Configure the priority/execution system of Sub-VIs

Hi,
I wonder if it is possible to configure a VI to run with different priorities or in different execution systems when called on different occations. It seems to me that the only way to influence this is by changing the properties of a VI and then saving it. That would leave me having n just slightly different VIs for n settings.
Sören

Hello,
VI server exposes properties which allow you to change the priority and execution of a VI dynamically. However, these properties cannot be set while the VI is running, and therefore a VI cannot set its own priority or execution system. This means that you have to use a plug-in architecture (dynamically called VIs) in order to dynamically choose the priority and execution system of VIs. I've attached a short example written in LV 7.1. If you are unfamiliar with VI server or dynamically calling VIs, the LabVIEW Intermediate II course covers these topics and I'm sure there is also plenty of good content on these forums and in the developer zone.
Regards,
Ryan K.
Note: You should be careful when adjusting the priorities and execution systems on a VI, as you can often end up with undesired results due to priority inversion.
Attachments:
Priority Demo.zip ‏20 KB

Similar Messages

Is this roughly how the labVIEW Execution Systems work?

I've not taken a class in OS design, so I don't know the strategies used to implement multitasking, preemptive or cooperative. The description below is a rough guess.
LabVIEW compiles Vis to execute within its own multitasking execution environment. This execution environment is composed of 6 execution systems. Each execution system has 5 priority queues (say priorities 0->4). Vis are compiled to one or more tasks which are posted for execution in these queues.
An execution system may either have multiple threads assigned to execute tasks from each priority queue, or may have a single thread executing all tasks from all priority queues. The thread priorities associated with a multithreaded execution system are assigned according to the queue that they service. There are therefore 5 available thread priority levels, one for each of the 5 priority level queues.
In addition to the execution queues, there are additional queues that are associated with tasks suspended in various wait states. (I don't know whether there are also threads associated with these queues. It seems there is.)
According to app. note 114, the default execution environment provides 1 execution system with 1 thread having a priority level of 1, and 5 execution systems with 10 prioritized threads, 2 threads per priority queue. NI has titled the single threaded execution system "user interface" and also given names to the other 5. Here they will be called either "user interface" or "other".
The "user interface" system is responsible for all GUI actions. It monitors the keyboard and mouse, as well as drawing the controls. It is also used to execute non-thread-safe tasks; tasks whose shared objects are not thread mutex protected.
Vis are composed of a front panel and diagram. The front panel provides an interface between the vi diagram, the user, and the calling vi. The diagram provides programmatic data flow between various nodes and is compiled into one or more machine coded tasks. In addition to it own tasks, a diagram may also call other vis. A vi that calls another vi does not actually programmatically branch to that vi. Rather, in most cases the call to another vi posts the tasks associated with the subvi to the back of one of the labVIEW execution system�s queues.
If a vi is non-reentrant, its tasks cannot run simultaneously on multiple threads. This implies a mutex like construction around the vi call to insure only one execution system is executing the vi. It doesn�t really matter where or how this happens, but somehow labVIEW has to protect an asynchronous vi from simultaneous execution, somehow that has to be performed without blocking an execution queue, and somehow a mutex suspended vi has to be returned to the execution queue when the mutex is freed. I assume this to be a strictly labVIEW mutex and does not involve the OS. If a vi is reentrant, it can be posted/ran multiple times simultaneously. If a vi is a subroutine, its task (I think there is always only one) will be posted to the front of the caller's queue rather than at the back of the queue (It actually probably never gets posted but is simply mutex tested at the call.) A reentrant-subroutine vi may be directly linked to its caller since it has no restrictions. (Whether in fact labVIEW does this, I don�t know. In any event, it would seem in general vis that can be identified as reentrant should be specified as such to avoid the overhead of mutexing. This would include vis that wrap reentrant dll calls.)
