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• rails using jruby 1.5 - slow!!

  - by gucki

  Hi! I'm currently using passenger with ree 1.8.7 in production for a rails 2.3.5 project using postgresql as a database. ab -n 10000 -c 100: 285.69 [#/sec] (mean) I read jruby should be the fastest solution, so I installed jruby-1.5.0.rc2 together with jdbc postgres adapter and glassfish. As the performance is really poor, I also started running my application using "jruby --server -J-Druby.jit.threshold=0 script/server -e production". Anyway, I only get ab -n 10000 -c 100: 43.88 [#/sec] (mean) Thread_safe! is activated in my rails config. Java seems to use all cores, cpu usage is around 350% (top). ruby -v: jruby 1.5.0.RC2 (ruby 1.8.7 patchlevel 249) (2010-04-28 7c245f3) (Java HotSpot(TM) 64-Bit Server VM 1.6.0_16) [amd64-java] I wonder what I'm doing wrong and how to get better performancre with jruby than with ree? Thanks, Corin

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• SQL Server: how to optimize "like" queries?

  - by duke84

  I have a query that searches for clients using "like" with wildcard. For example: SELECT TOP (10) [t0].[CLIENTNUMBER], [t0].[FIRSTNAME], [t0].[LASTNAME], [t0].[MI], [t0].[MDOCNUMBER] FROM [dbo].[CLIENT] AS [t0] WHERE (LTRIM(RTRIM([t0].[DOCREVNO])) = '0') AND ([t0].[FIRSTNAME] LIKE '%John%') AND ([t0].[LASTNAME] LIKE '%Smith%') AND ([t0].[SSN] LIKE '%123%') AND ([t0].[CLIENTNUMBER] LIKE '%123%') AND ([t0].[MDOCNUMBER] LIKE '%123%') AND ([t0].[CLIENTINDICATOR] = 'ON') It can also use less parameters in "where" clause, for example: SELECT TOP (10) [t0].[CLIENTNUMBER], [t0].[FIRSTNAME], [t0].[LASTNAME], [t0].[MI], [t0].[MDOCNUMBER] FROM [dbo].[CLIENT] AS [t0] WHERE (LTRIM(RTRIM([t0].[DOCREVNO])) = '0') AND ([t0].[FIRSTNAME] LIKE '%John%') AND ([t0].[CLIENTINDICATOR] = 'ON') Can anybody tell what is the best way to optimize performance of such query? Maybe I need to create an index? This table can have up to 1000K records in production.

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• Difference between Document-oriented-DB and Bigtable clones

  - by chen

  We are looking for a suitable storage engine for our weblog history data. We looked at Bigtable's paper and understand it is suitable to us well. However, I also understand that Document-oriented-DB such as MongoDB seems to provide a little more powerful schema power -- i.e, it can model our data as well. I wonder how nowadays ppl choose a scalable NoSQL DB --- I read enough articles like "we looked at A, B and C, and we decided to use C". But I'd like to see some benchmark number. What I am saying is that if MongoDB and the like can provide same level of performance as Bigtable clones, why don't web companies choose it (preparing to deal with various potentially more complex data problem)? Thanks, By the way, I read an article (which convinced me at the moment) saying Cassandra does not fit the M/R operation, any comments?

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• Gallery items become off-center when switching into landscape orientation.

