gh-110722: Make `-m test -T -j` use sys.monitoring (GH-111710)

Now all results from worker processes are aggregated and
displayed together as a summary at the end of a regrtest run.

The traditional trace is left in place for use with sequential
in-process test runs but now raises a warning that those
numbers are not precise.

`-T -j` requires `--with-pydebug` as it relies on `-Xpresite=`.

1 files changed, 9 insertions, 1 deletions

diff --git a/Doc/library/trace.rst b/Doc/library/trace.rst
index e9b59a6..8854905 100644
--- a/Doc/library/trace.rst
+++ b/Doc/library/trace.rst
@@ -187,7 +187,8 @@ Programmatic Interface
 
       Merge in data from another :class:`CoverageResults` object.
 
-   .. method:: write_results(show_missing=True, summary=False, coverdir=None)
+   .. method:: write_results(show_missing=True, summary=False, coverdir=None,\
+                             *, ignore_missing_files=False)
 
       Write coverage results.  Set *show_missing* to show lines that had no
       hits.  Set *summary* to include in the output the coverage summary per
@@ -195,6 +196,13 @@ Programmatic Interface
       result files will be output.  If ``None``, the results for each source
       file are placed in its directory.
 
+      If *ignore_missing_files* is ``True``, coverage counts for files that no
+      longer exist are silently ignored. Otherwise, a missing file will
+      raise a :exc:`FileNotFoundError`.
+
+      .. versionchanged:: 3.13
+         Added *ignore_missing_files* parameter.
+
 A simple example demonstrating the use of the programmatic interface::
 
    import sys