDomainCreationException) +1167 [HttpException (0x80004005): Could not load file or assembly 'Base' or one of its dependencies. Access is denied.] System.Web.HttpRuntime.FirstRequestInit(HttpContext context) +11700896 System.Web.HttpRuntime.EnsureFirstRequestInit(HttpContext context) +141 System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest wr, HttpContext context) +4869125

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  • Improving Javascript Load Times - Concatenation vs Many + Cache

    - by El Yobo
    I'm wondering which of the following is going to result in better performance for a page which loads a large amount of javascript (jQuery + jQuery UI + various other javascript files). I have gone through most of the YSlow and Google Page Speed stuff, but am left wondering about a particular detail. A key thing for me here is that the site I'm working on is not on the public net; it's a business to business platform where almost all users are repeat visitors (and therefore with caches of the data, which is something that YSlow assumes will not be the case for a large number of visitors). First up, the standard approach recommended by tools such as YSlow is to concatenate it, compress it, and serve it up in a single file loaded at the end of your page. This approach sounds reasonably effective, but I think that a key part of the reasoning here is to improve performance for users without cached data. The system I currently have is something like this * All javascript files are compressed and loaded at the bottom of the page * All javascript files have far future cache expiration dates, so will remain (for most users) in the cache for a long time * Pages only load the javascript files that they require, rather than loading one monolithic file, most of which will not be required Now, my understanding is that, if the cache expiration date for a javascript file has not been reached, then the cached version is used immediately; there is no HTTP request sent at to the server at all. If this is correct, I would assume that having multiple tags is not causing any performance penalty, as I'm still not having any additional requests on most pages (recalling from above that almost all users have populated caches). In addition to this, not loading the JS means that the browser doesn't have to interpret or execute all this additional code which it isn't going to need; as a B2B application, most of our users are unfortunately stuck with IE6 and its painfully slow JS engine. Another benefit is that, when code changes, only the affected files need to be fetched again, rather than the whole set (granted, it would only need to be fetched once, so this is not so much of a benefit). I'm also looking at using LabJS to allow for parallel loading of the JS when it's not cached. So, what do people think is a better approach? In a similar vein, what do you think about a similar approach to CSS - is monolithic better?

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  • How can I improve my select query for storing large versioned data sets?

    - by Jason Francis
    At work, we build large multi-page web applications, consisting mostly of radio and check boxes. The primary purpose of each application is to gather data, but as users return to a page they have previously visited, we report back to them their previous responses. Worst-case scenario, we might have up to 900 distinct variables and around 1.5 million users. For several reasons, it makes sense to use an insert-only approach to storing the data (as opposed to update-in-place) so that we can capture historical data about repeated interactions with variables. The net result is that we might have several responses per user per variable. Our table to collect the responses looks something like this: CREATE TABLE [dbo].[results]( [id] [bigint] IDENTITY(1,1) NOT NULL, [userid] [int] NULL, [variable] [varchar](8) NULL, [value] [tinyint] NULL, [submitted] [smalldatetime] NULL) Where id serves as the primary key. Virtually every request results in a series of insert statements (one per variable submitted), and then we run a select to produce previous responses for the next page (something like this): SELECT t.id, t.variable, t.value FROM results t WITH (NOLOCK) WHERE t.userid = '2111846' AND (t.variable='internat' OR t.variable='veteran' OR t.variable='athlete') AND t.id IN (SELECT MAX(id) AS id FROM results WITH (NOLOCK) WHERE userid = '2111846' AND (t.variable='internat' OR t.variable='veteran' OR t.variable='athlete') GROUP BY variable) Which, in this case, would return the most recent responses for the variables "internat", "veteran", and "athlete" for user 2111846. We have followed the advice of the database tuning tools in indexing the tables, and against our data, this is the best-performing version of the select query that we have been able to come up with. Even so, there seems to be significant performance degradation as the table approaches 1 million records (and we might have about 150x that). We have a fairly-elegant solution in place for sharding the data across multiple tables which has been working quite well, but I am open for any advice about how I might construct a better version of the select query. We use this structure frequently for storing lots of independent data points, and we like the benefits it provides. So the question is, how can I improve the performance of the select query? I assume the nested select statement is a bad idea, but I have yet to find an alternative that performs as well. Thanks in advance. NB: Since we emphasize creating over reading in this case, and since we never update in place, there doesn't seem to be any penalty (and some advantage) for using the NOLOCK directive in this case.

