[prev in list] [next in list] [prev in thread] [next in thread]
List: kde-devel
Subject: Re: Review Request 116692: Lower memory usage of akonadi_baloo_indexer with frequent commits
From: "Vishesh Handa" <me () vhanda ! in>
Date: 2014-07-07 10:00:41
Message-ID: 20140707100041.3848.78672 () probe ! kde ! org
[Download RAW message or body]
--===============8329231332594971382==
MIME-Version: 1.0
Content-Type: text/plain; charset="utf-8"
Content-Transfer-Encoding: 7bit
> On March 21, 2014, 10:58 a.m., Christian Mollekopf wrote:
> > It turned out that most of the memory was used the ItemFetchJob loading all items \
> > into memory. We've now optimized this, and for me the indexer never goes beyond \
> > ~250MB (initial indexing), and during normal usage stays around 10MB. I made some \
> > experiments with notmuch mail (which also uses xapian), and it also stayed around \
> > 200MB. This could probably be further tweaked by adjusting XAPIAN_FLUSH_THRESHOLD \
> > to lower the amounts of commits that are held in memory, but IMO 250MB for the \
> > initial indexing is a sane default value.
> > The only optimization that I think would be viable is releasing the memory again \
> > using malloc_free or alike (as we used to do in the nepomuk indexer).
> > So have the recent fixes also fixed the memory consumption for you or do you \
> > still think this patch should go in?
Ping. If there are no objections, I'll discard this review request.
- Vishesh
-----------------------------------------------------------
This is an automatically generated e-mail. To reply, visit:
https://git.reviewboard.kde.org/r/116692/#review53637
-----------------------------------------------------------
On March 10, 2014, 11:12 a.m., Aaron J. Seigo wrote:
>
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> https://git.reviewboard.kde.org/r/116692/
> -----------------------------------------------------------
>
> (Updated March 10, 2014, 11:12 a.m.)
>
>
> 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#acbea2163142de795024880a7123bc693 \
> 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 day
s. 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/emailindexer.cpp 05f80cf
> 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
>
> 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)
>
> Thanks,
>
> Aaron J. Seigo
>
>
--===============8329231332594971382==
MIME-Version: 1.0
Content-Type: text/html; charset="utf-8"
Content-Transfer-Encoding: 7bit
<html>
<body>
<div style="font-family: Verdana, Arial, Helvetica, Sans-Serif;">
<table bgcolor="#f9f3c9" width="100%" cellpadding="12" style="border: 1px #c9c399 \
solid; border-radius: 6px; -moz-border-radius: 6px; -webkit-border-radius: 6px;"> \
<tr> <td>
This is an automatically generated e-mail. To reply, visit:
<a href="https://git.reviewboard.kde.org/r/116692/">https://git.reviewboard.kde.org/r/116692/</a>
</td>
</tr>
</table>
<br />
<blockquote style="margin-left: 1em; border-left: 2px solid #d0d0d0; padding-left: \
10px;"> <p style="margin-top: 0;">On March 21st, 2014, 10:58 a.m. UTC, <b>Christian \
Mollekopf</b> wrote:</p> <blockquote style="margin-left: 1em; border-left: 2px solid \
#d0d0d0; padding-left: 10px;"> <pre style="white-space: pre-wrap; white-space: \
-moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: \
break-word;">It turned out that most of the memory was used the ItemFetchJob loading \
all items into memory. We've now optimized this, and for me the indexer never \
goes beyond ~250MB (initial indexing), and during normal usage stays around 10MB. I \
made some experiments with notmuch mail (which also uses xapian), and it also stayed \
around 200MB. This could probably be further tweaked by adjusting \
XAPIAN_FLUSH_THRESHOLD to lower the amounts of commits that are held in memory, but \
IMO 250MB for the initial indexing is a sane default value.
The only optimization that I think would be viable is releasing the memory again \
using malloc_free or alike (as we used to do in the nepomuk indexer).
So have the recent fixes also fixed the memory consumption for you or do you still \
think this patch should go in?</pre> </blockquote>
</blockquote>
<pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: \
-pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;"><p style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">Ping. \
If there are no objections, I'll discard this review request.</p></pre> <br />
<p>- Vishesh</p>
<br />
<p>On March 10th, 2014, 11:12 a.m. UTC, Aaron J. Seigo wrote:</p>
<table bgcolor="#fefadf" width="100%" cellspacing="0" cellpadding="12" style="border: \
1px #888a85 solid; border-radius: 6px; -moz-border-radius: 6px; \
-webkit-border-radius: 6px;"> <tr>
<td>
<div>Review request for Akonadi and Baloo.</div>
<div>By Aaron J. Seigo.</div>
<p style="color: grey;"><i>Updated March 10, 2014, 11:12 a.m.</i></p>
<div style="margin-top: 1.5em;">
<b style="color: #575012; font-size: 10pt;">Repository: </b>
baloo
</div>
<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Description </h1>
<table width="100%" bgcolor="#ffffff" cellspacing="0" cellpadding="10" \
style="border: 1px solid #b8b5a0"> <tr>
<td>
<pre style="margin: 0; padding: 0; white-space: pre-wrap; white-space: \
-moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: \
break-word;">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#acbea2163142de795024880a7123bc693 \
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 1 00k 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</pre> </td>
</tr>
</table>
<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Testing </h1>
<table width="100%" bgcolor="#ffffff" cellspacing="0" cellpadding="10" style="border: \
1px solid #b8b5a0"> <tr>
<td>
<pre style="margin: 0; padding: 0; white-space: pre-wrap; white-space: \
-moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: \
break-word;">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)</pre> </td>
</tr>
</table>
<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Diffs</b> </h1>
<ul style="margin-left: 3em; padding-left: 0;">
<li>src/pim/agent/emailindexer.cpp <span style="color: grey">(05f80cf)</span></li>
<li>src/pim/agent/abstractindexer.h <span style="color: grey">(8ae6f5c)</span></li>
<li>src/pim/agent/abstractindexer.cpp <span style="color: \
grey">(fa9e96f)</span></li>
<li>src/pim/agent/akonotesindexer.h <span style="color: grey">(83f36b7)</span></li>
<li>src/pim/agent/akonotesindexer.cpp <span style="color: \
grey">(ac3e66c)</span></li>
<li>src/pim/agent/contactindexer.h <span style="color: grey">(49dfdeb)</span></li>
<li>src/pim/agent/contactindexer.cpp <span style="color: grey">(a5a6865)</span></li>
<li>src/pim/agent/emailindexer.h <span style="color: grey">(9a5e5cf)</span></li>
</ul>
<p><a href="https://git.reviewboard.kde.org/r/116692/diff/" style="margin-left: \
3em;">View Diff</a></p>
</td>
</tr>
</table>
</div>
</body>
</html>
--===============8329231332594971382==--
>> Visit http://mail.kde.org/mailman/listinfo/kde-devel#unsub to unsubscribe <<
[prev in list] [next in list] [prev in thread] [next in thread]
Configure |
About |
News |
Add a list |
Sponsored by KoreLogic