Thread Safe Queue Between DLL and EXE

Hello,
We wondered if this architecture would work:
An exe would create a thread safe queue. A dll routine would write to the queue using CmtWriteTSQData. The exe in turn would have an installed callback for the queue for when there are a certain number of items in the queue.
The exe is linked to DLL.
Thank you,
Solved!
Go to Solution.

Hi jharris66,
It sounds like that architecture you suggest should work. However I am not sure what you mean when you say the exe is linked to the DLL. Could you clarify what you mean when you say that?
Thank you!
Rachel M.
Applications Engineer
National Instruments

Similar Messages

Thread safe Queue implementation

Dear all,
I have implemented Queue functionality using Blocking concurent linked list based java queue, but i am facing problem of deadlock/program hang.
There are 10 threads which are trying to see that is there any object in Queue, they get that object and process it.
Any idea what is wrong ??
Thanks
public class MyQueue
    private LinkedBlockingQueue<Object> elements;
    private Object obj;
    public MyQueue() {
        elements = new LinkedBlockingQueue<Object>();
        obj=null;
    public Object pull() {
         try {
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          } catch (InterruptedException e) {
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Thanks,
I analyzed the hanged/deadlocked program by killing its process with command "kil -3 <pid>"
i have seen following state for my JobHandler threads
is any wrong with Queue implementation or some thing else , Any idea?
"JobHandler" prio=10 tid=0xaec22000 nid=0x51c7 waiting on condition [0xaeb0b000..0xaeb0c030]
   java.lang.Thread.State: WAITING (parking)
        at sun.misc.Unsafe.park(Native Method)
        - parking to wait for <0xee01fa00> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
        at java.util.concurrent.locks.LockSupport.park(LockSupport.java:158)
        at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:1925)
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When building an appllication the data display changes between VI and EXE

I have an application where data is written in exponential notation (1.0E-9) into a file and then read and displayed. In the VI this works fine, but when I build an application containing this VI, the graphical display is wrong, even though the values written into the file are the same.
(See pictures). My suspicion is that the scale formatting gets lost.
How can I solve this ?
Attachments:
Wrong_Display.jpg ‏64 KB
Right_Display.jpg ‏63 KB
Data_Viewer_Pressures.vi ‏44 KB

Hello Mike,
i think I have posted the wrong VIs, so here are the right ones as a llb. plus the text file.
Attachments:
Pressure_File.llb ‏135 KB
440011_Pressures.txt ‏2 KB

Locking a non-thread-safe DLL, innovative solutions?

Hi,
I need to be able to lock access to a non-thread-safe third party DLL, so that multiple threads cannot access DLL simultaneously. I know that I can use semaphore or a single element queue. Are there any other innovative solutions that would limit the access to the DLL to a single call simultaneously.
If I use either semaphores or single element queue and use the semaphore (queue) with the same name in multiple programs (independent VIs), will the access to the DLL be handled without problems i.e. no collisions can happen? What if I build multiple applications (.exe) or application libraries (.dll), does a single semaphore (queue) still work between different applications or do they need to be initiated from the same application?
Tomi
Message Edited by Tomi M on 03-06-2006 08:01 PM
Tomi Maila

Tomi M wrote:
One more thing, with
innovative solutions I meant something like the following. Is there a
way to use some properties of Labview execution system to automatically
restrict the access to the DLL i.e. allow only single thread with
certain properties to call the DLL while all other threads with the
same properties are waiting in the execution queue. So if I set the
execution priority to something specific and execution system to
another something specific, will Labview thisway restrict access to DLL
to be sequential?
The proper way to
call non multithread safe DLLs in LabVIEW is to configure the Call
Library Node in the configuration dialog to be NOT reentrant. This
tells LabVIEW that the DLL may behave badly or at least you do not want
LabVIEW to call the DLL just from any thread. LabVIEW then will call
this DLL function from the UI execution system which is guaranteed to
only have one single thread at all times and therefore protect your DLL
from being called frm different threads at the same time.
Rlf Kalbermatter
Rolf Kalbermatter
CIT Engineering Netherlands
a division of Test & Measurement Solutions

