Hello All, first of all I'd like to emphasize that suspend/resume_all functions are potentially unsafe and should be used with care.
secondly, those methods were designed mainly to support stop_the_world_enumeration and thus usually being used under certain conditions.
1) I found that hythread_suspend_all calls thread_safe_point_impl inside. There is no assertion regarding thread's state upon entering hythread_suspend_all. So it can be called in suspend disabled state and nobody (at least me) expects to have a safe point during hythread_suspend_all. The problem seems to be very similar with the one discussed in "[drlvm][threading] Possible race condition in implementation of conditional variables?" Your thoughts?
The code of suspend_all method is dedicated to the cyclic suspension problem. The fact that this method is being called from suspend_disable region and have safe_point in within is all about cyclic suspension. A lot of time was spent to resolve deadlocks cause by two threads trying to suspend each other. I agree that problem is similar to one with conditions, but I believe that this one should be discussed as a part of particular scenario.
2) Assume I need to suspend all threads in particular group. Ok I pass that group to hythread_suspend_all. Later when all suspended threads should be resumed I pass the same group to hythread_resume_all. But threads were suspended group has changed. For example one new thread was added to it. So the questions are. Is it acceptable to have such "unsafe" functionality? Would it better to lock the group in hythread_suspend_all and unlock it in hythread_resume_all.
First of all I would differentiate j.l.ThreadGroup and thread groups defined by thread manager(saying that I mean that this method was not designed for ordinary use, like ThreadGroup.suspend()), and after that return to the question why we would need it (I mean, it would be better to have particular scenario) and then we can discuss how to implement this. Till now suspend_all method was designed to work within one group(in particular default group, containing java threads), and called be GC. Thank you. Nik.
Thanks Evgueni --------------------------------------------------------------------- Terms of use : http://incubator.apache.org/harmony/mailing.html To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
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