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  • Performance - FunctionCall vs Event vs Action vs Delegate

    - by hwcverwe
    Currently I am using Microsoft Sync Framework to synchronize databases. I need to gather information per record which is inserted/updated/deleted by Microsoft Sync Framework and do something with this information. The sync speed can go over 50.000 records per minute. So that means my additional code need to be very lightweight otherwise it will be a huge performance penalty. Microsoft Sync Framework raises an SyncProgress event for each record. I am subscribed to that code like this: // Assembly1 SyncProvider.SyncProgress += OnSyncProgress; // .... private void OnSyncProgress(object sender, DbSyncProgressEventArgs e) { switch (args.Stage) { case DbSyncStage.ApplyingInserts: // MethodCall/Delegate/Action<>/EventHandler<> => HandleInsertedRecordInformation // Do something with inserted record info break; case DbSyncStage.ApplyingUpdates: // MethodCall/Delegate/Action<>/EventHandler<> => HandleUpdatedRecordInformation // Do something with updated record info break; case DbSyncStage.ApplyingDeletes: // MethodCall/Delegate/Action<>/EventHandler<> => HandleDeletedRecordInformation // Do something with deleted record info break; } } Somewhere else in another assembly I have three methods: // Assembly2 public class SyncInformation { public void HandleInsertedRecordInformation(...) {...} public void HandleUpdatedRecordInformation(...) {...} public void HandleInsertedRecordInformation(...) {...} } Assembly2 has a reference to Assembly1. So Assembly1 does not know anything about the existence of the SyncInformation class which need to handle the gathered information. So I have the following options to trigger this code: use events and subscribe on it in Assembly2 1.1. EventHandler< 1.2. Action< 1.3. Delegates using dependency injection: public class Assembly2.SyncInformation : Assembly1.ISyncInformation Other? I know the performance depends on: OnSyncProgress switch using a method call, delegate, Action< or EventHandler< Implementation of SyncInformation class I currently don't care about the implementation of the SyncInformation class. I am mainly focused on the OnSyncProgress method and how to call the SyncInformation methods. So my questions are: What is the most efficient approach? What is the most in-efficient approach? Is there a better way than using a switch in OnSyncProgress?

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  • Can you get a Func<T> (or similar) from a MethodInfo object?

    - by Dan Tao
    I realize that, generally speaking, there are performance implications of using reflection. (I myself am not a fan of reflection at all, actually; this is a purely academic question.) Suppose there exists some class that looks like this: public class MyClass { public string GetName() { return "My Name"; } } Bear with me here. I know that if I have an instance of MyClass called x, I can call x.GetName(). Furthermore, I could set a Func<string> variable to x.GetName. Now here's my question. Let's say I don't know the above class is called MyClass; I've got some object, x, but I have no idea what it is. I could check to see if that object has a GetName method by doing this: MethodInfo getName = x.GetType().GetMethod("GetName"); Suppose getName is not null. Then couldn't I furthermore check if getName.ReturnType == typeof(string) and getName.GetParameters().Length == 0, and at this point, wouldn't I be quite certain that the method represented by my getName object could definitely be cast to a Func<string>, somehow? I realize there's a MethodInfo.Invoke, and I also realize I could always create a Func<string> like: Func<string> getNameFunc = () => getName.Invoke(x, null); I guess what I'm asking is if there's any way to go from a MethodInfo object to the actual method it represents, incurring the performance cost of reflection in the process, but after that point being able to call the method directly (via, e.g., a Func<string> or something similar) without a performance penalty. What I'm envisioning might look something like this: // obviously this would throw an exception if GetActualInstanceMethod returned // something that couldn't be cast to a Func<string> Func<string> getNameFunc = (Func<string>)getName.GetActualInstanceMethod(x); (I realize that doesn't exist; I'm wondering if there's anything like it.) If what I'm asking doesn't make sense, or if I'm being unclear, I'll be happy to attempt to clarify.

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  • Is it OK to put a standard, pure C header #include directive inside a namespace?

    - by mic_e
    I've got a project with a class log in the global namespace (::log). So, naturally, after #include <cmath>, the compiler gives an error message each time I try to instantiate an object of my log class, because <cmath> pollutes the global namespace with lots of three-letter methods, one of them being the logarithm function log(). So there are three possible solutions, each having their unique ugly side-effects. Move the log class to it's own namespace and always access it with it's fully qualified name. I really want to avoid this because the logger should be as convenient as possible to use. Write a mathwrapper.cpp file which is the only file in the project that includes <cmath>, and makes all the required <cmath> functions available through wrappers in a namespace math. I don't want to use this approach because I have to write a wrapper for every single required math function, and it would add additional call penalty (cancelled out partially by the -flto compiler flag) The solution I'm currently considering: Replace #include <cmath> by namespace math { #include "math.h" } and then calculating the logarithm function via math::log(). I have tried it out and it does, indeed, compile, link and run as expected. It does, however, have multiple downsides: It's (obviously) impossible to use <cmath>, because the <cmath> code accesses the functions by their fully qualified names, and it's deprecated to use in C++. I've got a really, really bad feeling about it, like I'm gonna get attacked and eaten alive by raptors. So my question is: Is there any recommendation/convention/etc that forbid putting include directives in namespaces? Could anything go wrong with diferent C standard library implementations (I use glibc), different compilers (I use g++ 4.7, -std=c++11), linking? Have you ever tried doing this? Are there any alternate ways to banish the math functions from the global namespace? I've found several similar questions on stackoverflow, but most were about including other C++ headers, which obviously is a bad idea, and those that weren't made contradictory statements about linking behaviour for C libraries. Also, would it be beneficial to additionally put the #include <math.h> inside extern "C" {}?

