How to avoid race conditions?

Similar Questions

• Update only one item in the cluster while avoiding race conditions

  I have a cluster called "Inputs" that has a bunch of data within all kinds of data types.

  I have several loops in the code I want each of them to update a specific element within the cluster.

  I have to get the cluster use this Bundle by name on the specific item and then rewrite in the cluster.

  This way I have racing conditions because two loops can 'be' the cluster at the same time, but when they rewrite a wiil overwrites the other.

  How can I avoid these race conditions?

  I am familiar with Globals functional if it is connected to a possible solution (I have the feeling that it is..)

  Thank you!

  I still think that my suggestion to use the value of data references would be easier. The structure of the International preliminary examination will block the concurrent access to the data cluster: no race condition.

  

  The last loop (option) shows how to query the State of the heap of data.

• Locking access to Global Variables to avoid race conditions?

  Hi all

  I'm developing an application where 'control' Subvi accesses a Subvi 'action '. The Subvi action is actually limited by a number of different high-level subVIs to I really need to use globals.

  I wrote the next part of the code and was struck that it could lead to a race condition. Essentially my Subvi control runs two loops in parallel. Each loop reads the global increments a different value in each of them, wait a while and then returns to its previous value.

  I wrote this piece of code to demo what I mean. The table of waveform takes the place of the Subvi 'action '. Running this code resulted in a competitive situation (one of the values goes from 0 to 5 range to the range of 5-10) after its loading into memory using a second time usually allows it to operate for a long time.

  

  I modified the VI to exaggerate the effect of the condition of competition for demonstration. I've also implemented a solution using a local variable to stop the globals accessed at the same time. However, it is far more elegent and I don't think it will work for more than two loops. Finally, I need to use three loops.

  I have attached my demo/exaggerated solution. If you can suggest a better way to solve this problem, I would be very grateful.

  Thank you

  Dave

  DeltaJ wrote:

  I'm just out of the laboratory for a bit of fresh air--after watching this problem for hours - and he hit me. If I write access to my Globals in a Subvi - what I can do - and do the reentrant VI will not program only be able to access the globals in the order and avoid the condtion race in this way?

  A reentrant VI uses its own separate for each instance memory space, so it means it can be called in parallel with another instance. In other words, it gives you just the same situation as what you currently have.

  Or do you mean I can access to the global queue - I'm able to do it without a huge rewrite!

  No, I wasn't talking about the queue access globally. I was talking to store the data in a queue.

  Encapsulation of the value in a Subvi refresh, it's what you would do with a motor of Action. Note that you want an 'update' action so the write occurs inside the engine of Action VI.  This will give you as close to an atomic operation that you can get.

• Avoid race Conditions, using Variables of network w / RT

  SYSTEM:
  I use a cRIO system connected to a host via ethernet PC.
  One of the parts of my system of cRIO with that I'm having a problem using CAN.

  BACKGROUND:
  FPGA waits for a reading, and when a message is received (U8 table format), he shoves every element in a target-to-Host U8 FIFO.
  RT sees the message in the FIFO, it collects and it integrates an array 2D U8 (in the case where more than one message is received) and adds to a growing range of U8 2D.

  PROBLEM:
  Originally, I was misleading this table 2D to the host computer via a Variable network and display on the façade of the host machine.  This works, except over time, this table 2D-U8 gets huge-especially if I use an echo.

  Ultimately, I want the host to display entire history, but including the RT rewrite this entire variable each time and send them over the network it slows down.

  FAILED ATTEMPTS:
  I expect to change to a queue, but apparently it is accessible by other elements in the host (in this case, the Module LabVIEW RT.)

  Writing an empty array in the network Variable after reading it obviously causes problems of condition Whitneys.

  QUESTION:
  Any suggestions on how to transmit these data to the host without losing data?

  Is it possible to have something similar to a queue or FIFO on the network?

  Thank you

  ~ Andrew

  (There are two routes that you might go: 1) for broadcast continues to the host network streams gives the effect of the queue on the network but it requires something to transmitted data namely hard if you need connect/disconnect your host. (2) stick with static variables, but your RT code will be expected to handle the buffer. For example, you can set up a circular buffer of the last samples n that is written to the variable. Based on what you say, I'd go with 2 though, so he can give that a complete history is difficult.

