Concurrency issue with virtual threads

[Alan Bateman]

On 28/07/2024 13:59, Сергей Цыпанов wrote:

> :
>   
> In the file pay attention to these lines:
>   
> 12 org.apache.http.pool.AbstractConnPool.getPoolEntryBlocking(AbstractConnPool.java:319)
> 92 org.apache.http.pool.AbstractConnPool.getPoolEntryBlocking(AbstractConnPool.java:391)

Further up in the stack is AbstractConnPool.get with the synchronized 
block that is causing the issue here. A limitation right now is that a 
virtual thread cannot unmount when inside a synchronized statement or 
method. In this case it seems that all carriers are pinned by virtual 
threads that are all blocked in the same place. The other short term fix 
is to this to migrate this code to also use a j.u.concurrent lock.

There is work under way to remove this limitation. There are EA builds 
available [1] that we looking for help testing before the changes are 
proposed for the main line and a future JDK release.

-Alan

[1] https://jdk.java.net/loom/
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