Hi Remi,
On 09/29/17 22:49, Remi Forax wrote:
----- Mail original -----
De: "mandy chung" <mandy.ch...@oracle.com>
À: "Peter Levart" <peter.lev...@gmail.com>, "Xueming Shen" <xueming.s...@oracle.com>,
"core-libs-dev"
<core-libs-dev@openjdk.java.net>
Envoyé: Vendredi 29 Septembre 2017 22:34:52
Objet: Re: RFR JDK-8185582, Update Zip implementation to use Cleaner, not
finalizers
On 9/27/17 2:31 AM, Peter Levart wrote:
Up to a point where 'this' is dereferenced to obtain the 'zsRef' value
(line 261), the Deflater instance is reachable. But after that, even
ensureOpen() may be inlined and 'this' is not needed any more. After
that point, obtaining zsRef.address() and calling setDictionaly on the
obtained address may be racing with Cleaner thread invoking
ZStreamRef.run():
What about making the native setDictionary method as an instance method
(currently it's a static method) so that this object remains strongly
reachable until the method returns?
Mandy,
unlike in C or C++, in Java a reference is garbage collected as soon as you do
not need it anymore,
so using an instance method will not change the issue here.
I might be wrong, but native instance method is an exception. It can't
be inlined. The preparation for native method invocation makes sure
'this' is kept reachable because it can be dereferenced from the native
code then and native code is out-of-bounds for JIT optimization.
Regards, Peter
one way to be sure that a referenced object is not garbage collected is to use
http://docs.oracle.com/javase/9/docs/api/java/lang/ref/Reference.html#reachabilityFence-java.lang.Object-
Mandy
Rémi
