On Monday 10 March 2014 10:08:29 Aaron J. Seigo wrote: > ----------------------------------------------------------- > This is an automatically generated e-mail. To reply, visit: > https://git.reviewboard.kde.org/r/116692/ > ----------------------------------------------------------- > > Review request for Akonadi and Baloo. > > > Repository: baloo > > > Description > ------- > > Baloo is using Xapian for storing processed results from data fed to it by > akonadi; in doing so it processes all the data it is sent to index and only > once this is complete is the data committed to the Xapian database. From > http://xapian.org/docs/apidoc/html/classXapian_1_1WritableDatabase.html#acb > ea2163142de795024880a7123bc693 we see: "For efficiency reasons, when > performing multiple updates to a database it is best (indeed, almost > essential) to make as many modifications as memory will permit in a single > pass through the database. To ensure this, Xapian batches up > modifications." This means that *all* the data to be stored in the Xapian > database first ends up in RAM. When indexing large mailboxes (or any other > large chunk of data) this results in a very large amount of memory > allocation. On one test of 100k mails in a maildir folder this resulted in > 1.5GB of RAM used. In normal daily usage with maildir I find that it easily > balloons to several hundred megabytes within days. This makes the Baloo > indexer unusable on systems with smaller amounts of memory (e.g. mobile > devices, which typically have only 512MB-2GB of RAM) > > Making this even worse is that the indexer is both long-lived *and* the > default glibc allocator is unable to return the used memory back to the OS > (probably due to memory fragmentation, though I have not confirmed this). > Use of other allocators shows the temporary ballooning of memory during > processing, but once that is done the memory is released and returned back > to the OS. As such, this is not a memory leak .. but it behaves like one on > systems with the default glibc allocator with akonai_baloo_indexer taking > increasingly large amounts of memory on the system that never get returned > to the OS. (This is actually how I noticed the problem in the first place.) > > The approach used to address this problem is to periodically commit data to > the Xapian database. This happens uniformly and transparently to the > AbstractIndexer subclasses. The exact behavior is controlled by the > s_maxUncommittedItems constant which is set arbitrarily to 100: after an > indexer hits 100 uncommitted changes, the results are committed > immediately. Caveats: > > * This is not a guaranteed fix for the memory fragmentation issue > experienced with glibc: it is still possible for the memory to grow slowly > over time as each smaller commit leaves some % of un-releasable memory due > to fragmentation. It has helped with day to day usage here, but in the > "100k mails in a maildir structure" test memory did still balloon upwards. > > * It make indexing non-atomic from akonadi's perspective: data fed to > akonadi_baloo_indexer to be indexed may show up in chunks and even, in the > case of a crash of the indexer, be only partially added to the database. > > Alternative approaches (not necessarily mutually exclusive to this patch or > each other): > > * send smaller data sets from akonadi to akonadi_baloo_indexer for > processing. This would allow akonadi_baloo_indexer to retain the atomic > commit approach while avoiding the worst of the Xapian memory usage; it > would not address the issue of memory fragmentation * restart > akonadi_baloo_indexer process from time to time; this would resolve the > fragmentation-over-time issue but not the massive memory usage due to > atomically indexing large datasets * improve Xapian's chert backend (to > become default in 1.4) to not fragment memory so much; this would not > address the issue of massive memory usage due to atomically indexing large > datasets * use an allocator other than glibc's; this would not address the > issue of massive memory usage due to atomically indexing large datasets > > > Diffs > ----- > > src/pim/agent/abstractindexer.h 8ae6f5c > src/pim/agent/abstractindexer.cpp fa9e96f > src/pim/agent/akonotesindexer.h 83f36b7 > src/pim/agent/akonotesindexer.cpp ac3e66c > src/pim/agent/contactindexer.h 49dfdeb > src/pim/agent/contactindexer.cpp a5a6865 > src/pim/agent/emailindexer.h 9a5e5cf > src/pim/agent/emailindexer.cpp 05f80cf > > Diff: https://git.reviewboard.kde.org/r/116692/diff/ > > > Testing > ------- > > I have been running with the patch for a couple of days and one other person > on irc has tested an earlier (but functionally equivalent) version. Rather > than reaching the common 250MB+ during regular usage it now idles at ~20MB > (up from ~7MB when first started; so some fragmentation remains as noted in > the description, but with far better long-term results)
Just curious - did this get into Beta2? I just had to restart Akonadi with a akonadi-baloo-feeder process of 2.2 gb... (I just upgraded from KDE PIM 4.12 to 4.13 beta 2) > > Thanks, > > Aaron J. Seigo > > _______________________________________________ > KDE PIM mailing list kde-...@kde.org > https://mail.kde.org/mailman/listinfo/kde-pim > KDE PIM home page at http://pim.kde.org/ >> Visit http://mail.kde.org/mailman/listinfo/kde-devel#unsub to unsubscribe <<