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  • Symmetric Encryption: Performance Questions

    - by cam
    Does the performance of a symmetric encryption algorithm depend on the amount of data being encrypted? Suppose I have about 1000 bytes I need to send over the network rapidly, is it better to encrypt 50 bytes of data 20 times, or 1000 bytes at once? Which will be faster? Does it depend on the algorithm used? If so, what's the highest performing, most secure algorithm for amounts of data under 512 bytes?

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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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  • Performance analysis for java application

    - by user1827614
    I want to do a performance measurement of my application and would like to be able to configure the stats for specific module like (enable for specific module and disable for some) and I want to measure things like memory usage, threads, average band width etc.. Can any one suggest something please, I am new to this. I think Visual VM is good but it doesnot support configuring for different modules. Does Perf4j or Admin4j work here? any one has used these before?

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  • Dell 2950 Perc 6/i "physical disk" and "Enclosure(Backplane)" under Connector 1 in OMSA tree- Troubleshoot help

    - by user66357
    Just looking for someone who might know why this could occur... In OMSA, on my Dell 2950, there usually is only one "Physical Disks" child under "Enclosure (Backplane)" in the tree view. Currently, the tree looks like this: Dell PERC 6/i Integrated Connector 1 (RAID) Enclosure (Backplane) Physical Disks (1:04 good, 1:05 removed) Physical Disks (1:33 Ready but unused) Normally it's like this: Connector 1 (RAID) Enclosure (Backplane) Physical Disks (1:04 good, 1:05 good) From the front, 6 of 6 3.5" SAS drives are connected. The server is showing Slot 5 as bad and the disk as removed. It seems that the drive in Slot 5 is being sensed as external to the Enclosure. Any ideas why this would happen? Think I can get away with rebuilding the virtual disk by replacing 1:05 with 1:33? Thanks. UPDATE: The only options on the Physical Disk 1:33 were Assign as Global Hot Spare and Clear... After clearing, I assigned it as the Global Hot Spare. This allowed the rebuilding of the virtual disk. Hopefully it won't fail. I'm still unsure of the reason for this odd behavior. I'm checking the firmware next.

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  • Mysql: Disk is full writing

    - by elma
    Hi there, I'm having some problems with my mysql server lately, so I've decided to check the error logs: [root@LSN-D1179 log]# tail -10 mysqld.log 100325 19:30:03 [ERROR] /usr/libexec/mysqld: Table './lfe/actions' is marked as crashed and should be repaired 100325 19:30:03 [ERROR] /usr/libexec/mysqld: Table './lfe/actions' is marked as crashed and should be repaired 100325 19:30:18 [ERROR] /usr/libexec/mysqld: Disk is full writing './omuz/ibf_task_logs.MYD' (Errcode: 122). Waiting for someone to free space... Retry in 60 secs 100325 19:34:34 [ERROR] /usr/libexec/mysqld: Disk is full writing './omuz/ibf_profile_portal_views.MYD' (Errcode: 122). Waiting for someone to free space... Retry in 60 secs 100325 19:39:46 [ERROR] /usr/libexec/mysqld: Disk is full writing './omuz/ibf_posts.TMD' (Errcode: 122). Waiting for someone to free space... Retry in 60 secs 100325 19:40:18 [ERROR] /usr/libexec/mysqld: Disk is full writing './omuz/ibf_task_logs.MYD' (Errcode: 122). Waiting for someone to free space... Retry in 60 secs 100325 19:44:34 [ERROR] /usr/libexec/mysqld: Disk is full writing './omuz/ibf_profile_portal_views.MYD' (Errcode: 122). Waiting for someone to free space... Retry in 60 secs 100325 19:49:46 [ERROR] /usr/libexec/mysqld: Disk is full writing './omuz/ibf_posts.TMD' (Errcode: 122). Waiting for someone to free space... Retry in 60 secs 100325 19:50:18 [ERROR] /usr/libexec/mysqld: Disk is full writing './omuz/ibf_task_logs.MYD' (Errcode: 122). Waiting for someone to free space... Retry in 60 secs 100325 19:54:34 [ERROR] /usr/libexec/mysqld: Disk is full writing './omuz/ibf_profile_portal_views.MYD' (Errcode: 122). Waiting for someone to free space... Retry in 60 secs And here's is my df -h output [root@LSN-D1179 log]# df -h Filesystem Size Used Avail Use% Mounted on /dev/mapper/VolGroup00-LogVol00 143G 6.2G 129G 5% / /dev/sda1 99M 12M 83M 13% /boot tmpfs 490M 0 490M 0% /dev/shm As you can see, I have plenty of free space; so I couldn't figure out these "Disk is full" errors in mysqld.log. Does anyone know what should I do to fix this? Ugur

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  • Performance problems loading XML with SSIS, an alternative way!