The execution queue to which a vi's tasks are posted depends upon the vi execution settings and the caller's execution priority. If the caller's execution priority is less than or equal the callee's execution settings, then the callee's tasks are posted to the back of the callee's specified execution queue. If the caller's execution priority is greater than the callee's specifications, then the callee's tasks are posted to the back of the caller's queue. Under most conditions, the vi execution setting is set to "same as caller" in which case the callee�s tasks are always posted to the back of the caller's execution queue. This applies to cases where two vis are set to run either in the other execution systems or two vis are set to run in the user interface execution system. (It�s not clear what happens when one vi is in the �user interface� system and the other is not. If the rule is followed by thread priority, any background tasks in the �other� systems will be moved to the user interface system. Normal task in the �other� systems called by a vi in the �user interface� system will execute in their own systems and vice versa. And �user interface� vis will execute in the caller�s �other� system if the caller has a priority greater than normal.)
Additionally, certain nodes must execute in the "user interface" execution system because their operations are not thread-safe. While the above generally specifies where a task will begin and end execution, a non-thread safe node can move a task to the �user interface� system. The task will continue to execute there until some unspecified event moves it back to its original execution system. Note, other task associated to the vi will be unaffected and will continue to execute in the original system.
Normally, tasks associated with a diagram run in one of the �other� execution systems. The tasks associated with drawing the front panel and monitoring user input always execute in the user interface execution system. Changes made by a diagram to it own front panel are buffered (the diagram has its own copy of the data, the front panel has its own copy of the data, and there seems to be some kind of exchange buffer that is mutexed), and the front panel update is posted as a task to the user interface execution system. Front panel objects also have the advanced option of being updated sequentially; presumably this means the diagram task that modifies the front panel will be moved to the user interface execution system as well. What this does to the data exchanged configuration between the front panel and diagram is unclear as presumably both the front panel and diagram are executing in the same thread and the mutex and buffer would seem to be redundant. While the above is true for a control value it is not clear whether this is also true for the control properties. Since a referenced property node can only occur on the local diagram, it is not clear it forces the local diagram to execute in the user interface system or whether they too are buffered and mutexed with the front panel.
If I were to hazard a guess, I would say that only the control values are buffered and mutexed. The control properties belong exclusively to the front panel and any changes made to them require execution in the �user interface� system. If diagram merely reads them, it probably doesn�t suffer a context switch.
Other vis can also modify the data structure defining the control appearance and values remotely using un-reference property nodes. These nodes are required to run in the user interface system because the operation is not thread-safe and apparently the diagram-front-panel mutex is specifically between the user interface execution system and the local diagram thread. Relative to the local diagram, remote changes by other vis would appear to be user entries.
It is not clear how front panels work with reentrant vis. Apparently every instance gets its own copy of the front panel values. If all front panel data structures were unique to an instance, and if I could get a vi reference to an instance of a reentrant vi, I could open multiple front panels, each displaying its own unique data. It might be handy, sort of like opening multiple Word documents, but I don�t think that it�s available.
A note: It is said that the front panel data is not loaded unless the front panel is opened. Obviously the attributes required to draw an object are not required, nor the buffer that interfaces with the user. This rule doesn�t apply though that if property references are made to front panel objects, and/or local variables are used. In those cases at least part of the front panel data has to be present. Furthermore, since all data is available via a control reference, if used, the control�s entire data structure must be present.
I use the vi server but haven�t really explored it yet, nor vi reference nodes, but obviously they too make modifications to unique data structures and hence are not thread-safe. And in general, any node that accesses a shared object is required to run in the user interface thread to protect the data associated with the object. LabVIEW, does not generally create OS level thread mutexes to protect objects probably because it becomes to cumbersome... Only a guess...
Considering the extra overhead of dealing with preemptive threading, I�m wondering if my well-tuned single threaded application in LV4.1 won�t out perform my well-tuned multithreaded application in LV6.0, given a single processor environment�
Please modify those parts that require it.
Thanks�
Kind Regards,
Eric