Difference Between BAPI And RFC in ABAP

Hi,
i want to know difference between BAPI and RFC in SAP,
can we call SAP GUI screen from NON SAP System Using BAPI.
Reg,
Hariharan

Hi Ravishankar,
The difference is not importat while you understand the concept.
I think, RFC is the protocol for calling functions from external systems in R/3.
I understand like BAPI a series of complet functions that SAP offers you for use and model a business use.
But if I need program a function that can be called for external system i would call it RFC_NAME, because is a unique function that makes a single task.
In other words, the difference i think is about work idea more than another thing.
RFC
A remote function call is a call to a function module running in a system different from the caller's. The remote function can also be called from within the same system (as a remote call).
RFC consists of two interfaces : A calling interface for ABAP Programs and a calling interface for Non-SAP programs.
The RFC Interface takes care of :-
- Converting all parameter data to the representation needed in the remote system
Calling the communication routines needed to talk to the remote system.
Handling communications errors, and notifying the caller, if desired ( using EXCEPTIONS paramater of the CALL FUNCTION).
BAPI
BAPIs are standardized programming interfaces (methods) enabling external applications to access business processes and data in the R/3 System.
BAPIs provide stable and standardized methods to achieve seamless integration between the R/3 System and external applications, legacy systems and add-ons.
BAPIs are defined in the BOR(Business object repository) as methods of SAP business object types that carry out specific business functions.
BAPIs are implemented as RFC-enabled function modules and are created in the Function Builder of the ABAP Workbench.
The most critical difference btwn BAPI and FM is that BAPI can be wrapped in Business objects whereas RFC cant.
BAPI are RFC enabled function modules. the difference between RFc and BAPI are business objects. You create business objects and those are then registered in your BOR (Business Object Repository) which can be accessed outside the SAP system by using some other applications (Non-SAP) such as VB or JAVA. in this case u only specify the business object and its method from external system in BAPI there is no direct system call. while RFC are direct system call Some BAPIs provide basic functions and can be used for most SAP business object types. These BAPIs should be implemented the same for all business object types. Standardized BAPIs are easier to use and prevent users having to deal with a number of different BAPIs. Whenever possible, a standardized BAPI must be used in preference to an individual BAPI.
The following standardized BAPIs are provided:
Reading instances of SAP business objects
GetList ( ) With the BAPI GetList you can select a range of object key values, for example, company codes and material numbers.
The BAPI GetList() is a class method.
GetDetail() With the BAPI GetDetail() the details of an instance of a business object type are retrieved and returned to the calling program. The instance is identified via its key. The BAPI GetDetail() is an instance method. BAPIs that can create, change or delete instances of a business object type
The following BAPIs of the same object type have to be programmed so that they can be called several times within one transaction. For example, if, after sales order 1 has been created, a second sales order 2 is created in the same transaction, the second BAPI call must not affect the consistency of the sales order 2. After completing the transaction with a COMMIT WORK, both the orders are saved consistently in the database.
Create( ) and CreateFromData! ( )
The BAPIs Create() and CreateFromData() create an instance of an SAP business object type, for example, a purchase order. These BAPIs are class methods.
Change( )
The BAPI Change() changes an existing instance of an SAP business object type, for example, a purchase order. The BAPI Change () is an instance method.
Delete( ) and Undelete( ) The BAPI Delete() deletes an instance of an SAP business object type from the database or sets a deletion flag.
The BAPI Undelete() removes a deletion flag. These BAPIs are instance methods.
Cancel ( ) Unlike the BAPI Delete(), the BAPI Cancel() cancels an instance of a business object type. The instance to be cancelled remains in the database and an additional instance is created and this is the one that is actually canceled. The Cancel() BAPI is an instance method.
Add<subobject> ( ) and Remove<subobject> ( ) The BAPI Add<subobject> adds a subobject to an existing object inst! ance and the BAPI and Remove<subobject> removes a subobject from an object instance. These BAPIs are instance methods.
Check these Links out
http://searchsap.techtarget.com/ateQuestionNResponse/0,289625,sid21_cid558752_tax293481,00.html
http://www.sap-img.com/abap/interview-question-on-bapi-rfc-abap-objects-tables.htm
http://www.sap-img.com/fu033.htm
http://www.sap-img.com/abap/ale-bapi.htm
Refer following SDN threads:
Diff. Between BAPI and RFC
Re: BAPI and RFC
Hope this resolves your query.
Reward all the helpful answers.
Regards