    - by AtulThakor
    I recently needed to load several thousand XML files into a SQL database, I created an SSIS package which was created as followed: Using a foreach container to loop through a directory and load each file path into a variable, the “Import XML” dataflow would then load each XML file into a SQL table.       Running this, it took approximately 1 second to load each file which seemed a massive amount of time to parse the XML and load the data, speaking to my colleague Martin Croft, he suggested the use of T-SQL Bulk Insert and OpenRowset, so we adjusted the package as followed:     The same foreach container was used but instead the following SQL command was executed (this is an expression):     "INSERT INTO MyTable(FileDate) SELECT   CAST(bulkcolumn AS XML)     FROM OPENROWSET(         BULK         '" + @[User::CurrentFile]  + "',         SINGLE_BLOB ) AS x"     Using this method we managed to load approximately 20 records per second, much faster…for data loading! For what we wanted to achieve this was perfect but I’ll leave you with the following points when making your own decision on which solution you decide to choose!      Openrowset Method Much faster to get the data into SQL You’ll need to parse or create a view over the XML data to allow the data to be more usable(another post on this!) Not able to apply validation/transformation against the data when loading it The SQL Server service account will need permission to the file No schema validation when loading files SSIS Slower (in our case) Schema validation Allows you to apply transformations/joins to the data Permissions should be less of a problem Data can be loaded into the final form through the package When using a schema validation errors can fail the package (I’ll do another post on this)

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  • Full disk encryption with seperate boot and encrypted keyfile storage: Two-Form Authentication

    - by Cain
    I am trying to setup true Full Disk encryption with two-form authentication on 12.04 and can not find out how to call a keyfile for the encrypted root out of another encrypted partition. All documentation or questions I am finding for whole or full disk encryption only encrypts separate partitions on the same disk. This is not what most are calling full disk encryption, /boot is not on a partition on the root drive, rather it is on a usb stick as sdx1. Instead root is on a logical partition on top of a LUKS container. Luks is run on the whole disk, encrypting the partition table as well. All drives in the machine are completely encrypted and to open it it requires a USB drive (what I have) as well as a passphrase (what I know) resulting in Two-Form Authentication to boot the machine. Device sdx cryptroot vg00 lvroot / There is no passphrase to open the encrypted root device, only a keyfile. That keyfile is kept on the usb drive with /boot, in its own encrypted partition (I'll call this cryptkey). In order for the root file system (cryptroot) to be opened, initramfs must ask for the passphrase to cryptkey on the usb drive, then use the keyfile inside that to open cryproot. I did manage to find what I think is the how-to I used to do this once before: http://wiki.ubuntu.org.cn/UbuntuHelp:FeistyLUKSTwoFormFactor I already have the system installed and can chroot into it, however, I can not get it to call for the keys on the USB during boot. I did find a how-to saying I needed to make a cryptroot conf for initramfs but, I believe that is for a passphrase: https://help.ubuntu.com/community/EncryptedFilesystemLVMHowto#Notes_for_making_it_work_in_Ubuntu_12.04_.22Precise_Pangolin.22_amd64 I also tried to setup crypttab. However, crypttab only works for drives mounted after the root drive as calling for a keyfile on a device not yet mounted to the system doesnt work. The Feisty how-to included scripts that would be run during boot instructing initramfs to mount the usb drive temporarily and call the keyfile for root which worked quite well except those scripts are outdated now, many of the things they relied on have been merged into something else, changed, or simply don't exist anymore. If I have missed a clear how-to for this, that would be wonderful, I just don't think I have.

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  • What will be a good python script (or your favorite language goes here) to test a system's performance and capabilities?

    - by dassouki
    Let's say you're in a computer store looking at 10 laptops, you want to really compare the system's capabilities. What will be an efficient "your fav language goes here" script that will allow you to do this? As an example, when I go to the store I usually open a macbook and a pro's terminal and write an equation in python, iterate it a million or so times, and time them. I like to compare the difference in time. What would be an ideal and simple script that can efficiently compare systems?

