Hi,
Right, the test calls the correctly synchronized method in JDK7. The fix
for 6914123 in JDK8 moves synchronization to the other method (the one
taking CharSequence as parameter type), so in JDK8 it doesn't matter
which method is called, but in JDK7 it makes a difference. The same test
could be modified to call the unsynchronized method in JDK7 (by casting
StringBuffer to CharSequence) in case a backport to JDK7 is attempted,
but for JDK8 it is good as it is.
Regards, Peter
On 05/16/2013 06:08 AM, David Holmes wrote:
Okay mea culpa - I was testing on the wrong JDK. I wrongly assumed
this would impact 7 as well but it doesn't as the bug was introduced
with the changes in 6914123.
Sorry about that.
Good to go. Has anyone offered to sponsor this yet?
David
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On 15/05/2013 5:50 PM, Peter Levart wrote:
Mike, David,
Could you try this variant of the test:
http://cr.openjdk.java.net/~plevart/jdk8-tl/String.contentEquals/webrev.05/
I tried it on 3 different machines (4-core i7 Linux, 8-core sparc T-2
Solaris, 4-core amd64 Solaris) x 2 different JDK8 JVMs (64bit and 32bit)
and it fails immediately on all 6 of them.
Regards, Peter
On 05/14/2013 05:39 PM, Mike Duigou wrote:
Good to see the test added. I was also unable to reproduce the failure
on my Core 2 Duo Mac laptop but the test and fix match up.
Mike
On May 14 2013, at 04:34 , Peter Levart wrote:
On 05/14/2013 01:17 PM, David Holmes wrote:
Thanks Peter this looks good to me.
One minor thing please set the correct copyright year in the test,
it should just be
Copyright (c) 2013, Oracle ...
Ok, fixed:
http://cr.openjdk.java.net/~plevart/jdk8-tl/String.contentEquals/webrev.04/
I couldn't get the test to actually fail, but I can see that it
could.
Hm, do you have a multi-core chip? On my computer (i7 CPU) it fails
immediately and always. You could try varying the number of
concurrent threads and or the time to wait for exception to be
thrown...
David
On 14/05/2013 9:04 PM, Peter Levart wrote:
Ok, here's the corrected fix:
http://cr.openjdk.java.net/~plevart/jdk8-tl/String.contentEquals/webrev.03/
I also added a reproducer for the bug.
Regards, peter
On 05/14/2013 07:53 AM, Peter Levart wrote:
Right, sb.length() should be used. I will correct that as soon as I
get to the keyboard.
Regards, Peter
On May 14, 2013 7:22 AM, "David Holmes" <david.hol...@oracle.com
<mailto:david.hol...@oracle.com>> wrote:
Thanks Peter! I've filed
8014477
Race condition in String.contentEquals when comparing with
StringBuffer
On 14/05/2013 8:34 AM, Peter Levart wrote:
On 05/14/2013 12:09 AM, Peter Levart wrote:
I noticed a synchronization bug in String.contentEquals
method. If
called with a StringBuffer argument while concurrent
thread is
modifying the StringBuffer, the method can either throw
ArrayIndexOutOfBoundsException or return true even
though
the content
of the StringBuffer has never been the same as the
String's.
Here's a proposed patch:
http://cr.openjdk.java.net/~plevart/jdk8-tl/String.contentEquals/webrev.01/
<http://cr.openjdk.java.net/%7Eplevart/jdk8-tl/String.contentEquals/webrev.01/>
Regards, Peter
Or even better (with some code clean-up):
http://cr.openjdk.java.net/~plevart/jdk8-tl/String.contentEquals/webrev.02/
<http://cr.openjdk.java.net/%7Eplevart/jdk8-tl/String.contentEquals/webrev.02/>
This part is not correct I believe:
1010 private boolean
nonSyncContentEquals(AbstractStringBuilder sb) {
1011 char v1[] = value;
1012 char v2[] = sb.getValue();
1013 int n = v1.length;
1014 if (n != v2.length) {
1015 return false;
1016 }
v2 can be larger than v1 if v2 is not being fully used (ie
count <
length).
David
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