RFR: 8296270: Memory leak in ClassLoader::setup_bootstrap_search_path_impl

[Man Cao]

On Fri, 4 Nov 2022 01:20:41 GMT, Man Cao <manc at openjdk.org> wrote:

> Hi all,
> 
> Could anyone help review this fix for a memory leak? There is a redundant code branch in ClassLoader::setup_bootstrap_search_path_impl() for exploded-image build that is unnecessary and causes a leak.
> 
> I'm sponsoring colleague Justin King (jcking at google.com) for this contribution, who remarkably made LeakSanitizer working for HotSpot and found this leak.
> 
> @jianglizhou also helped validate this fix. Quoting her comment:
>> For the ClassPathEntry* new_entry = create_class_path_entry(current, path, &st, false, false); else case with an exploded build in jdk head codebase, it does appear to be not needed. It only creates the class path entry for <path>/modules/java.base, which is handled by [ClassLoader::add_to_exploded_build_list](http://google3/third_party/java_src/jdk/head/src/src/hotspot/share/classfile/classLoader.cpp;l=671;rcl=478881875) later again. Just to be sure, I checked in lldb. The <path>/modules/java.base module path entry is created twice.
> 
> -Man

Results from `make exploded-test` for tier1 and tier2:

Without any change:

   TEST                                              TOTAL  PASS  FAIL ERROR   
>> jtreg:test/hotspot/jtreg:tier1                     2201  2146    55     0 <<
>> jtreg:test/jdk:tier1                               2205  2178    27     0 <<
>> jtreg:test/langtools:tier1                         4351  4346     5     0 <<
   jtreg:test/jaxp:tier1                                 0     0     0     0   
   jtreg:test/lib-test:tier1                             0     0     0     0   
>> jtreg:test/hotspot/jtreg:tier2                      741   494   247     0 <<
>> jtreg:test/jdk:tier2                               3986  3806   178     2 <<
   jtreg:test/langtools:tier2                           11    11     0     0   
>> jtreg:test/jaxp:tier2                               470   379    91     0 <<

With this change and JDK-8296347

   TEST                                              TOTAL  PASS  FAIL ERROR   
>> jtreg:test/hotspot/jtreg:tier1                     2197  2144    53     0 <<
>> jtreg:test/jdk:tier1                               2205  2178    27     0 <<
>> jtreg:test/langtools:tier1                         4351  4346     5     0 <<
   jtreg:test/jaxp:tier1                                 0     0     0     0   
   jtreg:test/lib-test:tier1                             0     0     0     0   
>> jtreg:test/hotspot/jtreg:tier2                      742   494   248     0 <<
>> jtreg:test/jdk:tier2                               3986  3806   178     2 <<
   jtreg:test/langtools:tier2                           11    11     0     0   
>> jtreg:test/jaxp:tier2                               470   379    91     0 <<


Some tests are apparently flaky.
I compared the diff of `summary.txt`, and did not find any new failures.

There seems some problem with counting the total tests. `summary.txt` for hotspot/tier1 shows 2201 lines in both runs, but second run only counts 2197 total tests. Similarly `summary.txt` for hotspot/tier2 shows 742 lines in both runs.

Overall, I think this is good to go. The presubmit test failures also seem unrelated.

-------------

PR: https://git.openjdk.org/jdk/pull/10973