Does the .net function Parallel.ForEach block the calling thread? My guess as to the behavior is one of these:
Or perhaps something else is happening, anyone know for sure?
This question came up when implementing this in a logging class:
public class MultipleLoggingService : LoggingServiceBase
{
private readonly List<LoggingServiceBase> loggingServices;
public MultipleLoggingService(List<LoggingServiceBase> loggingServices)
{
this.loggingServices = loggingServices;
LogLevelChanged += OnLogLevelChanged;
}
private void OnLogLevelChanged(object sender, LogLevelChangedArgs args)
{
loggingServices.ForEach(l => l.LogLevel = LogLevel);
}
public override LogMessageResponse LogMessage(LogMessageRequest request)
{
if (request.LogMessage)
Parallel.ForEach(loggingServices, l => l.LogMessage(request));
return new LogMessageResponse{MessageLogged = request.LogMessage};
}
}
Notice the LogMessage
method calls some other logging services. I need that part to return immediately, so it doesn't block the calling thread.
Update: Based on comments from others (we have confirmed the behavior is #1). So I have taken advice to use the Task library and rewritten the loop like this:
if (request.LogMessage)
foreach (var loggingService in loggingServices)
Task.Factory.StartNew(() => loggingService.LogMessage(request));
Number 1 is correct; Parallel.ForEach
does not return until the loop has completed. If you don't want that behavior, you can simply execute your loop as a Task
and run it on another thread.