可以在闭包中调用setTimeout导致内存泄漏吗？

Question

I have a third-party JavaScript object on which I'm calling a method “search” and passing in a search query string along with a function to execute once the search is complete. This third-party object then goes away and attempts to retrieve data from a service. If the service call fails to return within 10 seconds, the third-party object logs a timeout error but unfortunately doesn't execute the callback function with a status of “Timeout” or something else applicable.

In order to have the callback execute when there has been a timeout, I've wrapped the third-party object call as per the code below:

var SEARCH_TIMEOUT_MILLISECONDS = 10500;

var thirdPartyObject = ... // Global variable

function search(searchTerm, onCompleteCallback) {

    var searchTimeoutHandler = setTimeout(function () {
        onCompleteCallback(null, 'TIMEOUT');
    }, SEARCH_TIMEOUT_MILLISECONDS);

    thirdPartyObject.search({
        searchTerm: searchTerm,
        onComplete: function (searchResponse, status) {

            clearTimeout(searchTimeoutHandler);

            onCompleteCallback(searchResponse, status);
        }
    });
}

Where a closure is being created, if this function was called hundreds of times (some concurrently), would there be any memory issues in the scenarios of the setTimeout function either being or not being called?

Answer 1

No, there shouldn't be any memory leaks. There are only two scenarios as far as the timeout is concerned:

• Timeout handler is called, after which it is garbage collected.
• Timeout is cleared, after which it is also garbage collected.

However, if you have multiple searches being done hundreds of times, those timeout handlers can pile up, but they will eventually be cleared (after taking at most n * SEARCH_TIMEOUT_MILLISECONDS , where n is the number of times search has been called which is also the number of instances of timeout handlers you will have). So there is no memory-leak per se, but you can have things stacking up. You might have to tune the SEARCH_TIMEOUT_MILLISECONDS variable so that you don't have things stacking up. You can also look at memory usage on Chrome Developer Tools to see how much memory is being used up.