[RFC] Making tracing/debugging of client requests easier

[Alan Coopersmith]

Rami Ylimäki wrote:
> 3. Collecting client information in X server
> 
> Whenever a client connects to X server, its PID and process name (for
> local clients) would be determined by the functions described in
> previous section and stored in a private data structure. This would
> make it easy to quickly determine a sensible name for any connected
> client for debugging purposes. Also having a map from client XIDs to
> PIDs would make implementation of the new XRES query described in
> first section fast.

The Xorg shipped in Solaris/OpenSolaris already does this as part of
the SolarisIA extension, which gives a kernel scheduler priority boost
to the client that has window manager focus.   It's on the list of things
I know I should work on getting upstream someday, but have never gotten
to, but you can see the fairly simple code on the opensolaris site at:

http://src.opensolaris.org/source/xref/x-cons/xnv-clone/open-src/xserver/xorg/sun-src/IA/interactive.c

It keeps track of multiple PIDs per client, so that your terminal can
register the shell its running to also be boosted, or other related
processes.

Certainly if we're going to have multiple things doing this, a generic
framework makes sense.

> Some existing clients using XRES are iterating window hierarchy and
> searching for _NET_WM_PID, but that approach is too slow and
> unreliable for finding out client PIDs. At least the xres and cnee
> clients would be able take advantage of this new request and make it
> easier to identify local clients. 

I've wondered before if it would be sensible to have either Xlib or the
server set the _NET_WM_PID automatically for new clients.   Clients could
always override it later (and any client that already has code to set it
would effectively do so, since their setting would come after the initial
connection setup).  That doesn't solve the problem of having to walk the
window tree to find it though.

-- 
	-Alan Coopersmith-        alan.coopersmith at oracle.com
	 Oracle Solaris Platform Engineering: X Window System