Camus Compressor merges files created by Camus and saves them in a compressed format.
Camus is massively used at Allegro for dumping more than 200 Kafka topics onto HDFS. The script runs every 15 minutes and creates one file per Kafka partition which results in about 76800 small files per day. Most of the files do not exceed Hadoop block size. This is a clear Hadoop antipattern which leads to performance issues, for example extensive number of mappers in SQL queries’ executions.
Camus Compressor solves this issue by merging files within Hive partition and compressing them. It does not change Camus directories structure and supports well daily and hourly partitioning. The tool runs in YARN and is build on Spark.
- LZO (needs extra hadoop-lzo package on nodes)
- None (without compression, files are compacted only).
How to use
As mentioned above You need Spark packages to run
Camus Compressor. Provided
src/main/resources/compressor.sh file helps executing
spark-submit commands by setting options:
P: Configuration file path (default:
q: YARN queue name (default:
e: Parrallelism level of task (number of spark executors, default: 2);
--confoption. You can use it to pass extra arguments to job.
--driver-memoryoption. If you have huge number of partitions to compress, please consider set this option to, for example,
In a configuration file (
/etc/camus-compressor/camus-compressor.properties) you can set following options:
spark.compressor.input.format- input files format (
spark.compressor.processing.mode- processing mode, can be either:
all: compress all camus dir, put main camus dir as input path
topic: compress only one topic, put topic dir as the input path
unit: compress low-level camus directory (hour dir on hourly patitioning and day dir on daily partitioning), put appropriate input path to unit
spark.compressor.input.path- path to the uncompressed file
allmode is a path to the directory containing topics that should be compressed (
topicmode is a path to the topic directory (
unitmode is a path to one partition (directory containing files:
spark.compressor.output.compression- output compression (
spark.compressor.avro.schema.repository.class- currently only schema-repo is supported. Use
pl.allegro.tech.hadoop.compressor.schema.SchemaRepoSchemaRepositoryas a value.
spark.compressor.avro.schema.repository.url- URL to the schema-repo, for example:
pl.allegro.tech.hadoop.compressor.schema.KafkaTopicNameRetrieverif directories on HDFS are named after Kafka topics with dots replaced with underscores (
topic.nameon Kafka would be
pl.allegro.tech.hadoop.compressor.schema.IdentityTopicNameRetrieverif directories on HDFS have names identical to topic names.
spark.compressor.zookeeper.paths- when using
KafkaTopicNameRetriever, please provide Zookeeper connection string.
spark.compressor.processing.delay- compression delay, in days (compress data older than given number of days, default: 2).
spark.compressor.processing.mode.all.excludes- comma separated list of directories excluded from compression. If you want to blacklist some topics, you can pass their names here.
spark.compressor.processing.mode.all.timeout.minutes- after this period of time Compressor will be termineted.
spark.compressor.processing.mode.topic.pattern- comma separated list of directories that contains data that need to be compressed. For Camus you can use
spark.compressor.processing.force- by default Camus Compressor doesn't compress directories again. Set this option to
trueto force recompression.
spark.compressor.processing.working.dir- directory where temprary files will be stored.
spark.compressor.processing.calculate.counts- if set to
true, Compressor will calculate counts for every unit (i.e. partition) before and after compression. If they are not equal, it will throws an exception and leaves compressed files in
spark.executors.instances- number of topics concurrently processed.
How to build
Camus Compressor is shipped as fatjar file or Debian package and build using Gradle.
To build fat-jar run in
To build debian package
./gradlew shadowJar prepareControlFile buildDeb
compressor.sh script, make sure that
SPARK_SUBMIT variable is set to the
of Spark in version 1.6.1 or above.
export SPARK_SUBMIT="/usr/bin/spark-submit" compressor.sh -P /etc/camus-compressor/camus-compressor.properties \ -e 10 \ -q default \ -d 4g \ -m yarn-cluster \ -c "spark.executor.extraJavaOptions=-XX:+PrintGCDetails -XX:+PrintGCTimeStamps"
Copyright 2015 Allegro Group
Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at
Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.