Java Garbage Collection

Tuning the garbage collector is the most important thing that can be done to improve the performance of a Java application. GC is typically caused when the JVM decides GC is necessary, specifically when: a minor GC will be triggered when the new generation is full; a full GC will be triggered when the old … Read moreJava Garbage Collection

Performance Analysis

Overview In 2015, Brendan Gregg posted two great articles on Netflix blog: Linux Performance Analysis in 60 seconds, and Linux Perfomrance Tools. They have great value when I was in a urgency to spot performance issues. The articles cover the essential tools for performance troubleshooting, including: Check out load averages: w or uptime Print kernel … Read morePerformance Analysis

Lightweight Directory Access Protocol (LDAP)

Introduction Originally LDAP only refers to the connectivity protocol to the directory server. This term is being used loosely today and it also refers to the actual directory service that supports and complies with LDAP. LDAP v3 is the current version developed in RFC 2251. A directory is information about some set of entities such … Read moreLightweight Directory Access Protocol (LDAP)

Nginx as a reverse proxy for Nifi web UI and Kibana

Nginx can act as a application neutral proxy. One example is to front Nifi. The nifi default configuration provides an HTTP access point, specified in the following entries in nifi.properties: Nifi can provide secure port by commenting out the lines above and provide the followings: However, it does require configuring JKS keystore for Java, as … Read moreNginx as a reverse proxy for Nifi web UI and Kibana

Networking Basics 3 of 3 – common network protocols and technologies

The 5 layer TCP/IP model (or its more rigorously defined alternative OSI model) leads to a whole world of network protocols. Understanding these new protocols requires one to map it out agains the network layers (e.g. at Layer 4 whether it is TCP or UDP, etc) . VPN is a whole family of technologies with … Read moreNetworking Basics 3 of 3 – common network protocols and technologies

Networking basics 2 of 3 – Layer 4 and common network configurations

Transport Layer Transport Layer handles multiplexing & de-multiplexing through ports. Port is more or less a virtual concept. Source port is usually ephemeral. Two dominant protocols are TCP and UDP. TCP relies on acknowledgement. TCP control flags are SYN, ACK, FIN, URG, PSH, RST, ECE, CWR. TCP connection is established by 3-way handshake and torn … Read moreNetworking basics 2 of 3 – Layer 4 and common network configurations