PATCH: ShutdownHooks and LoggingDeadlock2

[Mandy Chung]

Alan Bateman wrote:
> That bug is that deleteOnExit is throwing IllegalStateException during 
> shutdown when it shouldn't. That bug has been there for a while but 
> has been masked by 6526376 (fixed early in jdk7). 
Before the fix for 6829503 (after 6526376 was fixed), 
DeleteOnExitHook#add never throws IllegalStateException since the files 
field is never null as it is initialized in the static initializer.

I'll fix this bug.

Mandy

Alan Bateman wrote:
> Mandy Chung wrote:
>> Hi Martin,
>>
>> Thanks for catching the regression.  I created a Sun bug # 6829503 
>> for bug 2.
>>
>> With the fix for 6829503, ApplicationShutdownHook and 
>> DeleteOnExitHook are both lazily initialized.  Since it is possible 
>> that a file could be added to the list for DeletedOnExit during 
>> shutdown, perhaps we also need to change the Shutdown.add method to 
>> allow DeleteOnExitHook to be added during shutdown.
>> I should pick up this bug since my fix caused this regression.  Or do 
>> you want to revise the patch?
>>
> I also missed this case when reviewing the changes (sorry) but at 
> least it has been caught in good time  I think you will need to allow 
> hooks be added during the shutdown, if only to allow deleteOnExit to 
> register a first file for deletion when invoked from a shutdown hook 
> (I realize this isn't the issue that Martin ran into but I see we've 
> got this issue also).
>
> One idea is for Shutdown#add to not check the state but instead return 
> a boolean to indicate if shutdown is in progress. 
> ApplicationShutdownHooks.<clinit> could use this to determine if its 
> hooks map should be initialized or not. That way, addShutdownHook will 
> behave as expected and throw IllegalStateException during shutdown. If 
> addShutdownHook is first invoked during shutdown it will be harmless 
> because its runHooks will simply process an empty map. As you said, 
> deleteOnExit  also has a problem in that DeleteOnExitHook.<clinit> can 
> fail to register its hook. You'll actually be fixing a second (and I 
> think unreported) bug that has existed for some time. That bug is that 
> deleteOnExit is throwing IllegalStateException during shutdown when it 
> shouldn't. That bug has been there for a while but has been masked by 
> 6526376 (fixed early in jdk7).
>
> -Alan.