  - by Sandile

  Hey Guys, Thanks for your time. I'm writing an application for android 2.2 and I'm using a gallery to circulate through a list of images that the user can then click to navigate other portions of the application. In portrait orientation, everything is kosher: the images are displaying correctly (completely in the center of the screen as I intended); however, in landscape orientation, all the images in the gallery are strangely displaced a fixed distance to the left of the center of the screen. I've been researching this issue for hours now and haven't found a solution. I'm hoping that some android guru can aid me in the resolution of this bizarre rendering issue. MainMenuActivity.java relevant code snippet (the activity in which the gallery resides) Gallery optionList = (Gallery)findViewById(R.id.mainMenuOptionList); GalleryItem[] optionListItemIdArray = new GalleryItem[] { new GalleryItem(R.drawable.icon_main_menu_option_list_blackboard, "Start Next Lesson", "Start the next planned vocab lesson."), new GalleryItem(R.drawable.icon_main_menu_option_list_index_cards, "Review Words", "Manually look over old words."), new GalleryItem(R.drawable.icon_main_menu_option_list_dice, "Play Vocab Games", "Play games to reinforce knowledge."), new GalleryItem(R.drawable.icon_main_menu_option_list_calendar, "View Lesson Plan", "View the schedule for coming lessons."), new GalleryItem(R.drawable.icon_main_menu_option_list_pie_chart, "View Performance Report", "Evaluate your overall performance statistics."), new GalleryItem(R.drawable.icon_main_menu_option_list_settings, "Manage Settings", "Change and modify application settings.") }; optionList.setAdapter(new GalleryImageAdapter(this, optionListItemIdArray)); NOTE: A GalleryItem is a POJO with an image resource id, title and description. GalleryImageAdapter.java: public class GalleryImageAdapter extends BaseAdapter { private Context context; private GalleryItem[] galleryItemArray; public GalleryImageAdapter(Context context, GalleryItem[] galleryItemArray) { this.context = context; this.galleryItemArray = galleryItemArray; } @Override public int getCount() { return galleryItemArray.length; } @Override public Object getItem(int position) { return position; } @Override public long getItemId(int position) { return position; } @Override public View getView(int position, View convertView, ViewGroup parent) { ImageView imageView = new ImageView(context); imageView.setImageResource(galleryItemArray[position].getImageId()); imageView.setScaleType(ImageView.ScaleType.FIT_START); imageView.setLayoutParams(new Gallery.LayoutParams(Gallery.LayoutParams.WRAP_CONTENT, Gallery.LayoutParams.WRAP_CONTENT)); return imageView; } } Portrait version of main_menu.xml <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/mainMenuLinearLayout" android:background="#3067a8" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent" > <TextView android:id="@+id/mainMenuHeadingTextView" android:layout_width="wrap_content" android:layout_height="wrap_content" android:paddingLeft="10dip" android:textColor="#ffffff" android:textSize="50sp" android:text="@string/main_menu_heading" android:shadowColor="#555555" android:shadowDx="0" android:shadowDy="0" android:shadowRadius="2" /> <TextView android:id="@+id/mainMenuSubHeadingTextView" android:layout_width="wrap_content" android:layout_height="wrap_content" android:paddingLeft="15dip" android:textColor="#ffffff" android:textSize="15sp" android:text="@string/main_menu_sub_heading" android:shadowColor="#555555" android:shadowDx="0" android:shadowDy="0" android:shadowRadius="2" /> <Gallery xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/mainMenuOptionList" android:layout_width="fill_parent" android:layout_height="wrap_content" android:paddingTop="20dip" android:paddingBottom="10dip" android:spacing="40dip" /> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/mainMenuOptionListDetailLinearLayout" android:gravity="center_vertical|center_horizontal" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent" > <TextView android:id="@+id/mainMenuOptionListLabelTextView" android:layout_width="wrap_content" android:layout_height="wrap_content" android:textColor="#ffffff" android:textSize="25sp" android:shadowColor="#555555" android:shadowDx="0" android:shadowDy="0" android:shadowRadius="2" /> <TextView android:id="@+id/mainMenuOptionListDescriptionTextView" android:layout_width="wrap_content" android:layout_height="wrap_content" android:textColor="#ffffff" android:textSize="15sp" android:shadowColor="#555555" android:shadowDx="0" android:shadowDy="0" android:shadowRadius="2" /> </LinearLayout> </LinearLayout> Landscape version of main_menu.xml <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/mainMenuLinearLayout" android:background="#3067a8" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent" > <TextView android:id="@+id/mainMenuHeadingTextView" android:layout_width="wrap_content" android:layout_height="wrap_content" android:paddingLeft="10dip" android:textColor="#ffffff" android:textSize="50sp" android:text="@string/main_menu_heading" android:shadowColor="#555555" android:shadowDx="0" android:shadowDy="0" android:shadowRadius="2" /> <TextView android:id="@+id/mainMenuSubHeadingTextView" android:layout_width="wrap_content" android:layout_height="wrap_content" android:paddingLeft="15dip" android:textColor="#ffffff" android:textSize="15sp" android:text="@string/main_menu_sub_heading" android:shadowColor="#555555" android:shadowDx="0" android:shadowDy="0" android:shadowRadius="2" /> <Gallery xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/mainMenuOptionList" android:layout_width="fill_parent" android:layout_height="128dip" android:paddingLeft="0dip" android:paddingTop="5dip" android:spacing="10dip" /> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/mainMenuOptionListDetailLinearLayout" android:gravity="center_vertical|center_horizontal" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent" > <TextView android:id="@+id/mainMenuOptionListLabelTextView" android:layout_width="wrap_content" android:layout_height="wrap_content" android:textColor="#ffffff" android:textSize="25sp" android:shadowColor="#555555" android:shadowDx="0" android:shadowDy="0" android:shadowRadius="2" /> <TextView android:id="@+id/mainMenuOptionListDescriptionTextView" android:layout_width="wrap_content" android:layout_height="wrap_content" android:textColor="#ffffff" android:textSize="15sp" android:shadowColor="#555555" android:shadowDx="0" android:shadowDy="0" android:shadowRadius="2" /> </LinearLayout> </LinearLayout> Thank you for your time!

