2 files changed, 24 insertions, 1 deletions

diff --git a/bitbake/lib/bb/event.py b/bitbake/lib/bb/event.py
index 952c85c0bd..a12adbc937 100644
--- a/bitbake/lib/bb/event.py
+++ b/bitbake/lib/bb/event.py
@@ -194,7 +194,12 @@ def fire_ui_handlers(event, d):
         ui_queue.append(event)
         return
 
-    with bb.utils.lock_timeout(_thread_lock):
+    with bb.utils.lock_timeout_nocheck(_thread_lock) as lock:
+        if not lock:
+            # If we can't get the lock, we may be recursively called, queue and return
+            ui_queue.append(event)
+            return
+
         errors = []
         for h in _ui_handlers:
             #print "Sending event %s" % event
@@ -213,6 +218,9 @@ def fire_ui_handlers(event, d):
         for h in errors:
             del _ui_handlers[h]
 
+    while ui_queue:
+        fire_ui_handlers(ui_queue.pop(), d)
+
 def fire(event, d):
     """Fire off an Event"""
 
diff --git a/bitbake/lib/bb/utils.py b/bitbake/lib/bb/utils.py
index da026fe5bf..67e22f4389 100644
--- a/bitbake/lib/bb/utils.py
+++ b/bitbake/lib/bb/utils.py
@@ -1857,6 +1857,9 @@ def path_is_descendant(descendant, ancestor):
 # If we don't have a timeout of some kind and a process/thread exits badly (for example
 # OOM killed) and held a lock, we'd just hang in the lock futex forever. It is better
 # we exit at some point than hang. 5 minutes with no progress means we're probably deadlocked.
+# This function can still deadlock python since it can't signal the other threads to exit
+# (signals are handled in the main thread) and even os._exit() will wait on non-daemon threads
+# to exit.
 @contextmanager
 def lock_timeout(lock):
     try:
@@ -1869,3 +1872,15 @@ def lock_timeout(lock):
     finally:
         lock.release()
         signal.pthread_sigmask(signal.SIG_SETMASK, s)
+
+# A version of lock_timeout without the check that the lock was locked and a shorter timeout
+@contextmanager
+def lock_timeout_nocheck(lock):
+    try:
+        s = signal.pthread_sigmask(signal.SIG_BLOCK, signal.valid_signals())
+        l = lock.acquire(timeout=10)
+        yield l
+    finally:
+        if l:
+            lock.release()
+        signal.pthread_sigmask(signal.SIG_SETMASK, s)