Ben,
There are two types of memory which would be of concern. There is temporary and persistent. Generally, if a reentrant vi has persistent memory requirements, then it is being used specifically to retain those values at every instance. More generally, reentrant code requires no persistent memory. It is passed all the information it needs to perform its function, and nothing is retained. For this type of reentrant vi, memory concern to which you refer could become important if the vis are using several MBytes of temporary storage for intermediate results. In that case, as you could have several copies executing at once, your temporary storage requirements have multiplied by the number of simultaneous copies executing. Your max memory use is going to rise, and as labview allocates memory rather independently and freely, the memory use of making them reentrant might be a bit of a surprise.
On the other hand, the whole idea of preemtive threading is to give those tasks which require execution in a timely fashion the ability to do so regardless of what other tasks might be doing. We are, after all, suffering the computational overhead of multithreading to accomplish this. If memory requirements are going to defeat the original objective, then we really are traversing a circle.
Anyway, as Greg has advised, threads are supposed to be used judiciously. It isn't as though your going to have all 51 threads up at the same time. In general I think, overall coding stategy should be to minimize the number of threads while protecting those tasks that absolutely require timely execution.
In that sense, it would have been nice if NI had retained two single threaded systems, one for the GUI and one for the GUI interface diagrams. I've noticed that control drawing is somewhat slower under LV6.0 than LV4.1. I cannot, for example, make a spreadsheet scroll smoothly anymore, even using buffered graphics. This makes me wonder how many of my open front panel diagrams are actually running on the GUI thread.
And, I wonder if threads go to sleep when not in use, for example, on a wait, or wait multiple node. My high priority thread doesn't do a lot of work, but the work that it does is critical. I don't know what it's doing the rest of the time. From some of Greg's comments, my impression is it in some kind of idle mode: waking up and sleeping, waking up and sleeping,..., waking up, doing something and sleeping... etc. I suppose I should try to test this.
Anyway that's all an aside...
With regard to memory, your right, there are no free lunches... Thanks for reminding me. If I try this, I might be dismayed by the additional memory use, but I won't be shocked.
Kind Regards,
Eric

The report server has encountered a configuration error. Logon failed for the unattended execution account. (rsServerConfigurationError) Log on failed. Ensure the user name and password are correct. (rsLogonFailed) The user name or password is incorrect

I am able to run the report fine in BIDS in the preview window, and it deployes fine. When it goes to view the report in the browser, I get the following error. There is no domain, I am using a standalone computer with SQL Server and SSRS on
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The report server has encountered a configuration error. Logon failed for the unattended execution account. (rsServerConfigurationError)
Log on failed. Ensure the user name and password are correct. (rsLogonFailed)
The user name or password is incorrect
Steven DeSalvo

Hi StevenDE2012,
Based on the error message "The report server has encountered a configuration error. Logon failed for the unattended execution account. (rsServerConfigurationError)", it seems that the Unattended Execution Account settings in Reporting Services
Configuration is not correct.
Reporting Services provides a special account that is used for unattended report processing and for sending connection requests across the network. Unattended report processing refers to any report execution process that is triggered by an event rather than
a user request. The report server uses the unattended report processing account to log on to the computer that hosts the external data source. This account is necessary because the credentials of the Report Server service account are never used to connect
to other computers. To configure the account, please refer to the following steps:
Start the Reporting Services Configuration tool and connect to the report server instance you want to configure.
On the Execution Account page, select Specify an execution account.
Type the account and password, retype the password, and then click Apply.
In addition, please verify you have access to the Report Server database by following steps:
Go to SQL Server Reporting Services Configuration Manager, make sure the configuration is correct.
Go to Database, Verify that you can connect to the database.
Make sure you are granted public and RSExecRole roles.
Reference:
Configure the Unattended Execution Account
Configure a Report Server Database Connection
If the problem is unresolved, i would appreciate it if you could give us detailed error log, it will help us move more quickly toward a solution.
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Preferred execution system

What is the exact meaning of:
User interface (I know)
Standard ?
Instrument IO ?
Data acquisition ?
Other 1 ???
Other 2 ???
Same as caller (I know)
I know that it also depend on if your computer is a Single or Dual Processor
Thanks!
Nitrof

> Greg McKaskle has written several good answers about execution systems:
>
> http://exchange.ni.com/servlet/ProcessRequest?RHIVEID=101...http://exchange.ni.com has been obsoleted by http://forums.ni.com/ni/ . I'm not sure how to find those three documents, but I found the following...
1999: priority of VIs
http://forums.ni.com/ni/board/message?board.id=170&message.id=5587
2001: Need some clarification on Execution Systems, Priorities, and threads with Labview on Windows NT
http://forums.ni.com/ni/board/message?board.id=170&thread.id=11944
2002: Multithreading in LabView loops doesn't work?
http://forums.ni.com/ni/board/message?board.id=170&message.id=23498&requireLogin=False
2002: best way to do parallel activities
http://forums.ni.com/ni/board/message?board.id=170&thread.id=24932
2003: Is this roughly how the labVIEW Execution Systems work?
http://forums.ni.com/ni/board/message?board.id=170&thread.id=45194
Is there anything more current?