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• Symfony app - how to add calculated fields to Propel objects?

  - by Thomas Kohl

  What is the best way of working with calculated fields of Propel objects? Say I have an object "Customer" that has a corresponding table "customers" and each column corresponds to an attribute of my object. What I would like to do is: add a calculated attribute "Number of completed orders" to my object when using it on View A but not on Views B and C. The calculated attribute is a COUNT() of "Order" objects linked to my "Customer" object via ID. What I can do now is to first select all Customer objects, then iteratively count Orders for all of them, but I'd think doing it in a single query would improve performance. But I cannot properly "hydrate" my Propel object since it does not contain the definition of the calculated field(s). How would you approach it?

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• How to populate List<string> with Datarow values from single columns...

  - by James

  Hi, I'm still learning (baby steps). Messing about with a function and hoping to find a tidier way to deal with my datatables. For the more commonly used tables throughout the life of the program, I'll dump them to datatables and query those instead. What I'm hoping to do is query the datatables for say column x = "this", and convert the values of column "y" directly to a List to return to the caller: private List<string> LookupColumnY(string hex) { List<string> stringlist = new List<string>(); DataRow[] rows = tblDataTable.Select("Columnx = '" + hex + "'", "Columny ASC"); foreach (DataRow row in rows) { stringlist.Add(row["Columny"].ToString()); } return stringlist; } Anyone know a slightly simpler method? I guess this is easy enough, but I'm wondering if I do enough of these if iterating via foreach loop won't be a performance hit. TIA!

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• SqlServer / MySql Connection pool: is it really important ?

  - by stighy

  Hy guys, after a lot of problem with my hoster, i decided to disable connection pooling of my application. The problem was related to the number of concurrent connections : only five. So i decided to disable connection pooling: the result is that my web app don't crash. So i'm asking you: are there some "collateral" effect disabling connection pooling ? Is it so important ? I didn't noticed bad performance after disabling it. Thank you for your (i'm sure) precious advice!