Urgent : Difference between EP6 and EP 7?

Hi All,
Could some one send me the details of the differences between EP6 an EP7 urgently on the address [email protected]
Thanks
Saurav

Hi Saurabh,
You can see the following threads..
difference between EP6 and EP7
Netweaver Portal 6.0 Vs 7.0 - Delta Features 1
I hope it helps..
Regards,
Uday.
Edited by: Naga Uday kasu on Mar 26, 2008 8:13 PM

Material replication between SAP and SRM

Howdy friends.
Is there any way to stop having to manually activate the material replication queue between SAP and SRM each time please?
Our admin team go to transaction SMQ2 each day and for 2-3 years have been manually activating each queue manually and doing this several times per queue as the entries do not reach zero. Surely, it is possible to set this up to be automatic as a job?
Ciao,
Mike

Hello,
I could not find the SDN Weblog but here a link to an article that migh help you....[url]http://searchsap.techtarget.com/tip/0,289483,sid21_gci1245134_mem1,00.html[url]
That should help you check your settings, et al and resolve your issue.
Regards, Dean.

Is ThreadPoolExecutor.execute(Runnable) thread-safe?

Is ThreadPoolExecutor.execute(Runnable) thread-safe, i.e. is it safe
to invoke this method from multiple threads without making any
special arrangements to ensure that not more than one thread is
in the execute() method of the ThreadPoolExecutor object at the same time
(such as synchronizing on the ThreadPoolExecutor object)?
I can find nothing in the Java 6 documentation to say it is thread-safe
(Executor, ExecutorService, ThreadPoolExecutor and package documentation).
Note that I am not asking anything about the actual execution of the Runnables.
I am asking about the act of inserting the Runnables into the thread pool.

Thanks to everyone who replied.
The three example implementations in the interface documentation for Executor, including the one where the Runnable is executed by the invoking thread, are thread-safe but only the last one needs to do anything special (namely make the execute(...) method synchronized) to be thread-safe. It is not clear whether the thread-safety of the first two implementations is conscious or accidental. Even if conscious that would not imply that it is necessary.
I think the published documentation (unless I've missed something) is deficient. The method would not be useless if not thread-safe. I don't think thread-safety is a safe default assumption. I think a package that supports concurrent programming should be clear on where it is thread-safe.
I've had a quick look at the source code in the 1.6 JDK implementation. It makes a serious and plausible effort to be thread-safe. It was written by Doug Lea.
I'm going to assume the method is thread-safe, based on looking at the source code.

Link Table between CRM and ERP

Hi Experts,
Does anyone knows the link table between CRM and ERP for Contact Person (Buss Part) CRM and Contact Person ERP.
In my customer system, contacts are automatically duplicated in CRM.
When you make a change in ERP, this change is automatically done in CRM.
So I suppose that there is a table between the both systems to find the corresponding number...
Thank you for your help and hope my English is good enough to understand :o)
Best regards,
Luis.

