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From "Dave Cottlehuber (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (COUCHDB-1334) Indexer speedup (for non-native view servers)
Date Tue, 11 Dec 2012 19:37:21 GMT

    [ https://issues.apache.org/jira/browse/COUCHDB-1334?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13529253#comment-13529253
] 

Dave Cottlehuber commented on COUCHDB-1334:
-------------------------------------------

NB this break the Windows build, specifically the erlang VM hangs (no console access nor HTTP
response) during tests such as purge. Killing couchjs causes the VM to be freed again, until
the next deadlock.

Viewed in windbg or similar debugger, couchjs has unexpected data in the buffer, and is waiting
for a response from the port. The port is apparently waiting on data to return from couchjs,
a mexican standoff occurs. Why this causes the VM to hang is not yet clear. More details (and
a lot of unrelated stuff) in COUCHDB-1346.
                
> Indexer speedup (for non-native view servers)
> ---------------------------------------------
>
>                 Key: COUCHDB-1334
>                 URL: https://issues.apache.org/jira/browse/COUCHDB-1334
>             Project: CouchDB
>          Issue Type: Improvement
>          Components: Database Core, JavaScript View Server, View Server Support
>            Reporter: Filipe Manana
>            Assignee: Filipe Manana
>             Fix For: 1.3
>
>         Attachments: 0001-More-efficient-view-updater-writes.patch, 0002-More-efficient-communication-with-the-view-server.patch,
master-0002-More-efficient-communication-with-the-view-server.patch, master-2-0002-More-efficient-communication-with-the-view-server.patch,
master-3-0002-More-efficient-communication-with-the-view-server.patch, master-4-0002-More-efficient-communication-with-the-view-server.patch
>
>
> The following 2 patches significantly improve view index generation/update time and reduce
CPU consumption.
> The first patch makes the view updater's batching more efficient, by ensuring each btree
bulk insertion adds/removes a minimum of N (=100) key/value pairts. This also makes the index
file size grow not so fast with old data (old btree nodes basically). This behaviour is already
done in master/trunk in the new indexer (by Paul Davis).
> The second patch maximizes the throughput with an external view server (such as couchjs).
Basically it makes the pipe (erlang port) communication between the Erlang VM (couch_os_process
basically) and the view server more efficient since the 2 sides spend less time block on reading
from the pipe.
> Here follow some benchmarks.
> test database at  http://fdmanana.iriscouch.com/test_db  (1 million documents)
> branch 1.2.x
> $ echo 3 > /proc/sys/vm/drop_caches
> $ time curl http://localhost:5984/test_db/_design/test/_view/test1
> {"rows":[
> {"key":null,"value":1000000}
> ]}
> real	2m45.097s
> user	0m0.006s
> sys	0m0.007s
> view file size: 333Mb
> CPU usage:
> $ sar 1 60
> 22:27:20  %usr  %nice   %sys   %idle
> 22:27:21   38      0     12     50
> (....)
> 22:28:21   39      0     13     49
> Average:     39      0     13     47   
> branch 1.2.x + batch patch (first patch)
> $ echo 3 > /proc/sys/vm/drop_caches
> $ time curl http://localhost:5984/test_db/_design/test/_view/test1
> {"rows":[
> {"key":null,"value":1000000}
> ]}
> real	2m12.736s
> user	0m0.006s
> sys	0m0.005s
> view file size 72Mb
> branch 1.2.x + batch patch + os_process patch
> $ echo 3 > /proc/sys/vm/drop_caches
> $ time curl http://localhost:5984/test_db/_design/test/_view/test1
> {"rows":[
> {"key":null,"value":1000000}
> ]}
> real	1m9.330s
> user	0m0.006s
> sys	0m0.004s
> view file size:  72Mb
> CPU usage:
> $ sar 1 60
> 22:22:55  %usr  %nice   %sys   %idle
> 22:23:53   22      0      6     72
> (....)
> 22:23:55   22      0      6     72
> Average:     22      0      7     70   
> master/trunk
> $ echo 3 > /proc/sys/vm/drop_caches
> $ time curl http://localhost:5984/test_db/_design/test/_view/test1
> {"rows":[
> {"key":null,"value":1000000}
> ]}
> real	1m57.296s
> user	0m0.006s
> sys	0m0.005s
> master/trunk + os_process patch
> $ echo 3 > /proc/sys/vm/drop_caches
> $ time curl http://localhost:5984/test_db/_design/test/_view/test1
> {"rows":[
> {"key":null,"value":1000000}
> ]}
> real	0m53.768s
> user	0m0.006s
> sys	0m0.006s

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