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• Subclassing UIScrollView for drawing w/o views

  - by David Dunham

  I'm contemplating subclassing UIScrollView (the way UITextView does) to draw a fairly large amount of text (formatted in ways that NSTextView can't). So far the view won't actually scroll. I'm setting contentSize, and when I drag, I see the scroll indicator. But nothing changes (and I don't get a drawRect: message). An alternate approach is to use a child view, and I've done this. The view can be over 5000 pixels high, however, and I'm a bit concerned about performance on an actual device. (The other approach, be like UITableView, would be a huge pain -- I'm "porting" Mac Cocoa code, and a collection of views would be a huge architecture change.) I've done some searching, but haven't found anyone who is using UIScrollView to do the drawing. Has anyone done this and know of any pitfalls?

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• Sinatra Gem install error

  - by lakshmanan

  I have been trying to install sinatra in a macbook running leopard system, and I am not able to do it. I get the following error. MacBook:rubygems-1.3.7 lakshmanan$ gem install sinatra WARNING: RubyGems 1.2+ index not found for: http://rubygems.org/ RubyGems will revert to legacy indexes degrading performance. Bulk updating Gem source index for: http://rubygems.org/ ERROR: While executing gem ... (NoMethodError) undefined method `gems' for #<Array:0x101901008> Please help. I reinstalled gems also. Still I get the same error.

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• Reasons why one should not call the garbage collector directly.

  - by Shimrod

  Hi everyone, I'm currently writing a paper for my company, about how to avoid calling the garbage collector directly from the code (when playing with COM objects for instance). I know this is a bad practice, and should be only considered in very rare cases, but I can't seem to find a way to tell why it should be avoided. And I don't want to rely on the "The G.C. is smarter than you" principle (even if it is the truth :-) ) So can you tell me some clues about why you think one should avoid to call the garbage collector directly ? (performance impact?) Or maybe if you have links about this particular topic, they would be very helpful. Thanks in advance !

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• Situations to prefer Apache Lucene over Solr?

  - by Karussell

  There are several advantages to use Solr (out-of-the-box facetting search, grouping, replication, http administration vs. luke, ...). Even if I embed a search-functionality in my Java application I could use SolrJ to avoid the HTTP trade-off when using Solr. So, when would you recommend to use "pure-Lucene"? Does it have a better performance or requires less RAM? Is it better unit-testable? PS: I am aware of this question.

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• problems mounting an external IDE drive via USB in ubuntu

