ParallelTaskExecute (Function)

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ParallelTaskExecute (Function)

In french: TâcheParallèleExécute

Triggers the execution of a parallel task.

Example

See additional examples

// Utilisation de la syntaxe 1 
t1 is ParallelTask = ParallelTaskExecute(ProcédureA, (), ptoMainThread)

// Utilisation de la syntaxe 2 
t1 is ParallelTask
t1.Procedure = Procédure3
t2 is ParallelTask = ParallelTaskExecute(t1)

// Utilisation de la syntaxe 3 
t3 is Description of ParallelTask
t3.Procedure = Procédure3
ParallelTaskExecute(t3)

// Utilisation de la syntaxe 3 
t3bis is Description of ParallelTask
t3bis.Procedure = Procédure3bis
t3bis.Parameter[1] = Today()
t3bis.Parameter[2] = TimeSys()
ParallelTaskExecute(t3bis)

// Déclaration de plusieurs tâches et exécution d'un traitement à la fin de toutes ces tâches
MaDescriptionTâche is Description of ParallelTask
tabMesTâches is array of ParallelTask // Résultat des fonctions tâches parallèles 
// Tâche N°1
MaDescriptionTâche.Procedure = Exemple2_Etape1
// Exécute les tâches parallèles
// On ajoute la tâche renvoyée à un tableau de tâches 
// pour pouvoir les réutiliser dans la fonction TâcheParallèleExécuteAprèsToutes
Add(tabMesTâches, ParallelTaskExecute(MaDescriptionTâche))
// Tâche N°2
MaDescriptionTâche.Procedure = Exemple2_Etape2
Add(tabMesTâches, ParallelTaskExecute(MaDescriptionTâche))
// On donne la procédure à exécuter une fois que 
// toutes les tâches contenues dans le tableau tabMesTâches sont terminées
ParallelTaskExecuteAfterAll(tabMesTâches, Exemple2_Fin, (), ptoMainThread)

Syntax

Running a parallel task Hide the details

<Result> = ParallelTaskExecute(<Procedure> [, <Parameters> [, <Options>]])

<Result>: ParallelTask variable

ParallelTask variable corresponding to the task to run.

<Procedure>: Character string or Procedure variable

Procedure to be executed. This parameter can correspond to:
the name of the procedure to be executed.
the name of the Procedure variable corresponding to the procedure to be executed.

<Parameters>: List of values enclosed in brackets, separated by commas

Parameters of the procedure to be executed. This list of parameters has the following format:
(<Parameter 1>, ..., <Parameter N>)
where:
<Parameter 1> is the first parameter of the procedure.
...
<Parameter N> is the nth parameter of the procedure.
Warning Parameters are passed by value. In the case of variables of complex types (arrays, object), the value is the element itself.. To restrict access to this variable, you can:
make a copy of the variable (with the LOCAL keyword),
use critical sections (with CriticalSectionStart (Function) or the <critical section> attribute)

<Options>: Optional Integer constant (or combination of constants)

Options of task to run:
ptoDelayedCopyHFSQLContext
(Default value) Triggers a light copy of HFSQL context during the first access to the HFSQL data.
ptoFullCopyHFSQLContext Triggers the immediate copy of the current HFSQL context.
Recommended, for example, if the parallel task must take into account the current positions in the files and queries of the context of the caller.
ptoLightCopyHFSQLContext Triggers the immediate copy of a part of the current HFSQL context.
Only the directories containing the data files in HFSQL Classic mode and/or the connections in HFSQL Client/Server mode are stored.
ptoMainThread Runs the task in the main thread.
This constant can be combined with one of the other constants. Warning: This constant cannot be used to execute a parallel task in the main thread from within the main thread.

Note: To find out which type of copy to choose, see comparison between the different copy modes.

Running a parallel task described beforehand (ParallelTask variable) Hide the details

<Result> = ParallelTaskExecute(<Task>)

<Result>: ParallelTask variable

ParallelTask variable corresponding to the task run.

<Task>: ParallelTask variable

Name of the ParallelTask variable corresponding to the task to run.
Warning: If the task is already running or has already been executed, a WLanguage error will be triggered.

Running a parallel task identified by its description (Description of ParallelTask variable) Hide the details

<Result> = ParallelTaskExecute(<Task description>)

<Result>: ParallelTask variable

ParallelTask variable corresponding to the task run.

<Task description>: Description of ParallelTask variable

Name of the Description of ParallelTask variable that describes the task to be executed.

Remarks

The task is saved in the queue of tasks to run.
ParallelTaskExecute is not a blocking function and does not wait for task to be completed.

Comparison between the different types of copy for the HFSQL context:

Type of copy	Benefits	Drawbacks

Full copy	Copies: the extensive connection parameters (connections, physical paths, ...). positions, filters, etc. defined on data files. the queries.	Memory consumption (on the client and on the server).
Light copy	Copies the extensive connection parameters (connections, physical paths, ...). No memory consumption on the server.	The records and the current filters are not copied. Therefore, the records must be repositioned by HReadSeek for example. No copy of queries. Memory consumption on the Client computer
Delayed copy	No memory consumption (on the client and on the server).	Risk: If the connection parameters are modified, the last modification will be taken into account. The records and the current filters are not copied. Therefore, the records must be repositioned by HReadSeek for example. No copy of queries.

In most cases, the delayed copy is recommended provided that you don't change the connection parameters and that you perform the necessary calls to HReadSeek.

Related Examples:

Unit examples (WINDEV): Using parallel tasks

[ + ] The parallel tasks are used to speed up the process times and to improve the reactivity of an application.
This example presents the functions and types of variables required to use the parallel tasks:
- running parallel tasks,
- interaction with the controls,
- continuation tasks.

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