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  • How to keep subtree removal (`rm -rf`) from starving other processes for Disk I/O?

    - by David Eyk
    We have a very large (multi-GB) Nginx cache directory for a busy site, which we occasionally need to clear all at once. I've solved this in the past by moving the cache folder to a new path, making a new cache folder at the old path, and then rm -rfing the old cache folder. Lately, however, when I need to clear the cache on a busy morning, the I/O from rm -rf is starving my server processes of disk access, as both Nginx and the server it fronts for are read-intensive. I can watch the load average climb while the CPUs sit idle and rm -rf takes 98-99% of Disk IO in iotop. I've tried ionice -c 3 when invoking rm, but it seems to have no appreciable effect on the observed behavior. Is there any way to tame rm -rf to share the disk more? Do I need to use a different technique that will take its cues from ionice? Update: The filesystem in question is an AWS EC2 instance store (the primary disk is EBS). The /etc/fstab entry looks like this: /dev/xvdb /mnt auto defaults,nobootwait,comment=cloudconfig 0 2

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  • Disk doesn't contain a valid partition table

    - by Jeevan Dongre
    I was running a m1.small instance ec2 ubuntu instance. I was running out of disk space, so I upgraded my instance to medium. When I upgraded I actually got 429.5 GB of space and after that I added 10 gb of volume too. When I run the "sudo fdisk -l" command I got this results. Disk /dev/sda1: 8589 MB, 8589934592 bytes 255 heads, 63 sectors/track, 1044 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Disk /dev/sda1 doesn't contain a valid partition table Disk /dev/sda2: 429.5 GB, 429461078016 bytes 255 heads, 63 sectors/track, 52212 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Disk /dev/sda2 doesn't contain a valid partition table Disk /dev/sdf: 10.7 GB, 10737418240 bytes 255 heads, 63 sectors/track, 1305 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 sda1 is the primary parition and sda2 is what I got added upgrading my system to medium. But the problem persists, I am not able to pull the code from git, it is giving me this error. remote: Counting objects: 409, done. remote: Compressing objects: 100% (236/236), done. fatal: write error: No space left on device fatal: index-pack failed

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  • disk partition centos

    - by FlourishDNA
    I am setting up server for hosting two WordPress which has size of around 70GB. I have already installed CentOS as OS and I would like to partition the Disk. Is there any tool which can help me or can someone guide me though the process as I am not expert is SSH commands. Here are some output that might help. OS: CentOS release 6.3 fdisk -l Disk /dev/xvdb: 214.7 GB, 214748364800 bytes 255 heads, 63 sectors/track, 26108 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x000b91e0 Device Boot Start End Blocks Id System Disk /dev/xvda: 21.5 GB, 21474836480 bytes 255 heads, 63 sectors/track, 2610 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x000e542c Device Boot Start End Blocks Id System /dev/xvda1 * 1 64 512000 83 Linux Partition 1 does not end on cylinder boundary. /dev/xvda2 64 2611 20458496 8e Linux LVM Disk /dev/mapper/vg_flourish-lv_root: 16.7 GB, 16718495744 bytes 255 heads, 63 sectors/track, 2032 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Disk /dev/mapper/vg_flourish-lv_swap: 4227 MB, 4227858432 bytes 255 heads, 63 sectors/track, 514 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 df Filesystem 1K-blocks Used Available Use% Mounted on /dev/mapper/vg_flourish-lv_root 16070076 758184 14495560 5% / tmpfs 958500 0 958500 0% /dev/shm /dev/xvda1 495844 31926 438318 7% /boot df -h Filesystem Size Used Avail Use% Mounted on /dev/mapper/vg_flourish-lv_root 16G 741M 14G 5% / tmpfs 937M 0 937M 0% /dev/shm /dev/xvda1 485M 32M 429M 7% /boot Thanks

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  • Damaged external NTFS hard disk

