This patch tries to solve a serious problem with zathura leaking a horrendous amount of memory during scrolling through a document.
The problem is that the current way of periodically reclaiming the cairo surfaces of the pages widgets is not working at all. The only case in which it seems to work is the first time (and "only" the first time) the timeout function purge_pages is triggered, and even this first time sometimes doesn't free the memory if it happened while scrolling through the document. To see it in action, try opening a large document (e.g. 500+ pages), and scroll through it by dragging the scrollbar or continuously pressing <shift-j>, or <shift-k>. Meanwhile, watch the output of 'top $(pidof zathura)' until you end up with a throttled system riddled with continuous swapping. Zathura will fiercely eat all the physical system memory while scrolling through a relatively big document. I've spent a while trying to figure out why the memory isn't freed after the first time the timeout function is triggered, but quite frankly, I couldn't manage to get to any reasonable conclusion. Injecting debug messages in zathura_page_widget_update_surface shows that all the pages, but the current visible one, are eventually reclaimed. This means that cairo_surface_destroy must have been called on every surface of a page that exceeded it's end-of-life threshold, but without actually doing it's job of freeing the surface memory. So, this patch bypasses this mechanism by freeing a surface as soon as it's associated page becomes invisible. Try repeating the same experiment as above with this patch, and watch the rate of memory consumption drops dramatically. I scrolled the entire length of a 1300-pages document and the end result was 500 MB. And I don't think this is leaking memory due to cairo surfaces pixel buffers, because it never increases after reaching this limit. Maybe it's some internal allocations done by GTK or GDK. This doesn't seem very far-fetched for an application with 1300+ GTK widgets in this case. While browsing the bug tracker for related issues, I found the one at http://bugs.pwmt.org/issue95 which points out the 0.0.8.5 version as not suffering from this problem. I built it and experimented. The result was that the total amount of memory consumed by scrolling through the length of the 1300-pages document was comparable to the one with this patch. So, there must be something messy happening with cairo_surface_destroy when it's get called from the timeout function while scrolling. Maybe it's non-reentrant and some mess happens when it's called concurrently from both the timeout function and the render thread. But if that's the case, then why doesn't it free the memory after the first time, even when there is no scrolling? Also, I tried to experiment with mutexes around the cairo_surface_destroy calls on the render thread and zathura_page_widget_update_surface but nothing surprising has happened. So, what's your suggestions, ideas (or maybe patches :-))? And what's the final destiny of the periodic page reclaiming code? Marwan Tanager (1): Fix a horrible memory leak. callbacks.c | 3 +++ page-widget.c | 9 +++++++++ page-widget.h | 8 ++++++++ 3 files changed, 20 insertions(+) -- 1.7.10.4 _______________________________________________ zathura mailing list zathura@lists.pwmt.org http://lists.pwmt.org/mailman/listinfo/zathura
