Integrated: 8267920: Create separate Events buffer for VMOperations

[Stefan Karlsson]

On Fri, 28 May 2021 11:22:49 GMT, Stefan Karlsson <stefank at openjdk.org> wrote:

> The Events classes collect events in a circular buffer that gets dumped into the hs_err files. There are different sections to sort out different types of events. See:
> 
>   // A log for internal exception related messages, like internal
>   // throws and implicit exceptions.
>   static ExceptionsEventLog* _exceptions;
> 
>   // Deoptization related messages
>   static StringEventLog* _deopt_messages;
> 
>   // Redefinition related messages
>   static StringEventLog* _redefinitions;
> 
>   // Class unloading events
>   static UnloadingEventLog* _class_unloading;
> 
> There's also a buffer for non-categorized events:
> 
>   // A log for generic messages that aren't well categorized.
>   static StringEventLog* _messages;
> 
> I propose that we create a separate buffer for VMOperations. This will make it easier to debug GC related bugs.
> 
> With the proposed patch, the hs_err files will now have a section that looks like this.
> 
> VM Operations (20 events):
> Event: 0,186 Executing VM operation: HandshakeAllThreads
> Event: 0,186 Executing VM operation: HandshakeAllThreads done
> Event: 0,230 Executing VM operation: ZMarkStart
> Event: 0,230 Executing VM operation: ZMarkStart done
> Event: 0,232 Executing VM operation: HandshakeAllThreads
> Event: 0,232 Executing VM operation: HandshakeAllThreads done
> Event: 0,232 Executing VM operation: HandshakeAllThreads
> Event: 0,232 Executing VM operation: HandshakeAllThreads done
> Event: 0,232 Executing VM operation: HandshakeAllThreads
> Event: 0,233 Executing VM operation: HandshakeAllThreads done
> Event: 0,233 Executing VM operation: ZMarkEnd
> Event: 0,233 Executing VM operation: ZMarkEnd done
> Event: 0,234 Executing VM operation: HandshakeAllThreads
> Event: 0,234 Executing VM operation: HandshakeAllThreads done
> Event: 0,234 Executing VM operation: ZVerify
> Event: 0,234 Executing VM operation: ZVerify done
> Event: 0,234 Executing VM operation: CleanClassLoaderDataMetaspaces
> Event: 0,234 Executing VM operation: CleanClassLoaderDataMetaspaces done
> Event: 0,235 Executing VM operation: ZRelocateStart
> Event: 0,235 Executing VM operation: ZRelocateStart done

This pull request has now been integrated.

Changeset: 47677580
Author:    Stefan Karlsson <stefank at openjdk.org>
URL:       https://git.openjdk.java.net/jdk/commit/476775808f82a4b0d42ac58fdb801812b54e01a1
Stats:     69 lines in 3 files changed: 49 ins; 3 del; 17 mod

8267920: Create separate Events buffer for VMOperations

Reviewed-by: coleenp, dholmes, tschatzl

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PR: https://git.openjdk.java.net/jdk/pull/4243