RFR: 8064909: FragmentMetaspace.java got OutOfMemoryError

Michail Chernov michail.chernov at oracle.com
Thu Dec 4 15:02:54 UTC 2014


Hi,

Here the updated webrev:
http://cr.openjdk.java.net/~eistepan/~mchernov/8064909/webrev.01/


On 01.12.2014 22:52, Jon Masamitsu wrote:
>
> On 11/27/2014 05:28 AM, Michail Chernov wrote:
>> Hi,
>>
>> CC'ed hotspot-runtime-dev.
>>
>> Here is not test failure - test works as expected. OOME is occurred 
>> in compiler instance.
>>
>> private JavaCompiler javac;
>> ...
>>         javac = ToolProvider.getSystemJavaCompiler();
>> ...
>>         int exitcode = javac.run(null, null, null, 
>> file.getCanonicalPath());
>>         if (exitcode != 0) {
>>             throw new RuntimeException("javac failure when compiling: 
>> " +
>>         file.getCanonicalPath());
>>
>> Here is 2 ways - rewrite getGeneratedClass 
>> (runtime/testlibrary/GeneratedClassLoader.java) to allow them to 
>> throw not only RuntimeException,
>
> Seems like this would be more precise with regard to recognizing the
> cause of the failure.  Are there too many places which would have to
> change to catch the OOME.
>
>> or to catch RuntimeException and check exception message comparing 
>> with "javac failure when compiling:". Both ways seem to me are not as 
>> clear as expected for this simple test. More - javac does not throw 
>> anything - it just returns exitcode (non-zero) and writes its 
>> messages to System.err.
>>
>> Also I can add comment to code like "OOME with message 
>> "java.lang.OutOfMemoryError: Java heap space" doesn't mean that 
>> something wrong with metaspace - need just to increase -Xmx".
>
> That would be enough for me if you don't think
> throwing the OOME from  GeneratedClassLoader()
> adds much value.
>
> Jon
>
>>
>> Thanks,
>> Michail
>>
>> On 27.11.2014 2:00, Jon Masamitsu wrote:
>>> Dima,
>>>
>>> If this test fails with an OOME in the future, I would like it to be
>>> obvious that the failure is not that an OOME occurred.   I cannot
>>> tell that from looking at the test.    Can the test be changed so
>>> I don't have to spend time figuring out that the OOME is not
>>> a failure mode  of the test?
>>>
>>> Jon
>>>
>>>
>>> On 11/26/2014 12:51 PM, Dmitry Fazunenko wrote:
>>>> Hi Jon,
>>>>
>>>> The original version of test worked for 80 seconds trying to 
>>>> perform as many iterations as possible. The number of iterations 
>>>> performed depended on how fast is the machine. With each next 
>>>> iteration the size of generated and loaded classes is growing, so 
>>>> on fast enough machines 80 seconds is enough to run out of heap 
>>>> while generating a class.
>>>>
>>>> The fix not only sets the heap, but limits iterations.  300m heap 
>>>> is enough for 200 iterations.
>>>>
>>>> Your approach, with catching OOME(heap) and passing will also work, 
>>>> but it will reduce the test readability (and potentially could 
>>>> bring more problems).
>>>>
>>>> An alternative approach would be to limit metaspace and heap 
>>>> accordingly and load classes until we don't run out metaspace... 
>>>> But this might take awhile.
>>>>
>>>> So, I hope that Michael's fix is good.
>>>>
>>>> Thanks for looking and expressing comments.
>>>> Dima
>>>>
>>>>
>>>>
>>>>
>>>> On 26.11.2014 22:04, Jon Masamitsu wrote:
>>>>> Michail,
>>>>>
>>>>> Your change makes this test pass but it seems like at
>>>>> some future date 300m might not be big enough
>>>>> (for whatever reason).  Could the test be make to
>>>>> caught an OOME, print out a message saying that
>>>>> an OOME doesn't mean the test failed  but that
>>>>> the test needs a larger heap?  Then pass an
>>>>> exception up (maybe some type of Runtime
>>>>> exception - sorry if that is vague but I don't
>>>>> what type of exception would make sense).  That
>>>>> would mean we wouldn't have to spend time
>>>>> diagnosing what the OOME means again.
>>>>>
>>>>> Jon
>>>>>
>>>>> On 11/26/2014 5:36 AM, Michail Chernov wrote:
>>>>>> Hi,
>>>>>>
>>>>>> Please review this simple fix for nightly test failure:
>>>>>>
>>>>>> Webrev:
>>>>>> http://cr.openjdk.java.net/~eistepan/~mchernov/8064909/webrev.00/
>>>>>> Bug:
>>>>>> https://bugs.openjdk.java.net/browse/JDK-8064909
>>>>>>
>>>>>> Problem: test fails because of OOME (not enough heap size).
>>>>>> Solution: heap size were increased.
>>>>>>
>>>>>> Testing:
>>>>>> jtreg
>>>>>>
>>>>>> Thanks,
>>>>>> Michail
>>>>>
>>>>
>>>
>>>
>>>
>>
>
>
>



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