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  • Windows 7 Boot to VHD using a VHD clone of the system drive

    - by daveh551
    This seems like a not too difficult problem, and, after several hurdles, I'm maddeningly close. But I can't quite get there. I'm running Windows 7 in development shop. I want to start using VS2010 to work on some stuff that won't be released for awhile. My boss said no beta code on the production machine, but I could run VS2010 for this project IF I could do it in an isolated environment, like a virtual PC. Well, I've used the beta and RC of Win7 on VPC's before, and it was painfully slow because of the VPC environment. But everyone has been singing the praises of Windows 7's boot-to-VHD capability, where only the disk is virtualized, and you're actually running on the hardware. Supposed to be little slower, but nowhere near the speed penalty of VPC. I've spent a fair amount of time getting everything installed the way I want it. So I figured, I'll just clone my system drive using Disk2VHD, and boot off of that, and then install VS2010 onto that. (I keep most of my user data, including all my projects, in a separate partition, so that wouldn't have to be duplicated and would still be available.) Well, I had some difficulties with that, owing mainly to the fact that I was using an old version of Disk2VHD - (get the latest if you're going to try it.) But I did finally get it to boot. (Scott Hanselman has a good blog post on boot to VHD). But it wasn't exactly what I was expecting or hoping for. What I expected was that the VHD would become the C: drive, and the original (physical) C: drive would be either hidden or mounted under a different letter, and thus isolated and protected from any changes. What you actually get is that the VHD becomes the D: drive AND you boot from the D: drive, BUT your original C: drive is still there. Which is sort of okay EXCEPT that the Registry on the VHD is a clone of the Registry on C: drive, and includes many hard-coded references to C:. So the result is that some things come from (and modify) D: (the VHD), but some things come from (and modify) C:. (If you open a cmd prompt and do a SET to look at your environment variables, you will see a mixture of D:\ and C:\ paths.) So I don't really have an isolated environment. Most importantly, %ProgramFiles% is still set to C:\Program Files. What I really need is a tool that can access the registry files on the mounted VHD AS FILES, not as registry entries, and do a global search and replace on all the C:\ in strings to D:. I haven't found such a program. (I've tried to do it with a program called Registry Replace, but, even when running as Administrator, there are certain entries that the Registry won't let you change.) Does anyone know of one? Or any other solution to my problem (other than starting from scratch with a clean VHD and installing Win7 and all my programs on it.)?

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  • Linux software RAID6: rebuild slow

    - by Ole Tange
    I am trying to find the bottleneck in the rebuilding of a software raid6. ## Pause rebuilding when measuring raw I/O performance # echo 1 > /proc/sys/dev/raid/speed_limit_min # echo 1 > /proc/sys/dev/raid/speed_limit_max ## Drop caches so that does not interfere with measuring # sync ; echo 3 | tee /proc/sys/vm/drop_caches >/dev/null # time parallel -j0 "dd if=/dev/{} bs=256k count=4000 | cat >/dev/null" ::: sdbd sdbc sdbf sdbm sdbl sdbk sdbe sdbj sdbh sdbg 4000+0 records in 4000+0 records out 1048576000 bytes (1.0 GB) copied, 7.30336 s, 144 MB/s [... similar for each disk ...] # time parallel -j0 "dd if=/dev/{} skip=15000000 bs=256k count=4000 | cat >/dev/null" ::: sdbd sdbc sdbf sdbm sdbl sdbk sdbe sdbj sdbh sdbg 4000+0 records in 4000+0 records out 1048576000 bytes (1.0 GB) copied, 12.7991 s, 81.9 MB/s [... similar for each disk ...] So we can read sequentially at 140 MB/s in the outer tracks and 82 MB/s in the inner tracks on all the drives simultaneously. Sequential write performance is similar. This would lead me to expect a rebuild speed of 82 MB/s or more. # echo 800000 > /proc/sys/dev/raid/speed_limit_min # echo 800000 > /proc/sys/dev/raid/speed_limit_max # cat /proc/mdstat md2 : active raid6 sdbd[10](S) sdbc[9] sdbf[0] sdbm[8] sdbl[7] sdbk[6] sdbe[11] sdbj[4] sdbi[3](F) sdbh[2] sdbg[1] 27349121408 blocks super 1.2 level 6, 128k chunk, algorithm 2 [9/8] [UUU_UUUUU] [=========>...........] recovery = 47.3% (1849905884/3907017344) finish=855.9min speed=40054K/sec But we only get 40 MB/s. And often this drops to 30 MB/s. # iostat -dkx 1 sdbc 0.00 8023.00 0.00 329.00 0.00 33408.00 203.09 0.70 2.12 1.06 34.80 sdbd 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 sdbe 13.00 0.00 8334.00 0.00 33388.00 0.00 8.01 0.65 0.08 0.06 47.20 sdbf 0.00 0.00 8348.00 0.00 33388.00 0.00 8.00 0.58 0.07 0.06 48.00 sdbg 16.00 0.00 8331.00 0.00 33388.00 0.00 8.02 0.71 0.09 0.06 48.80 sdbh 961.00 0.00 8314.00 0.00 37100.00 0.00 8.92 0.93 0.11 0.07 54.80 sdbj 70.00 0.00 8276.00 0.00 33384.00 0.00 8.07 0.78 0.10 0.06 48.40 sdbk 124.00 0.00 8221.00 0.00 33380.00 0.00 8.12 0.88 0.11 0.06 47.20 sdbl 83.00 0.00 8262.00 0.00 33380.00 0.00 8.08 0.96 0.12 0.06 47.60 sdbm 0.00 0.00 8344.00 0.00 33376.00 0.00 8.00 0.56 0.07 0.06 47.60 iostat says the disks are not 100% busy (but only 40-50%). This fits with the hypothesis that the max is around 80 MB/s. Since this is software raid the limiting factor could be CPU. top says: PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 38520 root 20 0 0 0 0 R 64 0.0 2947:50 md2_raid6 6117 root 20 0 0 0 0 D 53 0.0 473:25.96 md2_resync So md2_raid6 and md2_resync are clearly busy taking up 64% and 53% of a CPU respectively, but not near 100%. The chunk size (128k) of the RAID was chosen after measuring which chunksize gave the least CPU penalty. If this speed is normal: What is the limiting factor? Can I measure that? If this speed is not normal: How can I find the limiting factor? Can I change that?

