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  1. #1
    Join Date
    Jun 2009

    [RESOLVED] GUI app runs fast and then slows down


    Program: Downloads thumbnails from photobucket.com galleries and displays them in ListView controls on the main form.
    there is a ListView for each gallery that is downloaded. each gallery is chosen by a TabControl
    also there is a second form that has a ListBox on it that lists the url's for download

    My problem is that the GUI in my program works fine and all the thumbnails are added to the ListView pretty much instantly after its been downloaded. after a few galleries have been downloaded. the process of adding the thumbnails to the ListView is noticeably slow. even tho the thumbnails are already downloaded.

    i am using threads in this program.
    The main thread which is for the gui of the main form.
    the 2nd form is running on its own thread.
    a specified amount of threads are started to download images that are inserted in to a download queue (at the moment this is 10)
    a thread is also added to add the images to the ListViews (this was an attempt to fix this problem and better then the previous way of adding the images)

    the process
    main thread:
    link to gallery
    -> download the gallery and extract the links to the thumbnails
    -> each thumbnail link is inserted in to the download queue

    downloadqueue thread:
    loops till there is a link in the queue
    -> downloads the thumbnail
    -> the thumbnail image is inserted in to a List<> which holds information about the thumbnail

    addtolistview thread:
    loops till there is a thumbnail in the List<>
    -> creates a Bitmap of the image data
    -> using .Invoke adds the Bitmap to a ImageList on the main form
    -> using .Invoke adds an item to the ListView linking to the correct image

    as i said it works nicely to start off with and then gradually the performance slows

    any help will be appreciated
    thank you in advance

  2. #2
    Join Date
    Mar 2004
    Prague, Czech Republic, EU

    Re: GUI app runs fast and then slows down

    How much memory doest the application consume? Maybe there is a memory leak which forces OS to swap. What¨s disk activity? Does it significantly increase?
    • Make it run.
    • Make it right.
    • Make it fast.

    Don't hesitate to rate my post.

  3. #3
    Join Date
    Jun 2009

    Re: GUI app runs fast and then slows down

    it doesnt actually download the thumbnails to the disk it creates a Bitmap using a Byte[] dynamically
    it does use fair amount of memory ive seen it at about 160MB
    as far as i can tell its not paging the memory ...
    the cpu is at about 65% for my dual core
    is there an easy way to check for a memory link
    thanks boudino

  4. #4
    Join Date
    Jun 2009

    Re: GUI app runs fast and then slows down

    ok i think ive fixed it...
    but what i did was to create a new ImageList for each Tab.
    i think it was going slow because there would be over 1000-2000+ images in the one ImageList and i was using a String key to link it to the thumbnail that was added to the ListView
    Thank You for your Help

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