Hi Micky,
Thanks for your answer.
Unfortunatelly, number are differents...
I move this question to CRM forum ;o)
Kr,
Luis.
This has been solved in this thread:
Link Table between CRM and ERP
Edited by: Luis Loredo Marino on Feb 24, 2010 1:24 PM

Are static objects thread safe?

hi,
i have seen code that looks like this:
private static TestObject _to;
static {
_to = new TestObject();
if methods within TestObject contain local variables, will local variables inside _to be threadsafe when hit by 2 requests?
eg.
User 1 makes a request to:
_to.setStuff("abc");
User 2 make a request to:
_to.setStuff("def");
Will User 1's now see "def" instead of "abc"?
thanks
- Edward Han
[email protected]

so what happens to the local variable holder? if 2
people access the static variable _to and call
setStuff() one right after the other, is there a
chance that the first person in will print out what
the second person in set as the holder?
Local variables are thread specific and live on an execution stack, and each thread gets its own stack. If there are two threads, there are two stacks, and if both threads are "in" setstuff(), there are two distinct references called "holder" -- one per stack. And regardless of the order in which the threads enter that method, the references themselves are not clobbered. Now, what you see printed is an entirely different issue, as is the case if the "holder" references point to the same (shared) object.
The key is this: a thread-specific resource is thread safe; a shared (unprotected and/or mutable) resource is not.

Any body explain me the differrence between BAPI and RFC

Hi gurues,
The main difference between rfc and bapi is calling the non sap system. Other than that what r the differrence . How sap modules works other machine without sap is installed.

The difference is not importat while you understand the concept.
I think, RFC is the protocol for calling functions from external systems in R/3.
I understand like BAPI a series of complet functions that SAP offers you for use and model a business use.
But if I need program a function that can be called for external system i would call it RFC_NAME, because is a unique function that makes a single task.
In other words, the difference i think is about work idea more than another thing.
RFC
A remote function call is a call to a function module running in a system different from the caller's. The remote function can also be called from within the same system (as a remote call).
RFC consists of two interfaces : A calling interface for ABAP Programs and a calling interface for Non-SAP programs.
The RFC Interface takes care of :-
Converting all parameter data to the representation needed in the remote system
Calling the communication routines needed to talk to the remote system.
Handling communications errors, and notifying the caller, if desired ( using EXCEPTIONS paramater of the CALL FUNCTION).
BAPI
BAPIs are standardized programming interfaces (methods) enabling external applications to access business processes and data in the R/3 System.
BAPIs provide stable and standardized methods to achieve seamless integration between the R/3 System and external applications, legacy systems and add-ons.
BAPIs are defined in the BOR(Business object repository) as methods of SAP business object types that carry out specific business functions.
BAPIs are implemented as RFC-enabled function modules and are created in the Function Builder of the ABAP Workbench.
The most critical difference btwn BAPI and FM is that BAPI can be wrapped in Business objects whereas RFC cant.
BAPI are RFC enabled function modules. the difference between RFc and BAPI are business objects. You create business objects and those are then registered in your BOR (Business Object Repository) which can be accessed outside the SAP system by using some other applications (Non-SAP) such as VB or JAVA. in this case u only specify the business object and its method from external system in BAPI there is no direct system call. while RFC are direct system call Some BAPIs provide basic functions and can be used for most SAP business object types. These BAPIs should be implemented the same for all business object types. Standardized BAPIs are easier to use and prevent users having to deal with a number of different BAPIs. Whenever possible, a standardized BAPI must be used in preference to an individual BAPI.
The following standardized BAPIs are provided:
Reading instances of SAP business objects
GetList ( ) With the BAPI GetList you can select a range of object key values, for example, company codes and material numbers.
The BAPI GetList() is a class method.
GetDetail() With the BAPI GetDetail() the details of an instance of a business object type are retrieved and returned to the calling program. The instance is identified via its key. The BAPI GetDetail() is an instance method. BAPIs that can create, change or delete instances of a business object type
The following BAPIs of the same object type have to be programmed so that they can be called several times within one transaction. For example, if, after sales order 1 has been created, a second sales order 2 is created in the same transaction, the second BAPI call must not affect the consistency of the sales order 2. After completing the transaction with a COMMIT WORK, both the orders are saved consistently in the database.
Create( ) and CreateFromData! ( )
The BAPIs Create() and CreateFromData() create an instance of an SAP business object type, for example, a purchase order. These BAPIs are class methods.
Change( )
The BAPI Change() changes an existing instance of an SAP business object type, for example, a purchase order. The BAPI Change () is an instance method.
Delete( ) and Undelete( ) The BAPI Delete() deletes an instance of an SAP business object type from the database or sets a deletion flag.
The BAPI Undelete() removes a deletion flag. These BAPIs are instance methods.
Cancel ( ) Unlike the BAPI Delete(), the BAPI Cancel() cancels an instance of a business object type. The instance to be cancelled remains in the database and an additional instance is created and this is the one that is actually canceled. The Cancel() BAPI is an instance method.
Add<subobject> ( ) and Remove<subobject> ( ) The BAPI Add<subobject> adds a subobject to an existing object inst! ance and the BAPI and Remove<subobject> removes a subobject from an object instance. These BAPIs are instance methods.
Check these Links out
http://searchsap.techtarget.com/ateQuestionNResponse/0,289625,sid21_cid558752_tax293481,00.html
http://www.sap-img.com/abap/interview-question-on-bapi-rfc-abap-objects-tables.htm
http://www.sap-img.com/fu033.htm
http://www.sap-img.com/abap/ale-bapi.htm
Refer following SDN threads:
Diff. Between BAPI and RFC
Re: BAPI and RFC
difference between RFC and BAPI
Re: Difference Between BAPI and RFC?
Reward all the helpful answers.