    - by Thanos
    A few days ago, I used my external hard disk (a 2TB Seagate) in order to transfer some files on Windows Vista. During that, I noticed some malfunctions on my system (it was running too slow, Windows Explorer crashed). When Explorer crashed, file transportation stopped. I was afraid, but I tried to access my files and it seemed to be working. I tried to open a movie (from the external disk) but it couldn't load. I thought of restarting, but this took sooo long... So I unplugged the hard disk and at that time it managed to shut down. I logged on to Windows Vista but the hard disk couldn't be mounted. I plugged it but nothing happened. I unplugged it and I heard this specific sound that notifies that something has been unplugged. I thought of logging to Ubuntu 10.04 and see what I can do. I plugged the hard disk, but I couldn't see it. I opened GParted but I couldn't see it either. I tried with Disc Utility and there it was! I tried to mount it but a got an error message stating that an error occured with Windows, there is a file (0,0) that has problem or something like that. It suggested to log into Windows and run chkdsk /f and reboot twice. The thing is that I am somehow afraid to do so because I don't really know the impact on that. Plus I don't trust doing even a check on Vista... I finally risked it and I typed chkdsk/f on a cmd. I cannot, however, actually run it because I don't have admin privileges. So from search I found chkdsk, I right cliked and selected “run as administrator”. It run but I got a message like NTFS file system. It should check at the coming restart. At that point I am mistaken. I thought that f meant F but this is not the case here... Does anyone have any suggestions and advice?

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  • Horrorble performance using ListViews with nested objects in WPF

