open source linter and code coverage for C/C++ No ratings yet.

A poor man C/C++ linter and code coverage (gtests) C/C++ Linter: Cppcheck apt-get install cppcheck cppcheck –enable=all /your_cpp_source_dir   Test Code coverage : gcov/lcov g++ -o main –fprofile-arcs -ftest-coverage main_test.cpp -L /usr/lib -I/usr/include ./main gcov main_test.cpp lcov –coverage –directory . –output-file main_coverage.info genhtml main_coverage.info –output-directory out   https://medium.com/@naveen.maltesh/generating-code-coverage-report-using-gnu-gcov-lcov-ee54a4de3f11 https://dr-kino.github.io/2019/12/22/test-coverage-using-gtest-gcov-and-lcov/   CMake and code coverage for: • Read More »


column-oriented DB No ratings yet.

Free and open-source software Columnar DB   Database Name Language Implemented in Notes Apache Druid Java started in 2011 for low-latency massive ingestion and queries Apache Kudu C++ released in 2016 to complete the Apache Hadoop ecosystem Apache Pinot Java open sourced in 2015 for real-time low-latency analytics Calpont InfiniDB C++ ClickHouse C++ released in 2016 to • Read More »


zookeeper vs etcd 1/5 (1)

Use cases both provide strong consistance for key/value store. zookeeper use ZAB, etcd use raft, usually one leader. normally use as configure store Zookeeper more like file system https://zookeeper.apache.org/doc/r3.3.6/zookeeperStarted.html bin/zkCli.sh -server 127.0.0.1:2181 LD_LIBRARY_PATH=. cli_mt 127.0.0.1:2181 set /zk_test junk get /zk etcd: https://etcd.io/docs/v3.5/quickstart/ etcdctl put greeting “Hello, etcd” etcdctl get greeting Documents https://www.youtube.com/watch?v=BhosKsE8up8&ab_channel=BitTiger%E5%AE%98%E6%96%B9%E9%A2%91%E9%81%93BitTigerOfficialChannel Please rate this • Read More »


understand CAP theorem No ratings yet.

The CAP theorem states that a distributed system cannot simultaneously be consistent, available, and partition tolerant No distributed system is safe from network failures, thus network partitioning generally has to be tolerated.[7][8] In the presence of a partition, one is then left with two options: consistency or availability. CAP is often misunderstood as a choice at all times of • Read More »


Raft consensus algorithm on distributed system No ratings yet.

Raft: paxos hard to understand, new consensus algorithm consensus algorithm:  Leader elections, log replicate https://github.com/etcd-io/etcd/blob/main/raft/README.md   This Raft library is stable and feature complete. As of 2016, it is the most widely used Raft library in production, serving tens of thousands clusters each day. It powers distributed systems such as etcd, Kubernetes, Docker Swarm, Cloud Foundry Diego, • Read More »


Cassandra Query No ratings yet.

Time Series db using cassandra https://docs.datastax.com/en/tutorials/Time_Series.pdf Try it out https://www.datastax.com/try-it-out   cqlsh:demo> create TABLE demo.users3(lastname text, firstname text, time timestamp , primary key(lastname, time)); cqlsh:demo> INSERT INTO users2(lastname, firstname , time ) VALUES ( ‘test1’, ‘testfir’, 164447) USING TTL 20; cqlsh:demo> select firstname FROM demo.users2;   Data Modeling However, in Cassandra, the data access queries • Read More »


bigdata OLTP , OLAP No ratings yet.

row-based vs col based db or format row based –> good for OLTP ( transcation),   e.g: cassendra col based –> good for OLAP (? easy to aggreation etc?), druid Parquet https://www.jumpingrivers.com/blog/parquet-file-format-big-data-r/ hadoop: big data storage, what is the alternatives? S3 on cloud? https://www.alluxio.io/learn/hdfs/basic-file-operations-commands/ https://stackoverflow.com/questions/31011078/data-retention-in-hadoop-hdfs   pinot vs cassandra druid https://imply.io/post/apache-cassandra-vs-apache-druid If your queries ALWAYS constrain • Read More »


grpc deep drive No ratings yet.

GRPC   client side msg: header, msg, EOS server side msg:  header, msg, msg,  Trailer over http2 keep live? c++ async or sync? https://grpc.io/docs/languages/cpp/async/ , does it provider more performance than sync one? https://github.com/grpc/grpc/blob/v1.41.0/examples/cpp/helloworld/greeter_async_server.cc https://stackoverflow.com/questions/68767309/difference-between-sync-and-async-grpc https://docs.microsoft.com/en-us/dotnet/standard/async-in-depth https://www.hellsoft.se/understanding-cpu-and-i-o-bound-for-asynchronous-operations/ CPU Bound means the rate at which process progresses is limited by the speed of the CPU. A task that • Read More »


bigdata platform with Kubernets or Hadoop No ratings yet.

Hadoop: Hadoop kubernets MapReduce Spark on K8s Flink stream HDFS S3? any better one Resource manager Yarn/Mesos K8s itself   During its evolution phase, Hadoop provided three main functionalities that made it a Big Data-ready solution: a distributed computer mechanism (MapReduce), a robust data storage (HDFS), and a resource manager (YARN/Mesos). But modern technologies now • Read More »


Some notes about An Elegant Puzzle – Systems of Engineering Management No ratings yet.

Some notes: Team size 8 engineers/manager Managers should support six to eight   Documents to avoid interruption Finally, the one thing that I’ve found at companies with very few interruptions and have observed almost nowhere else: really great, consistently available documentation. It’s probably even harder to bootstrap documentation into a non-documenting company than it is • Read More »