ConcurrentHashMap::computeIfAbsent and synchronized

[Alan Bateman]

On 20/01/2023 13:17, mikmoila wrote:
> :
>
> If you set the "cpus" to Runtime.getRuntime().availableProcessors() - 
> 1 it completes, otherwise it hangs.
>

Right, it effectively deadlocks because one of the virtual threads is 
executing the mapping function and is in STS.join waiting for a child 
task to complete. The child task can't execute because all carriers are 
pinned by other virtual threads trying to execute the same mapping 
function. If you generate a thread dump with `jcmd <pid> 
Thread.dump_to_file -format=json <file>` it should be easy to see.

-Alan