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b6b2c84316
"This series introduces a tracing infrastructure that may be used
for tracing CQL commands execution and measuring latencies of separate
stages of CQL handling as defined by a CQL binary protocol specification.
To begin tracing one should create a "tracing session", which may then
be used to issuing tracing events.
If execution of a specific CQL command involves other Nodes (not only a Coordinator),
then a "tracing session ID" is passed to that Node (in the context of the
corresponding RPC call). Then this "session ID" may be used to create a
"secondary tracing session" to issue tracing events in the context of the original session.
The series contains an implementation of tracing that uses a keyspace in the current
cluster for storing tracing information.
This series contains a demo per-request tracing instrumentation of a QUERY
CQL command and even this instrumentation is partial: it only fully instruments
a QUERY->SELECT->read_data call chain.
This is by all means a very beginning of the proper instrumentation which is
to come.
Right now the latencies for a single SELECT for a single raw with RF 1 from a 2 Nodes cluster
on my laptop started using ccm (for C* all default parameters, for scylla - memory 256MB, --smp 2)
are as follows (pseudo-graphics warning):
--------------------------------------------------------------------------------------------
| scylla (2 Nodes x 2 shards each) | C* 2.1.8
_______________________________________|___________________________________|________________
Coordinator and replica are same Node | |
(TRACING OFF): | 0.3ms | 0.3ms
c-s with a single thread mean latency | (was 0.2ms before the last |
value | rebase with a master) |
--------------------------------------------------------------------------------------------
Coordinator and replica are same Node | |
(TRACING ON) | ~250us | ~1200us
Running a SELECT command from a cqlsh | |
a few times | |
--------------------------------------------------------------------------------------------
Coordinator and replica are not on the | |
same Node | ~700us | >2500us
(TRACING ON) | |
--------------------------------------------------------------------------------------------
To begin tracing one may use a cqlsh "TRACING ON/OFF" commands:
cqlsh> TRACING ON
Now Tracing is enabled
cqlsh> select "C0", "C1" from keyspace1.standard1 where key=0x12345679;
C0 | C1
--------------------+------
0x000000000001e240 | null
(1 rows)
Tracing session: 146f0180-21e7-11e6-b244-000000000000
activity | timestamp | source | source_elapsed
-------------------------------------------------------------------+----------------------------+-----------+----------------
select "C0", "C1" from keyspace1.standard1 where key=0x12345679; | 2016-05-24 22:38:24.536000 | 127.0.0.1 | 0
message received from /127.0.0.1 [0] | 2016-05-24 22:38:24.537000 | 127.0.0.2 | --
Done reading options [0] | 2016-05-24 22:38:24.537000 | 127.0.0.1 | 3
read_data handling is done [0] | 2016-05-24 22:38:24.537000 | 127.0.0.2 | 37
Parsing a statement [0] | 2016-05-24 22:38:24.537000 | 127.0.0.1 | 3
Processing a statement [0] | 2016-05-24 22:38:24.537000 | 127.0.0.1 | 56
Done processing - preparing a result [0] | 2016-05-24 22:38:24.537000 | 127.0.0.1 | 550
Request complete | 2016-05-24 22:38:24.536560 | 127.0.0.1 | 560
cqlsh>"
#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 yum 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
- 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/.