    - by Christian
    Hi community, like mentioned in the title I get a horrible performance if I use ListViews with nested objects. My scenario is: Each row of a ListView presents an object of the class Transaction with following attributes: private int mTransactionID; private IBTTransactionSender mSender; private IBTTransactionReceiver mReceiver; private BTSubstrate mSubstrate; private double mAmount; private string mDeliveryNote; private string mNote; private DateTime mTransactionDate; private DateTime mCreationTimestamp; private BTEmployee mEmployee; private bool mImported; private bool mDescendedFromRecurringTransaction; Each attribute can be accessed by its corresponding property. An ObservableCollection<Transaction> is bound to the ItemsSource of a ListView. The ListView itself looks like the following: </ListView.GroupStyle> <ListView.View> <GridView> <GridViewColumn core:SortableListView.SortPropertyName="Transaction.ToSave" Width="80"> <GridViewColumnHeader Name="GVCHLoadedToSave" Style="{StaticResource ListViewHeaderStyle}">Speichern</GridViewColumnHeader> <GridViewColumn.CellTemplate> <DataTemplate> <Grid> <CheckBox Name="CBListViewItem" IsChecked="{Binding Path=Transaction.ToSave, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"></CheckBox> </Grid> </DataTemplate> </GridViewColumn.CellTemplate> </GridViewColumn> <GridViewColumn core:SortableListView.SortPropertyName="Transaction.TransactionDate" Width="80"> <GridViewColumnHeader Name="GVCHLoadedDate" Style="{StaticResource ListViewHeaderStyle}">Datum</GridViewColumnHeader> <GridViewColumn.CellTemplate> <DataTemplate> <Grid> <TextBlock Text="{Binding ElementName=DPDate, Path=Text}" Style="{StaticResource GridBlockStyle}"/> <toolkit:DatePicker Name="DPDate" Width="{Binding ElementName=GVCHDate, Path=ActualWidth}" SelectedDateFormat="Short" Style="{StaticResource GridEditStyle}" SelectedDate="{Binding Path=Transaction.TransactionDate, Mode=TwoWay}" SelectedDateChanged="DPDate_SelectedDateChanged"/> </Grid> </DataTemplate> </GridViewColumn.CellTemplate> </GridViewColumn> <GridViewColumn core:SortableListView.SortPropertyName="Transaction.Sender.Description" Width="120"> <GridViewColumnHeader Name="GVCHLoadedSender" Style="{StaticResource ListViewHeaderStyle}">Von</GridViewColumnHeader> <GridViewColumn.CellTemplate> <DataTemplate> <Grid> <TextBlock Text="{Binding Path=Transaction.Sender.Description}" Style="{StaticResource GridBlockStyle}"/> <ComboBox Name="CBSender" Width="{Binding ElementName=GVCHSender, Path=ActualWidth}" SelectedItem="{Binding Path=Transaction.Sender}" DisplayMemberPath="Description" Text="{Binding Path=Sender.Description, Mode=OneWay}" ItemsSource="{Binding ElementName=Transaction, Path=SenderList}" Style="{StaticResource GridEditStyle}"> </ComboBox> </Grid> </DataTemplate> </GridViewColumn.CellTemplate> </GridViewColumn> <GridViewColumn core:SortableListView.SortPropertyName="Transaction.Receiver.Description" Width="120"> <GridViewColumnHeader Name="GVCHLoadedReceiver" Style="{StaticResource ListViewHeaderStyle}">Nach</GridViewColumnHeader> <GridViewColumn.CellTemplate> <DataTemplate> <Grid> <TextBlock Text="{Binding Path=Transaction.Receiver.Description}" Style="{StaticResource GridBlockStyle}"/> <ComboBox Name="CBReceiver" Width="{Binding ElementName=GVCHReceiver, Path=ActualWidth}" SelectedItem="{Binding Path=Transaction.Receiver}" DisplayMemberPath="Description" Text="{Binding Path=Receiver.Description, Mode=OneWay}" ItemsSource="{Binding ElementName=Transaction, Path=ReceiverList}" Style="{StaticResource GridEditStyle}"> </ComboBox> </Grid> </DataTemplate> </GridViewColumn.CellTemplate> </GridViewColumn> <GridViewColumn core:SortableListView.SortPropertyName="Transaction.Substrate.Description" Width="140"> <GridViewColumnHeader Name="GVCHLoadedSubstrate" Style="{StaticResource ListViewHeaderStyle}">Substrat</GridViewColumnHeader> <GridViewColumn.CellTemplate> <DataTemplate> <Grid> <TextBlock Text="{Binding Path=Transaction.Substrate.Description}" Style="{StaticResource GridBlockStyle}"/> <ComboBox Name="CBSubstrate" Width="{Binding ElementName=GVCHSubstrate, Path=ActualWidth}" SelectedItem="{Binding Path=Transaction.Substrate}" DisplayMemberPath="Description" Text="{Binding Path=Substrate.Description, Mode=OneWay}" ItemsSource="{Binding ElementName=Transaction, Path=SubstrateList}" Style="{StaticResource GridEditStyle}"> </ComboBox> </Grid> </DataTemplate> </GridViewColumn.CellTemplate> </GridViewColumn> <GridViewColumn core:SortableListView.SortPropertyName="Transaction.Amount" Width="80"> <GridViewColumnHeader Name="GVCHLoadedAmount" Style="{StaticResource ListViewHeaderStyle}">Menge [kg]</GridViewColumnHeader> <GridViewColumn.CellTemplate> <DataTemplate> <Grid> <TextBlock Text="{Binding Path=Transaction.Amount}" Style="{StaticResource GridBlockStyle}"/> <TextBox Name="TBAmount" Text="{Binding Path=Transaction.Amount, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" Width="{Binding ElementName=GVCHAmount, Path=ActualWidth}" Style="{StaticResource GridTextBoxStyle}" /> </Grid> </DataTemplate> </GridViewColumn.CellTemplate> </GridViewColumn> <GridViewColumn core:SortableListView.SortPropertyName="Transaction.DeliveryNote" Width="100"> <GridViewColumnHeader Name="GVCHLoadedDeliveryNote" Style="{StaticResource ListViewHeaderStyle}">Lieferschein Nr.</GridViewColumnHeader> <GridViewColumn.CellTemplate> <DataTemplate> <Grid> <TextBlock Text="{Binding Path=Transaction.DeliveryNote}" Style="{StaticResource GridBlockStyle}"/> <TextBox Name="TBDeliveryNote" Text="{Binding Path=Transaction.DeliveryNote, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" Width="{Binding ElementName=GVCHDeliveryNote, Path=ActualWidth}" Style="{StaticResource GridEditStyle}" /> </Grid> </DataTemplate> </GridViewColumn.CellTemplate> </GridViewColumn> <GridViewColumn core:SortableListView.SortPropertyName="Transaction.Note" Width="190"> <GridViewColumnHeader Name="GVCHLoadedNote" Style="{StaticResource ListViewHeaderStyle}">Bemerkung</GridViewColumnHeader> <GridViewColumn.CellTemplate> <DataTemplate> <Grid> <TextBlock Text="{Binding Path=Transaction.Note}" Style="{StaticResource GridBlockStyle}"/> <TextBox Name="TBNote" Text="{Binding Path=Transaction.Note, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" Width="{Binding ElementName=GVCHNote, Path=ActualWidth}" Style="{StaticResource GridEditStyle}" /> </Grid> </DataTemplate> </GridViewColumn.CellTemplate> </GridViewColumn> <GridViewColumn core:SortableListView.SortPropertyName="Transaction.Employee.LastName" Width="100"> <GridViewColumnHeader Name="GVCHLoadedEmployee" Style="{StaticResource ListViewHeaderStyle}">Mitarbeiter</GridViewColumnHeader> <GridViewColumn.CellTemplate> <DataTemplate> <Grid> <TextBlock Text="{Binding Path=Transaction.Employee.LastName}" Style="{StaticResource GridBlockStyle}"/> <ComboBox Name="CBEmployee" Width="{Binding ElementName=GVCHEmployee, Path=ActualWidth}" SelectedItem="{Binding Path=Transaction.Employee}" DisplayMemberPath="LastName" Text="{Binding Path=Employee.LastName, Mode=OneWay}" ItemsSource="{Binding ElementName=Transaction, Path=EmployeeList}" Style="{StaticResource GridEditStyle}"> </ComboBox> </Grid> </DataTemplate> </GridViewColumn.CellTemplate> </GridViewColumn> </GridView> </ListView.View> </ListView> As you can see in the screenshot the user got the possibility to change the values of the transaction attributes with comboboxes. Ok now to my problem. If I click on the "Laden" button the application will load about 150 entries in the ObservableCollection<Transaction>. Before I fill the collection I set the ItemsSource of the ListView to null and after filling I bind the collection to the ItemsSource once again. The loading itself takes a few milliseconds, but the rendering of the filled collection takes a long time (150 entries = about 20 sec). I tested to delete all Comboboxes out of the xaml and i got a better performance, because I don't have to fill the ComboBoxes for each row. But I need to have these comboboxes for modifing the attributes of the Transaction. Does anybody know how to improve the performance? THX

