[Wrapper-user] wrapper and jvm in the same process

[Glen <gle...@mo...>]

What features would be lost if wrapper.exe ran the jvm in the same 
process (via JNI)?  From looking at the code the wrapper starts the JVM 
(in a separate process) then connects to it over a socket to make sure 
it is still "living and breathing".  The JVM churns away at it's task 
and the wrapper has the wrappereventloop.c stuff run every tenth of a 
second.  If running in the same process the wrapper event loop could run 
in a separate (non-java) thread.  My question is if the JVM crashes (IBM 
jvm's lock up,SUN's jvm crashes hard) would they kill the wrapper event 
loop thread?  Fairly sure on the IBM jvm it wouldn't.  Need to see what 
would happen on the SUN jvm.

To save everyone from the obvious I totally agree having wrapper and run 
in separate processes is the most reliable and for mission critical 
stuff I will always do that.  There are use cases for the same process.  
My need is I have several servers that can have up to 30 wrappers 
running ( = 60 processes).  3 of which are mission critical the rest are 
"background" batch tasks that can be easily restarted and pick up where 
they left off (which is exactly what we do under load).

Some more thoughts on this.  I think crash detection is likely not to 
work reliably.  I can think of page faults as an example where the whole 
process would get killed.  Conversely many features would work fine 
restarts from within jvm app, ctrl-c and ctrl-break trapping, anchor 
file restarts, cross platform scripting, jvm deadlock.

Anyways looking forward to hearing people's thoughts...