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  • In C# how can I serialize a List<int> to a byte[] in order to store it in a DB field?

    - by Matt
    In C# how can I serialize a List to a byte[] in order to store it in a DB field? I know how to serialize to a file on the disk, but how do I just serialize to a variable? Here is how I serialized to the disk: List<int> l = IenumerableofInts.ToList(); Stream s = File.OpenWrite("file.bin"); BinaryFormatter bf = new BinaryFormatter(); bf.Serialize(s, lR); s.Close(); I'm sure it's much the same but I just can't wrap my head around it.

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  • What is the optimal number of threads for performing IO operations in java?

    - by marc
    In Goetz's "Java Concurrency in Practice", in a footnote on page 101, he writes "For computational problems like this that do not I/O and access no shared data, Ncpu or Ncpu+1 threads yield optimal throughput; more threads do not help, and may in fact degrade performance..." My question is, when performing I/O operations such as file writing, file reading, file deleting, etc, are there guidelines for the number of threads to use to achieve maximum performance? I understand this will be just a guide number, since disk speeds and a host of other factors play into this. Still, I'm wondering: can 20 threads write 1000 separate files to disk faster than 4 threads can on a 4-cpu machine?

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  • Click-Once deployment is leaving multiple versions (yes, more than 2)

    - by Clyde
    I've got a click once application that is leaving all old versions on my disk. It's an internal corporate application that gets frequent updates, so this is a disaster for rapidly inflating our backup size. According to the docs and other SO questions, it is supposed to only leave the current and previous versions on disk. However, each time I deploy the project and upgrade a client, I get another copy of all exe/dll/data files. I'm making no changes whatsoever to the application, just pushing deploy again in Visual Studio. Any ideas? Updates: The problem seems to happen on both Windows 7 and XP. 64 bit windows and 32. I've done a diff of the folders where the version is installed and the following files are different: MyApp.exe.manifest MyApp.exe.cdf-ms MyDll1.cdf-ms MyDll2.cdf-ms No actual executable files are different, nor the MyApp.manifest, MyDll1.manifest, etc.

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  • Fully automated MS SQL Restore

    - by hasen j
    I'm not very fluent with MS-SQL commands. I need a script to restore a database from a .bak file and move the logical_data and logical_log files to a specific path. I can do: restore filelistonly from disk='D:\backups\my_backup.bak' This will give me a result set with a column LogicalName, next I need to use the logical names from the result set in the restore command: restore database my_db_name from disk='d:\backups\my_backups.bak' with file=1, move 'logical_data_file' to 'd:\data\mydb.mdf', move 'logical_log_file' to 'd:\data\mylog.ldf' How do I capture the logical names from the first result set into variables that can be supplied to the "move" command? I think the solution might be trivial, but I'm pretty new to mssql.

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  • NoSQL replacement for memcache

    - by Juan Antonio Gomez Moriano
    We are having a situation in which the values we store on memcache are bigger than 1MB. It is not possible to make such values smaller, and even if there was a way, we need to persist them to disk. One solution would be to recompile the memcache server to allow say 2MB values, but this is either not clean nor a complete solution (again, we need to persist the values). Good news is that We can predict quite acurately how many key/values pair we are going to have We can also predict the total size we will need. A key feature for us is the speed of memcache. So question is: is there any noSQL replacement for memcache which will allow us to have values longer than 1MB AND store them in disk without loss of speed? In the past I have used tokyotyrant/cabinet but seems to be deprecated now. Any idea?

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  • GetDiskFreeSpaceEx in winCE 5.0 emulator?

    - by vidhyarthi
    Hi, I am trying to use GetDiskFreeSpaceEx in wince5.0 emulator. This is the following code I have written. ULARGE_INTEGER notused, totalBytes, freeBytes; GetDiskFreeSpaceEx(_T("\\Windows"),&notused,&totalBytes,&freeBytes); printf(" Error in disk %d ", GetLastError()); printf(" values = notused %d,totalBytes %d,freeBytes %d",notused,totalBytes,freeBytes); *Output * 14540 PID:3db620e TID:3e5c83e Error in disk 0 14540 PID:3db620e TID:3e5c83e values = notused 25987296,totalBytes 0,freeBytes 26234880 The total bytes that I get is zero. Am I missing something or in emulator is that OK?

