Ben Chuanlong Du's Blog

It is never too late to learn.

Rust Error "error: expected item, found 'let'"

Things on this page are fragmentary and immature notes/thoughts of the author. Please read with your own judgement!

The error message "error: expected item, found 'let'" is commonly encountered in Rust when you mistakenly place a let statement in an invalid location. A let statement can only be used …

Error Handling in Rust

Things on this page are fragmentary and immature notes/thoughts of the author. Please read with your own judgement!

PCIe BUS Error: Severity=Corrected, Type=Physical Layer

Things on this page are fragmentary and immature notes/thoughts of the author. Please read with your own judgement!

Note: You might have to do this every time you upgrade your Linux kernel!!

Symptoms

Below are step-by-step symptoms from superficial to root causes.

  1. Your Linux system becomes very slow even …

Spark Issue: IllegalArgumentException: Wrong FS

Things on this page are fragmentary and immature notes/thoughts of the author. Please read with your own judgement!

Symptoms

java.lang.IllegalArgumentException: Wrong FS: hdfs://..., expected: viewfs://...

Possible Causes

The Spark cluster has migrated to Router-based Federation (RBF) namenodes, and viewfs:// (instead of hdfs://) is required to access HDFS …

Spark Issue: ViewFs: Cannot Initialize: Empty Mount Table in Config

Things on this page are fragmentary and immature notes/thoughts of the author. Please read with your own judgement!

Symptoms

java.io.IOException: ViewFs: Cannot initialize: Empty Mount table in config for viewfs://cluster-name-ns02/

Possible Causes

As the error message says, viewfs://cluster-name-ns02 is not configured.

  1. It is possible that …