DLL and LVLIB

Could anyone explain what is the difference between DLL and LVLIB?
Anandelamaran Duraisamy,
Senior Project Engineer,
Soliton Technologies (P) Ltd,
www.solitontech.com
Solved!
Go to Solution.

One more thing:
DLLs *contain* the code that is shared, this means that to distribute a shared library in this form, all you need to do is supply the 1 file (admitidly header files and documentation are nice, but not essential).
On the other hand LVLibs do not contain the actual code, they only contain a list of the VIs that should be included (and where to find them) etc. So, to distribute a LVlib shared library you need to include the lvlib file AND the associated VIs.
PS. LabVIEW 2010 has a new feature called Packed Project Libraries that are much close to DLLs than regular Project Libraries (LVLibs) - in simple terms, they are a lvlib and all of its contained VIs packed into a single file.

Sapmmc - jstart.exe keeps restarting, switching between green and yellow

Hi Friends,
I installed the SAP core server ( as part of SAP convergent charging) , but jstart.exe and dispatcher-1 process in sapmmc are noticed keep switching between yellow and green. when the jstart.exe turns green (all process running) , dispatcher-1 turns yellow (waiting to start) and when dispatcher-1 turns green (restart-yes) , jstart.exe turns yellow (some processes running). Only for a small duration , they both remain green (may be during transition).
Trace File is as below: Iam not sure as what is missing here to be installed, as it is complaining about JEE directory in
C:\usr\sap\C06\CCD09\j2ee\cluster\bin, which is not present., which was never installed as part of the installation.
trc file: "dev_jstart.new", trc level: 1, release: "711"
sysno      09
sid        C06
systemid   562 (PC with Windows NT)
relno      7110
patchlevel 0
patchno    92
intno      20020600
make       multithreaded, Unicode, 64 bit, optimized
profile    C:\usr\sap\C06\SYS\profile\C06_CCD09_W2K8-Sap-01
pid        3596
ACTIVE TRACE LEVEL           1
ACTIVE TRACE COMPONENTS      All, egi
Wed Oct 26 04:53:47 2011
trace logging activated, max size = 52428800 bytes, 2 versions
arguments :
arg[ 0] : C:\usr\sap\C06\CCD09\exe\jstart.EXE
arg[ 1] : pf=C:\usr\sap\C06\SYS\profile\C06_CCD09_W2K8-Sap-01
trc file: "C:\usr\sap\C06\CCD09\work\dev_jstart", trc level: 1, release: "711"
ACTIVE TRACE LEVEL           1
ACTIVE TRACE COMPONENTS      All, egi
F
F [Thr 3600] Wed Oct 26 04:53:47 2011
F [Thr 3600] *** ERROR => SfCheckJeeVersion: Cannot find JEE binary directory C:\usr\sap\C06\CCD09\j2ee\cluster\bin. [sfxxmain.cpp 848]
trc file: "C:\usr\sap\C06\CCD09\work\dev_jstart", trc level: 1, release: "711"
ACTIVE TRACE LEVEL           1
ACTIVE TRACE COMPONENTS      All, egi
F [Thr 3600] *** ERROR => SfCheckJeeVersion: Cannot find JEE application directory C:\usr\sap\C06\CCD09\j2ee\cluster\apps. [sfxxmain.cpp 857]
F ********************************************************************************
F Java environment properties (C:\usr\sap\C06\CCD09\work\jstart.jvm)
