[HBASE-21827] CompletableFuture may wrap the original Throwable with CompletionException while propagating it

• Type: Umbrella
• Status: Resolved
• Priority: Critical
• Resolution: Fixed
• Component/s: asyncclient, Client
• Assignee: Duo Zhang
• Reporter: Duo Zhang
• Created: 02/Feb/19 03:53
• Updated: 29/Apr/19 09:31
• Resolved: 29/Apr/19 09:31

Description

See the stack overflow post

https://stackoverflow.com/questions/49230980/does-completionstage-always-wrap-exceptions-in-completionexception

It seems that, for a chain of CompletableFutures, the first child will receive the original exception, and the latter ones will receive a CompletionException, which is the wrapper of the original exception.

This is also what I observed when debugging HBASE-21779. We need to fix this, at least, we should unwrap it when we want to return exceptions to users.

Sub-Tasks

• Make sure we do not return CompletionException when locating region: Resolved
• Use FutureUtils.addListener instead of calling whenComplete directly: Resolved