Bug #15360

Updated by brockspratlen (Brock Spratlen) almost 2 years ago

I think I've discovered a Ruby bug, possibly introduced in 2.5. 

 I've attached a reproduction script; running it on Ruby 2.5.0+ (including previews of 2.6.0) seems to always produce a flood of printed `ThreadError: deadlock; recursive locking` exceptions, even though the reproduction code doesn't appear to do any recursive locking.  

 Running the same script on Ruby 2.4.5 doesn't produce any `ThreadError: deadlock; recursive locking` exceptions. I've run the script several times on Ruby 2.4.5, I simply can't reproduce the raising of `ThreadError: deadlock; recursive locking` with this script on 2.4.5. 

 Curiously, removing the `puts e.class` on line 24 25 causes the bug to go away: `ThreadError: deadlock; recursive locking` never gets raised regardless of which Ruby version I'm running. Given this oddity, I can't help but think the issue is something around writing to stdout. This change in particular looks suspect: 

 Thank you!