F    root directory    : C:\usr\sap\C06\CCD09\exe\sapjvm_6
F    vendor            : SAP AG
F    version           : 1.6.0_24
F    cpu               : amd64
F    java vm type      : server
F    java vm version   : 6.1.027 1.6-b07
F    jvm library name : jvm.dll
F    library path      : C:\usr\sap\C06\CCD09\exe\sapjvm_6\jre\bin\server;C:\usr\sap\C06\CCD09\exe\sapjvm_6\jre\bin
F    executable path   : C:\usr\sap\C06\CCD09\exe\sapjvm_6\bin
F ********************************************************************************
F    SAP extensions    : available
F ********************************************************************************
I [Thr 3600] MtxInit: 30002 0 2
dispatcher trace
trc file: "C:\usr\sap\C06\CCD09\work\dev_dispatcher-1", trc level: 1, release: "711"
sysno      09
sid        C06
systemid   562 (PC with Windows NT)
relno      7110
patchlevel 0
patchno    92
intno      20020600
make       multithreaded, Unicode, 64 bit, optimized
profile    C:\usr\sap\C06\SYS\profile\C06_CCD09_W2K8-Sap-01
pid        428
ACTIVE TRACE LEVEL           1
ACTIVE TRACE COMPONENTS      All, egi
Wed Oct 26 06:22:16 2011
trace logging activated, max size = 52428800 bytes, 2 versions
arguments :
arg[ 0] : C:\usr\sap\C06\CCD09\exe\jstart.EXE
arg[ 1] : -appTrc
arg[ 2] : -nodeId=0
arg[ 3] : pf=C:\usr\sap\C06\SYS\profile\C06_CCD09_W2K8-Sap-01
arg[ 4] : -hostvm
arg[ 5] : -nodeName=dispatcher-1
arg[ 6] : -file=C:\usr\sap\C06\CCD09\config\jstart.config
arg[ 7] : -jvmFile=C:\usr\sap\C06\CCD09\work\jstart.jvm
arg[ 8] : -traceFile=C:\usr\sap\C06\CCD09\work\dev_dispatcher-1
arg[ 9] : -javaOutFile=C:\usr\sap\C06\CCD09\work\jvm_dispatcher-1.out
F
F Wed Oct 26 06:22:16 2011
F ********************************************************************************
F Java environment properties
F    root directory    : C:\usr\sap\C06\CCD09\exe\sapjvm_6
F    vendor            : SAP AG
F    version           : 1.6.0_24
F    cpu               : amd64
F    java vm type      : server
F    java vm version   : 6.1.027 1.6-b07
F    jvm library name : jvm.dll
F    library path      : C:\usr\sap\C06\CCD09\exe\sapjvm_6\jre\bin\server;C:\usr\sap\C06\CCD09\exe\sapjvm_6\jre\bin
F    executable path   : C:\usr\sap\C06\CCD09\exe\sapjvm_6\bin
F    SAP extensions    : available
F ********************************************************************************
I [Thr 3828] MtxInit: 10000 0 2
M [Thr 3828] NiInit3: NI already initialized; param 'maxHandles' ignored (init=2;par=202;cur=2048)
M [Thr 3828] CCMS: AlInitGlobals : alert/use_sema_lock = TRUE.
M [Thr 3828] CCMS: Initalized shared memory of size 60000000 for monitoring segment.
M [Thr 3828] CCMS: Checking Downtime Configuration of Monitoring Segment.
M
M [Thr 3828] Wed Oct 26 06:22:17 2011
M [Thr 3828] CCMS: AlMsUpload called by wp 1004.
M [Thr 3828] CCMS: AlMsUpload failed for C:\usr\sap\C06\CCD09\log\ALMTTREE.DAT.
M [Thr 3828] CCMS: CCMS Monitoring Initialization finished, rc=0.
F
Please help.
Thanks.
Edited by: Zain Ahmed on Oct 26, 2011 9:07 PM

