Hi Ioi,
I like the more structural way of reading/writing the compact table with
SimpleCompactHashtable. It looks quite clean overall.
- How about using VALUE_ONLY_BUCKET_TYPE, which is more descriptive than
TINY_BUCKET_TYPE?
- The following assert in CompactSymbolTableWriter::add() limits the total
shared space size to be less than MAX_SHARED_DELTA unnecessarily. Symbols are
allocated from the RO space at dump time. We only need to make sure the max
delta between the ‘base_address’ and the end of RO space is less than
MAX_SHARED_DELTA. This is not a new issue introduced by your change, you don’t
have to address that as part of this change if you prefer. I’ll file a separate
RFE.
171 void CompactSymbolTableWriter::add(unsigned int hash, Symbol *symbol) {
172 address base_address = address(MetaspaceShared::shared_rs()->base());
173 uintx max_delta = uintx(MetaspaceShared::shared_rs()->size());
174 assert(max_delta <= MAX_SHARED_DELTA, "range check");
- Why is the default RO space size increased?
- src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/memory/SymbolTable.java
-
src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/utilities/CompactHashTable.java
Copyright year.
Thanks,
Jiangli
> On Mar 31, 2016, at 10:43 PM, Ioi Lam <ioi....@oracle.com> wrote:
>
> Please review
>
> http://cr.openjdk.java.net/~iklam/jdk9/8150607_cleanup_compact_hashtable.v01/
>
> Bug: Clean up CompactHashtable
>
> https://bugs.openjdk.java.net/browse/JDK-8150607
>
> Summary of fix:
>
> [1] Instead of reading/writing the table bit-by-bit, which is tedious and
> error prone, use SimpleCompactHashtable::serialize(), which is more
> structural.
>
> [2] Split up the _buckets and _entries into two separate arrays, so the
> dumping and walking code is easier to understand
>
> (see comments above SimpleCompactHashtable declaration)
> These 2 arrays are now allocated from the RO region (used to be in RW)
>
> [3] Renamed a few things
>
> COMPACT_BUCKET_TYPE -> TINY_BUCKET_TYPE
> (having something called "compact" in CompactHashtable is confusing)
>
> The old names "dump_table" (actually dumping the buckets) and
> "dump_buckets" (actually dumping the entries) were conflicting with
> terminology used elsewhere. Now the terminology is unified:
> "buckets" = the main index, "entries" = the second level.
>
> lookup_entry -> decode_entry (it wasn't doing any lookup)
>
> [4] Changed all "*p++" to "array->at_put", so out-of-bounds can be
> checked with assert.
>
> [5] Replaced all juint to u4 (suggested by Coleen)
>
> [6] templatize the iterator (see CompactHashtable::symbols_do ->
> SimpleCompactHashtable::iterate)
>
> [7] I also added a test case using Serviceability Agent -- due to the lack of
> a regression test, the walking of the compact hashtable in SA had been
> broken for a while before it was fixed in JDK-8151368, so having a test
> case would make the code more maintainable.
>
> Tests:
>
> Hotspot JTREG tests
>
> Thanks
> - Ioi