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  • Adding DTrace Probes to PHP Extensions

    - by cj
    The powerful DTrace tracing facility has some PHP-specific probes that can be enabled with --enable-dtrace. DTrace for Linux is being created by Oracle and is currently in tech preview. Currently it doesn't support userspace tracing so, in the meantime, Systemtap can be used to monitor the probes implemented in PHP. This was recently outlined in David Soria Parra's post Probing PHP with Systemtap on Linux. My post shows how DTrace probes can be added to PHP extensions and traced on Linux. I was using Oracle Linux 6.3. Not all Linux kernels are built with Systemtap, since this can impact stability. Check whether your running kernel (or others installed) have Systemtap enabled, and reboot with such a kernel: # grep CONFIG_UTRACE /boot/config-`uname -r` # grep CONFIG_UTRACE /boot/config-* When you install Systemtap itself, the package systemtap-sdt-devel is needed since it provides the sdt.h header file: # yum install systemtap-sdt-devel You can now install and build PHP as shown in David's article. Basically the build is with: $ cd ~/php-src $ ./configure --disable-all --enable-dtrace $ make (For me, running 'make' a second time failed with an error. The workaround is to do 'git checkout Zend/zend_dtrace.d' and then rerun 'make'. See PHP Bug 63704) David's article shows how to trace the probes already implemented in PHP. You can also use Systemtap to trace things like userspace PHP function calls. For example, create test.php: <?php $c = oci_connect('hr', 'welcome', 'localhost/orcl'); $s = oci_parse($c, "select dbms_xmlgen.getxml('select * from dual') xml from dual"); $r = oci_execute($s); $row = oci_fetch_array($s, OCI_NUM); $x = $row[0]->load(); $row[0]->free(); echo $x; ?> The normal output of this file is the XML form of Oracle's DUAL table: $ ./sapi/cli/php ~/test.php <?xml version="1.0"?> <ROWSET> <ROW> <DUMMY>X</DUMMY> </ROW> </ROWSET> To trace the PHP function calls, create the tracing file functrace.stp: probe process("sapi/cli/php").function("zif_*") { printf("Started function %s\n", probefunc()); } probe process("sapi/cli/php").function("zif_*").return { printf("Ended function %s\n", probefunc()); } This makes use of the way PHP userspace functions (not builtins) like oci_connect() map to C functions with a "zif_" prefix. Login as root, and run System tap on the PHP script: # cd ~cjones/php-src # stap -c 'sapi/cli/php ~cjones/test.php' ~cjones/functrace.stp Started function zif_oci_connect Ended function zif_oci_connect Started function zif_oci_parse Ended function zif_oci_parse Started function zif_oci_execute Ended function zif_oci_execute Started function zif_oci_fetch_array Ended function zif_oci_fetch_array Started function zif_oci_lob_load <?xml version="1.0"?> <ROWSET> <ROW> <DUMMY>X</DUMMY> </ROW> </ROWSET> Ended function zif_oci_lob_load Started function zif_oci_free_descriptor Ended function zif_oci_free_descriptor Each call and return is logged. The Systemtap scripting language allows complex scripts to be built. There are many examples on the web. To augment this generic capability and the PHP probes in PHP, other extensions can have probes too. Below are the steps I used to add probes to OCI8: I created a provider file ext/oci8/oci8_dtrace.d, enabling three probes. The first one will accept a parameter that runtime tracing can later display: provider php { probe oci8__connect(char *username); probe oci8__nls_start(); probe oci8__nls_done(); }; I updated ext/oci8/config.m4 with the PHP_INIT_DTRACE macro. The patch is at the end of config.m4. The macro takes the provider prototype file, a name of the header file that 'dtrace' will generate, and a list of sources files with probes. When --enable-dtrace is used during PHP configuration, then the outer $PHP_DTRACE check is true and my new probes will be enabled. I've chosen to define an OCI8 specific macro, HAVE_OCI8_DTRACE, which can be used in the OCI8 source code: diff --git a/ext/oci8/config.m4 b/ext/oci8/config.m4 index 34ae76c..f3e583d 100644 --- a/ext/oci8/config.m4 +++ b/ext/oci8/config.m4 @@ -341,4 +341,17 @@ if test "$PHP_OCI8" != "no"; then PHP_SUBST_OLD(OCI8_ORACLE_VERSION) fi + + if test "$PHP_DTRACE" = "yes"; then + AC_CHECK_HEADERS([sys/sdt.h], [ + PHP_INIT_DTRACE([ext/oci8/oci8_dtrace.d], + [ext/oci8/oci8_dtrace_gen.h],[ext/oci8/oci8.c]) + AC_DEFINE(HAVE_OCI8_DTRACE,1, + [Whether to enable DTrace support for OCI8 ]) + ], [ + AC_MSG_ERROR( + [Cannot find sys/sdt.h which is required for DTrace support]) + ]) + fi + fi In ext/oci8/oci8.c, I added the probes at, for this example, semi-arbitrary places: diff --git a/ext/oci8/oci8.c b/ext/oci8/oci8.c index e2241cf..ffa0168 100644 --- a/ext/oci8/oci8.c +++ b/ext/oci8/oci8.c @@ -1811,6 +1811,12 @@ php_oci_connection *php_oci_do_connect_ex(char *username, int username_len, char } } +#ifdef HAVE_OCI8_DTRACE + if (DTRACE_OCI8_CONNECT_ENABLED()) { + DTRACE_OCI8_CONNECT(username); + } +#endif + /* Initialize global handles if they weren't initialized before */ if (OCI_G(env) == NULL) { php_oci_init_global_handles(TSRMLS_C); @@ -1870,11 +1876,22 @@ php_oci_connection *php_oci_do_connect_ex(char *username, int username_len, char size_t rsize = 0; sword result; +#ifdef HAVE_OCI8_DTRACE + if (DTRACE_OCI8_NLS_START_ENABLED()) { + DTRACE_OCI8_NLS_START(); + } +#endif PHP_OCI_CALL_RETURN(result, OCINlsEnvironmentVariableGet, (&charsetid_nls_lang, 0, OCI_NLS_CHARSET_ID, 0, &rsize)); if (result != OCI_SUCCESS) { charsetid_nls_lang = 0; } smart_str_append_unsigned_ex(&hashed_details, charsetid_nls_lang, 0); + +#ifdef HAVE_OCI8_DTRACE + if (DTRACE_OCI8_NLS_DONE_ENABLED()) { + DTRACE_OCI8_NLS_DONE(); + } +#endif } timestamp = time(NULL); The oci_connect(), oci_pconnect() and oci_new_connect() calls all use php_oci_do_connect_ex() internally. The first probe simply records that the PHP application made a connection call. I already showed a way to do this without needing a probe, but adding a specific probe lets me record the username. The other two probes can be used to time how long the globalization initialization takes. The relationships between the oci8_dtrace.d names like oci8__connect, the probe guards like DTRACE_OCI8_CONNECT_ENABLED() and probe names like DTRACE_OCI8_CONNECT() are obvious after seeing the pattern of all three probes. I included the new header that will be automatically created by the dtrace tool when PHP is built. I did this in ext/oci8/php_oci8_int.h: diff --git a/ext/oci8/php_oci8_int.h b/ext/oci8/php_oci8_int.h index b0d6516..c81fc5a 100644 --- a/ext/oci8/php_oci8_int.h +++ b/ext/oci8/php_oci8_int.h @@ -44,6 +44,10 @@ # endif # endif /* osf alpha */ +#ifdef HAVE_OCI8_DTRACE +#include "oci8_dtrace_gen.h" +#endif + #if defined(min) #undef min #endif Now PHP can be rebuilt: $ cd ~/php-src $ rm configure && ./buildconf --force $ ./configure --disable-all --enable-dtrace \ --with-oci8=instantclient,/home/cjones/instantclient $ make If 'make' fails, do the 'git checkout Zend/zend_dtrace.d' trick I mentioned. The new probes can be seen by logging in as root and running: # stap -l 'process.provider("php").mark("oci8*")' -c 'sapi/cli/php -i' process("sapi/cli/php").provider("php").mark("oci8__connect") process("sapi/cli/php").provider("php").mark("oci8__nls_done") process("sapi/cli/php").provider("php").mark("oci8__nls_start") To test them out, create a new trace file, oci.stp: global numconnects; global start; global numcharlookups = 0; global tottime = 0; probe process.provider("php").mark("oci8-connect") { printf("Connected as %s\n", user_string($arg1)); numconnects += 1; } probe process.provider("php").mark("oci8-nls_start") { start = gettimeofday_us(); numcharlookups++; } probe process.provider("php").mark("oci8-nls_done") { tottime += gettimeofday_us() - start; } probe end { printf("Connects: %d, Charset lookups: %ld\n", numconnects, numcharlookups); printf("Total NLS charset initalization time: %ld usecs/connect\n", (numcharlookups 0 ? tottime/numcharlookups : 0)); } This calculates the average time that the NLS character set lookup takes. It also prints out the username of each connection, as an example of using parameters. Login as root and run Systemtap over the PHP script: # cd ~cjones/php-src # stap -c 'sapi/cli/php ~cjones/test.php' ~cjones/oci.stp Connected as cj <?xml version="1.0"?> <ROWSET> <ROW> <DUMMY>X</DUMMY> </ROW> </ROWSET> Connects: 1, Charset lookups: 1 Total NLS charset initalization time: 164 usecs/connect This shows the time penalty of making OCI8 look up the default character set. This time would be zero if a character set had been passed as the fourth argument to oci_connect() in test.php.

