[Opensim-users] I want to switch default XEngine ScriptStopStrategy to co-op from abort soon

[Justin Clark-Casey]

Hi folks.  The current method of terminating script threads that do not exit an event in a timely manner is to abort 
their threads in the VM.

However, in some cases this can leave the VM unstable, with symptoms such as simulator crash with native stack trace or 
a leap up to 100% CPU use for no apparent reason.  I experienced these problems myself.

In response, almost a year and a half ago [1], I implemented an alternative method of script stop ("co-op") that relies 
on checks inserted at script compile time.  No changes at the LSL level are required.  With this method, the compiled 
script will always realize that it needs to stop and so no aborts are needed.

I have used co-op extensively over the last year and a half as have others (e.g. it's used on at least some OSGrid 
Plazas) without incident and with apparent increased stability.

It hasn't been default before now because changing to co-op required the user to manually clear their compiled DLL cache 
or set DeleteScriptsOnStartup = true for one simulator session.  This seems trivial but I felt it would be too 
disruptive to people who upgrade at release time.

However, as of git master d7b92604 (11th July 2014), I've implemented a mechanism that will automatically recompile the 
scripts as necessary and use the new ones on the next simulator restart.  Switching the ScriptStopStrategy should now 
require no further user intervention.

I've written the details of this up at [2].  Note that switching the stop strategy does not have any impact on saved 
script variables or other state - scripts will behave as they did before.

Hence, I now want to switch the default script stop strategy to co-op.  If anybody does want to continue using "abort" 
for any reason, then this can be done by setting ScriptStopStrategy = abort in the [XEngine] section of OpenSim.ini.

Please let me know if there are any questions or concerns about this.

[1] http://opensimulator.org/pipermail/opensim-dev/2013-January/023985.html
[2] http://opensimulator.org/wiki/XEngine#ScriptStopStrategy

-- 
Justin Clark-Casey (justincc)
OSVW Consulting
http://justincc.org
http://twitter.com/justincc