Wrap calls to deferToThread() in a thing which uses a child logcontext to
attribute CPU usage to the right request.
While we're in the area, remove the logcontext_tracer stuff, which is never
used, and afaik doesn't work.
Fixes#4064
The old style raise is invalid syntax in python3. As noted in the docs,
this adds one more frame in the traceback, but I think this is
acceptable:
<ipython-input-7-bcc5cba3de3f> in <module>()
16 except:
17 pass
---> 18 six.reraise(*x)
/usr/lib/python3.6/site-packages/six.py in reraise(tp, value, tb)
691 if value.__traceback__ is not tb:
692 raise value.with_traceback(tb)
--> 693 raise value
694 finally:
695 value = None
<ipython-input-7-bcc5cba3de3f> in <module>()
9
10 try:
---> 11 x()
12 except:
13 x = sys.exc_info()
Also note that this uses six, which is not formally a dependency yet,
but is included indirectly since most packages depend on it.
Signed-off-by: Adrian Tschira <nota@notafile.com>