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Type:
Bug
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Resolution: Done
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Priority:
Major - P3
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None
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Affects Version/s: None
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Component/s: Performance
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None
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Environment:* mongodb 3.0.3
* 4x 244GiB servers on Amazon's cloud (r3.8xlarge running Ubuntu 14.04.1 LTS)
* 2 shards, s01 and s02
db.shards.find()
{ "_id" : "s01", "host" :
"s01/s01r01.mongo.shopcade.com:27018,s01r02.mongo.shopcade.com:27018",
"tags" : [ "main" ] }
{ "_id" : "s02", "host" :
"s02/s02r01.mongo.shopcade.com:27018,s02r02.mongo.shopcade.com:27018",
"tags" : [ "products" ] }
* s01r01 and s02r01 are MMAP
* s01r02 and s02r02 are wiredTiger.
The MMAP instances are primaries.
* mongodb 3.0.3 * 4x 244GiB servers on Amazon's cloud (r3.8xlarge running Ubuntu 14.04.1 LTS) * 2 shards, s01 and s02 db.shards.find() { "_id" : "s01", "host" : "s01/s01r01.mongo.shopcade.com:27018,s01r02.mongo.shopcade.com:27018", "tags" : [ "main" ] } { "_id" : "s02", "host" : "s02/s02r01.mongo.shopcade.com:27018,s02r02.mongo.shopcade.com:27018", "tags" : [ "products" ] } * s01r01 and s02r01 are MMAP * s01r02 and s02r02 are wiredTiger. The MMAP instances are primaries.
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Linux
When we switch primaries to be the wiredTiger instances, while there
is almost no additional stress on the machines, the time taken for
queries goes out of whack.
For our homepage, https://www.shopcade.com/, to load for a logged in
user (me), about 200 mongo queries execute in 200 ms. Please find
attached a screen capture (homepage-mongo-debug.png) from our in-house
web-request level profiling tool.
When we switch our primaries to the wiredTiger instances, the time on
average for each query goes up by a factor of 10/20 times. There
aren't a few queries that are slow, but all of them, compared to MMAP.
The total load time for the page goes from 1-2 seconds into 10s of
seconds.
I've got only marginal improvements changing to the following configuration
wiredTiger:
collectionConfig:
blockCompressor: "none"
engineConfig:
cacheSizeGB: 180
journalCompressor: "none"
indexConfig:
prefixCompression: false
- related to
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- Closed
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