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  • Master-slave vs. peer-to-peer archictecture: benefits and problems

    - by Ashok_Ora
    Normal 0 false false false EN-US X-NONE X-NONE Almost two decades ago, I was a member of a database development team that introduced adaptive locking. Locking, the most popular concurrency control technique in database systems, is pessimistic. Locking ensures that two or more conflicting operations on the same data item don’t “trample” on each other’s toes, resulting in data corruption. In a nutshell, here’s the issue we were trying to address. In everyday life, traffic lights serve the same purpose. They ensure that traffic flows smoothly and when everyone follows the rules, there are no accidents at intersections. As I mentioned earlier, the problem with typical locking protocols is that they are pessimistic. Regardless of whether there is another conflicting operation in the system or not, you have to hold a lock! Acquiring and releasing locks can be quite expensive, depending on how many objects the transaction touches. Every transaction has to pay this penalty. To use the earlier traffic light analogy, if you have ever waited at a red light in the middle of nowhere with no one on the road, wondering why you need to wait when there’s clearly no danger of a collision, you know what I mean. The adaptive locking scheme that we invented was able to minimize the number of locks that a transaction held, by detecting whether there were one or more transactions that needed conflicting eyou could get by without holding any lock at all. In many “well-behaved” workloads, there are few conflicts, so this optimization is a huge win. If, on the other hand, there are many concurrent, conflicting requests, the algorithm gracefully degrades to the “normal” behavior with minimal cost. We were able to reduce the number of lock requests per TPC-B transaction from 178 requests down to 2! Wow! This is a dramatic improvement in concurrency as well as transaction latency. The lesson from this exercise was that if you can identify the common scenario and optimize for that case so that only the uncommon scenarios are more expensive, you can make dramatic improvements in performance without sacrificing correctness. So how does this relate to the architecture and design of some of the modern NoSQL systems? NoSQL systems can be broadly classified as master-slave sharded, or peer-to-peer sharded systems. NoSQL systems with a peer-to-peer architecture have an interesting way of handling changes. Whenever an item is changed, the client (or an intermediary) propagates the changes synchronously or asynchronously to multiple copies (for availability) of the data. Since the change can be propagated asynchronously, during some interval in time, it will be the case that some copies have received the update, and others haven’t. What happens if someone tries to read the item during this interval? The client in a peer-to-peer system will fetch the same item from multiple copies and compare them to each other. If they’re all the same, then every copy that was queried has the same (and up-to-date) value of the data item, so all’s good. If not, then the system provides a mechanism to reconcile the discrepancy and to update stale copies. So what’s the problem with this? There are two major issues: First, IT’S HORRIBLY PESSIMISTIC because, in the common case, it is unlikely that the same data item will be updated and read from different locations at around the same time! For every read operation, you have to read from multiple copies. That’s a pretty expensive, especially if the data are stored in multiple geographically separate locations and network latencies are high. Second, if the copies are not all the same, the application has to reconcile the differences and propagate the correct value to the out-dated copies. This means that the application program has to handle discrepancies in the different versions of the data item and resolve the issue (which can further add to cost and operation latency). Resolving discrepancies is only one part of the problem. What if the same data item was updated independently on two different nodes (copies)? In that case, due to the asynchronous nature of change propagation, you might land up with different versions of the data item in different copies. In this case, the application program also has to resolve conflicts and then propagate the correct value to the copies that are out-dated or have incorrect versions. This can get really complicated. My hunch is that there are many peer-to-peer-based applications that don’t handle this correctly, and worse, don’t even know it. Imagine have 100s of millions of records in your database – how can you tell whether a particular data item is incorrect or out of date? And what price are you willing to pay for ensuring that the data can be trusted? Multiple network messages per read request? Discrepancy and conflict resolution logic in the application, and potentially, additional messages? All this overhead, when all you were trying to do was to read a data item. Wouldn’t it be simpler to avoid this problem in the first place? Master-slave architectures like the Oracle NoSQL Database handles this very elegantly. A change to a data item is always sent to the master copy. Consequently, the master copy always has the most current and authoritative version of the data item. The master is also responsible for propagating the change to the other copies (for availability and read scalability). Client drivers are aware of master copies and replicas, and client drivers are also aware of the “currency” of a replica. In other words, each NoSQL Database client knows how stale a replica is. This vastly simplifies the job of the application developer. If the application needs the most current version of the data item, the client driver will automatically route the request to the master copy. If the application is willing to tolerate some staleness of data (e.g. a version that is no more than 1 second out of date), the client can easily determine which replica (or set of replicas) can satisfy the request, and route the request to the most efficient copy. This results in a dramatic simplification in application logic and also minimizes network requests (the driver will only send the request to exactl the right replica, not many). So, back to my original point. A well designed and well architected system minimizes or eliminates unnecessary overhead and avoids pessimistic algorithms wherever possible in order to deliver a highly efficient and high performance system. If you’ve every programmed an Oracle NoSQL Database application, you’ll know the difference! /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin;}

