----- Original Message -----
From: "Dan Kenigsberg" danken@redhat.com To: "Nir Soffer" nsoffer@redhat.com Cc: "Yaniv Bronheim" ybronhei@redhat.com, "VDSM Project Development" vdsm-devel@lists.fedorahosted.org Sent: Tuesday, February 4, 2014 3:51:02 PM Subject: Re: [vdsm] suggested patch for python-pthreading
On Tue, Feb 04, 2014 at 05:14:51AM -0500, Nir Soffer wrote:
----- Original Message -----
From: "Yaniv Bronheim" ybronhei@redhat.com To: "Nir Soffer" nsoffer@redhat.com Cc: "VDSM Project Development" vdsm-devel@lists.fedorahosted.org Sent: Tuesday, February 4, 2014 11:53:52 AM Subject: Re: [vdsm] suggested patch for python-pthreading
----- Original Message -----
From: "Nir Soffer" nsoffer@redhat.com To: "Yaniv Bronheim" ybronhei@redhat.com Cc: "VDSM Project Development" vdsm-devel@lists.fedorahosted.org Sent: Tuesday, February 4, 2014 11:39:56 AM Subject: Re: [vdsm] suggested patch for python-pthreading
----- Original Message -----
From: "Yaniv Bronheim" ybronhei@redhat.com To: "VDSM Project Development" vdsm-devel@lists.fedorahosted.org Sent: Tuesday, February 4, 2014 11:04:37 AM Subject: [vdsm] suggested patch for python-pthreading
according to coredumps we found in the scope of the bug [1] we opened [2] that suggested to override python's implementation of thread.allocate_lock in each coredump we saw few threads stuck with the bt:
#16 0x00007fcb69288c93 in PyEval_CallObjectWithKeywords (func=0x2527820, arg=0x7fcb6972f050, kw=<value optimized out>) at Python/ceval.c:3663 #17 0x00007fcb692ba7ba in t_bootstrap (boot_raw=0x250a820) at Modules/threadmodule.c:428 #18 0x00007fcb68fa3851 in start_thread (arg=0x7fcb1bfff700) at pthread_create.c:301 #19 0x00007fcb6866694d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:115
in pystack the threads were stuck in /usr/lib64/python2.6/threading.py (513): __bootstrap_inner
in bootstrap_inner we use thread.allocate_lock which python-pthreading does not override.
we suggest the following commit:
From 9d89e9be1a379b3d93b23dd54a381b9ca0973ebc Mon Sep 17 00:00:00 2001 From: Yaniv Bronhaim ybronhei@redhat.com Date: Mon, 3 Feb 2014 19:24:30 +0200 Subject: [PATCH] Mocking thread.allocate_lock with Lock imp
Signed-off-by: Yaniv Bronhaim ybronhei@redhat.com
pthreading.py | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/pthreading.py b/pthreading.py index 916ca7f..96df42c 100644 --- a/pthreading.py +++ b/pthreading.py @@ -132,6 +132,10 @@ def monkey_patch(): Thus, Queue and SocketServer can easily enjoy them. """
import thread
thread.allocate_lock = Lock
import threading
threading.Condition = Condition
-- 1.8.3.1
[1] https://bugzilla.redhat.com/show_bug.cgi?id=1022036 [2] https://bugzilla.redhat.com/show_bug.cgi?id=1060749
Replacing allocate_lock in thread is correct. However, since threading copies thread.allocate_lock, and you don't control import order, you have to monkeypatch threading.allocate_lock as well.
The full should be:
import thread thread.allocate_lock = Lock
import threading threading.allocate_lock = Lock threading.Lock = Lock
Nir
thanks Nir for the reply and review I guess you meant threading._allocate_lock, but we monkey patch it in an order so we do control the import order.. not sure its necessary
Correct, threading._allocate_lock. And we also have to patch threading._active_limbo_lock.
We don't control the user import order - If I import threading before pthreading, both threading._allocate_lock and threading._active_limbo_lock are using the incorrect lock. Since many library modules import threading, it is impossible to require any import order.
The safest way would be to patch all places that may use the original thread.allocate_lock.
The safest way would be to say loud and clear: the user must call pthreading.monkey_patch() on the begining of his main module, before threading is imported and most certainly before it is ever used.
If we give the impression that doing anything else is fine, and we can end up replacing _active_limbo_lock while there's an entity (such as a _MainThread object) depending on its uniqueness.
Then we should find a way to assert that the user did not import threading yet, otherwise our requirement is not very useful.
If you import threading or another module that import threading, importing pthreading should raise something like:
"You must import pthreading before threading is imported"
Nir