RFR: 8259067: bootclasspath append takes out object lock [v2]

[Serguei Spitsyn]

On Tue, 5 Jan 2021 04:19:29 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

>> Hi Coleen,
>> 
>> LGTM++
>> 
>> Thanks,
>> Serguei
>
> Thanks Serguei.  Ioi convinced me offline to simplify and just use a mutex, so I updated the patch to do that.  I tested with jdi and jvmti tests and will rerun tier1-3.

Coleen, the function `ClassLoader::add_to_boot_append_entries` is also called from `ClassLoader::update_class_path_entry_list` and `ClassLoaderExt::append_boot_classpath`. It is not clear why the `Bootclasspath_lock` is not used for sync in these contexts. Could you consider to move this `MutexLocker` from `JvmtiEnv::AddToBootstrapClassLoaderSearch` to `ClassLoader::add_to_boot_append_entries`?

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PR: https://git.openjdk.java.net/jdk/pull/1935