Re: Threading Model 1:1 and Java
xu_feng_xu@yahoo.com writes:
It seems that the Java Virtual Machine uses the 1:1 threading mapping
model. According to the theory of this model, all the threads
management and synchronisation are done in the kernel. In particular,
the switching between threads requires kernel intervention and system
calls, which really surprises me considering the speed and
instantaneous execution of some multithreaded applications that i am
running.
Why do you believe that kernel context switch are slower than
userland context switches (where, if preemptive, the kernel
has to be involved in delivering some form of signal anyway and
all potential gain of userland switching is instanteneously lost)
Is Java based application threads switching done in the kernel and
through system calls?
Depends on the JVM implementation and the OS'es threading
model. E.g., on Solaris there were at least three observable
models over time:
- Java's original greenthreads (userland)
- Java on Solaris native threads (N:M model)
- Java on new Solaris native threads (1:1 model)
Where can i set in JVM another threading model (many to many, one to
one)?
Not.
Casper
--
Expressed in this posting are my opinions. They are in no way related
to opinions held by my employer, Sun Microsystems.
Statements on Sun products included here are not gospel and may
be fiction rather than truth.