JDK Version java -version openjdk version "1.8.0_151" OpenJDK Runtime Environment (build 1.8.0_151-8u151-b12-0ubuntu0.16.04.2-b12) OpenJDK 64-Bit Server VM (build 25.151-b12, mixed mode) Verify that the target server is configured to serve SSL https://www.ssllabs.com/ssltest/
Connecting to SSL services https://confluence.atlassian.com/kb/unable-to-connect-to-ssl-services-due-to-pkix-path-building-failed-779355358.html
If you are getting an exception due to “Illegal key size” and you are using Sun’s JDK, you need to install the Java Cryptography Extension (JCE) Unlimited Strength Jurisdiction Policy Files. See the following links for more information:
Organizations are looking for ways to reduce their physical data center footprints, particularly for secondary workloads such as backups, files, or on-demand workloads. However, bridging data between private data centers and the public cloud comes with a unique set of challenges. Traditional data center services rely on low-latency network attached storage (NAS) and storage area network (SAN) protocols to access storage locally. Cloud-native applications are generally optimized for API access to data in scalable and durable cloud object storage, such as Amazon Simple Storage Service (Amazon S3).
准备 初始化
draft init ... Installing default plugins... Preparing to install into /home/bigo/.draft/plugins/draft-pack-repo draft-pack-repo installed into /home/bigo/.draft/plugins/draft-pack-repo/draft-pack-repo Installed plugin: pack-repo Installation of default plugins complete Installing default pack repositories... Installing pack repo from https://github.com/Azure/draft Installed pack repository github.com/Azure/draft Installation of default pack repositories complete $DRAFT_HOME has been configured at /home/bigo/.draft. ... 设置docker镜像寄存器
draft config set registry registry.cn-beijing.aliyuncs.com/k4s or
skip the push process entirely using the –skip-image-push flag
PersistentVolume A PersistentVolume (PV) is a piece of storage in the cluster that has been manually provisioned by an administrator, or dynamically provisioned by Kubernetes using a StorageClass. Many cluster environments have a default StorageClass installed. When a StorageClass is not specified in the PersistentVolumeClaim, the cluster’s default StorageClass is used instead
Local volumes can only be used as a statically created PersistentVolume. Dynamic provisioning is not supported yet
在windows上搭建Leveldb的开发环境
Leveldb使用了checkstyle
https://github.com/wubigo/leveldb/blob/master/src/checkstyle/checks.xml
<module name="RegexpMultiline"> <property name="format" value="\r"/> <property name="message" value="Line contains carriage return"/> </module> 使用git默认设置拣出代码的时候,换行设置编译的时候会报错如下
[ERROR] src\main\java\org\iq80\leveldb\WriteOptions.java:[6] (regexp) RegexpMultiline: Line contains carriage return [ERROR] src\main\java\org\iq80\leveldb\WriteOptions.java:[7] (regexp) RegexpMultiline: Line contains carriage return 解决办法之一是调整git换行设置
git换行设置(line endings) 换行设置的3个选项:
Checkout Windows-style, commit Unix-style Git will convert LF to CRLF when checking out text files. When committing text files, CRLF will be converted to LF. For cross-platform projects, this is the recommended setting on Windows (“core.
表分区 主键=((分区键) + [簇键])
create table kvstor ( k_part_one text, k_part_two int, k_clust_one text, k_clust_two int, k_clust_three uuid, data text, PRIMARY KEY((k_part_one, k_part_two), k_clust_one, k_clust_two, k_clust_three) ); 分区键 分区键决定数据在集群内的分布在哪个分区
簇键 簇建决定数据的在分区内的排列顺序
Cassandra DB 主要缺点 Cassandra has big issue with Data Read Latency Hard to tune-up for both latency and throughput Highly depended on Work load and type Max 20 % P99 latency drop Most memory consumed by storage engine To store huge amount of data, JVM is required to manage the memory to clean up garbage collection that is not done by the application but by a language in Cassandra Cassandra is not recommended if you have following use cases :
Amazon Aurora Serverless is an on-demand, auto-scaling configuration for
Amazon Aurora (MySQL-compatible and PostgreSQL-compatible editions),
where the database will automatically start up, shut down, and scale
capacity up or down based on your application’s needs. It enables you
to run your database in the cloud without managing any database instances.
It’s a simple, cost-effective option for infrequent, intermittent, or
unpredictable workloads.
webpack-simple Webpack is a module bundler for Javascript applications,
it starts at the entrypoint and then build a dependency
graph of the whole application, pulling those dependencies
into one or more bundles that can be included in application.
It supports multiple different file types through loaders,
loaders will take files that have no concept of modules (e.g. css)
and process them in a way that allows them to participate
EMQX单节点吞吐量 EMQX 5.0 23个节点的集群支持:(100 million MQTT连接 + 1 million message)每秒
每个节点的吞吐量为4万每秒
The dispersed nature of the Internet of Things (IoT) presents a major operational challenge that is uncommon in the traditional Internet or enterprise networks[5]. Devices that are managed together — say a fleet of railcars — are not physically colocated. Instead, they are widely geographically distributed. The operational approaches for management and security used in enterprise networks, where most hosts are densely contained in buildings or campuses, do not translate to the IoT.