I bisected the issue to: f993091e7db81b0420e23c485378cba112278839 is the first bad commit commit f993091e7db81b0420e23c485378cba112278839 Author: Keith Packard <kei...@keithp.com> Date: Thu May 26 10:40:44 2016 -0700
os: Switch server to poll(2) [v3]
Eliminates all of the fd_set mangling in the server main thread
v2: Listen for POLLOUT while writes are blocked.
v3: Only mark client not ready on EAGAIN return from read
Signed-off-by: Keith Packard <kei...@keithp.com>
Reviewed-by: Adam Jackson <a...@redhat.com>
---
I'll see if I can dig into it a bit later, but my time is a bit thin. If
anyone else has a hunch as to what might be going on to narrow my search, I'd
appreciate it. If not, I'll probably start by taking a closer look at this
particular change to understand what's going wrong.
Thanks,
Jeremy
> On Sep 11, 2016, at 16:54, Jeremy Huddleston Sequoia <jerem...@apple.com>
> wrote:
>
> Upon a bit more digging, it looks like the clients are listed in
> output_pending_clients, but it's not getting delivered.
>
> This situation reveals another issue with a use-after-free during
> CloseDownClient() in which a client will get re-added to the
> output_pending_clients during FlushClient() as part of CloseDownConnection().
>
> See https://bugs.freedesktop.org/show_bug.cgi?id=97770 for more details on
> that.
>
>> On Sep 11, 2016, at 12:24, Jeremy Huddleston Sequoia <jerem...@apple.com>
>> wrote:
>>
>> Using current master plus the various patches I submitted to the list last
>> night, I'm able to launch the server fairly reliably under ASan again, but
>> some clients are getting wedged. Most notably, xterm gets stuck waiting for
>> a reply from XLoadQueryFont(). Looking at the state of the server threads,
>> it looks fine. It's processing other requests just fine from other clients.
>>
>> Has anyone noticed anything odd like this or have some hunch as to where I
>> might start looking other than to do yet another bisect? =/
>>
>> Thread 0x344e96 DispatchQueue 1 1000 samples (1-1000)
>> priority 31 (base 31)
>> 1000 start + 52 (xterm + 6312) [0x10d3bf8a8]
>> 1000 main + 3752 (xterm + 146228) [0x10d3e1b34]
>> 1000 spawnXTerm + 977 (xterm + 148776) [0x10d3e2528]
>> 1000 VTInit + 22 (xterm + 68248) [0x10d3cea98]
>> 1000 XtRealizeWidget + 135 (libXt.6.dylib + 84572) [0x10d4ffa5c]
>> 1000 RealizeWidget + 871 (libXt.6.dylib + 85805) [0x10d4fff2d]
>> 1000 RealizeWidget + 365 (libXt.6.dylib + 85299) [0x10d4ffd33]
>> 1000 VTRealize + 324 (xterm + 82404) [0x10d3d21e4]
>> 1000 SetVTFont + 335 (xterm + 121728) [0x10d3dbb80]
>> 1000 xtermLoadFont + 514 (xterm + 114081) [0x10d3d9da1]
>> 1000 xtermOpenFont + 86 (xterm + 112342) [0x10d3d96d6]
>> 1000 XLoadQueryFont + 311 (libX11.6.dylib + 29419)
>> [0x10d54f2eb]
>> 1000 _XQueryFont + 163 (libX11.6.dylib + 32127)
>> [0x10d54fd7f]
>> 1000 _XReply + 279 (libX11.6.dylib + 143484)
>> [0x10d56b07c]
>> 1000 xcb_wait_for_reply + 103 (libxcb.1.dylib +
>> 8247) [0x10d711037]
>> 1000 wait_for_reply + 251 (libxcb.1.dylib +
>> 8521) [0x10d711149]
>> 1000 _xcb_conn_wait + 466 (libxcb.1.dylib +
>> 4166) [0x10d710046]
>> 1000 _xcb_in_read + 1051 (libxcb.1.dylib
>> + 12750) [0x10d7121ce]
>> 1000 __select + 10
>> (libsystem_kernel.dylib + 106318) [0x7fffc5e2df4e]
>> *1000 _sleep_continue + 0
>> (kernel.development + 7459248) [0xffffff800091d1b0]
>>
>>
>
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