On 1/19/2015 5:59 PM, Anton V. Tarasov wrote:
Hi Mikhail,
It seems the problem is not limited to EventQueue only. Even if you
solve it for EventQueue, the EventQueue ctor may cause a chain of
calls where some other AWT class is first accessed and initialized.
What if it contains the same getLogger() call in a static block?
it can, but currently EventQueue doesn't do such things.
If you agree with this, then there should be a generic solution for
the deadlock.
What comes to my mind is the following. The deadlock happens due to a
reverse lock taking order. Can we change it?
In LogManager.getUserContext() it seems like the javaAwtAccess lock
scope can be narrowed down. Namely, we can move the
javaAwtAccess.getAppletContext() line out of it.
it's already done:
http://hg.openjdk.java.net/jdk9/dev/jdk/rev/83f20d8bc13a
In which case the method implementation should be additionally
synchronized. For instance, we can use the getAppContextLock for the
whole body of the method. Is the method implemented somewhere else
except the AppContext class?
Will it work from your point of view? (Probably, I didn't take into
account all the details.)
All this tricky synchronizations was done on purpose, I believe it was
done for performance sake.
So I want to make as less changes as possible, it's better to still miss
couple cases then introduce a
new big issue in the last public update. Anyway, this fix plus
http://hg.openjdk.java.net/jdk9/dev/jdk/rev/83f20d8bc13a
should cover all cases, the only possible if EQ ctor will lead to
javaAwtAccess, but it doesn't.
Regards,
Anton.
On 16.01.2015 17:18, mikhail cherkasov wrote:
Hi all,
JBS: https://bugs.openjdk.java.net/browse/JDK-8065709
Webrev: http://cr.openjdk.java.net/~mcherkas/8065709/webrev.00/
AppContext creation is guarder by getAppContextLockand, but during
AppContext creation
we also call EventQueue initialization, during EQ initialization
logger initialization happens
it acquires "javaAwtAccess". if "javaAwtAccess" is acquired by other
it can lead to deadlock:
T1 T2
start AppContext creation
acquire
javaAwtAccess
acquire getAppContextLock
init EQ call getAppContext
init Logger waiting for
getAppContextLock
waiting for javaAwtAccess
I applied the fix suggested in jbs comments by Petr.
I replaced eager logger initialization in EQ with lazy, so we won't
invoke Logger
during EQ initialization as result no deadlock.
Thanks,
Mikhail.
