RFR: 8259067: bootclasspath append takes out object lock

[Zhengyu Gu]

On Mon, 4 Jan 2021 17:28:30 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

> See CR for details.
> I made the classpath append list lock-free.  Calling experts in Atomic operations...
> Tested with tier1-6.
> Thanks,
> Coleen

src/hotspot/share/classfile/classLoader.cpp line 843:

> 841:           assert(first_append_entry() == NULL, "boot loader's append class path entry list not empty");
> 842:           Atomic::store(&_first_append_entry_list, new_entry);
> 843:           return;

Not sure if it is a problem. There is a chance that an entry is added, e.g. _last_append_entry = new_entry, but _first_append_entry_list == NULL. If contains_append_entry() queries on this new entry, it may return false.

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