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  • What is the cost of memory access?

    - by Jurily
    We like to think that a memory access is fast and constant, but on modern architectures/OSes, that's not necessarily true. Consider the following C code: int i = 34; int *p = &i; // do something that may or may not involve i and p {...} // 3 days later: *p = 643; What is the estimated cost of this last assignment in CPU instructions, if i is in L1 cache, i is in L2 cache, i is in L3 cache, i is in RAM proper, i is paged out to an SSD disk, i is paged out to a traditional disk? Where else can i be? Of course the numbers are not absolute, but I'm only interested in orders of magnitude. I tried searching the webs, but Google did not bless me this time.

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  • .resx file data inaccessible in Visual C#

    - by dsp_099
    What I'm trying to do: include some files along with the executable to extract them later. I have two projects, both with a Resource1.resx file (and some resources included from disk). In one project, I can use File.WriteAllBytes(path, Resource1.Image); to dump the resource to disk. In another, Resource1 is does not exist. I've done this before but all I can find is information about localizations (?) when I search MSDN for how to work with Resources.

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  • Shared data in an ASP.NET application

    - by Barguast
    I have a basic ASP.NET application which is used to request data which is stored on disk. This is loaded from files and sent as the response. I want to be able to store the data loaded from these files in memory to reduce the number of reads from disk. All of the requests will be asking for the same data, so it makes sense to have a single cache of in-memory data which is accessible to all requests. What is the best way to create a single accessible object instance which I can use to store and access this cached data? I've looked into HttpApplication, but apparently a new instance of this is created for parallel requests and so it doesn't fit my needs.

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  • Why does C++ linking use virtually no CPU? (updated)

    - by John
    On a native C++ project, linking right now can take a minute or two, yet during this time CPU drops from 100% during compilation to virtually zero. Does this mean linking is primarily a disk activity? If so, is this the main area an SSD would make big changes? But, why aren't all my OBJ files (or as many as possible) kept in RAM after compilation to avoid this? With 4Gb of RAM I should be able to save a lot of disk access and make it CPU-bound again, no? update: so the obvious follow-up is, can VC++ compiler and linker talk together better to streamline things and keep OBJ files in memory, similar to how Delphi does?

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  • Performance of Serialized Objects in C++

    - by jm1234567890
    Hi Everyone, I'm wondering if there is a fast way to dump an STL set to disk and then read it back later. The internal structure of a set is a binary tree, so if I serialize it naively, when I read it back the program will have to go though the process of inserting each element again. I think this is slow even if it is read back in correct order, correct me if I am wrong. Is there a way to "dump" the memory containing the set into disk and then read it back later? That is, keep everything in binary format, thus avoiding the re-insertion. Do the boost serialization tools do this? Thanks! EDIT: oh I should probably read, http://www.parashift.com/c++-faq-lite/serialization.html I will read it now... no it doesn't really help

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  • USB device Set Attribute in C#

    - by p19lord
    I have this bit of code: DriveInfo[] myDrives = DriveInfo.GetDrives(); foreach (DriveInfo myDrive in myDrives) { if (myDrive.DriveType == DriveType.Removable) { string path = Convert.ToString(myDrive.RootDirectory); DirectoryInfo mydir = new DirectoryInfo(path); String[] dirs = new string[] {Convert.ToString(mydir.GetDirectories())}; String[] files = new string[] {Convert.ToString(mydir.GetFiles())}; foreach (var file in files) { File.SetAttributes(file, ~FileAttributes.Hidden); File.SetAttributes(file, ~FileAttributes.ReadOnly); } foreach (var dir in dirs) { File.SetAttributes(dir, ~FileAttributes.Hidden); File.SetAttributes(dir, ~FileAttributes.ReadOnly); } } } I have a problem. It is trying the code for Floppy Disk drive first which and because no Floppy disk in it, it threw the error The device is not ready. How can I prevent that?

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  • MySQL TEXT field performance

    - by Jonathon
    I have several TEXT and/or MEDIUMTEXT fields in each of our 1000 MySQL tables. I now know that TEXT fields are written to disk rather than in memory when queried. Is that also true even if that field is not called in the query? For example, if I have a table (tbExam) with 2 fields (id int(11) and comment text) and I run SELECT id FROM tbExam, does MySQL still have to write that to disk before returning results or will it run that query in memory? I am trying to figure out if I need to reconfigure our actual db tables to switch to varchar(xxxx) or keep the text fields and reconfigure the queries.