• Having a very bad Friday afternoon, no idea how I can eliminate a possible race condition?  I have a working script intermittently :(

  I have a script that seems to work intermittently, usually it fails on the line of characters 1 128 (in bold below) I think that the VC will not return with information and therefore the script fails on the capture...

  on the other

  {

  Write-Host "space is insufficient on the target data store. Please increase the space to continue.

  Write-Output "space is insufficient on the target data store. Please increase the space to continue"> > $logfile

  Write-Host "Exiting with code 1.

  Write-Output "exit with code 1" > > $logfile

  Send-MailMessage-to $From-$To-CC $Cc - subject $Subject '

  -Body $BodyFailure1 - SmtpServer $SMTPServer - port $SMTPPort

  Output 1

  The architect suggested it might be a race condition, can someone with a lot more experience than me (it's pretty anyone) suggests an alteration that may well solve this problem?  I guess I could put breaks in but I'm not 100% where would be the best place to do so or if maybe it's the mickey mouse method?

  Error

  # ==============================================================================================

  # NAME: CloneVMs

  #

  # AUTHOR: Luc

  # DATE: 10/09/2015

  #

  # COMMENT: Creates a clone/backup of virtual machines described in the text and names using the

  # past param.  Virtual MACHINE will be appointed in accordance with the following VM1-12345678 example

  #

  #

  #

  # * Software dependencies: *.

  # - Microsoft PowerShell *.

  # - VMWare PowerCLI *.

  # ==============================================================================================

  # Parameters

  # ==============================================================================================

  # Below is provided by Control-M parameter refers to the prefix point cycle and restoration,

  # the date can be added automatically, however, this feature has been disabled.

  Param ([string] $CYRPYYMMDD)

  # ==============================================================================================

  # Functions

  # ==============================================================================================

  #Function for you to check if a command is responsible

  Function Check-Command ($cmdname)

  {

  return [bool] (Get-Command - Name $cmdname - ErrorAction SilentlyContinue)

  }

  # ==============================================================================================

  # Varibles

  # ==============================================================================================

  # Add the snap of vmware for powershell

  # Add - PSSnapin VMware.VimAutomation.Core

  # Add the snap of vmware for powershell (keeps see you error messages)

  If (control "Connect-VIServer")

  {

  Write-Host "already automation tool for".

  }

  on the other

  {

  #If not already loaded load the snap

  Write-Host "loading automation tools.

  Add-PSSnapin VMware.VimAutomation.Core

  }

  backup of # = true adds date; false creates a clone with the same name.

  $backup = 'True '.

  debugging of #-true: clones not vm. FALSE will clone the virtual machine.

  $debug = "FALSE".

  # Target Datastore

  $targetdatastore = "LUN9_BASIC_MATADM_ONLY".

  Check the #Refers the percentage of free space for space DS

  $freePerc = 10

  # Target location - folder existing in vcenter structure, where the clones will be held

  $targetlocation = "DMAT DNT for Cycles compatibleM BackUp.

  # Set a date

  $datestart = (get-date - uformat %Y %m %d)

  # Name a log file to record the results.

  $logfile = $datestart + "_VMClones_bulk.txt".

  #

  Write-output "new journal ($datestart) - ($logfile)" > > $logfile

  # Gets the list of virtual machines from the file associated with this script

  $VmFileList = get-Content VmsToCloneList.list | Select-Object - jump 3

  #

  $ds = get-Datastore-name $targetdatastore

  #Email varibles

  $From = «»

  $To = «»

  $Cc = «»

  #$Attachment = "C:\temp\Some random file.txt".

  $Subject = «!» DMAT TEST createRP TEST! »

  $BodySuccess = "A DMAT VM has correctly saved to the specified folder of destination organizational data store and inventory in vSphere"

  $BodyFailure1 = "the combined use of VMDK put in service of the virtual machine is greater than the capacity of the destination database or the datstore does not exist, coming out with code 1"

  $BodyFailure2 = "there is not enough space on the target data store, increase the space to continue, exit with code 1"

  $BodyFailure3 = "a virtual machine with the specified name is not found maybe it does not exist? Exit with code 1 "

  $SMTPServer = «»

  $SMTPPort = "25".

