RFR: 8212995: Consider placing the Integer.IntegerCache and cached Integer objects in the closed archive heap region

[Jiangli Zhou]

On 10/31/18 12:08 PM, Jiangli Zhou wrote:

> Hi Ioi,
>
> Here is an updated webrev with renaming of the 'is_shared' argument. I 
> decided to go with your suggestion, 'is_closed_archive'.
>
> http://cr.openjdk.java.net/~jiangli/8212995/webrev.01/

BTW, in above webrev, I also included a typo fix for the following 
warning that Mandy found (thanks Mandy!)

@@ -1324,11 +1329,11 @@
    // header data
    const char* prop = Arguments::get_property("java.system.class.loader");
    if (prop != NULL) {
      warning("Archived non-system classes are disabled because the "
              "java.system.class.loader property is specified (value = 
\"%s\"). "
-            "To use archived non-system classes, this property must be 
not be set", prop);
+            "To use archived non-system classes, this property must not 
be set", prop);
      _has_platform_or_app_classes = false;
    }

Thanks,
Jiangli
>
> Thanks,
>
> Jiangli
>
>
> On 10/30/18 4:19 PM, Jiangli Zhou wrote:
>> Hi Ioi,
>>
>> On 10/30/18 3:00 PM, Ioi Lam wrote:
>>
>>> Hi Jiangli,
>>>
>>> This looks promising.
>>>
>>> Now a full review yet, but I am wondering about the name of the 
>>> is_shared parameter
>>>
>>>   void add_subgraph_entry_field(int static_field_offset, oop v, bool 
>>> is_shared);
>>>
>>> Since this is part of "heapShared", everything is "shared" in some 
>>> sense of the word. It could be confusing to say something is more 
>>> shared than other things which also shared ...
>>>
>>> How "is_closed_archive" instead?
>> Yes, our 'shared' has broader meaning. "is_closed_archive" or 
>> "is_closed_space" sounds good to me. I'll rename.
>>
>> Thanks,
>> Jiangli
>>>
>>> Thanks
>>> - Ioi
>>>
>>>
>>> On 10/30/2018 01:57 PM, Jiangli Zhou wrote:
>>>> Please review the following change for moving the archived 
>>>> Integer.IntegerCache and it's cached Integer objects (256) to the 
>>>> closed archiving heap region. The IntegerCache subgraph does not 
>>>> contain any reference that's changed at runtime (good candidate for 
>>>> sharing). Moving the whole subgraph into the closed archive heap 
>>>> region allows the memory to be shared by different JVM instances at 
>>>> runtime. The saving is 4K per JVM instance running the same or 
>>>> different java application simultaneously. Although 4K is not 
>>>> significant, in a larger picture the saving is much bigger (4k * 
>>>> (JVM_instance_num - 1) * host_num).
>>>>
>>>> As part of the change, I also restructured the code to allow us to 
>>>> plug in more shareable subgraphs in the closed archive heap region 
>>>> for runtime footprint saving in the future.
>>>>
>>>> The 'st' space is renamed to 'ca' (closed archive) space since it 
>>>> now contains other types of objects besides j.l.Strings.
>>>>
>>>> webrev: http://cr.openjdk.java.net/~jiangli/8212995/webrev.00/
>>>> RFE: https://bugs.openjdk.java.net/browse/JDK-8212995
>>>>
>>>> Before:
>>>>
>>>> mc  space:      8416 [  0.0% of total] out of     12288 bytes [ 
>>>> 68.5% used] at 0x0000000800000000
>>>> rw  space:   3946640 [ 21.4% of total] out of   3948544 bytes 
>>>> [100.0% used] at 0x0000000800003000
>>>> ro  space:   7319328 [ 39.6% of total] out of   7319552 bytes 
>>>> [100.0% used] at 0x00000008003c7000
>>>> md  space:      2416 [  0.0% of total] out of      4096 bytes [ 
>>>> 59.0% used] at 0x0000000800ac2000
>>>> od  space:   6475944 [ 35.0% of total] out of   6479872 bytes [ 
>>>> 99.9% used] at 0x0000000800ac3000
>>>> st0 space:    438272 [  2.4% of total] out of    438272 bytes 
>>>> [100.0% used] at 0x00000007ffc00000 <<<<<<<<<<
>>>> oa0 space:    282624 [  1.5% of total] out of    282624 bytes 
>>>> [100.0% used] at 0x00000007ff800000 <<<<<<<<<<
>>>> total    :  18473640 [100.0% of total] out of  18485248 bytes [ 
>>>> 99.9% used]
>>>>
>>>> After:
>>>>
>>>> mc  space:      8416 [  0.0% of total] out of     12288 bytes [ 
>>>> 68.5% used] at 0x0000000800000000
>>>> rw  space:   3946640 [ 21.4% of total] out of   3948544 bytes 
>>>> [100.0% used] at 0x0000000800003000
>>>> ro  space:   7319304 [ 39.6% of total] out of   7319552 bytes 
>>>> [100.0% used] at 0x00000008003c7000
>>>> md  space:      2416 [  0.0% of total] out of      4096 bytes [ 
>>>> 59.0% used] at 0x0000000800ac2000
>>>> od  space:   6475920 [ 35.0% of total] out of   6479872 bytes [ 
>>>> 99.9% used] at 0x0000000800ac3000
>>>> ca0 space:    442368 [  2.4% of total] out of    442368 bytes 
>>>> [100.0% used] at 0x00000007ffc00000 <<<<<<<<<<
>>>> oa0 space:    278528 [  1.5% of total] out of    278528 bytes 
>>>> [100.0% used] at 0x00000007ff800000 <<<<<<<<<<
>>>> total    :  18473592 [100.0% of total] out of  18485248 bytes [ 
>>>> 99.9% used]
>>>>
>>>> Tested with appcds tests on linux-x64 locally. Running tier1-teir4 
>>>> tests.
>>>>
>>>> Thanks,
>>>>
>>>> Jiangli
>>>>
>>>>
>>>
>>
>