  - by Roy Rico

  I am having a problem connecting a specific IDE drive to my linux box. It's an old drive which I just want to get about 3 GB of files off of. INFO I am trying to connect a 200GB IDE Maxtor Drive, internally and externally... externally: I am using an self powered USB IDE external drive enclosure which I have used to connect various drives, under ubuntu and windows, in the past. The other posts stated it coudl be a problem I think i may have formatted the /dev/sdc partition instead of /dev/sdc1 partition when i originally formatted the drive. internally: I only have one machine left that has an internal IDE interface, and it's got XP on it. I plugged this drive internally into this machine with windows XP and used the ext2/ext3 drivers to mount this drive, but some files have question marks (?) in the file names which is messing up my copy process in windows. I can't delete the files under windows. Ubuntu Linux will not install on my only remaining machine that has IDE controller. I have tried the suggestions in the questions below http://superuser.com/questions/88182/mount-an-external-drive-in-ubuntu http://superuser.com/questions/23210/ubuntu-fails-to-mount-usb-drive it looks like i can see the drive in /proc/partitions $ cat /proc/partitions major minor #blocks name 8 0 78125000 sda 8 1 74894998 sda1 8 2 1 sda2 8 5 3229033 sda5 8 16 199148544 sdb <-- could be my drive? but it's not listed under fdisk -l $ fdisk -l Disk /dev/sda: 80.0 GB, 80000000000 bytes 255 heads, 63 sectors/track, 9726 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Disk identifier: 0xd0f4738c Device Boot Start End Blocks Id System /dev/sda1 * 1 9324 74894998+ 83 Linux /dev/sda2 9325 9726 3229065 5 Extended /dev/sda5 9325 9726 3229033+ 82 Linux swap / Solaris and here is my log of /var/log/messages. with a bunch of weird output, can someone let me know what that weird output is? Mar 3 19:49:40 mala kernel: [687455.112029] usb 1-7: new high speed USB device using ehci_hcd and address 3 Mar 3 19:49:41 mala kernel: [687455.248576] usb 1-7: configuration #1 chosen from 1 choice Mar 3 19:49:41 mala kernel: [687455.267450] Initializing USB Mass Storage driver... Mar 3 19:49:41 mala kernel: [687455.269180] scsi4 : SCSI emulation for USB Mass Storage devices Mar 3 19:49:41 mala kernel: [687455.269410] usbcore: registered new interface driver usb-storage Mar 3 19:49:41 mala kernel: [687455.269416] USB Mass Storage support registered. Mar 3 19:49:46 mala kernel: [687460.270917] scsi 4:0:0:0: Direct-Access Maxtor 6 Y200P0 YAR4 PQ: 0 ANSI: 2 Mar 3 19:49:46 mala kernel: [687460.271485] sd 4:0:0:0: Attached scsi generic sg2 type 0 Mar 3 19:49:46 mala kernel: [687460.278858] sd 4:0:0:0: [sdb] 398297088 512-byte logical blocks: (203 GB/189 GiB) Mar 3 19:49:46 mala kernel: [687460.280866] sd 4:0:0:0: [sdb] Write Protect is off Mar 3 19:50:16 mala kernel: [687460.283784] sdb: Mar 3 19:50:16 mala kernel: [687491.112020] usb 1-7: reset high speed USB device using ehci_hcd and address 3 Mar 3 19:50:47 mala kernel: [687522.120030] usb 1-7: reset high speed USB device using ehci_hcd and address 3 Mar 3 19:51:18 mala kernel: [687553.112034] usb 1-7: reset high speed USB device using ehci_hcd and address 3 Mar 3 19:51:49 