How can I turn this into parallel.foreach-CodePudding

This is a web scraping project in C# and responses are the https responses we get but my project works so slow, so I was thinking to change those foreach calls to parallel.foreach.

var index = 0;

foreach (var response in responses) 
{
    if (index == 0) 
    {
        ParseHtmlVatan(response);
    }

    if (index == 1) 
    {
        ParseHtmlTrendyol(response);
    }

    if (index == 2) 
    {
        ParseHtmln11(response);
    }

    index  ;
}

CodePudding user response：

Parallel.ForEach provides the index as an argument to the lambda.

Parallel.ForEach(responses, (response, _, index) =>
{
    if (index == 0)
    {
        ParseHtmlVatan(response);
    }
    if (index == 1)
    {
        ParseHtmlTrendyol(response);
    }
    if (index == 2)
    {
        ParseHtmln11(response);
    }
});

Since it looks like you've got a hard-coded set of responses to start with, you could use Parallel.Invoke:

Parallel.Invoke(
    () => ParseHtmlVatan(responses[0]),
    () => ParseHtmlTrendyol(responses[1]),
    () => ParseHtmln11(responses[2])
);

CodePudding user response：

You can accomplish this easily using Parallel.For (it's a little less code than using Parallel.ForEach given your current code).

Parallel.For(0, responses.Count, index =>
{
    var response = responses[index];
    if (index == 0)
    {
        ParseHtmlVatan(response);               
    }
    if (index == 1)
    {
        ParseHtmlTrendyol(response);
    }
    if (index == 2)
    {
       ParseHtmln11(response);
    }
});

Note that hard-coding the parsing method based on the index is pretty fragile. You might want to store some information in each response instance indicating which parser to use.