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  • SqlCE Flush Interval - Will the default setting lead to corruption?

    - by NormD
    SqlCE has a parameter set on the Connect String called Flush Interval. It is defined as: The interval time (in seconds) before all committed transactions are flushed to disk. If not specified, the default value is 10. I thought that a committed transaction, by definition, is a transaction that has been flushed to disk, specifically the database file. If a transaction is only stored in RAM then cannot the transaction be easily lost? I thought that transactions were first written to a log file and then applied to the database file itself, so perhaps this parameter could mean the time to wait until the transaction log is applied to the database file? I would have thought that this parameter should be 0.

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  • How to actually defragment a JFFS2 filesystem

    - by Julie in Austin
    I have searched all over the Internet, including on a number of StackExchange forums, for a workable method for defragmenting a JFFS2 filesystem and cannot find an answer. The system in question has a 256MB NAND flash part. It is being accessed as a MTD device which is divided into three partitions. The third partition is where the root file system is being stored as a JFFS2 file system. The issue is that writes to the root file system have non-deterministic performance due to the usual issues of the JFFS2 garbage collector deciding to run at the worst possible times. When that happens, the product is hung for some unknown length of time while the garbage collector (and pdflush) run. Changing the file system isn't an option. The solution needs to be something that can run during off-hours that after having been run results in more predictable write performance. Right now I am working on a program that will attempt to force the garbage collector to run, then delete the file with the hope that all of the freed nodes are suddenly more readily available and make writes perform better. Thoughts?

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  • Windows 7 .NET 3.5.1 - 2.0 Slightly Corrupted, How to Repair?

    - by Quinxy von Besiex
    My Windows 7 included .NET installation (3.5 to 2.0) appears very slightly and particularly corrupted and I am trying to fix it without reinstalling Windows or trying to revert to backups. Everything was working and then my hard drive started corrupting a few files and checkdisk found bad clusters so I imaged the drive to a new one. As soon as I booted on the new drive everything worked except programs which call the System.Net.NetworkInformation methods within .NET 3.5 to 2.0 (like Ping() and IsNetworkAvailable()), which immediately crash the app in which the calls are (those calls in .NET 4.0 works fine). Those methods are found inside System.dll, and I assume call native methods which I believe are inside winnsi.dll or iphlpapi.dll or something else (I've not found this yet); I assume it calls native methods because the exception which causes the crash is Fatal Execution Engine Error which people mention is usually related to calling native methods and marshaling data between them. A huge clue about the culprit is likely found in the fact that when I launch the exact same crashing application through a code profiler (which executes the exe and captures stats on which methods took the longest) the app works fine, no crash at all! How could running it within the profiler work and running it outside not work? That seems the key to the mystery. I've used procmon to catch all the registry, filesystem, and network events from the crashing execution and the profiler-run successful execution and compared the two outputs but didn't learn much (I see the moment at which the non-profiled app crashes, but up until then they behave the same, loaded the same modules, ). The only big difference seems to be that at the moment before the app crash the profiler-executed code creates 4-6 new threads and the directly executed code only creates 1-2. I have diffed the files/directories which seemed most relevant (the .NET stuff under Windows and Program Files) pre- and post- disk trouble and seen no changes where I didn't expect any (no obvious file corruption). I have diffed the software and system registry hives pre- and post- disk trouble and seen no changes which seemed relevant. I have created a new user account and cleaned up any environment variables in case environment was related. No change. I did "sfc /scannow" and it found no integrity problems. I tried "ngen update" to regenerate pre-compiled code in case I missed something that might be damaged and nothing changed. I assume I need to repair my .NET installation but because Windows 7 included .NET 3.5 - 2.0 you can't just re-run a .NET installer to redo it. I do not have access to the Windows disks to try to re-install Windows over itself (the computer has a recovery partition but it is unusable); also the drive uses a whole-disk encryption solution and re-installing would be difficult. I absolutely do not want to start from scratch here and install a fresh Windows, reinstall dozens of software packages, try and remember dozens of development-related customizations/etc. Given all that... does anyone have any helpful advice? I need .NET 3.5 - 2.0 working as I am a developer and need to build and test against it. Thanks! Quinxy

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  • KVM guest io is much slower than host io: is that normal?

