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Posted to notifications@james.apache.org by GitBox <gi...@apache.org> on 2021/06/05 12:18:39 UTC
[GitHub] [james-project] chibenwa opened a new pull request #476: [PERFORMANCE] Reduce Cassandra chunk length for some read intensive t…
chibenwa opened a new pull request #476:
URL: https://github.com/apache/james-project/pull/476
…ables
- The table should be read heavy
- Have a small PARTITION size
Reducing the compression chunk size reduces the amount of data Cassandra have to
pull and deflate, at the expense of a lower compression and of more object creation.
The proposed values lead to a net performance improvement both for mean and p99
response time (106 ms mean time for JMAP queries to 85ms)
Testing infrastructure: 2*2 CPU James with 4GB RAM, 3 Cassandra being OVH B2-30,
~900 requests per second
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## After
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[GitHub] [james-project] chibenwa commented on a change in pull request #476: [PERFORMANCE] Reduce Cassandra chunk length for some read intensive t…
Posted by GitBox <gi...@apache.org>.
chibenwa commented on a change in pull request #476:
URL: https://github.com/apache/james-project/pull/476#discussion_r647892845
##########
File path: mailbox/cassandra/src/main/java/org/apache/james/mailbox/cassandra/modules/CassandraMailboxModule.java
##########
@@ -42,7 +42,8 @@
.comment("Holds the mailboxes information.")
.options(options -> options
.caching(SchemaBuilder.KeyCaching.ALL,
- SchemaBuilder.rows(CassandraConstants.DEFAULT_CACHED_ROW_PER_PARTITION)))
+ SchemaBuilder.rows(CassandraConstants.DEFAULT_CACHED_ROW_PER_PARTITION))
+ .compressionOptions(SchemaBuilder.lz4().withChunkLengthInKb(8)))
Review comment:
I do think compression is more related to the workload than the infrastructure.
That being said I'm fine keeping defaults, and requiring expertise to come and tune these settings.
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[GitHub] [james-project] chibenwa commented on a change in pull request #476: [PERFORMANCE] Reduce Cassandra chunk length for some read intensive t…
Posted by GitBox <gi...@apache.org>.
chibenwa commented on a change in pull request #476:
URL: https://github.com/apache/james-project/pull/476#discussion_r647370004
##########
File path: mailbox/cassandra/src/main/java/org/apache/james/mailbox/cassandra/modules/CassandraMailboxModule.java
##########
@@ -42,7 +42,8 @@
.comment("Holds the mailboxes information.")
.options(options -> options
.caching(SchemaBuilder.KeyCaching.ALL,
- SchemaBuilder.rows(CassandraConstants.DEFAULT_CACHED_ROW_PER_PARTITION)))
+ SchemaBuilder.rows(CassandraConstants.DEFAULT_CACHED_ROW_PER_PARTITION))
+ .compressionOptions(SchemaBuilder.lz4().withChunkLengthInKb(8)))
Review comment:
https://thelastpickle.com/blog/2018/08/08/compression_performance.html
TLDR: Using out of the box settings for compression on read heavy or mixed workloads will almost certainly put unnecessary strain on your disk while hurting your read performance.
Basically I tried a couple of values and 8KB worked well.
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[GitHub] [james-project] jeantil commented on a change in pull request #476: [PERFORMANCE] Reduce Cassandra chunk length for some read intensive t…
Posted by GitBox <gi...@apache.org>.
jeantil commented on a change in pull request #476:
URL: https://github.com/apache/james-project/pull/476#discussion_r647352874
##########
File path: mailbox/cassandra/src/main/java/org/apache/james/mailbox/cassandra/modules/CassandraMailboxModule.java
##########
@@ -42,7 +42,8 @@
.comment("Holds the mailboxes information.")
.options(options -> options
.caching(SchemaBuilder.KeyCaching.ALL,
- SchemaBuilder.rows(CassandraConstants.DEFAULT_CACHED_ROW_PER_PARTITION)))
+ SchemaBuilder.rows(CassandraConstants.DEFAULT_CACHED_ROW_PER_PARTITION))
+ .compressionOptions(SchemaBuilder.lz4().withChunkLengthInKb(8)))
Review comment:
how did you come to choose `8` Kb ?
is it based on BufferedReader's defaultCharBufferSize to align with memory page size or is based on the estimated size of a mailbox row ?
(https://stackoverflow.com/questions/37404068/why-is-the-default-char-buffer-size-of-bufferedreader-8192)
a comment would be nice :D
(if the answer is size of a mailbox row, the same question applies to all the following `8` that appear in the PR)
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[GitHub] [james-project] chibenwa merged pull request #476: [PERFORMANCE] Reduce Cassandra chunk length for some read intensive t…
Posted by GitBox <gi...@apache.org>.
chibenwa merged pull request #476:
URL: https://github.com/apache/james-project/pull/476
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[GitHub] [james-project] chibenwa commented on a change in pull request #476: [PERFORMANCE] Reduce Cassandra chunk length for some read intensive t…
Posted by GitBox <gi...@apache.org>.
chibenwa commented on a change in pull request #476:
URL: https://github.com/apache/james-project/pull/476#discussion_r647370004
##########
File path: mailbox/cassandra/src/main/java/org/apache/james/mailbox/cassandra/modules/CassandraMailboxModule.java
##########
@@ -42,7 +42,8 @@
.comment("Holds the mailboxes information.")
.options(options -> options
.caching(SchemaBuilder.KeyCaching.ALL,
- SchemaBuilder.rows(CassandraConstants.DEFAULT_CACHED_ROW_PER_PARTITION)))
+ SchemaBuilder.rows(CassandraConstants.DEFAULT_CACHED_ROW_PER_PARTITION))
+ .compressionOptions(SchemaBuilder.lz4().withChunkLengthInKb(8)))
Review comment:
https://thelastpickle.com/blog/2018/08/08/compression_performance.html
TLDR: Using out of the box settings for compression on read heavy or mixed workloads will almost certainly put unnecessary strain on your disk while hurting your read performance.
Basically I tried a couple of values (4K, 8K, 16K, ...) and 8KB worked well.
Globally the idea is to decrease this value for all the relevant tables.
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[GitHub] [james-project] jeantil commented on a change in pull request #476: [PERFORMANCE] Reduce Cassandra chunk length for some read intensive t…
Posted by GitBox <gi...@apache.org>.
jeantil commented on a change in pull request #476:
URL: https://github.com/apache/james-project/pull/476#discussion_r647485941
##########
File path: mailbox/cassandra/src/main/java/org/apache/james/mailbox/cassandra/modules/CassandraMailboxModule.java
##########
@@ -42,7 +42,8 @@
.comment("Holds the mailboxes information.")
.options(options -> options
.caching(SchemaBuilder.KeyCaching.ALL,
- SchemaBuilder.rows(CassandraConstants.DEFAULT_CACHED_ROW_PER_PARTITION)))
+ SchemaBuilder.rows(CassandraConstants.DEFAULT_CACHED_ROW_PER_PARTITION))
+ .compressionOptions(SchemaBuilder.lz4().withChunkLengthInKb(8)))
Review comment:
> TLDR: Using out of the box settings for compression on read heavy or mixed workloads will almost certainly put unnecessary strain on your disk while hurting your read performance.
I understand the logic behind the change, I challenge the arbitrary number that was chosen :D
> Basically I tried a couple of values (4K, 8K, 16K, ...) and 8KB worked well.
Aren't you worried that it is highly dependendant on the cassandra infrastructure ? After all 640k is enough memory for everything ;p
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