[SERVER-20176] Deletes with j:true slower on WT than MMAPv1 - MongoDB

Details

Type: Bug
Status: Closed
Priority: Major - P3
Resolution: Fixed
Affects Version/s: 3.0.6, 3.1.7
Fix Version/s: 3.0.7, 3.1.9
Component/s: WiredTiger
Labels:
None

Backwards Compatibility:
Fully Compatible
Operating System:
ALL
Backport Completed:

3.0.7
Epic Link:
WT As Default
Sprint:
Quint 9 09/18/15

Description

j:true is expectedly slower than not, but WT is much slower than MMAPv1:

MMAPv1

> for(x=0;x<10000;x++){db.test.insert( { x : x } ) }

WriteResult({ "nInserted" : 1 })

> var start=new Date();db.test.remove( { } );duration=new Date() - start

> for(x=0;x<10000;x++){db.test.insert( { x : x } ) }

WriteResult({ "nInserted" : 1 })

> var start=new Date();db.test.remove( { }, { writeConcern : {j:true}} );duration=new Date() - start

> for(x=0;x<10000;x++){db.test.insert( { x : x } ) }

WriteResult({ "nInserted" : 1 })

> var start=new Date();db.test.remove( { } );duration=new Date() - start

> for(x=0;x<10000;x++){db.test.insert( { x : x } ) }

WriteResult({ "nInserted" : 1 })

> var start=new Date();db.test.remove( { }, { writeConcern : {j:true}} );duration=new Date() - start

Issue Links

depends on

WT-2104 add support for flushing the transaction log.

Resolved

is duplicated by

SERVER-20576 Calling WiredTigerRecoveryUnit::waitUntilDurableWiredtiger without journaling returns an error

Closed

SERVER-18746 ensure WT write-ahead log flush is asynchronous from writes

Closed

related to

SERVER-20617 wt_nojournal_toggle.js failing intermittently in noPassthrough_WT

Closed

SERVER-17489 in bulk ops, only mark last operation with commit=synchronous

Closed

Activity

Comments

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Githook User added a comment - Sep 19 2015 03:26:34 AM +00:00

Author:

{u'username': u'GeertBosch', u'name': u'Geert Bosch', u'email': u'geert@mongodb.com'}

Message: ~~SERVER-20176~~: For writeConcern j:1 only sync once at end of operation
Branch: master
https://github.com/mongodb/mongo/commit/37b328aeda5696ff21c86b1258708fe5bede3a16

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Githook User added a comment - Sep 19 2015 03:26:34 AM +00:00 Author: {u'username': u'GeertBosch', u'name': u'Geert Bosch', u'email': u'geert@mongodb.com'} Message: SERVER-20176 : For writeConcern j:1 only sync once at end of operation Branch: master https://github.com/mongodb/mongo/commit/37b328aeda5696ff21c86b1258708fe5bede3a16

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Githook User added a comment - Sep 23 2015 04:42:34 PM +00:00

Author:

{u'username': u'GeertBosch', u'name': u'Geert Bosch', u'email': u'geert@mongodb.com'}

Message: ~~SERVER-20176~~: Use a checkpoint instead of log_flush for --nojournal
Branch: master
https://github.com/mongodb/mongo/commit/617a1eb81610f2cc00b6aac06e408dfc17246f04

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Githook User added a comment - Sep 23 2015 04:42:34 PM +00:00 Author: {u'username': u'GeertBosch', u'name': u'Geert Bosch', u'email': u'geert@mongodb.com'} Message: SERVER-20176 : Use a checkpoint instead of log_flush for --nojournal Branch: master https://github.com/mongodb/mongo/commit/617a1eb81610f2cc00b6aac06e408dfc17246f04

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Githook User added a comment - Sep 23 2015 10:26:16 PM +00:00

Author:

{u'username': u'GeertBosch', u'name': u'Geert Bosch', u'email': u'geert@mongodb.com'}