  # Connect

  $Creds = get-VICredentialStoreItem-Host 127.0.0.1 - folder C:\Users\matadm\PS_ITC_BAS.xml

  SE connect-VIServer 127.0.0.1-$ username-password Creds.User $Creds.Password

  # Gets the total ProvisionedSpaceGB of VM for all s VM in the list.

  # Ensures whitespace and hashes are effectively ignored

  # create a clean list that calculates / creates the variable required for the validation check 1

  $vmCleanedList = New-Object system. Collections.ArrayList

  # Loop through our VM file list and own is in place, check for incorrectly specified VM

  ForEach ($vmname to $VmFileList)

  {

  If ([string]: IsNullOrWhiteSpace ($vmname) - or $vmname.) StartsWith("#"))

  {

  writing-host("Invalid machine name-$vmname")

  }

  on the other

  {

  #Should trim vmname to ensure that we have no spaces before or the end

  $vm = get - VM $vmname

  $vmCleanedList.Add ($vmname)

  $TotalRequiredGB += $vm. ProvisionedSpaceGB

  }

  Write-Host "Total needed = $TotalRequiredGB.

  }

  # ==============================================================================================

  # Validation checks before launching the clone script

  # ==============================================================================================

  # Updates the prior to storage data store information.

  $ds. ExtensionData.RefreshDatastoreStorageInfo)

  # Validation check 1, check if the combined usage of VMDK put into service of the virtual machine is greater than the capacity of the destination database?

  If (($ds.)) FreeSpaceGB - gt $TotalRequiredGB))

  {

  Write-Host 'continue with your script.

  }

  on the other

  {

  Write-Host "space is insufficient on the target data store. Please increase the space to continue.

  Write-Output "space is insufficient on the target data store. Please increase the space to continue"> > $logfile

  Write-Host "Exiting with code 1.

  Write-Output "exit with code 1" > > $logfile

  Send-MailMessage-to $From-$To-CC $Cc - subject $Subject '

  -Body $BodyFailure1 - SmtpServer $SMTPServer - port $SMTPPort

  Output 1

  }

  $ds = get-Datastore-name $targetdatastore

  # 2 validation control, you have X % datatstorespace free?

  If ((($ds.)) FreeSpaceGB / $ds. CapacityGB) * 100)-ge $freePerc)

  {

  Write-Host 'continue with your script.

  }

  on the other

  {

  Write-Host "there is less than X % of free space on the data store. Please increase the space to continue.

  Write-Output "there less than X % of free space on the data store. Please increase the space to continue"> > $logfile

  Write-Host "Exiting with code 2.

  Write-Output 'output with code 2' > > $logfile

  Send-MailMessage-to $From-$To-CC $Cc - subject $Subject '

  -Body $BodyFailure2 - SmtpServer $SMTPServer - port $SMTPPort

  Output 2

  }

  #Hack + of the duplication of efforts

  #$VmListFile = get-Content VmsToCloneList.list | Select-Object - jump 3

  ForEach ($vmname to $vmCleanedList)

  {

  # The virtual computer object

  $vm = get-VM-name $vmname

  # Target host - use the same host as the current VM (it's faster than the cloning on hosts).

  $targethost = $vm.vmhost.name

  # Target VM name - name if the BACKUP is FALSE

  $vmtarget = $vmname

  #

  $datastore = get-datastore $targetdatastore - vmhost $targethost

  # ==============================================================================================

  # Start the real clone script

  # ==============================================================================================

  If ($vm - no $null)

  {

  Write-Host "a virtual machine named $VM exists. From clone "

  Write-output "a virtual machine named $VM exists. From clone"> > $logfile

  }

  on the other

  {

  Write-Host "a virtual machine with the specified name is not found maybe it does not exist?

  Write-Output "a virtual machine with the specified name is not found there is perhaps no?" > > $logfile

  Write-Host "Exiting with code 3.

