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bf02ca831d
"This series changes the tracing back pressure scheme from limiting the amount traces in
a single session by a fixed number to have a per-shard budget consumed by all active tracing
sessions.
It was really easy to cause the traces to be dropped even if there weren't too many
active traces: e.g. if there was a single active session which creates more traces
than a per-session limit (30) the traces above 30-th were going to be dropped. Namely
traces were dropped when there were only 30 active traces, which is ridiculous.
This series introduces two main changes:
- Changes the records budgeting from being per-session to be per-shard. This substantially
increases the amount of active records after which new records are going to be dropped.
- Introduces a flow when events' records are written BEFORE the corresponding tracing
session is over (right now traces are written to I/O back end only when the session object
is destroyed).
The later is meant to virtually eliminate the traces drops in normal situations at all.
Of course, if a back end is slow or if there are a lot of small sessions that do not complete we would still have
to drop new sessions/records in order to avoid uncontrolled growth of a memory foot print of Tracing.
If we see the later case happening a lot in the future we may add lowres timers to each session that would
commit the cached records for writing every X time. But let's not try to optimize something that we
are not completely sure has to be optimized... "
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 --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
- 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>
Contributing to Scylla
Do not send pull requests.
Send patches to the mailing list address scylladb-dev@googlegroups.com. Be sure to subscribe.
In order for your patches to be merged, you must sign the Contributor's License Agreement, protecting your rights and ours. See http://www.scylladb.com/opensource/cla/.