Running gtkperf -a
in a loop, and running xpra info
in another loop in parallel eventually causes the server to hang.
It shows new connection but times them all out.
Running gtkperf -a
in a loop alone does not crash.
Running xpra info
alone in a loop does not crash or leak any memory.
The server goes AWOL following this message in the server log:
(Xpra:7593): Gdk-WARNING **: 21:51:39.364: GdkWindow 0x400d81 unexpectedly destroyed /usr/lib64/python3.7/site-packages/xpra/x11/models/window.py:327: Warning: g_object_get_qdata: assertion 'G_IS_OBJECT (object)' failed self.corral_window = None /usr/lib64/python3.7/site-packages/xpra/x11/models/window.py:327: Warning: g_object_set_qdata_full: assertion 'G_IS_OBJECT (object)' failed self.corral_window = None /usr/lib64/python3.7/site-packages/xpra/x11/models/window.py:327: Warning: g_object_remove_toggle_ref: assertion 'G_IS_OBJECT (object)' failed self.corral_window = None 2019-03-18 21:51:48,306 Warning: timeout on screen updates for window 1, 2019-03-18 21:51:48,306 already delayed for more than 15 seconds (Xpra:7593): Gdk-WARNING **: 21:51:53.976: GdkWindow 0x400def unexpectedly destroyed 2019-03-18 21:51:55,098 Error: connection timed out: unix-domain socket:/run/user/1000/xpra/desktop-20
Even with python2, things can degenerate, though not as fast and not as badly.
xpra info of a hung python2 server after ~10000 gtkperf windows are shown
python3 server just before it hung
verify that we are in the main thread in more places
r22114 adds extra thread checking to the gtk X11 context manager code, and the patch above adds yet more checks. But none of those trigger any warnings.
Could it be a race condition that is made more likely by the extra delay introduced by the "xpra info" query?
When the server seems stuck, it is consuming a lot of CPU time in the X11 event loop.
Simply killing the gtkperf
client loop and waiting for things to settle eventually brings it back to life, so I'm lowering the priority as it's not a crash, "just" an X11 DoS.
Is GTK3 that much slower? (New ticket: #2219) Less efficient? Gets more events?
The hang is often preceded by:
2019-03-18 23:56:53,637 Warning: timeout on screen updates for window 1, 2019-03-18 23:56:53,637 already delayed for more than 15 seconds
Which could happen if the main thread is too busy to answer.
How can we avoid getting in this situation, or detect it and deal with it? Maybe as part of the move to wayland, we can move away from GTK? We already have window models, do we really need those GDK windows to wrap the X11 window?
GTK3 is now slower: ticket:2219#comment:3
last server info captured before it becomes unresponsive, without keyboard data
Different symptoms this time:
2019-09-05 13:10:10,898 Error: connection timed out: unix-domain socket:/run/user/1000/xpra/localhost.localdomain-2 2019-09-05 13:10:11,309 New unix-domain connection received on /run/user/1000/xpra/localhost.localdomain-2 2019-09-05 13:10:12,312 New unix-domain connection received on /run/user/1000/xpra/localhost.localdomain-2 2019-09-05 13:10:12,312 New unix-domain connection received on /run/xpra/localhost.localdomain-2 2019-09-05 13:10:12,390 Warning: timeout on screen updates for window 1, 2019-09-05 13:10:12,390 already delayed for more than 15 seconds 2019-09-05 13:10:28,884 Warning: timeout on screen updates for window 2472, 2019-09-05 13:10:28,884 already delayed for more than 15 seconds 2019-09-05 13:10:31,200 Warning: timeout on screen updates for window 1, 2019-09-05 13:10:31,200 already delayed for more than 15 seconds 2019-09-05 13:10:32,311 Error: connection timed out: unix-domain socket:/run/user/1000/xpra/localhost.localdomain-2 2019-09-05 13:10:32,735 New unix-domain connection received on /run/user/1000/xpra/localhost.localdomain-2 2019-09-05 13:10:33,320 Error: connection timed out: unix-domain socket:/run/user/1000/xpra/localhost.localdomain-2 2019-09-05 13:10:33,321 Error: connection timed out: unix-domain socket:/run/xpra/localhost.localdomain-2 2019-09-05 13:10:33,415 Missing property or wrong property type _MOTIF_WM_HINTS (motif-hints) 2019-09-05 13:10:33,736 New unix-domain connection received on /run/user/1000/xpra/localhost.localdomain-2 2019-09-05 13:10:33,736 New unix-domain connection received on /run/xpra/localhost.localdomain-2 2019-09-05 13:10:40,357 Missing property or wrong property type WM_TRANSIENT_FOR (window) 2019-09-05 13:10:40,361 Missing property or wrong property type _NET_WM_WINDOW_TYPE (['atom']) 2019-09-05 13:10:49,568 Warning: timeout on screen updates for window 2617, 2019-09-05 13:10:49,568 already delayed for more than 15 seconds 2019-09-05 13:10:53,737 Error: connection timed out: unix-domain socket:/run/user/1000/xpra/localhost.localdomain-2 2019-09-05 13:10:54,170 New unix-domain connection received on /run/user/1000/xpra/localhost.localdomain-2 2019-09-05 13:10:54,737 Error: connection timed out: unix-domain socket:/run/user/1000/xpra/localhost.localdomain-2 2019-09-05 13:10:54,737 Error: connection timed out: unix-domain socket:/run/xpra/localhost.localdomain-2 2019-09-05 13:10:55,115 Warning: timeout on screen updates for window 2657, 2019-09-05 13:10:55,115 already delayed for more than 15 seconds 2019-09-05 13:10:55,169 New unix-domain connection received on /run/user/1000/xpra/localhost.localdomain-2 2019-09-05 13:10:55,169 New unix-domain connection received on /run/xpra/localhost.localdomain-2 2019-09-05 13:10:58,143 Warning: timeout on screen updates for window 1, 2019-09-05 13:10:58,144 already delayed for more than 15 seconds ^C 2019-09-05 13:11:09,004 sound source got signal SIGINT