    - by Evolver
    I have a Qemu-KVM host system setup on CentOS 6.3. Four 1TB SATA HDDs working in Software RAID10. Guest CentOS 6.3 is installed on separate LVM. People say that they see guest performance almost equal to host performance, but I don't see that. My i/o tests are showing 30-70% slower performance on guest than on host system. I tried to change scheduler (set elevator=deadline on host and elevator=noop on guest), set blkio.weight to 1000 in cgroup, change io to virtio... But none of these changes gave me any significant results. This is a guest .xml config part: <disk type='file' device='disk'> <driver name='qemu' type='raw'/> <source file='/dev/vgkvmnode/lv2'/> <target dev='vda' bus='virtio'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/> </disk> There are my tests: Host system: iozone test # iozone -a -i0 -i1 -i2 -s8G -r64k random random KB reclen write rewrite read reread read write 8388608 64 189930 197436 266786 267254 28644 66642 dd read test: one process and then four simultaneous processes # dd if=/dev/vgkvmnode/lv2 of=/dev/null bs=1M count=1024 iflag=direct 1073741824 bytes (1.1 GB) copied, 4.23044 s, 254 MB/s # dd if=/dev/vgkvmnode/lv2 of=/dev/null bs=1M count=1024 iflag=direct skip=1024 & dd if=/dev/vgkvmnode/lv2 of=/dev/null bs=1M count=1024 iflag=direct skip=2048 & dd if=/dev/vgkvmnode/lv2 of=/dev/null bs=1M count=1024 iflag=direct skip=3072 & dd if=/dev/vgkvmnode/lv2 of=/dev/null bs=1M count=1024 iflag=direct skip=4096 1073741824 bytes (1.1 GB) copied, 14.4528 s, 74.3 MB/s 1073741824 bytes (1.1 GB) copied, 14.562 s, 73.7 MB/s 1073741824 bytes (1.1 GB) copied, 14.6341 s, 73.4 MB/s 1073741824 bytes (1.1 GB) copied, 14.7006 s, 73.0 MB/s dd write test: one process and then four simultaneous processes # dd if=/dev/zero of=test bs=1M count=1024 oflag=direct 1073741824 bytes (1.1 GB) copied, 6.2039 s, 173 MB/s # dd if=/dev/zero of=test bs=1M count=1024 oflag=direct & dd if=/dev/zero of=test2 bs=1M count=1024 oflag=direct & dd if=/dev/zero of=test3 bs=1M count=1024 oflag=direct & dd if=/dev/zero of=test4 bs=1M count=1024 oflag=direct 1073741824 bytes (1.1 GB) copied, 32.7173 s, 32.8 MB/s 1073741824 bytes (1.1 GB) copied, 32.8868 s, 32.6 MB/s 1073741824 bytes (1.1 GB) copied, 32.9097 s, 32.6 MB/s 1073741824 bytes (1.1 GB) copied, 32.9688 s, 32.6 MB/s Guest system: iozone test # iozone -a -i0 -i1 -i2 -s512M -r64k random random KB reclen write rewrite read reread read write 524288 64 93374 154596 141193 149865 21394 46264 dd read test: one process and then four simultaneous processes # dd if=/dev/mapper/VolGroup-lv_home of=/dev/null bs=1M count=1024 iflag=direct skip=1024 1073741824 bytes (1.1 GB) copied, 5.04356 s, 213 MB/s # dd if=/dev/mapper/VolGroup-lv_home of=/dev/null bs=1M count=1024 iflag=direct skip=1024 & dd if=/dev/mapper/VolGroup-lv_home of=/dev/null bs=1M count=1024 iflag=direct skip=2048 & dd if=/dev/mapper/VolGroup-lv_home of=/dev/null bs=1M count=1024 iflag=direct skip=3072 & dd if=/dev/mapper/VolGroup-lv_home of=/dev/null bs=1M count=1024 iflag=direct skip=4096 1073741824 bytes (1.1 GB) copied, 24.7348 s, 43.4 MB/s 1073741824 bytes (1.1 GB) copied, 24.7378 s, 43.4 MB/s 1073741824 bytes (1.1 GB) copied, 24.7408 s, 43.4 MB/s 1073741824 bytes (1.1 GB) copied, 24.744 s, 43.4 MB/s dd write test: one process and then four simultaneous processes # dd if=/dev/zero of=test bs=1M count=1024 oflag=direct 1073741824 bytes (1.1 GB) copied, 10.415 s, 103 MB/s # dd if=/dev/zero of=test bs=1M count=1024 oflag=direct & dd if=/dev/zero of=test2 bs=1M count=1024 oflag=direct & dd if=/dev/zero of=test3 bs=1M count=1024 oflag=direct & dd if=/dev/zero of=test4 bs=1M count=1024 oflag=direct 1073741824 bytes (1.1 GB) copied, 49.8874 s, 21.5 MB/s 1073741824 bytes (1.1 GB) copied, 49.8608 s, 21.5 MB/s 1073741824 bytes (1.1 GB) copied, 49.8693 s, 21.5 MB/s 1073741824 bytes (1.1 GB) copied, 49.9427 s, 21.5 MB/s I wonder is that normal situation or did I missed something?