mala kernel: [687584.116025] usb 1-7: reset high speed USB device using ehci_hcd and address 3 Mar 3 19:52:02 mala kernel: [687596.170632] type=1505 audit(1267671122.035:31): operation="profile_replace" pid=8426 name=/usr/lib/cups/backend/cups-pdf Mar 3 19:52:02 mala kernel: [687596.171551] type=1505 audit(1267671122.035:32): operation="profile_replace" pid=8426 name=/usr/sbin/cupsd Mar 3 19:52:06 mala kernel: [687600.908056] async/0 D c08145c0 0 7655 2 0x00000000 Mar 3 19:52:06 mala kernel: [687600.908062] e5601d38 00000046 e5774000 c08145c0 e4c2a848 c08145c0 d203973a 0002713d Mar 3 19:52:06 mala kernel: [687600.908072] c08145c0 c08145c0 e4c2a848 c08145c0 00000000 0002713d c08145c0 f0a98c00 Mar 3 19:52:06 mala kernel: [687600.908079] e4c2a5b0 c20125c0 00000002 e5601d80 e5601d44 c056f3be e5601d78 e5601d4c Mar 3 19:52:06 mala kernel: [687600.908087] Call Trace: Mar 3 19:52:06 mala kernel: [687600.908099] [<c056f3be>] io_schedule+0x1e/0x30 Mar 3 19:52:06 mala kernel: [687600.908107] [<c01b2cf5>] sync_page+0x35/0x40 Mar 3 19:52:06 mala kernel: [687600.908111] [<c056f8f7>] __wait_on_bit_lock+0x47/0x90 Mar 3 19:52:06 mala kernel: [687600.908115] [<c01b2cc0>] ? sync_page+0x0/0x40 Mar 3 19:52:06 mala kernel: [687600.908121] [<c020f390>] ? blkdev_readpage+0x0/0x20 Mar 3 19:52:06 mala kernel: [687600.908125] [<c01b2ca9>] __lock_page+0x79/0x80 Mar 3 19:52:06 mala kernel: [687600.908130] [<c015c130>] ? wake_bit_function+0x0/0x50 Mar 3 19:52:06 mala kernel: [687600.908135] [<c01b459f>] read_cache_page_async+0xbf/0xd0 Mar 3 19:52:06 mala kernel: [687600.908139] [<c01b45c2>] read_cache_page+0x12/0x60 Mar 3 19:52:06 mala kernel: [687600.908144] [<c0232dca>] read_dev_sector+0x3a/0x80 Mar 3 19:52:06 mala kernel: [687600.908148] [<c0233d3e>] adfspart_check_ICS+0x1e/0x160 Mar 3 19:52:06 mala kernel: [687600.908152] [<c023339f>] ? disk_name+0xaf/0xc0 Mar 3 19:52:06 mala kernel: [687600.908157] [<c0233d20>] ? adfspart_check_ICS+0x0/0x160 Mar 3 19:52:06 mala kernel: [687600.908161] [<c02334de>] check_partition+0x10e/0x180 Mar 3 19:52:06 mala kernel: [687600.908165] [<c02335f6>] rescan_partitions+0xa6/0x330 Mar 3 19:52:06 mala kernel: [687600.908171] [<c0312472>] ? kobject_get+0x12/0x20 Mar 3 19:52:06 mala kernel: [687600.908175] [<c0312472>] ? kobject_get+0x12/0x20 Mar 3 19:52:06 mala kernel: [687600.908180] [<c039fc43>] ? get_device+0x13/0x20 Mar 3 19:52:06 mala kernel: [687600.908185] [<c03c263f>] ? sd_open+0x5f/0x1b0 Mar 3 19:52:06 mala kernel: [687600.908189] [<c020fda0>] __blkdev_get+0x140/0x310 Mar 3 19:52:06 mala kernel: [687600.908194] [<c020f0ac>] ? bdget+0xec/0x100 Mar 3 19:52:06 mala kernel: [687600.908198] [<c020ff7a>] blkdev_get+0xa/0x10 Mar 3 19:52:06 mala kernel: [687600.908202] [<c0232f30>] register_disk+0x120/0x140 Mar 3 19:52:06 mala kernel: [687600.908207] [<c0308b4d>] ? blk_register_region+0x2d/0x40 Mar 3 19:52:06 mala kernel: [687600.908211] [<c03084f0>] ? exact_match+0x0/0x10 Mar 3 19:52:06 mala kernel: [687600.908216] [<c0308cf0>] add_disk+0x80/0x140 Mar 3 19:52:06 mala kernel: [687600.908221] [<c03084f0>] ? exact_match+0x0/0x10 Mar 3 19:52:06 mala kernel: [687600.908225] [<c0308860>] ? exact_lock+0x0/0x20 Mar 3 19:52:06 mala kernel: [687600.908230] [<c03c53df>] sd_probe_async+0xff/0x1c0