  Write-Output "output with code 3" > > $logfile

  Send-MailMessage-to $From-$To-CC $Cc - subject $Subject '

  -Body $BodyFailure3 - SmtpServer $SMTPServer - port $SMTPPort

  exit 3

  }

  If ($backup - eq "TRUE")

  {

  # Clone the virtual machine for backup_vmname_todaysdate

  $vmtarget = $vmtarget + '-' + $CYRPYYMMDD #+ '-' + $datestart

  }

  beautiful colors # if you look at the script runs

  write-host - foregroundcolor green 'cloning $vm to $vmtarget.

  Write-output - foregroundcolor green 'Cloning $vm to $vmtarget' > > $logfile

  new-vm-name $vmtarget - vm $vm vmhost - $targethost - $datastore - $targetlocation location data store - slim DiskStorageFormat

  Send-MailMessage-to $From-$To-CC $Cc - subject $Subject '

  -Body $BodySuccess - SmtpServer $SMTPServer - port $SMTPPort

  }

  Write-Host "complete."

  Exit 0

  # COMPLETED

  Have you ever tried to test if $ds-eq $null before you call the RefreshDatastoreStorageInfo method?

  In the error message, it looks like $ds contains $null, no idea why when the data store 'LUN9_BASIC_MATADM_ONLY' exists in the environment in which you are conencted.

  In fact, you could test immediately after the Get-data store.

  Ah, but wait, you seem to be doing the first Get-Datastore (there are two in the script, but I guess you know) before the connect-VIServer, it won't work.

  Unless I'm missing something here

• with 2 windows open, if I zoomed in Windows Active, expanded as this one. How to avoid this?

  Conditions:
  2 windows of firefox open 21.0, showing 2 different pages, which comes from the same server.
  One of the 2 pages it active, having shot on it with the mouse.
  If I try to zoom on active windows, is enlarged also another one that is not active.
  How to avoid this?

  Hello AngB, what you described is the expected behavior by default in firefox, since it will remember your custom of expansion on a per domain basis and apply it to every page of this area.

  If you want to change it, enter about: config in the address bar of firefox (confirmed the message information where it appears) and look for the named browser.zoom.siteSpecificpreference. Double-click it and change its value to false.

• Autofocus TextField when the user presses the keys (and possible race condition)

  Someone tried to implement a device by which a TextField (or text box, I guess) automatically gets the focus when a user starts to type anything? It is very convenient to have something, at least with a phone model Qwerty, in certain situations. (A use case is where a list that is too long for the useful shortcuts, but the TextField object is used to implement a filtering mechanism that can reduce the data set to a reasonable size, and the user can then scroll just to find a target element).

  I've set up something using a KeyListener (calling requestFocus() for the TextField object) attached to the container Page, but there are problems with it.

  It's a question that the first keystroke does not render in the TextField object, since it has not a focus when the key was first struck.

  To solve that you can enter the key (event.unicode) and that insert into the TextField object, and then the following keys go on the field you want... but there is also a problem with that.

  If you type two or three buttons in quick succession, probably less than 50ms between them, you can see that even if the KeyListener gets each of them, the TextField object receives the second or, sometimes, the third, even if you can check that by the time second keyPressed/output signal arrives in your earpiece the TextField claims to have developed (TextField.focused is true).

  This seems like a bug, but maybe it's just a case of corner cascading who is inevitable, given its design... I'm not sure.

  If anyone can reproduce it, thanks for posting here. I'll do a test case to prove and will report it as a bug if you do.

  If anyone has a reliable and quality approach, please post here too! :-)

  P.S. for a good laugh, a code here that I did for my particular case, which seeks to avoid the race condition. As you can see, this is a great hack, but it works 100% reliable for me so far with a fairly comprehensive test (including the tests with the movement of the cursor, copy/paste, etc.). It's too complicated to analyze and ensure that it is really robust, however, but feel free to use... If you care enough. ;-)  http://pastebin.com/r2VUtPJC

  Have you tried setting the primaryKeyTarget it's inputRoute?

  https://developer.BlackBerry.com/native/reference/Cascades/bb__cascades__inputrouteproperties.html

  Has been added to the 10.1, which should do what you want.

  You can also achieve the same messing around with pre FocusPolicy 10.1, but it is much simpler.