Message: ~~SERVER-20176~~: Don't assume visibility implies durability in test
Branch: master
https://github.com/mongodb/mongo/commit/2033a39cabed03c0efc598e439c5e1eec8767243

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Githook User added a comment - Sep 23 2015 10:26:16 PM +00:00 Author: {u'username': u'GeertBosch', u'name': u'Geert Bosch', u'email': u'geert@mongodb.com'} Message: SERVER-20176 : Don't assume visibility implies durability in test Branch: master https://github.com/mongodb/mongo/commit/2033a39cabed03c0efc598e439c5e1eec8767243

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Githook User added a comment - Sep 24 2015 06:47:08 PM +00:00

Author:

{u'username': u'GeertBosch', u'name': u'Geert Bosch', u'email': u'geert@mongodb.com'}

Message: ~~SERVER-20176~~: Clarify contract of waitUntilDurable
Branch: master
https://github.com/mongodb/mongo/commit/38f6c23578438a2d67c0846f9623740513829c33

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Githook User added a comment - Sep 24 2015 06:47:08 PM +00:00 Author: {u'username': u'GeertBosch', u'name': u'Geert Bosch', u'email': u'geert@mongodb.com'} Message: SERVER-20176 : Clarify contract of waitUntilDurable Branch: master https://github.com/mongodb/mongo/commit/38f6c23578438a2d67c0846f9623740513829c33

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Githook User added a comment - Sep 24 2015 08:54:45 PM +00:00

Author:

{u'username': u'GeertBosch', u'name': u'Geert Bosch', u'email': u'geert@mongodb.com'}

Message: ~~SERVER-20176~~: Add extra check for j:1 durability
Branch: master
https://github.com/mongodb/mongo/commit/f86c9a1dfd585947762296d232391ba0f1bd304a

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Githook User added a comment - Sep 24 2015 08:54:45 PM +00:00 Author: {u'username': u'GeertBosch', u'name': u'Geert Bosch', u'email': u'geert@mongodb.com'} Message: SERVER-20176 : Add extra check for j:1 durability Branch: master https://github.com/mongodb/mongo/commit/f86c9a1dfd585947762296d232391ba0f1bd304a

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Githook User added a comment - Sep 25 2015 04:40:46 PM +00:00

Author:

{u'username': u'GeertBosch', u'name': u'Geert Bosch', u'email': u'geert@mongodb.com'}

Message: ~~SERVER-20176~~: For writeConcern j:1 only sync once at end of operation

(cherry picked from commit 37b328aeda5696ff21c86b1258708fe5bede3a16)
(cherry picked from commit 617a1eb81610f2cc00b6aac06e408dfc17246f04)
(cherry picked from commit 38f6c23578438a2d67c0846f9623740513829c33)
(cherry picked from commit 2033a39cabed03c0efc598e439c5e1eec8767243)
(cherry picked from commit f86c9a1dfd585947762296d232391ba0f1bd304a)

Conflicts:
src/mongo/db/storage/recovery_unit.h
src/mongo/db/storage/wiredtiger/wiredtiger_recovery_unit.cpp
src/mongo/db/storage/wiredtiger/wiredtiger_recovery_unit.h
src/mongo/db/storage/wiredtiger/wiredtiger_snapshot_manager.cpp
src/mongo/db/storage/wiredtiger/wiredtiger_snapshot_manager.h
Branch: v3.0
https://github.com/mongodb/mongo/commit/88e5b19dc436208effc324daff5c54c7bd261803