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• Interspire to Magento migration

  - by patrikas

  Hello, I recently started with Magento and decided to migrate Interspire shopping cart I already made time ago to it. At first look Magento seems a very huge beast - lots of options, maybe lack of simplicity resulting in some performance loss. I've got user guide from which I am not getting much of benefit since there're just descriptions of very ordinary tasks that I could easily discover myself by poking around frontend/backend. So my first tasks are category and product export. Interspire seems to be exporting ONLY products in three available formats: Default MYOB Peachtree accounting I did some searching on Magento's product importing and found a blog post which says that I should create a few sample products with all the necessary attributes myself and then start the import. But what should I do with categories ? Is it possible to import them or instruct Magento to automatically create categories when importing product file if unknown category is encountered ? Thanks

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• Invoke ngen from NSIS installer

  - by BlackStar

  I am using NSIS to deploy a .Net application. The installation/uninstallation process works fine, but I would like to add a final ngen step to improve startup performance. Unfortunately, Google didn't reveal any relevant material. It's unlikely that noone has ever done this before - maybe someone here has some idea? In the unlikely case that this is impossible to support without ugly hacks, I would be willing to use a different installer technology provided it can run on my Linux build server. (This rules out WiX, for example.) Any ideas?

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• Separate Database for Integration Testing

  - by john doe

  I am performance integration testing where I fire up the ASPX pages using WatiN and fill the fields and insert into the database. There are couple of problems that I am facing. 1) Should I use a completely separate database for integration testing? I already gave db_test and db_dev. db_test is for unit testing and is cleared after each test. db_dev is for developers. 2) When I run WatiN test which are contained in a separate assembly (not separate from unit test assembly which should be better since WatiN test take so much time to run). So WatiN test fire up the WebApps project and uses their web.config which is pointing to the dev database. Is there anyway I can tell WatiN to use a separate web.config which contains a different database name?

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• OpenCL: does it play well with OpenMP, can I connect other languages to it, etc.

  - by Cem Karan

  The 1.0 spec for OpenCL just came out a few days ago (Spec is here) and I've just started to read through it. I want to know if it plays well with other high performance multiprocessing APIs like OpenMP (spec) and I want to know what I should learn. So, here are my basic questions: If I am already using OpenMP, will that break OpenCL or vice-versa? Is OpenCL more powerful than OpenMP? Or are they intended to be complementary? Is there a standard way of connecting an OpenCL program to a standard C99 program (or any other language)? What is it? Does anyone know if anyone is writing an OpenCL book? I'm reading the spec, but I've found books to be more helpful.

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• Limited IList<> implementation ?

  - by Wam

  Hello people, I'm doing some work with stats, and want to refactor the following method : public static blah(float[] array) { //Do something over array, sum it for example. } However, instead of using float[] I'd like to be using some kind of indexed enumerable (to use dynamic loading from disk for very large arrays for example). I had created a simple interface, and wanted to use it. public interface IArray<T> : IEnumerable<T> { T this[int j] { get; set; } int Length { get; } } My problem is : float[] only inherits IList, not IArray, and AFAIK there's no way to change that. I'd like to ditch IArray and only use IList, but my classes would need to implement many methods like Add, RemoveAt although they are fixed size And then my question : how can float[] implement IList whereas it doesn't have these methods ? Any help is welcome. Cheers

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• Running Awk command on a cluster

  - by alex

  How do you execute a Unix shell command (awk script, a pipe etc) on a cluster in parallel (step 1) and collect the results back to a central node (step 2) Hadoop seems to be a huge overkill with its 600k LOC and its performance is terrible (takes minutes just to initialize the job) i don't need shared memory, or - something like MPI/openMP as i dont need to synchronize or share anything, don't need a distributed VM or anything as complex Google's SawZall seems to work only with Google proprietary MapReduce API some distributed shell packages i found failed to compile, but there must be a simple way to run a data-centric batch job on a cluster, something as close as possible to native OS, may be using unix RPC calls i liked rsync simplicity but it seem to update remote notes sequentially, and you cant use it for executing scripts as afar as i know switching to Plan 9 or some other network oriented OS looks like another overkill i'm looking for a simple, distributed way to run awk scripts or similar - as close as possible to data with a minimal initialization overhead, in a nothing-shared, nothing-synchronized fashion Thanks Alex

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• opengl invert framebuffer pixels

  - by ToxIk

  I was wondering was the best way to invert the color pixels in the frame buffer is. I know it's possible to do with glReadPixels() and glDrawPixels() but the performance hit of those calls is pretty big. Basically, what I'm trying to do is have an inverted color cross-hair which is always visible no matter what's behind it. For instance, I'd have an arbitrary alpha mask bitmap or texture, have it render without depth test after the scene is drawn, and all the frame buffer pixels under the masked (full alpha) pixels of the texture would be inverted. I've been trying to do this with a texture, but I'm getting some strange results, also all the blending options I still find confusing.