• Refreshing the page creates a new record – how to avoid this?

  I have a 'submit' button that runs a 'record insertion.

  After insertion is made I branch (back) to this same page.

  The problem is that when I hit page refresh the folder gets reinserted.

  How to avoid this behavior?

  AZZ says:

  fac586,

  Yes. You are right. It was a late semi written post. My apologies. You must stop working after midnight.

  Let me clarify:

  I have a SUBMIT"" button.

  There are the conditional 'after send' (if the key) process.

  the process calls a function that inserts a new record in the table.

  Question:

  How can I avoid running the process on refreshing the page?

  I've simplified the situation - no record insertion. However, if you refresh the page the success of the function call message will be displayed.

  https://Apex.Oracle.com/pls/Apex/f?p=4000:1:126172565551184:no:RP:FB_FLOW_ID, F4000_P1_FLOW:21325, 21325

  user/pass help/help

  workspace - AZ_

  To reproduce:

  Click on the submit - observe green popup "OK!"

  Refresh the page (F5 or ctrl-R) - see 'OK!' again.

  No process is executed to see the page or page refresh. This can be confirmed by looking at track of debugging to see the processing page. The page contains no defined process to run at a show of page processing point; None of the calculations which could call a function that could not perform an insert as a side effect; None of the dynamic actions or calls JS could initiate an insertion using AJAX; Neither the source region contains any code that could do it. I'll draw the line search conditions that can contain deeply buried code which could be responsible and direct you to a previous thread of the same nature: success of process Message not tied to Conditions.

• I downloaded Safari 10 and now every page that uses Java asks me to activate or not. How to avoid this new feature? I have problems to access my bank account.

  I downloaded Safari 10 and now every page that uses Java asks me to activate or not. How to avoid this new feature? I have problems to access my bank account.

  I think they mean JavaScript.

  In your Safari menu bar, click Safari > Preferences and then select the Security tab, and then select: Enable JavaScript

• How to remove Code condition on iwatch after the last update

  How to remove Code condition on iWatch after the last update?

  Hello

  On your iPhone, in the application of the watch, go to: My Watch (tab) > password - tap on disable password.

• How to avoid the u letter when you type ' u?

  Hello community,

  I need to write ' u , but it automatically replaces these two letters by u on selection of keyboard we International PC.

  Can you suggest me how to avoid it?

  Thanks in advance,

  Gomez

  What exact keystrokes you type?

• Satellite Pro 4200 how to avoid the mistakes of the ACPI

  Satellite Pro 4200 how to avoid the ACPI errors after installing SP2 for windows XP Prof
  The problem is that my computer after installation service Pack 2 need about 15 minutes from time of shoutdown - what should I do to avoid this problem.
  Piotr Plecke

  Hello
  in this case it would be interesting what Type of laptop it is exactly.

  You will find this model on the bottom of your laptop. There is a review of it.

  Some models have a Bios update available, others not, for example.

  Please send additional information!

  Good bye

• How to avoid accidentally getting the split screen. I never want that. 3.6.11 version. Thank you

  I don't know how I did it, but now when I go to drag a web page below on the right scroll bar another mini bar appears. If I accidentally hit that all of a sudden I have two pages to the top at the same time and I can't get back to where I was without closing the page entirely.

  How to avoid this? I rarely want to two pages at the same time.

  Thank you

  This isn't a feature built into Firefox. You have an add-on like Fox Splitter installed? This one seems to do what you describe.

• My iPad detects inactivity while I'm listening to a story.  Then he slips into the mode "sleep" and interrupts the story.  Any suggestions on how to avoid this?

  My iPad detects inactivity while I'm listening to a story.  Then he slips into the mode "sleep" and interrupts the story.  Any suggestions on how to avoid this?

  Setting to never by using the auto-lock settings application.

  Settings > general > auto lock > never

• Camileo S10 - how to avoid the 'information' during video playback on TV

  I just received my Camileo S10... very nice indeed... but how to avoid the track and reading data to be shown on the screen during playback on my TV...?

  Go to the movies, then before you start playing click the OK button. This also works when you save. You must do this before playing or recording.