We have created an mdb module and some simple shell script wrappers
that can be used to retrieve various information from a running X server
or a X server core dump.
Currently available information includes:
- a list of the clients connected to an X server, including for each one:
- the sequence number of the last request it sent
- in the case of most local clients, their process id
- a list of the input devices connected to an X server and if any
active grabs are applied to them, which client has done so.
- if a server grab has been done, the id of the client that has the grab.
Scripts
-------
The simple shell script wrappers are all delivered in /usr/demo/Xserver/mdb
All of these scripts can be run on either a running process or a core file.
To use these scripts on a running Xserver, specify the process id with the
-p flag, such as "list_Xserver_clients -p 32999". To use on a core file,
simply provide the core file as an argument. (The command line arguments
are passed through to mdb, see the mdb(1) man page for more details.)
To use on a running Xorg server, you will need to run as root, due to the
restrictions
- list_Xserver_clients
This can be useful for trying to figure out which client is
responsible for the reads and writes you see to a certain file
descriptor in a truss and similar debugging activities. The sequence
number will basically be a count of the number of requests an X client
has sent during its lifetime.
You will get output like this:
max_clients = 1024
CLIENT SEQUENCE # FD PIDS
0 0 -1 9719
1 8 15 ??? - NULL OsCommPtr->process
2 9 16 9721
4 8 18 ??? - NULL OsCommPtr->process
5 17 ??? - NULL ClientPtr->osPrivate
6 14 19 9763
7 71 20 9814
8 13 21 9819
9 17 22 9836
10 501747 23 9837
11 147 24 9837
12 11 25 9837
13 9676 26 9843
14 38347 27 9843
15 11 28 9843
16 13251 29 9846 9857 9861 9871
18 5299 31 9847 9891 9894 9900 9904 9922
19 2397 32 9879
21 11 34 9879
23 34389507 36 9885
1342 /usr/dt/bin/dtlogin -daemon
9719 /usr/X11/bin/Xorg :0 -depth 24 -nobanner -auth /var/dt/A:0-epayvc
9721 /usr/openwin/bin/fbconsole -d :0
9720 /usr/dt/bin/dtlogin -daemon
9741 /bin/ksh /usr/dt/bin/Xsession
9819 /usr/dt/bin/sdt_shell -c unsetenv _ PWD; unsetenv DT;
9821 -csh -c unsetenv _ PWD; unsetenv DT; setenv DISP
9837 /usr/dt/bin/dtsession
9843 dtwm
9846 /usr/dt/bin/dtterm -session dtb2aitb -C -ls
9857 -csh
9861 -csh
9871 -csh
9847 /usr/dt/bin/dtterm -session dtP2aqtb -C -ls
9891 -csh
9894 -csh
9900 -csh
9904 -csh
9922 -csh
9879 dtfile -session dtqRaOFb
9949 dtfile -session dtqRaOFb
9885 sdtperfmeter -f -H -t cpu -t disk -s 1 -name fpperfmeter
9836 /usr/dt/bin/ttsession
The output at the end comes from ptree. From this example we can see
the busiest client in this CDE session has been sdtperfmeter since it
has sent 34389507 X requests in order to update the performance meter
once a second. (This session was running for 6 days before this output
was taken.)
- list_Xserver_devicegrab_client
This lists all the input devices known to the Xserver and if they have
been grabbed by any clients, which client holds an active grab.
For instance, on a machine where the xterm "Secure Keyboard" menu item
was chosen to grab the keyboard:
# list_Xserver_devicegrab_client -p 6072
Device "Virtual core pointer" id 2:
-- no active grab on device
Device "Virtual core keyboard" id 3:
-- active grab 5e00000 by client 47
Device "Virtual core XTEST pointer" id 4:
-- no active grab on device
Device "Virtual core XTEST keyboard" id 5:
-- no active grab on device
Device "mouse" id 6:
-- no active grab on device
Device "hotkey" id 7:
-- no active grab on device
Device "keyboard" id 8:
-- no active grab on device
You can then use list_Xserver_clients to find out what client 47 is:
CLIENT SEQUENCE # FD PIDS
[...]
47 3378 78 8936
[...]
8936 xterm
- list_Xserver_servergrab_client
This script checks a variable in the X server to determine if a server
grab has been done, and if so which client has done it.
Debugging with mdb
------------------
The mdb module can also be used directly in an mdb debugging session
on either a live server or a core file. The module is delivered in
/usr/lib/mdb/proc as Xorg.so, Xvfb.so, Xephyr.so and Xvnc.so so that
it should be automatically loaded when mdb attaches to a process or
core of any of those programs.
Two sets of dcmds are provided, each with a "walker" which simply
iterates over the entries in the X server internal tables, and a
command that prints the information for each entry.
The commands currently provided are:
::client_pids - prints information about a ClientRec entry
in the X server's array of currently connected X clients.
Switches:
-w Print arguments with process name when available.
::inputdev_grabs - prints information about a DeviceIntRec entry
in the X server's list of currently connected input devices.
The walkers to iterate over the lists of these structures in the X server are:
::client_walk - walks the array of ClientRec entries stored in the
global array "clients", from 0 to the value of the global
variable "currentMaxClients"
::inputdev_walk - walks the linked list of DeviceIntRec entries
starting at the entry stored in the global variable "InputInfo"
You can run them like this:
# mdb -p 9719
Loading modules: [ Xorg ld.so.1 libc.so.1 libproc.so.1 libnvpair.so.1 libuutil.so.1 libavl.so.1 libsysevent.so.1 ]
> ::walk client_walk
max_clients = 1024
1b7db8
1b7dbc
1b7dc0
[...]
> 1b7dc0 ::client_pids
CLIENT SEQUENCE # FD PROCESS
2 20 21 1285 /usr/bin/dbus-launch
If you run one of the commands (such as ::client_pids) without an address in
front, it will automatically call the associated walker to list the
information for all the entries in the list.
For more information about using mdb, see the Solaris Modular Debugger Guide
on http://docs.oracle.com and the mdb OpenSolaris Community website at
http://hub.opensolaris.org/bin/view/Community+Group+mdb/
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