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  • Performance surprise with "as" and nullable types

    - by Jon Skeet
    I'm just revising chapter 4 of C# in Depth which deals with nullable types, and I'm adding a section about using the "as" operator, which allows you to write: object o = ...; int? x = o as int?; if (x.HasValue) { ... // Use x.Value in here } I thought this was really neat, and that it could improve performance over the C# 1 equivalent, using "is" followed by a cast - after all, this way we only need to ask for dynamic type checking once, and then a simple value check. This appears not to be the case, however. I've included a sample test app below, which basically sums all the integers within an object array - but the array contains a lot of null references and string references as well as boxed integers. The benchmark measures the code you'd have to use in C# 1, the code using the "as" operator, and just for kicks a LINQ solution. To my astonishment, the C# 1 code is 20 times faster in this case - and even the LINQ code (which I'd have expected to be slower, given the iterators involved) beats the "as" code. Is the .NET implementation of isinst for nullable types just really slow? Is it the additional unbox.any that causes the problem? Is there another explanation for this? At the moment it feels like I'm going to have to include a warning against using this in performance sensitive situations... Results: Cast: 10000000 : 121 As: 10000000 : 2211 LINQ: 10000000 : 2143 Code: using System; using System.Diagnostics; using System.Linq; class Test { const int Size = 30000000; static void Main() { object[] values = new object[Size]; for (int i = 0; i < Size - 2; i += 3) { values[i] = null; values[i+1] = ""; values[i+2] = 1; } FindSumWithCast(values); FindSumWithAs(values); FindSumWithLinq(values); } static void FindSumWithCast(object[] values) { Stopwatch sw = Stopwatch.StartNew(); int sum = 0; foreach (object o in values) { if (o is int) { int x = (int) o; sum += x; } } sw.Stop(); Console.WriteLine("Cast: {0} : {1}", sum, (long) sw.ElapsedMilliseconds); } static void FindSumWithAs(object[] values) { Stopwatch sw = Stopwatch.StartNew(); int sum = 0; foreach (object o in values) { int? x = o as int?; if (x.HasValue) { sum += x.Value; } } sw.Stop(); Console.WriteLine("As: {0} : {1}", sum, (long) sw.ElapsedMilliseconds); } static void FindSumWithLinq(object[] values) { Stopwatch sw = Stopwatch.StartNew(); int sum = values.OfType<int>().Sum(); sw.Stop(); Console.WriteLine("LINQ: {0} : {1}", sum, (long) sw.ElapsedMilliseconds); } }

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  • Application Performance Episode 2: Announcing the Judges!

