RFR: 8264735: Make dynamic dump repeatable

[Yumin Qi]

On Fri, 2 Jul 2021 17:59:35 GMT, Calvin Cheung <ccheung at openjdk.org> wrote:

>> Hi, Please review
>> 
>>   Currently after dynamic dump, dump time tables (`_dumptime_talbles, _dumptime_lambda_proxy_class_dictionary and _saved_shared_path_table`) are corrupted and could not be used for next dump. The patch clones the three tables, and after dump restore them so the next dump is possible. With the fix, jcmd VM.cds dynamic_dump can do multiple dump to the same live process.
>> 
>>   Tests: tier1,tier2,tier3,tier4
>>   
>>   Thanks
>>   Yumin
>
> src/hotspot/share/classfile/systemDictionaryShared.cpp line 1554:
> 
>> 1552:   }
>> 1553:   bool do_entry(InstanceKlass* k, DumpTimeClassInfo& info) {
>> 1554:     if (!info.is_excluded()) {
> 
> Should assert_lock_strong(DumpTimeTable_lock) be added like at line 1574 below?

should check lock, thank.

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PR: https://git.openjdk.java.net/jdk/pull/4646