RFR: 8284161: Implementation of Virtual Threads (Preview) [v8]

[Markus Grönlund]

On Thu, 28 Apr 2022 14:41:04 GMT, Erik Gahlin <egahlin at openjdk.org> wrote:

>> Alan Bateman has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Refresh 7965cc6b168e567ac2596f2fbc3b00a7d99b7e1e
>
> src/hotspot/share/jfr/recorder/checkpoint/jfrCheckpointManager.cpp line 94:
> 
>> 92: static const size_t global_buffer_size = 512 * K;
>> 93: 
>> 94: static const size_t thread_local_buffer_prealloc_count = 32;
> 
> Why is more memory needed? Moore's law or something specific to virtual threads?

The carrier thread will write the metadata for the mounted virtual threads lazily with virtual threads as part of the event write. They write this thread locally, and the memory increase accommodates fewer roundtrips to fetch new buffers. The previous size was small because it would only hold at most one entry.

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PR: https://git.openjdk.java.net/jdk/pull/8166