    - by Michaela Murray
    The story so far… We’re writing a new book for ASP.NET developers, and we want you to be a part of it! If you work with ASP.NET applications, and have top tips, hard-won lessons, or sage advice for avoiding, finding, and fixing performance problems, we want to hear from you! And if your app uses SQL Server, even better – interaction with the database is critical to application performance, so we’re looking for database top tips too. There’s a Microsoft Surface apiece for the person who comes up with the best tip for SQL Server and the best tip for .NET. Of course, if your suggestion is selected for the book, you’ll get full credit, by name, Twitter handle, GitHub repository, or whatever you like. To get involved, just email your nuggets of performance wisdom to [email protected] – there are examples of what we’re looking for and full competition details at Application Performance: The Best of the Web. Enter the judges… As mentioned in my last blogpost, we have a mystery panel of celebrity judges lined up to select the prize-winning performance pointers. We’re now ready to reveal their secret identities! Judging your ASP.NET  tips will be: Jean-Phillippe Gouigoux, MCTS/MCPD Enterprise Architect and MVP Connected System Developer. He’s a board member at French software company MGDIS, and teaches algorithms, security, software tests, and ALM at the Université de Bretagne Sud. Jean-Philippe also lectures at IT conferences and writes articles for programming magazines. His book Practical Performance Profiling is published by Simple-Talk. Nik Molnar,  a New Yorker, ASP Insider, and co-founder of Glimpse, an open source ASP.NET diagnostics and debugging tool. Originally from Florida, Nik specializes in web development, building scalable, client-centric solutions. In his spare time, Nik can be found cooking up a storm in the kitchen, hanging with his wife, speaking at conferences, and working on other open source projects. Mitchel Sellers, Microsoft C# and DotNetNuke MVP. Mitchel is an experienced software architect, business leader, public speaker, and educator. He works with companies across the globe, as CEO of IowaComputerGurus Inc. Mitchel writes technical articles for online and print publications and is the author of Professional DotNetNuke Module Programming. He frequently answers questions on StackOverflow and MSDN and is an active participant in the .NET and DotNetNuke communities. Clive Tong, Software Engineer at Red Gate. In previous roles, Clive spent a lot of time working with Common LISP and enthusing about functional languages, and he’s worked with managed languages since before his first real job (which was a long time ago). Long convinced of the productivity benefits of managed languages, Clive is very interested in getting good runtime performance to keep managed languages practical for real-world development. And our trio of SQL Server specialists, ready to select your top suggestion, are (drumroll): Rodney Landrum, a SQL Server MVP who writes regularly about Integration Services, Analysis Services, and Reporting Services. He’s authored SQL Server Tacklebox, three Reporting Services books, and contributes regularly to SQLServerCentral, SQL Server Magazine, and Simple–Talk. His day job involves overseeing a large SQL Server infrastructure in Orlando. Grant Fritchey, Product Evangelist at Red Gate and SQL Server MVP. In an IT career spanning more than 20 years, Grant has written VB, VB.NET, C#, and Java. He’s been working with SQL Server since version 6.0. Grant volunteers with the Editorial Committee at PASS and has written books for Apress and Simple-Talk. Jonathan Allen, leader and founder of the PASS SQL South West user group. He’s been working with SQL Server since 1999 and enjoys performance tuning, development, and using SQL Server for business solutions. He’s spoken at SQLBits and SQL in the City, as well as local user groups across the UK. He’s also a moderator at ask.sqlservercentral.com.

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  • Linux Disk Setup for VMs

    - by zjherner
    Been trying to find the ideal way to setup disks/partitions for Linux guests on ESXi. Seems as though Linux is falling behind when it comes easily adding disk space. The end goal is to be able to add disk space to a Linux server without rebooting the server or taking the server offline. Ideally, I would expect adding disk to a Linux machine should be as easy as adding disk space to a Windows machine. I expand the vmdk file from vSphere Open disk mangler find the disk and extend volume. Would have to use command line tools in linux which is no big deal, but I haven't been able to find a solid way to exand filesystems on the fly. What is everyone else using for disk setups on their linux guests? Has anyone been able to acheive adding storage space to linux without downtime? Can it be done without using lvm?