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  • Creating an ITemplate from a String

    - by Damon
    I do a lot of work with control templates, and one of the pieces of functionality that I've always wanted is the ability to build a ITemplate from a string.  Throughout the years, the topic has come up from time to time, and I never really found anything about how to do it. though I have run across a number of postings from people who are also wanting the same capability.  As I was messing around with things the other day, I stumbled on how to make it work and I feel really foolish for not figuring it out sooner. ITemplate is an interface that exposes a single method named InstantiateIn.  I've been searching for years for some magical .NET framework component that would take a string and convert it into an ITemplate, when all along I could just build my own.  Here's the code: /// <summary> ///   Allows string-based ITempalte implementations /// </summary> public class StringTemplate : ITemplate {     #region Constructor(s)     ////////////////////////////////////////////////////////////////////////////////////////////     /// <summary>     ///   Constructor     /// </summary>     /// <param name="template">String based version of the control template.</param>     public StringTemplate(string template)     {         Template = template;     }     /// <summary>     ///   Constructor     /// </summary>     /// <param name="template">String based version of the control template.</param>     /// <param name="copyToContainer">True to copy intermediate container contents to the instantiation container, False to leave the intermediate container in place.</param>     public StringTemplate(string template, bool copyToContainer)     {         Template = template;         CopyToContainer = copyToContainer;     }     ////////////////////////////////////////////////////////////////////////////////////////////     #endregion     #region Properties     ////////////////////////////////////////////////////////////////////////////////////////////     /// <summary>     ///   String based template     /// </summary>     public string Template     {         get;         set;     }     /// <summary>     ///   When a StringTemplate is instantiated it is created inside an intermediate control     ///   due to limitations of the .NET Framework.  Specifying True for the CopyToContainer     ///   property copies all the controls from the intermediate container into instantiation     ///   container passed to the InstantiateIn method.     /// </summary>     public bool CopyToContainer     {         get;         set;     }     ////////////////////////////////////////////////////////////////////////////////////////////     #endregion     #region ITemplate Members     ////////////////////////////////////////////////////////////////////////////////////////////     /// <summary>     ///   Creates the template in the specified control.     /// </summary>     /// <param name="container">Control in which to make the template</param>     public void InstantiateIn(Control container)     {         Control tempContainer = container.Page.ParseControl(Template);         if (CopyToContainer)         {             for (int i = tempContainer.Controls.Count - 1; i >= 0; i--)             {                 Control tempControl = tempContainer.Controls[i];                 tempContainer.Controls.RemoveAt(i);                 container.Controls.AddAt(0, tempControl);             }                         }         else         {             container.Controls.Add(tempContainer);         }     }     ////////////////////////////////////////////////////////////////////////////////////////////     #endregion } //class Converting a string into a user control is fairly easy using the ParseControl method from a Page object.  Fortunately, the container passed into the InstantiateIn method has a Page property.  One caveat, however, is that the Page property only has a reference to a Page if the container is located ON the page.  If you run into this problem, you may have to find a creative way to get the Page reference (you can add it to the constructor, store it in the request context, etc).  Another issue that I ran into is that the ParseControl creates a new control, parses the string template, places any controls defined in the template onto the new control it created, and returns that new control with the template on it.  You cannot pass in your own container. Adding this directly to the container provided as a parameter in the InstantiateIn means that you end up with an additional "level" in the control hierarchy.  To avoid this, I added code in that removes each control from the intermediate container and places it into the actual container.  I am not, however, sure about the performance penalty associated with moving a bunch of control from one place to another, nor am I completely sure if doing such a move completely screws something up if you have a code behind, etc.  It seems to work when it's just a template, but my testing was ever-so-slightly shy of thorough when it comes to other crazy scenarios.  As a catch-all, I added a Boolean property called CopyToContainer that allows you to turn the copying on or off depending on your desires and needs. Technorati Tags: .NET,ASP.NET,ITemplate,Development,C#,Custom Controls,Server Controls

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  • Mobile App Data Syncronization

