Mark Lam's Blog

Mark Lam was previously a virtual machine engineer in the JavaME CDC team at Sun Microsystems for 8 years. Before joining Sun, he was a real-time embedded systems developer for 6+ years, working on application frameworks, graphics systems, networking protocols, game development, and fault tolerant systems amongst other things, on devices ranging from 64KB 8bit uControllers to 32-bit RISC machines. Currently, Mark is pursuing other interests in embedded development.

CVM Object Allocation

In a previous comment, Jamsheed asked, ...

"In CDC we have garbage collection invocation for fast lock contention case (From my understanding this is done for rolling the object allocation unsafe thread to gcsafe). My question is why should we invoke a gc call for reaching safe point while this can be achieved by simply making try heap lock a blocking lock in gc safe window(with slight modification to gc safe window). Or by polling try heaplock with safe point after every iteration."

Jamsheed, I presume that you are referring to the piece of allocation code that requests that all threads to reach a GC safe state. You're probably thinking that this is a rather slow operation, and that there are cheaper alternatives. So, why do this?

Here's why ...

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Not at Sun anymore

Tonight, I noticed that there were a few inquiries posted (back in May) as comments on some of my old entries. I apologize for not bring able to respond since I didn't know about them until now. Well, I left Sun back in April '08, and for some reason, the blog email notification wasn't redirected to my new email.

Anyway, for what it's worth, Jamsheed and hkpottyn, when I get a chance in the next few days, I'll try to give you an answer to the extent that I can. I don't work on CVM anymore, but I'd be happy to share my knowledge as before ... again, to the extent that I can, of course. Since, I don't work on CVM anymore, my knowledge may soon be obsoleted.

Regards,
Mark

August 2008

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CVM Object Allocation

Not at Sun anymore

JVMTI in Multi-tasking VMs (MVM)

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