[RFC]: Linkage Error fix.

[Andrew Haley]

On 04/18/2011 02:47 PM, Denis Lila wrote:
> I guess I should have read this before I responded to Deepak.
> 
>> This is exactly how ClassLoader does it in 1.7. However,
>> ClassLoader's code is a bit more clear:
>>
>> protected Class<?> loadClass(String name, boolean resolve)
>> throws ClassNotFoundException
>> {
>> synchronized (getClassLoadingLock(name)) {
>>
>> where
>>
>> protected Object getClassLoadingLock(String className) {
>> Object lock = this;
>> if (parallelLockMap != null) {
>> Object newLock = new Object();
>> lock = parallelLockMap.putIfAbsent(className, newLock);
>> if (lock == null) {
>> lock = newLock;
>> }
>> }
>> return lock;
>> }

Eww, nasty mailer broke indentation.  :-(

> Interesting. That's almost exactly the same as my solution
> (although, I don't know if it's clearer ;-).
> 
> In my e-mail with the patch I expressed some concern over
> the CHM getting too large after a while, and as a fix I
> proposed having one lock per class_name.hashCode() % small_prime_number
> instead of one lock for every class name. What do you
> think about this?

I think you are getting way past what this problem actually needs.
Ask yourself: will anyone ever notice the difference caused by making
this class loader concurrent?  is it possible actually to measure the
performance difference from simply making the method synchronized?  If
the answer to both these questions is "no", you know what to do...

Andrew.