[Python-checkins] r59724 - python/branches/release25-maint/Lib/threading.py

[guido.van.rossum]

Author: guido.van.rossum
Date: Fri Jan  4 20:06:02 2008
New Revision: 59724

Modified:
   python/branches/release25-maint/Lib/threading.py
Log:
Backport r57216 (see issue #1731).
Add a hack (originally devised in a slightly different form by Thomas Wouters)
to prevent spurious tracebacks when a daemon thread's cleanup happens to wake
up when the world around it has already been destroyed.

This also backports other small changes to this file, essentially making
it identical to the trunk version.


Modified: python/branches/release25-maint/Lib/threading.py
==============================================================================
--- python/branches/release25-maint/Lib/threading.py	(original)
+++ python/branches/release25-maint/Lib/threading.py	Fri Jan  4 20:06:02 2008
@@ -85,9 +85,10 @@
         self.__count = 0
 
     def __repr__(self):
+        owner = self.__owner
         return "<%s(%s, %d)>" % (
                 self.__class__.__name__,
-                self.__owner and self.__owner.getName(),
+                owner and owner.getName(),
                 self.__count)
 
     def acquire(self, blocking=1):
@@ -111,8 +112,8 @@
     __enter__ = acquire
 
     def release(self):
-        me = currentThread()
-        assert self.__owner is me, "release() of un-acquire()d lock"
+        if self.__owner is not currentThread():
+            raise RuntimeError("cannot release un-aquired lock")
         self.__count = count = self.__count - 1
         if not count:
             self.__owner = None
@@ -204,7 +205,8 @@
             return True
 
     def wait(self, timeout=None):
-        assert self._is_owned(), "wait() of un-acquire()d lock"
+        if not self._is_owned():
+            raise RuntimeError("cannot wait on un-aquired lock")
         waiter = _allocate_lock()
         waiter.acquire()
         self.__waiters.append(waiter)
@@ -245,7 +247,8 @@
             self._acquire_restore(saved_state)
 
     def notify(self, n=1):
-        assert self._is_owned(), "notify() of un-acquire()d lock"
+        if not self._is_owned():
+            raise RuntimeError("cannot notify on un-aquired lock")
         __waiters = self.__waiters
         waiters = __waiters[:n]
         if not waiters:
@@ -273,7 +276,8 @@
     # After Tim Peters' semaphore class, but not quite the same (no maximum)
 
     def __init__(self, value=1, verbose=None):
-        assert value >= 0, "Semaphore initial value must be >= 0"
+        if value < 0:
+            raise ValueError("semaphore initial value must be >= 0")
         _Verbose.__init__(self, verbose)
         self.__cond = Condition(Lock())
         self.__value = value
@@ -424,8 +428,10 @@
         return "<%s(%s, %s)>" % (self.__class__.__name__, self.__name, status)
 
     def start(self):
-        assert self.__initialized, "Thread.__init__() not called"
-        assert not self.__started, "thread already started"
+        if not self.__initialized:
+            raise RuntimeError("thread.__init__() not called")
+        if self.__started:
+            raise RuntimeError("thread already started")
         if __debug__:
             self._note("%s.start(): starting thread", self)
         _active_limbo_lock.acquire()
@@ -440,6 +446,26 @@
             self.__target(*self.__args, **self.__kwargs)
 
     def __bootstrap(self):
+        # Wrapper around the real bootstrap code that ignores
+        # exceptions during interpreter cleanup.  Those typically
+        # happen when a daemon thread wakes up at an unfortunate
+        # moment, finds the world around it destroyed, and raises some
+        # random exception *** while trying to report the exception in
+        # __bootstrap_inner() below ***.  Those random exceptions
+        # don't help anybody, and they confuse users, so we suppress
+        # them.  We suppress them only when it appears that the world
+        # indeed has already been destroyed, so that exceptions in
+        # __bootstrap_inner() during normal business hours are properly
+        # reported.  Also, we only suppress them for daemonic threads;
+        # if a non-daemonic encounters this, something else is wrong.
+        try:
+            self.__bootstrap_inner()
+        except:
+            if self.__daemonic and _sys is None:
+                return
+            raise
+
+    def __bootstrap_inner(self):
         try:
             self.__started = True
             _active_limbo_lock.acquire()
@@ -545,9 +571,13 @@
             _active_limbo_lock.release()
 
     def join(self, timeout=None):
-        assert self.__initialized, "Thread.__init__() not called"
-        assert self.__started, "cannot join thread before it is started"
-        assert self is not currentThread(), "cannot join current thread"
+        if not self.__initialized:
+            raise RuntimeError("Thread.__init__() not called")
+        if not self.__started:
+            raise RuntimeError("cannot join thread before it is started")
+        if self is currentThread():
+            raise RuntimeError("cannot join current thread")
+
         if __debug__:
             if not self.__stopped:
                 self._note("%s.join(): waiting until thread stops", self)
@@ -590,8 +620,10 @@
         return self.__daemonic
 
     def setDaemon(self, daemonic):
-        assert self.__initialized, "Thread.__init__() not called"
-        assert not self.__started, "cannot set daemon status of active thread"
+        if not self.__initialized:
+            raise RuntimeError("Thread.__init__() not called")
+        if self.__started:
+            raise RuntimeError("cannot set daemon status of active thread");
         self.__daemonic = daemonic
 
 # The timer class was contributed by Itamar Shtull-Trauring