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a4e414cb3b
SSTable load temporarily uses more space than needed to store metadata, due to: 1) All components are read using read_simple() which uses 128k buffer. file::dma_read_bulk() will allocate 128k, and may potentially allocate another big buffer (128k - read) for file::read_maybe_eof(). 2) read_filter() may use double the space it needs to. Due to the fact that sstable loading parallelism is unlimited, Scylla may require much more memory to load all sstables, and that may lead to OOM. Higher the number of sstables higher the memory overhead. To confirm this problem, I wrote a test[1] which loads 30k sstables in parallel and reports the memory usage peak in the end. When loading 30k sstables, each of which metadata is ~300kb, memory usage peak was ~18G. When loading completed, only ~9GB were needed to store all the metadata. [1]: https://gist.github.com/raphaelsc/2db37b4fb34301833ab9eeed3b1a524d To fix this problem, we need to set a limit on load parallelism (let's start with a small number like 3 and adjust later if needed) and rely on readahead so that the requirement drops considerably without increasing boot time. Actually, boot time is improved by it. Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com> Reviewed-by: Nadav Har'El <nyh@scylladb.com>
Scylla
Building Scylla
In addition to required packages by Seastar, the following packages are required by Scylla.
Submodules
Scylla uses submodules, so make sure you pull the submodules first by doing:
git submodule init
git submodule update --init --recursive
Building and Running Scylla on Fedora
- Installing required packages:
sudo dnf install yaml-cpp-devel lz4-devel zlib-devel snappy-devel jsoncpp-devel thrift-devel antlr3-tool antlr3-C++-devel libasan libubsan gcc-c++ gnutls-devel ninja-build ragel libaio-devel cryptopp-devel xfsprogs-devel numactl-devel hwloc-devel libpciaccess-devel libxml2-devel python3-pyparsing lksctp-tools-devel protobuf-devel protobuf-compiler systemd-devel libunwind-devel
- Build Scylla
./configure.py --mode=release --with=scylla --disable-xen
ninja-build build/release/scylla -j2 # you can use more cpus if you have tons of RAM
- Run Scylla
./build/release/scylla
- run Scylla with one CPU and ./tmp as data directory
./build/release/scylla --datadir tmp --commitlog-directory tmp --smp 1
- For more run options:
./build/release/scylla --help
Building Fedora RPM
As a pre-requisite, you need to install Mock on your machine:
# Install mock:
sudo yum install mock
# Add user to the "mock" group:
usermod -a -G mock $USER && newgrp mock
Then, to build an RPM, run:
./dist/redhat/build_rpm.sh
The built RPM is stored in /var/lib/mock/<configuration>/result directory.
For example, on Fedora 21 mock reports the following:
INFO: Done(scylla-server-0.00-1.fc21.src.rpm) Config(default) 20 minutes 7 seconds
INFO: Results and/or logs in: /var/lib/mock/fedora-21-x86_64/result
Building Fedora-based Docker image
Build a Docker image with:
cd dist/docker
docker build -t <image-name> .
Run the image with:
docker run -p $(hostname -i):9042:9042 -i -t <image name>