And another one:
2019-09-05 13:19:13,201 New unix-domain connection received on /run/user/1000/xpra/localhost.localdomain-2 2019-09-05 13:19:13,204 New unix-domain connection received on /run/xpra/localhost.localdomain-2 2019-09-05 13:19:13,607 New unix-domain connection received on /run/user/1000/xpra/localhost.localdomain-2 (Xpra:21966): Gdk-WARNING **: 13:19:14.578: GdkWindow 0x400a59 unexpectedly destroyed 2019-09-05 13:19:14,607 New unix-domain connection received on /run/user/1000/xpra/localhost.localdomain-2 2019-09-05 13:19:14,608 New unix-domain connection received on /run/xpra/localhost.localdomain-2 /usr/lib64/python3.7/site-packages/xpra/x11/models/window.py:327: Warning: g_object_get_qdata: assertion 'G_IS_OBJECT (object)' failed self.corral_window = None /usr/lib64/python3.7/site-packages/xpra/x11/models/window.py:327: Warning: g_object_set_qdata_full: assertion 'G_IS_OBJECT (object)' failed self.corral_window = None /usr/lib64/python3.7/site-packages/xpra/x11/models/window.py:327: Warning: g_object_remove_toggle_ref: assertion 'G_IS_OBJECT (object)' failed self.corral_window = None 2019-09-05 13:19:21,559 processed structured info request from unix-domain socket:/run/user/1000/xpra/localhost.localdomain-2 in 8ms 2019-09-05 13:19:22,041 New unix-domain connection received on /run/user/1000/xpra/localhost.localdomain-2 2019-09-05 13:19:23,042 New unix-domain connection received on /run/xpra/localhost.localdomain-2 2019-09-05 13:19:23,042 New unix-domain connection received on /run/user/1000/xpra/localhost.localdomain-2 (Xpra:21966): Gdk-WARNING **: 13:19:31.031: GdkWindow 0x400bda unexpectedly destroyed (Xpra:21966): Gdk-WARNING **: 13:19:39.869: GdkWindow 0x400c5b unexpectedly destroyed 2019-09-05 13:19:43,062 Error: connection timed out: unix-domain socket:/run/user/1000/xpra/localhost.localdomain-2 2019-09-05 13:19:43,462 New unix-domain connection received on /run/user/1000/xpra/localhost.localdomain-2
This seems to happen when we reach around 2200 to 2500 windows.
r23718 allows us to see how busy the UI thread is, logging the time it takes to service a timer call with a zero delay. Normally, that's around 0.10ms on my system. When running this stress test, it creeps up and by the time the server stops responding, the delay is around 35ms. Roughly 350 times higher.. Meanwhile the info requests are still being processed around 7ms. That's until the server no longer processes socket connection attempts.
The one thing that always seems to happen before the server goes AWOL is this:
(Xpra:31569): Gdk-WARNING **: 16:07:11.444: GdkWindow 0x400bf7 unexpectedly destroyed
The GTK3 code looks like this:
if (!GDK_WINDOW_DESTROYED (window)) { if (GDK_WINDOW_TYPE(window) != GDK_WINDOW_FOREIGN) g_warning ("GdkWindow %#lx unexpectedly destroyed", GDK_WINDOW_XID (window)); _gdk_window_destroy (window, TRUE); }
The window that is triggering this warning is not a foreign window, so it must be our corral window?
Traceback (most recent call last): File "/usr/lib64/python3.7/site-packages/xpra/client/gl/gl_window_backing_base.py", line 368, in redraw with self.gl_context(): AttributeError: __enter__ Traceback (most recent call last): File "/usr/lib64/python3.7/site-packages/xpra/client/gl/gl_window_backing_base.py", line 368, in redraw with self.gl_context(): AttributeError: __enter__ Traceback (most recent call last): File "/usr/lib64/python3.7/site-packages/xpra/client/gl/gl_window_backing_base.py", line 368, in redraw with self.gl_context(): AttributeError: __enter__ Traceback (most recent call last): File "/usr/lib64/python3.7/site-packages/xpra/client/gl/gl_window_backing_base.py", line 368, in redraw with self.gl_context(): AttributeError: __enter__
This should be fixed by r23712 and this is probably unrelated as the server problems occur even without having a client connected.
This does not cause any problems with python2 / GTK3, where the UI thread service time remains constant and usually lower than 0.10ms. Something might be leaking in GTK3.
xpra info shows us that the server has locked up, but it isn't required to trigger it.
The good news is that if the gtkperf loop is stopped quickly enough, the server does recover and can service new clients, including xpra info.
I don't know how to debug this further. It really looks like a regression in GTK, so I'm closing this as 'upstream'.
Applications that have a behaviour similar to gtkperf should be considered pathological and are not going to be supported with the GTK3 server.
this ticket has been moved to: https://github.com/Xpra-org/xpra/issues/2211