From f3e56f1b57584a136e14386fec2de95e73960eb4 Mon Sep 17 00:00:00 2001 From: Richard Purdie Date: Sat, 16 Feb 2019 14:01:56 +0000 Subject: lib/oe/utils: Fix hang in multiprocess_launch() If large results values are returned by the subprocesses, we can hit a deadlock where the subprocess is trying to write data back to the parent, the pipe is full and the parent is waiting for the child to exit. Avoid this by calling the update() method which would trigger reading a result from the child, avoiding the deadlock. The issue is described in https://bugs.python.org/issue8426 (From OE-Core rev: 0035e8066ecbbff94d6a1994a9f72b1368d660d2) Signed-off-by: Richard Purdie --- meta/lib/oe/utils.py | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/meta/lib/oe/utils.py b/meta/lib/oe/utils.py index 0c1d48a209..3a496090f3 100644 --- a/meta/lib/oe/utils.py +++ b/meta/lib/oe/utils.py @@ -307,6 +307,10 @@ def multiprocess_launch(target, items, d, extraargs=None): p.start() launched.append(p) for q in launched: + # Have to manually call update() to avoid deadlocks. The pipe can be full and + # transfer stalled until we try and read the results object but the subprocess won't exit + # as it still has data to write (https://bugs.python.org/issue8426) + q.update() # The finished processes are joined when calling is_alive() if not q.is_alive(): if q.exception: -- cgit v1.2.3-54-g00ecf