On Sat, 2018-11-10 at 08:59 -0700, Gary Gregory wrote:
> On Sat, Nov 10, 2018 at 8:51 AM Gary Gregory <[email protected]>
> wrote:
> 
> > On Sat, Nov 10, 2018 at 4:29 AM Oleg Kalnichevski <[email protected]
> > >
> > wrote:
> > 
> > > On Fri, 2018-11-09 at 15:36 -0700, Gary Gregory wrote:
> > > > On Fri, Nov 9, 2018 at 3:33 PM Oleg Kalnichevski <
> > > > [email protected]>
> > > 
> > > ...
> > > 
> > > > 
> > > > > Yes, it is. What would be the point if every single method
> > > > > synchronizes
> > > > > on exchangeState instance?
> > > > > 
> > > > > 
> > > > > 
> > > 
> > > 
https://github.com/apache/httpcomponents-core/blob/master/httpcore5/src/examples/org/apache/hc/core5/http/examples/AsyncReverseProxyExample.java#L275
> > > > 
> > > > 
> > > > OK, I can buy that all of the synchronized blocks are correct
> > > > and
> > > > schedule
> > > > thread access to those ivars.
> > > > But what about the absence of volatile causing threads to miss
> > > > updates to
> > > > fields from other threads?
> > > > 
> > > 
> > > Java runtime guarantees the state of variables inside
> > > synchronized
> > > block to be consistent for all threads of execution. The reason
> > > for
> > > making variables volatile is to avoid having to use
> > > expensive synchronization.
> > > 
> > 
> > Hi Oleg,
> > 
> > I am looking for confirmation of this in the JLS to make sure my
> > app is on
> > solid ground. I found:
> > 
> > "An unlock (synchronized block or method exit) of a monitor
> > *happens-before* every subsequent lock (synchronized block or
> > method
> > entry) of that same monitor. And because the *happens-before*
> > relation is
> > transitive, all actions of a thread prior to unlocking *happen-
> > before* all
> > actions subsequent to any thread locking that monitor."
> > 
> > in
> > 
https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/package-summary.html#MemoryVisibility
> > 
> > which I read as JLS-ese of your statement.
> > 
> > Check?
> > 
> 
> Hi Oleg,
> 
> Would you then say that we are missing a synchronized statement
> in
> org.apache.hc.core5.http.examples.AsyncReverseProxyExample.IncomingEx
> changeHandler.handleRequest(...).new
> FutureCallback() {...}.failed(Exception) ?
> 

I no longer remember why I omitted it. Probably it was by mistake. Feel
free to add synchronization.

Oleg  



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