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

Jiangli Zhou jiangli.zhou at oracle.com
Wed Oct 31 19:45:38 UTC 2018

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

Hi Ioi,

Here is an updated webrev with renaming of the 'isshared' argument. I decided to go with your suggestion, 'isclosedarchive'. 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 isshared parameter void addsubgraphentryfield(int staticfieldoffset, oop v, bool isshared); 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 "isclosedarchive" instead? Yes, our 'shared' has broader meaning. "isclosedarchive" or "isclosedspace" 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 * (JVMinstancenum - 1) * hostnum). 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

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