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  • ESXI guests not using available CPU resources

    - by Alan M
    I have a VMWare ESXI 5.0.0 (it's a bit old, I know) host with three guest VMs on it. For reasons unknown, the guests will not use much of the availble CPU resources. I have all three guests in a single pool, with the hosts all configured to use the same amount of resource shares, so they're basically 33% each. The three guests are basically identically configured as far as their VM resources go. So the problem is, even when the guests are performing what should be very 'busy' activitites, such as at bootup, the actual host CPU consumed is something tiny, like 33mhz, when seen via vSphere console's "Virtual Machines" tab when viewing properties for the pool. And of course, the performance of the guest VMs is terrible. The host has plenty of CPU to spare. I've tried tinkering with individual guest VM resource settings; cranking up the reservation, etc. No matter. The guests just refuse to make use of the abundant CPU available to them, and insist on using a sliver of the available resources. Any suggestions? Update after reading various comments below Per the suggestions below, I did remove the guests from the application pool; this didn't make any difference. I do understand that the guests are not going to consume resources they do not need. I have tried to do a remote perfmon on the guest which is experiencing long boot times, but I cannot connect to the guest remotely with perfmon (guest is w2k8r2 server). Host graphs for CPU, Mem, Disk are basically flatlining; very little demand. Same is true for the guest stats; while the guest itself seems to be crawling, the guest resource graphing shows very little activity across CPU, Mem, Disk. Host is a Dell PowerEdge 2900, has 2 physical CPU,20gb RAM. (it's a test/dev environment using surplus gear) Guest1 has: VM ver. 7, 2vCPU, 4gb RAM, 140gb storage which lives on a RAID-5 array on the host. Guest2 has: VM ver. 7, 2vCPU, 4gb RAM, 140gb storage which lives on a RAID-5 array on the host. Guest3 has: VM ver. 7, 1vCPU, 2gb RAM, 2tb storage which lives on a RAID-5 ISCSI NAS box Perhaps I am making a false assumption that if a guest has a demand for CPU (e.g. Windows Task Manager shows 100% CPU), the host would supply the guest with more CPU (mem, disk) on demand. Another Update After checking the stats, it would appear that the host is indeed not busy at all, neither is the guest. I believe I have a good idea on the issue, though; a messed-up VMWare Tools install. The guest has VMware Tools on it, but the host says it does not. VMWare Tools refuses to uninstall, refuses to be upgraded, refuses to be recognized. While I cannot say with authority, this would appear to be something worth investigation. I do not know the origin of the guest itself, nor the specifics on the original VMWare Tools install. Following various bits of googling, I did come up with a few suggestions that went nowhere. To that end, I was going to delete this question, but was prompted not to do so since so many folks answered. My suspicion right now is; the problem truly is the guest; the guest is not making a demand on the host, and as a natural result, the host is treating the guest accordingly. My Final Update I am 99% certain the guest VM had something fundamentally wrong with it re VMWare Tools. I created a clone of a different VM with a near-identical OS config, but a properly working install of VMWare tools. The guest runs just great, and takes up it's allotment of resources when it needs to; e.g. it eats up about 850mhz CPU during startup, then ticks down to idle once the guest OS is stable.

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