    - by Matt Rogish
    Let's say I have a mobile app that uses HTML5 SQLite DB (and/or the HTML5 key-value store). Assets (media files, PDFs, etc.) are stored locally on the mobile device. Luckily enough, the mobile device is a read-only copy of the "centralized" storage, so the mobile device won't have to propagate changes upstream. However, as the server changes assets (creates new ones, modifies existing, deletes old ones) I need to propagate those changes back to the mobile app. Assume that server changes are grouped into changesets (version number n) that contain some information (added element XYZ, deleted id = 45, etc.) and that the mobile device has limited CPU/bandwidth, so most of the processing has to take place on the server. I can think of a couple of methods to do this. All have trade-offs and at this point, I'm unsure which is the right course of action... Method 1: For change set n, store the "diff" of the current n and previous n-1. When a client with version y asks if there have been any changes, send the change sets from version y up to the current version. e.g. added item 334, contents: xxx. Deleted picture 44. Deleted PDF 11. Changed 33. added picture 99. Characteristics: Diffs take up space, although in theory would be kept small. However, all diffs must be kept around indefinitely (should a v1 app have not been updated for a year, must apply v2..v100). High latency devices (mobile apps) will incur a penalty to send lots of small files (assume cannot be zipped or tarr'd up into one file) Very few server CPU resources required, as all it does is send the client a list of files "Dumb" - if I change an item in change set 3, and change it to something else in 4, the client is going to perform both actions, even though #3 is rendered moot by #4. Or, if an asset is added in #4 and removed in #5 - the client will download a file just to delete it later. Method 2: Very similar to method 1 except on the server, do some sort of a diff between the change sets represented by the app version and server version. Package that up and send that single change set to the client. Characteristics: Client-efficient: The client only has to process one file, duplicate or irrelevant changes are stripped out. Server CPU/space intensive. The change sets must be diff'd and then written out to a file that is then sent to the client. Makes diff server scalability an issue. Possibly ways to cache the results and re-use them, but in the wild there's likely to be a lot of different versions so the diff re-use has a limit Diff algorithm is complicated. The change sets must be structured in such a way that an efficient and effective diff can be performed. Method 3: Instead of keeping diffs, write out the entire versioned asset collection to a mobile-database import file. When client requests an update, send the entire database to client and have them update their assets appropriately. Characteristics: Conceptually simple -- easy to develop and deploy Very inefficient as the client database is restored every update. If only one new thing was added, the whole database is refreshed. Server space and CPU efficient. Only the latest version DB needs kept around and the server just throws the file to the client. Others?? Thoughts? Thanks!!

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  • Thread Synchronisation 101

    - by taspeotis
    Previously I've written some very simple multithreaded code, and I've always been aware that at any time there could be a context switch right in the middle of what I'm doing, so I've always guarded access the shared variables through a CCriticalSection class that enters the critical section on construction and leaves it on destruction. I know this is fairly aggressive and I enter and leave critical sections quite frequently and sometimes egregiously (e.g. at the start of a function when I could put the CCriticalSection inside a tighter code block) but my code doesn't crash and it runs fast enough. At work my multithreaded code needs to be a tighter, only locking/synchronising at the lowest level needed. At work I was trying to debug some multithreaded code, and I came across this: EnterCriticalSection(&m_Crit4); m_bSomeVariable = true; LeaveCriticalSection(&m_Crit4); Now, m_bSomeVariable is a Win32 BOOL (not volatile), which as far as I know is defined to be an int, and on x86 reading and writing these values is a single instruction, and since context switches occur on an instruction boundary then there's no need for synchronising this operation with a critical section. I did some more research online to see whether this operation did not need synchronisation, and I came up with two scenarios it did: The CPU implements out of order execution or the second thread is running on a different core and the updated value is not written into RAM for the other core to see; and The int is not 4-byte aligned. I believe number 1 can be solved using the "volatile" keyword. In VS2005 and later the C++ compiler surrounds access to this variable using memory barriers, ensuring that the variable is always completely written/read to the main system memory before using it. Number 2 I cannot verify, I don't know why the byte alignment would make a difference. I don't know the x86 instruction set, but does mov need to be given a 4-byte aligned address? If not do you need to use a combination of instructions? That would introduce the problem. So... QUESTION 1: Does using the "volatile" keyword (implicity using memory barriers and hinting to the compiler not to optimise this code) absolve a programmer from the need to synchronise a 4-byte/8-byte on x86/x64 variable between read/write operations? QUESTION 2: Is there the explicit requirement that the variable be 4-byte/8-byte aligned? I did some more digging into our code and the variables defined in the class: class CExample { private: CRITICAL_SECTION m_Crit1; // Protects variable a CRITICAL_SECTION m_Crit2; // Protects variable b CRITICAL_SECTION m_Crit3; // Protects variable c CRITICAL_SECTION m_Crit4; // Protects variable d // ... }; Now, to me this seems excessive. I thought critical sections synchronised threads between a process, so if you've got one you can enter it and no other thread in that process can execute. There is no need for a critical section for each variable you want to protect, if you're in a critical section then nothing else can interrupt you. I think the only thing that can change the variables from outside a critical section is if the process shares a memory page with another process (can you do that?) and the other process starts to change the values. Mutexes would also help here, named mutexes are shared across processes, or only processes of the same name? QUESTION 3: Is my analysis of critical sections correct, and should this code be rewritten to use mutexes? I have had a look at other synchronisation objects (semaphores and spinlocks), are they better suited here? QUESTION 4: Where are critical sections/mutexes/semaphores/spinlocks best suited? That is, which synchronisation problem should they be applied to. Is there a vast performance penalty for choosing one over the other? And while we're on it, I read that spinlocks should not be used in a single-core multithreaded environment, only a multi-core multithreaded environment. So, QUESTION 5: Is this wrong, or if not, why is it right? Thanks in advance for any responses :)

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