Stability of UseCodeCacheFlushing option

[John O'Brien]

Excellent, will get back to my team and let you know. afaik we plan to
use it very soon.

On Mon, Oct 17, 2011 at 11:02 AM, Tom Rodriguez
<tom.rodriguez at oracle.com> wrote:
> There are no known issues.  We're going to be turning it on by default in hs23, so if you're interested in trying it out we'd love to know how it works for you.
>
> tom
>
> On Oct 17, 2011, at 9:14 AM, John O'Brien wrote:
>
>> Hi All,
>>
>> Is the useCodeCacheFlushing option working well. I read the thread
>> below and wonder if there are remaining issues?
>> How bad are they? Do I just need to go ahead and try it out?
>>
>> Is the best option to size a very large codeCache?
>>
>> Regards,
>> John
>>
>>
>>
>>
>> Tom Rodriguez tom.rodriguez at oracle.com
>> Thu Mar 3 12:14:32 PST 2011
>>
>> Previous message: inspecting the code cache
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>> AdvancedCompilationPolicy for tiered
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>>
>> ________________________________
>>
>>>>> Thanks for that information. I've been using PrintCompilation to
>>>> watch what was going on. I've gotten a question from a client that
>>>> claims that a method had seemingly been squeezed out of the cache. I'm
>>>> not sure what would cause a method to be squeezed out but I guess it
>>>> would have to be made not entrant before hand. But that got me
>>>> interested in poking about to see what information one could squeeze
>>>> out of the JVM wrt the code cache.
>>>>
>>>> Code will never get "squeezed" out in the current system.  We generate
>>>> code as needed and only get rid of it when it gets invalidated or if it
>>>> references classes which get unloaded.  If the code cache fills up you
>>>> might not be able to compile something that needs code though.
>>>>
>>>> tom
>>>>
>>>>
>>>>>
>>>>> TIA,
>>>>> Kirk
>>>>>
>>>
>>> Does -XX:+UseCodeCacheFlushing enable this clearing of invalidated code?
>>> Or does that do something different?
>>
>> No that's something different.  The clearing of the code is done by
>> something called the sweeper and you can't disable it.
>> UseCodeCacheFlushing implements an LRU-ish policy for keeping the code
>> cache from filling up.  It's currently not enabled by default because
>> we've seen some hard to track down problems when using it with very
>> long running programs.  They may not actually be the fault of the
>> flushing itself but the extra pressure it puts on the concurrent
>> sweeping that actually reclaims them.  It should become the default
>> once we track down the sweeping issue.
>>
>> tom
>>
>>>
>>>
>>> Thanks,
>>>
>>> David
>>>
>>>
>>>
>
>