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Githook User added a comment - Sep 25 2015 04:40:46 PM +00:00 Author: {u'username': u'GeertBosch', u'name': u'Geert Bosch', u'email': u'geert@mongodb.com'} Message: SERVER-20176 : For writeConcern j:1 only sync once at end of operation (cherry picked from commit 37b328aeda5696ff21c86b1258708fe5bede3a16) (cherry picked from commit 617a1eb81610f2cc00b6aac06e408dfc17246f04) (cherry picked from commit 38f6c23578438a2d67c0846f9623740513829c33) (cherry picked from commit 2033a39cabed03c0efc598e439c5e1eec8767243) (cherry picked from commit f86c9a1dfd585947762296d232391ba0f1bd304a) Conflicts: src/mongo/db/storage/recovery_unit.h src/mongo/db/storage/wiredtiger/wiredtiger_recovery_unit.cpp src/mongo/db/storage/wiredtiger/wiredtiger_recovery_unit.h src/mongo/db/storage/wiredtiger/wiredtiger_snapshot_manager.cpp src/mongo/db/storage/wiredtiger/wiredtiger_snapshot_manager.h Branch: v3.0 https://github.com/mongodb/mongo/commit/88e5b19dc436208effc324daff5c54c7bd261803

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Igor Canadi added a comment - Oct 02 2015 11:06:57 PM +00:00

Hey Geert, seems like we no longer call goingToAwaitDurable() before waitUntilDurable(). In tests, I see an invariant:

Invariant failure _sync src/mongo/db/modules/rocksdb/src/rocks_recovery_unit.cpp 261

Source: https://logkeeper.mongodb.org/build/560ea1af90413021b1b50d3d/test/560ea225be07c4135fb508c0

This is the code for invariant(), it's pretty straight-forward: https://github.com/mongodb-partners/mongo-rocks/blob/master/src/rocks_recovery_unit.cpp#L261

I'll try to debug where this happens, but if you can offer any insights, I'd be very grateful.

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Igor Canadi added a comment - Oct 02 2015 11:06:57 PM +00:00 Hey Geert, seems like we no longer call goingToAwaitDurable() before waitUntilDurable(). In tests, I see an invariant: Invariant failure _sync src/mongo/db/modules/rocksdb/src/rocks_recovery_unit.cpp 261 Source: https://logkeeper.mongodb.org/build/560ea1af90413021b1b50d3d/test/560ea225be07c4135fb508c0 This is the code for invariant(), it's pretty straight-forward: https://github.com/mongodb-partners/mongo-rocks/blob/master/src/rocks_recovery_unit.cpp#L261 I'll try to debug where this happens, but if you can offer any insights, I'd be very grateful.

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Geert Bosch added a comment - Oct 02 2015 11:31:27 PM +00:00

Yes, that's true. We have some cases where we don't really have anything to write, but still need to wait until the last write was durable. So in essence, we'd be doing an empty unit of work without any writes, but we still need to wait for any writes that happened previously to be durable.

I think this is unavoidable, as we avoid doing a write if no actual data changes, but the semantics of w:1 require that all previous writes be durable...

-Geert

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Geert Bosch added a comment - Oct 02 2015 11:31:27 PM +00:00 Yes, that's true. We have some cases where we don't really have anything to write, but still need to wait until the last write was durable. So in essence, we'd be doing an empty unit of work without any writes, but we still need to wait for any writes that happened previously to be durable. I think this is unavoidable, as we avoid doing a write if no actual data changes, but the semantics of w:1 require that all previous writes be durable... -Geert

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Igor Canadi added a comment - Oct 03 2015 12:14:48 AM +00:00

Cool. This should fix it: https://reviews.facebook.net/D48087

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Igor Canadi added a comment - Oct 03 2015 12:14:48 AM +00:00 Cool. This should fix it: https://reviews.facebook.net/D48087

People

Assignee:

Geert Bosch

Reporter:

André de Frere

Participants:

André de Frere, Geert Bosch, Githook User, Igor Canadi

Votes:

0 Vote for this issue

Watchers:

14 Start watching this issue

Dates

Created:

Aug 28 2015 01:19:52 PM +00:00

Updated:

Oct 07 2015 09:35:46 PM +00:00

Resolved:

Sep 19 2015 03:33:43 AM +00:00

Agile

Completed Sprint:

Quint 9 09/18/15 ended 21/Sep/15
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