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• How to simulate different CPU frequency and limit RAM

  - by user351103

  Hi I have to build a simulator with C#. This simulator should be able to run a second thread with configureable CPU speed and limited RAM size, e.g. 144MHz and 50 MB. Of course I know that a simulator can never be as accurate as the real hardware. But I try to get almost similar performance. At the moment I'm thinking about creating a thread which I will stop/sleep from time to time. Depending on the desired CPU speed the simulator should adjust the sleep time of this thread and therefore simulate different cpu frequency. To measure the achieved speed I though about using PerformanceCounters. But with this approach I have the problem that I don't know how to limit the RAM size the thread could use. Do you have any ideas how to realize such a simulator? Thanks in advance!!

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• Polling duplex does not scale... what's the alternative?

  - by user80855

  Our tests showed that the polling duplex binding simply does not scale and can not be used on a service within a web-farm or even a web garden. We have looked at TCP/IP sockets for a client push method, but the firewall issue is does allow us to use sockets. I was wondering what is the alternative "free" solution to this problem? allowing us to scale and allowing us to push data to client... I have also tried the solution in this article http://tomasz.janczuk.org/2009/09/scale-out-of-silverlight-http-polling.html but at the end, there was too much polling on a database, and performance was affected. Our Silverlight application need a pub/sub design, but it needs to be reliable and scalable... any ideas?

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• get the expanding node in a treeview

  - by Iulian

  I have a treeview control that functions like a folder browser. Because loading the entire folder structer from disk is taking a lot of time i'm trying to load only one level at a time. So i have a function that adds nodes for all the folders in the current node. I thought that the best method would be to run it on the BeforeExpand event of the treeview. UpdateTreeView(TreeView.SelectedNode); is not working because clicking the + sign to expand is not selecting the node also. So how to find the node that is expanding.

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• How to use sessions with django piston auth?

  - by xyld

  The problem is that I want to store authentication in a cookie that I can present to django piston rather than requiring user/password to be typed in each time (without hardcoding or storing the user/pass combo somewhere on disk). I was hoping to accomplish this with cookies like someone would without the piston API. Am I missing something? Django Piston doesn't seem to care about session cookies at all? Or can someone suggest a good alternative? Maybe I shouldn't use Piston?

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• Java - copy Jar Folder

  - by Ripei

  Hey Java - Developers Actually I am confronted with a Problem. I've got a ".apk-File" in one Package of my Application. apk is a kind of a jar File (apk = Android Package). I now want to copy this jar-file out of my Programm onto any other Location at the PC. Normally I would do this by using: FileInputStream is = new FileInputStream(this.getClass().getResource("/resources/myApp.apk").getFile()); And then write it on the disk with using a FileOutputStream. ... but since an .apk is a kind of a .jar it doesn't work. It just copies the .apk file. but without the containing other files. any help would be appreciated

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• Preserve images in Excel headers using Apache POI

  - by ddm

  I am trying to generate Excel reports using Apache POI 3.6 (latest). Since POI has limited support for header and footer generation (text only), I decided to start from a blank excel file with the header already prepared and fill the Excel cells using POI (cf. question 714172). Unfortunately, when opening the workbook with POI and writing it immediately to disk (without any cell manpulation), the header seems to be lost. Here is the code I used to test this behavior: public final class ExcelWorkbookCreator { public static void main(String[] args) { FileOutputStream outputStream = null; try { outputStream = new FileOutputStream(new File("dump.xls")); InputStream inputStream = ExcelWorkbookCreator.class.getResourceAsStream("report_template.xls"); HSSFWorkbook workbook = new HSSFWorkbook(inputStream, true); workbook.write(outputStream); } catch (Exception exception) { throw new RuntimeException(exception); } finally { if (outputStream != null) { try { outputStream.close(); } catch (IOException exception) { // Nothing much to do } } } } }

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