HTTPClient memory leaks issue

My env is : Titanium SDK 3.2.1.GA, OS X Mavericks, iOS7, Xcode 5.0.2.

I have an app that download numerous documents from server. After the download memory consumption by the application is on very high level and don't drop. My code is :

download.js

downloadFile : function(showFolder, showId, docType, remoteFileContainer) {
        var downloadParams = {
            password : App.applicationManager.globalVariables.password,
            user_id : App.applicationManager.globalVariables.user_id,
            username : App.applicationManager.globalVariables.username,
            pdf : "1"
        };
 
        var http = this.getHTTPClient();
 
        http.onreadystatechange = function() {
            if (http.readyState == 4 && http.status == 200){
                var file = Ti.Filesystem.getFile(showFolder + Ti.Filesystem.separator + docType, fileName);
                file.write(this.responseData);
            }
        };
 
        http.open("POST", App.applicationManager.serviceDownloadFile, true);
        http.send(downloadParams);
    },
 
    getHTTPClient : function() {
        var client = Ti.Network.createHTTPClient({
            timeout : 60 * 1000,
            validatesSecureCertificate : false,
            onerror : function(e) {
                Ti.API.log('Httpclient log. Response: ' + this.responseText + 'Status: ' + this.status);
            }
        });
        return client;
    },

Can anyone get me some hint about this one? I tried to set client to null (http = null inside if (http.readyState == 4 && http.status == 200)to be GC, also tried httpClient.abort() (was so desperate :).

Thanks in advance.