RFR 8166848: Performance bug: SystemDictionary - optimization

[coleen.phillimore at oracle.com]

Ioi, Thanks for pushing me to remove this duplication.  How's this?   I 
reran with runThese and -XX:+VerifyBeforeGC, and built product.

http://cr.openjdk.java.net/~coleenp/8166848.03/webrev

thanks,
Coleen

On 5/17/17 12:43 PM, Ioi Lam wrote:
> I know many people are not fans of macros or templates, but the 
> hashtable iteration code is repeated in many places.
>
> For example, the verification code is the same across these two tables:
>
>  352 void PackageEntryTable::verify() {
>  353   int element_count = 0;
>  354   int max_bucket_count = 0;
>  355   for (int index = 0; index < table_size(); index++) {
>  356     int bucket_count = 0;
>  357     for (PackageEntry* probe = bucket(index);
>  358                               probe != NULL;
>  359                               probe = probe->next()) {
>  360       probe->verify();
>  361       element_count++;
>  362       bucket_count++;
>  363     }
>  364     max_bucket_count = MAX2(max_bucket_count, bucket_count);
>  365   }
>  366   guarantee(number_of_entries() == element_count,
>  367             "Verify of Package Entry Table failed");
>  368   DEBUG_ONLY(verify_lookup_length(max_bucket_count, "Package 
> Entry Table"));
>  369 }
>
>  509 void ModuleEntryTable::verify() {
>  510   int element_count = 0;
>  511   int max_bucket_count = 0;
>  512   for (int i = 0; i < table_size(); i++) {
>  513     int bucket_count = 0;
>  514     for (ModuleEntry* probe = bucket(i);
>  515                               probe != NULL;
>  516                               probe = probe->next()) {
>  517       probe->verify();
>  518       element_count++;
>  519       bucket_count++;
>  520     }
>  521     max_bucket_count = MAX2(max_bucket_count, bucket_count);
>  522   }
>  523   guarantee(number_of_entries() == element_count,
>  524             "Verify of Module Entry Table failed");
>  525   DEBUG_ONLY(verify_lookup_length(max_bucket_count, "Module Entry 
> Table"));
>  526 }
>
>
> and void Dictionary::verify() only has a bit more code inside the 
> inner loop. How about using a template here. The following is probably 
> not the best way to do it (but it compiles :-)
>
> #include <stdio.h>
>
> class Hashtable {
> public:
>   template <class Table, class Entry> void do_verify() {
>     for (int i=0; i<10; i++) { // pseudo code for the table iteration
>       void *probe = NULL;      // pseudo code for getting an entry
>       Table::verify_entry((Entry*)probe);
>     }
>   }
> };
>
> class MyHashentry {/*...*/};
>
> class MyHashtable : public Hashtable {
> public:
>   void verify() {
>     do_verify<MyHashtable, MyHashentry>();
>   }
>   static void verify_entry(MyHashentry *probe) {
>     // ...
>   }
> };
>
>
> Thanks
> - Ioi
>
>
> On 5/15/17 5:30 AM, coleen.phillimore at oracle.com wrote:
>>
>>> Summary: Check instead that a bucket isn't 10x the average
>>>
>>> See bug and linked bugs for more details.
>>>
>>> Tested with RBT nightly tests (tier2-5).
>>>
>>> open webrev at http://cr.openjdk.java.net/~coleenp/8166848.01/webrev
>>> bug link https://bugs.openjdk.java.net/browse/JDK-8166848
>>>
>>> Thanks,
>>> Coleen
>>
>