Copy the list of dangling threads to make sure that the list of
"Dangling thread" is complete. Previously, the list was incomplete if
threads completed just before the list was displayed.
Changes:
* Rewrite the warning to make it easier to understand.
* Use support.sleeping_retry().
* threading_cleanup() no longer copies threading._dangling,
but only counts the number of dangling thread.
* Remove support.gc_support() call.
For a while now, pending calls only run in the main thread (in the main interpreter). This PR changes things to allow any thread run a pending call, unless the pending call was explicitly added for the main thread to run.
* Replace time.sleep(0.010) with sleeping_retry() to
use an exponential sleep.
* support.wait_process(): reuse sleeping_retry().
* _test_eintr: remove unused variables.
Victor Stinner
Eric Snow
Christian Heimes
Christian Clauss
Hai Shi