RFR: 8253064: monitor list simplifications and getting rid of TSM [v4]

[Daniel D.Daugherty]

On Tue, 10 Nov 2020 23:27:52 GMT, Daniel D. Daugherty <dcubed at openjdk.org> wrote:

>> Well since it controls async deflation, it should probably get a mention since this comment on its own is not true:
>> 
>> // Keep track of contention for JVM/TI and M&M queries and control async deflation.
>> 
>> The field _contentions has a good comment.
>
> The comment for **that** location is correct. That's the location
> where we keep track of contended monitors for JVM/TI and M&M.
> The comments at the other locations are also correct (very verbose
> for two of them, but correct).

Look at the entire context of that location:
  // Keep track of contention for JVM/TI and M&M queries.
  add_to_contentions(1);
  if (is_being_async_deflated()) {
    // Async deflation is in progress and our contentions increment
    // above lost the race to async deflation. Undo the work and
    // force the caller to retry.
    const oop l_object = object();
    if (l_object != NULL) {
      // Attempt to restore the header/dmw to the object's header so that
      // we only retry once if the deflater thread happens to be slow.
      install_displaced_markword_in_object(l_object);
    }
    Self->_Stalled = 0;
    add_to_contentions(-1);
    return false;
  }
We do the increment for JVM/TI and M&M purposes and
then we check to see if async deflation beat us...

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PR: https://git.openjdk.java.net/jdk/pull/642