HI Valerie,
Valerie (Yu-Ching) Peng said the following on 02/25/11 11:36:
Can someone please review for 7001933: Deadlock in
java.lang.classloader.getPackage()?
http://cr.openjdk.java.net/~valeriep/7001933/webrev.00/
The fixes are straightforward - release the lock when delegating to the
parent.
The change has been verified by the submitter.
1642 synchronized (packages) {
1643 if (packages.get(name) != null) {
1644 packages.put(name, pkg);
1645 }
1646 }
This looks wrong to me. Shouldn't you only do the put if the get returns
null? And if the get doesn't return null shouldn't the method return
that result ie:
synchronized (packages) {
Package pkg2 = null;
if ((pkg2 = packages.get(name)) == null) {
packages.put(name, pkg);
}
else
pkg = pkg2;
}
...
return pkg;
In general it is easy to break a deadlock by making an open-call, as you
have done, but the harder question to answer is: what possible
side-effects could there be due to races now that this method is not atomic?
Cheers,
David