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  • Need data on disk drive management by OS: getting base I/O unit size, "sync" option, Direct Memory A

    - by Richard T
    Hello All, I want to ensure I have done all I can to configure a system's disks for serious database use. The three areas I know of (any others?) to be concerned about are: I/O size: the database engine and disk's native size should either match, or the database's native I/O size should be a multiple of the disk's native I/O size. Disks that are capable of Direct Memory Access (eg. IDE) should be configured for it. When a disk says it has written data persistently, it must be so! No keeping it in cache and lying about it. I have been looking for information on how to ensure these are so for CENTOS and Ubuntu, but can't seem to find anything at all! I want to be able to check these things and change them if needed. Any and all input appreciated.

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  • Need data on disk drive management by OS: getting base I/O unit size, “sync” option, Direct Memory A

    - by Richard T
    Hello All, I want to ensure I have done all I can to configure a system's disks for serious database use. The three areas I know of (any others?) to be concerned about are: I/O size: the database engine and disk's native size should either match, or the database's native I/O size should be a multiple of the disk's native I/O size. Disks that are capable of Direct Memory Access (eg. IDE) should be configured for it. When a disk says it has written data persistently, it must be so! No keeping it in cache and lying about it. I have been looking for information on how to ensure these are so for CENTOS and Ubuntu, but can't seem to find anything at all! I want to be able to check these things and change them if needed. Any and all input appreciated.

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  • Why do Scala maps have poor performance relative to Java?

    - by Mike Hanafey
    I am working on a Scala app that consumes large amounts of CPU time, so performance matters. The prototype of the system was written in Python, and performance was unacceptable. The application does a lot with inserting and manipulating data in maps. Rex Kerr's Thyme was used to look at the performance of updating and retrieving data from maps. Basically "n" random Ints were stored in maps, and retrieved from the maps, with the time relative to java.util.HashMap used as a reference. The full results for a range of "n" are here. Sample (n=100,000) performance relative to java, smaller is worse: Update Read Mutable 16.06% 76.51% Immutable 31.30% 20.68% I do not understand why the scala immutable map beats the scala mutable map in update performance. Using the sizeHint on the mutable map does not help (it appears to be ignored in the tested implementation, 2.10.3). Even more surprisingly the immutable read performance is worse than the mutable read performance, more significantly so with larger maps. The update performance of the scala mutable map is surprisingly bad, relative to both scala immutable and plain Java. What is the explanation?

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  • WPF Binding Failure performance hit vs Exception

    - by Aran Mulholland
    when we bind to heterogeneous collection of objects, not all objects have the same set of properties. in the output window we get a message like: System.Windows.Data Error: 39 : BindingExpression path error: 'RoundingFactor' property not found on 'object' ''MultiLineTextMarkingScheme' (HashCode=7262386)'. BindingExpression:Path=RoundingFactor;.......... This doesn't appear to be an exception, but we are concerned it has a performance impact. Should we be concerned and create a view model that has all the properties we wish to bind to (and have the properties that dont exist on the underlying element return null) or can we just leave it. This situation often occurs in a grid scenario where there might be large numbers of these binding failures.

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  • Android Map Performance poor because of many Overlays?

    - by Dave
    Hi, I have a map in my android application that shows many markers (~20-50). But the app performs very poor when i try to scroll/zoom (in Google Android Maps i did a sample search for pizza and there were also some 20-50 results found and i didn't notice any particular performance problems when zooming/scrolling through the map). Here is my (pseudo)code: onCreate() { .... drawable = this.getResources().getDrawable(R.drawable.marker1); itemizedOverlay = new MyItemizedOverlay(drawable,mapView); ... callWebServiceToRetrieveData(); createMarkers(); } createMarkers(){ for(elem:bigList){ GeoPoint geoPoint = new GeoPoint((int)(elem.getLat()*1000000), (int) (elem.getLon()*1000000)); OverlayItem overlayItem = new OverlayItem(geoPoint, elem.getName(), elem.getData()); itemizedOverlay.addOverlay(overlayItem); mapOverlays.add(itemizedOverlay); } mapView.invalidate(); } the MyItemizedOverlay.addOverlay looks like this: public void addOverlay(OverlayItem overlay) { m_overlays.add(overlay); populate(); }

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