SSRS programmatically remove the unattended execution account

Hi,
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I also didn't find any terms that I could use with the rsconfig utility to do so, see
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Hi Emmanuel,
When we set the account in SSRS, it will add specify Encrypted characters in the RSreportserver.config file. If we want to programmatically remove the SSRS unattended execution account, we need find a way to delete the corresponding Encrypted characters
in the RSreportserver.config file.
Based on my test, I cannot programmatically remove the Encrypted characters. As per my understanding, delete the unattended report processing account is a simple step in SSRS. The manual steps may be simpler than programmatically remove the account.
Hope this helps.
Regards,
Alisa Tang
If you have any feedback on our support, please click
here.
Alisa Tang
TechNet Community Support

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Current execution system of labview 8.20

What is the Current execution system of labview 8.20

Hi,
I presume you mean how LabVIEW executes the code in your block diagram? You can see this happen using the "Highlight Execution" button located next to the run, run continuously and abort buttons.
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CLA | LabVIEW 7.1... 2013
www.renishaw.com

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Hi mike_22,
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The report server has encountered a configuration error. Logon failed for the unattended execution account. (rsServerConfigurationError) Log on failed. Ensure the user name and password are correct. (rsLogonFailed) Logon failure: unknown user name or bad

The report server has encountered a configuration error. Logon failed for the unattended execution account. (rsServerConfigurationError)
Log on failed. Ensure the user name and password are correct. (rsLogonFailed)
Logon failure: unknown user name or bad password
am using Windows integrated security,version of my sql server 2008R2
I have go throgh the different articuls, they have given different answers,
So any one give me the exact soluction for this problem,
Using service account then i will get the soluction or what?
pls help me out it is urgent based.
Regards
Thanks!

Hi Ychinnari,
I have tested on my local environment and can reproduce the issue, as
Vaishu00547 mentioned that the issue can be caused by the Execution Account you have configured in the Reporting Services Configuration Manager is not correct, Please update the Username and Password and restart the reporting services.
Please also find more details information about when to use the execution account, if possible,please also not specify this account:
This account is used under special circumstances when other sources of credentials are not available:
When the report server connects to a data source that does not require credentials. Examples of data sources that might not require credentials include XML documents and some client-side database applications.
When the report server connects to another server to retrieve external image files or other resources that are referenced in a report.
Execution Account (SSRS Native Mode)
If you still have any problem, please feel free to ask.
Regards
Vicky Liu
Vicky Liu
TechNet Community Support

I would like to know how i can create a bell graph with out using sub VIs, the data that i created consists in 500 readings with values of 0 to 100, i calculated the mean value and standard diviation. I hope some one can help me

I would like to know how i can create a bell graph with out using sub VIs, the data that i created consists in 500 readings with values of 0 to 100, i calculated the mean value and standard diviation. I hope some one can help me

Here's a quick example I threw together that generates a sort-of-bell-curve shaped data distribution, then performs the binning and plotting.
-Kevin P.
Message Edited by Kevin Price on 12-01-2006 02:42 PM
Attachments:
Binning example.vi ‏51 KB
Binning example.png ‏12 KB

[SOLVED] Configure The System (Beginners Guide) Question

Hello!
I'm currently working my way through the beginners guide, from the wiki. All going ok so far and I've reached the Configure The System section. Which is where I'm a bit stuck.
Beginners Guide wrote:You will be presented with a menu including the most important configuration files for your system. If you want to look up the available options as stated in /etc/rc.conf just press Alt+F2 to get a shell, look it up, and switch back to the installer with Alt+F1.
The problem I have is looking up the available options. For example, to find my locale it states I should run locale -a, however when I hit Alt+f2 and enter the command at the bash shell ([Arch Linux: /]# ) I get the following error
-bash: locale: command not found
When I attempt to lookup other items I'm also unable to find those (such as timezone in /usr/share/zoneinfo).
Can anyone let me know what I'm doing wrong, I'm missing something very obvious here, but sadly I just can't work it out!
Last edited by Laatia (2008-03-23 08:56:38)

dyscoria wrote:
I wouldn't skip all of the steps, particularly adding your hostname to /etc/hosts. Just fill in as much as you can, and edit the rest after you've finished installing, though I think the defaults are safe enough to have a running system.
If you typed in 'km' and chose your locale before you ran the /arch/setup command to start the installation, it should automatically enter in the locale you selected earlier (if you press yes in the dialog box that pops up).
Confirm this as that's what happended in this location on 2 recent install.

Configure the priority/execution system of Sub-VIs

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