WeChat public platform background response slow how to reply to the empty string after calling the customer service interface

What is the format of this empty string? is public function Responsetextcs ()
{
echo "";
Return "";
}
In this format, why do you want to send the request again?

Reply content:

What is the format of this empty string? is public function Responsetextcs ()
{
echo "";
Return "";
}
In this format, why do you want to send the request again?

It should be written like this ... Call the customer service interface please see multi-service.

No one answered the question.
I have encountered the same problem, I added, because
echo "", there are other business processes, such as the operation of the DB, may lead to delay, I understand because of the PHP single-threaded reason. So the solution is to use asynchronous scenarios. But PHP itself seems to have no better asynchronous solution to handle this kind of thing.

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