SIGSEGV after running virtual-thread jetty for a few minutes

[Ron Pressler]

Hi.

Thank you for reporting this. We are currently in the process of finding and fixing
a whole stream of stability bugs. This might take a while, but when we think things
are looking good, we’ll notify the list and ask all those who’ve encountered such
crashes to try again.

— Ron


On 12 August 2020 at 05:32:33, Michael Bien (mbien42 at gmail.com) wrote:

Hello Loomers,  

after some fun experiments with loom i decided to swap jetty's thread  
pool against the default virtual thread executor* to test some (old)  
apps on it.  

Most of it ran great, got some JVM crashes with the apache roller  
blogserver though:  

#  
# A fatal error has been detected by the Java Runtime Environment:  
#  
#  SIGSEGV (0xb) at pc=0x00007fc7deedb454, pid=58060, tid=58180  
#  
# JRE version: OpenJDK Runtime Environment (16.0) (build  
16-internal+0-adhoc.mbien.loom)  
# Java VM: OpenJDK 64-Bit Server VM (16-internal+0-adhoc.mbien.loom,  
mixed mode, sharing, tiered, compressed oops, parallel gc, linux-amd64)  
# Problematic frame:  
# V  [libjvm.so+0x719454]  frame::sender(RegisterMap*) const+0xb4  

(that would be today's version of loom from git, i got the same result  
with the official Build 16-loom+4-56)  

unfortunately this isn't super easy to reproduce. I ran a short load  
test for a minute, then i waited 1-5 minutes and ran it again - thats  
when it usually crashed. It might have something to do with old carrier  
threads despawning which blocked on native calls. When it ramps up again  
it crashes - but that is only a wild guess i got while looking at the  
visualvm thread graph for too long.  

if its a known issue... please ignore. Otherwise let me know how i can  
help. JVM error log attached.  

*https://urldefense.com/v3/__https://github.com/mbien/vt4jetty/blob/master/src/main/java/dev/mbien/virtualthreads4jetty/VirtualThreadExecutor.java__;!!GqivPVa7Brio!LUl7y2T2fvzBkGRze_482solKjdwuJtJemb-yWrlmfhoY3rQzlKxQP9ddnPFIuK8rw$  

best regards,  

michael bien