Observability Done Right: Best Practices and Anti-Patterns for Effective System Monitoring

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  WHAT Observability is a concept that refers to the ability to gain insights into the behavior and performance of complex systems. In the context of software engineering, observability involves the collection, analysis, and visualization of data from software applications, infrastructure, and other components of a system. In the animal kingdom, observability plays a critical role in survival, allowing animals to monitor their surroundings, detect threats, and find food. Dolphins use echolocation to observe their surroundings. They emit high-frequency sounds that bounce off objects, allowing them to create a 3D map of their environment. Thanks for reading Knowledge Cafe! Subscribe for free to receive new posts and support my work. Subscribed WHY In today's era, architectures are becoming increasingly large, complex, and fast-paced due to the faster development and deployment of software by distributed teams with the help of DevOps, continuous delivery, and agile development methodo...

Failfast Vs Failsafe in Java

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Difference between fail-safe and fail-fast Iterator is becoming favorite core java interview questions day by day, reason it touches concurrency a bit and interviewee can go deep on it to ask how fail-safe or fail-fast behavior is implemented. How does a system react when there is a failure characterizes it as a fail fast or a fail safe system. This article is to discuss whether fail safe or fail fast is better. Then what it has to do with java. Concept of fail-safe iterator are relatively new in Java and first introduced with Concurrent Collections in Java 5 like ConcurrentHashMap and CopyOnWriteArrayList.


fail-fast Iterators in Java


As name suggest fail-fast Iterators fail as soon as they realized that structure of Collection has been changed since iteration has begun. Structural changes means adding, removing or updating any element from collection while one thread is Iterating over that collection. fail-fast behavior is implemented by keepinga modification count and if iteration thread realizes the change in modification count it throwsConcurrentModificationException.


Java doc says this is not a guaranteed behavior instead its done of "best effort basis", So application programming can not rely on this behavior. Also since multiple threads are involved while updating and checking modification count and this check is done without synchronization, there is a chance that Iteration thread still sees a stale value and might not be ableto detect any change done by parallel threads. Iterators returned by most of JDK1.4 collection are fail-fast including Vector, ArrayList, HashSet etc.


fail-safe Iterator in java


Contrary to fail-fast Iterator, fail-safe iterator doesn't throw any Exception if Collection is modified structurally

while one thread is Iterating over it because they work on clone of Collection instead of original collection and that’s why they are called as fail-safe iterator. Iterator of CopyOnWriteArrayList is an example of fail-safe Iterator also iterator written by ConcurrentHashMap keySet is also fail-safe iterator and never throw ConcurrentModificationException in Java.

The CopyOnWriteArrayList does not fail when the internal structure changes, but ArrayList does.

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