HI,
Import the SAP profiles in SAP transaction RZ10: Utilities - Import profiles - of Active Server
OR
Check what messages do you have in jvm_server0.out, dev_server0.out and bootstrap traces,
also have a look at the note 142100.
The first problem is that in the SCS instance there are no running enqueue server as its starting line have no line break at the end in the start profile. Without this NT cannot parse the line. After adding the line break the enqueue server could start.
The second problem is that in the global dispatcher configuration for the LockingManager the en.port was set to 3201 instead of 3200 (which is correct as the SCS instance has the intance number 00).
After correcting these problems the J2EE engine could be started fine.
see similar threads
Dispatcher - Running but Dialog Queue info unavailable
/thread/96588 [original link is broken]
logon710
Message server not starting
Thanks
Swarup

Are Queues thread safe

Hi all,
Are Queues thread safe i.e. are enqueue, dequeue etc atomic?
I'm looking to use Queues to transfer object states between concurrent loops, but am concerned whether I need to protect access via a semaphore.
Thanks
Phill
Solved!
Go to Solution.

Hi all,
I've been discussing transfering the state of an object between concurrent loops here and was hoping to use a single element queue.
I'm still a little worried about a context switch while I'm updating the status of the object in the area highlighted.
Would I still need a semaphore lock to ensure the data integrity of the queue between the flush and enqueue in case the data loop sneaks in and tries to read the queue?

How to use CVI or VC function to exchange data between 78xxR and CVI or MFC exe

with the Labview FPGA module,I write down th FPGA program on the 78xxR,and then use Labview to program for the data exchange between the host PC and the FPGA board. the question is that I have many programs written in CVI or MFC, I think if some c function can access the FIFO of the 78xxRunder under CVI or VC,for example, some functions available to copy data to or from the FIFO, then the old program can easily be change to use 78xxR board. can someone tell me?
now I use "Call Library Function Node" to load a dll that open shared memory created in CVI or MFC exe, use "Call Library Function Node"to read data from the shared memory and then use LV function to write data to FPGA; use LV "read/write control" node to Read data from the FPGA and then use "Call Library Function Node" to write data to shared memory. and a CVI or MFC exe read or write data to or from the shared memory, it works but isn't a good method, can some one has better method?

Hi, david2K:
     As there is no FPGA module supported for CVI or MFC, using "Call library Function node" is the only way to solve your problem until now.
    You have many programs written in CVI or MFC, so you can build the LabVIEW program as dll, and call it in CVI.
    Hope it helpful!
Jing Zhang
Application engineer.
[email protected]

Thread Safe Queue Between DLL and EXE

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